US3060116A

US3060116A - Combination reforming and cracking process

Info

Publication number: US3060116A
Application number: US851939A
Authority: US
Inventors: Jr Edward P Hardin; Richard P Medlin
Original assignee: Socony Mobil Oil Co Inc
Current assignee: ExxonMobil Oil Corp
Priority date: 1959-11-06
Filing date: 1959-11-06
Publication date: 1962-10-23
Anticipated expiration: 1979-10-23

Description

Oct. 23, 1962 ETAL 3,060,116

COMBINATION REFORMING AND CRACKING PROCESS E. P. HA RDlN, JR.,

2 Sheets-Sheet 1 Filed NOV. 5, 1959 errno ...U

Oct. 23, 1962 E. P. HARDIN, JR., ETAL 3,060,116

COMBINATION REFORMNG AND CRACKING PROCESS 2 Sheets-Sheet 2 Filed Nov. 6, 1959 United States Patent O 3,060,116 ClVfNATION REFGRMING AND CRACKING PROCESS Edward P. Hardin, Jr., and Richard I. Medlin, Beaumont, Tex., assignors to Socony Mobil Oil Company,

Inc., a corporation of New York Filed Nov. 6, 1959, Ser. No. 851,939 22 Claims. (Cl. 20S-79) This application is a continuation-in-part of our application Serial Number 760,647, iiled in the United States Patent Office on September l2, 1958, now abandoned.

This invention relates to combination processing of stocks or fractions containing mixed hydrocarbons such as petroleum stocks to provide gaseous, unsaturated hydrocarbon products, particularly ethylene, Vand high antiknock gasoline products. Further, this invention relates to an improved combination process for converting gasoline fractions to liquid gasoline products of increased average anti-knock rating and of decreased content of 10W octane constituents contributing to gasoline volatility. The invention involves an improved combination of a number of processing operations, including reforming of gasoline fractions and cracking of selected aliphatic hydrocarbons or hydrocarbon mixtures to provide principally gaseous products rich in olens.

lt is known in the art that light aliphatic hydrocarbons may be converted by cracking to products rich in unsaturated, gaseous hydrocarbons, including ethylene, propylene and butadiene. Some commercial processes have been built for manufacture of ethylene and other gaseous oletins in this way and for recovery of the same as essentially pure petrochemical products or raw materials. These plants involve use of very high temperatures for cracking and complicated product recovery systems requiring extensive refrigeration. The investment and operating costs of ethylene manufacturing plants are, consequently, very high; so high, in fact, as to tend to discourage investment of capital in this type of plant.

In the past, it has been customary to employ C2 to C4 hydrocarbons as charge stocks to such cracking processes. Fractions yfrom petroleum crudes made up of C5 to C7 hydrocarbons or portions thereof have been employed either as such as gasoline constituents or as base material which is converted to upgrade gasoline constituents.

Processes for reforming gasoline fractions for the purpose of improving the anti-knock rating thereof are well known in the art. Such processes include thermal reforming of gasoline fractions at temperatures of the order of 900 to l,l F, and usually at superatmospheric pressures of the order of 200 to 1,000 pounds per square inch gauge. More recently, it has been the practice to reform gasoline `fractions over catalysts having a dehydrcgenation or aromatization activity. Such processes normally operate at S50 to 1,l00 F., and the conversion is usually conducted in the presence of hydrogen under pressure. In catalytic reforming processes, usually the principal reaction is dehydrogenation of naphthene hydrocarbons to form aromatics. However, isomerization, dehydrocyclization of paraflins to aromatics, dehydrogenation of parafiins to form olefins and cracking reactions may also occur to a greater or lesser extent, depending upon the catalyst and operating conditions involved.

lt has been the practice in some commercial reforming operations to remove C5 and C5 hydrocarbons from the reformer feed and blend them back in the final gasoline Patented Oct. 23, 1962 ice product. ln other commercial reforming operations, C5 and C5 hydrocarbons and sometimes C4 hydrocarbons have been included in the reformer feed stock. While, to a very substantial extent, the aliphatic C4 to C5 hydrocarbons tended to ride through the reforming operation unconverted, they and some isomers which were formed were considered as relatively desirable gasoline constituents. However, in recent years, the gasoline anti-knock ratings required to satisfy automobile and aviation engines have been gradually increasing, and this has required increasing reforming severities. Reforming severity has been gradually increased to a point where considerable portions of the aliphatic C4 to C5 hydrocarbons, if included in the reformer feed, would be lost due to concurrent hydrocracking resulting in conversion of these components to gas. 'Ihe unconverted C5 to C5 straight chain hydrocarbons carrying over into the reformate still would tend to drag down its overall anti-knock rating. The C7 hydrocarbons also involved the same problems, although to a somewhat lesser extent. Moreover, the presence of C5 to C7 aliphatic hydrocarbons tends to decrease the amount of higher octane C4 hydrocarbons which can be incorporated in the gasoline within volatility specification limits. The latter objections apply also to operations in which the C5 to C7 hydrocarbons are bypassed around the reformer and added to the final gasoline blend. It has been proposed, in the art, to remove C5, C5 or C7 hydrocarbons or all of them from the reformer feed' and to subject the same to upgrading by such operations as catalytic dehydrogenation, isomerization, cracking and other reactions to convert them, insofar as possible, to upgraded gasoline components which are employed in iinished gasoline blends. These proposals fail to provide any substantial improvement by Way of decreasing overall low octane volatility of total gasoline manufactured and do not achieve either upgrading or elimination of the straight chain C5 to C7 content of the reformate gasoline. Moreover, the antiknock improvements which are derived by operations of this type often do not justify the cost involved. Also, these proposed processes are neither concerned with nor adapted for manufacture of substantial quantities of petrochemical raw materials such as ethylene, acetylenes and butadiene in conjunction with the gasoline upgrading operation.

lt is an object of this invention to provide an integrated process combination for conversion of gasoline boiling range hydrocarbons to liquid gasoline products of increased average anti-knock value and decreased low octane volatility and to gaseous, unsaturated petrochemical products.

Another object is the provision, in a refining operation wherein a hydrocarbon gasoline yfeed is subjected to a reforming operation to improve the anti-knock value thereof, of an improved process for increasing the overall anti-knock rating and decreasing the overall volatility of the total normally liquid gasoline produced.

Another object is the provision, in an overall refining operation wherein fractions of mixed hydrocarbons from sources such as petroleum crude are converted by catalytic reforming and other refining process steps to a plurality of products, including a plurality of refinery pool gasoline fractions, each of which is ultimately utilized as a component in at least one final gasoline products, o-f an improved method for processing to more valuable products low octane C5 to C7 hydrocarbons which would otherwise be included in the pool gasoline, while,

at the same time, enhancing the overall quality of the total pool gasoline fractions without excessive loss 1n amount.

Another object is the provision of a process for upgrading C and heavier gasoline boiling range hydrocarbons to more valuable products, including a high antiknock gasoline of good motor fuel volatility characteristics, in which unusually large amounts of C4 hydrocarbons or other suitable high anti-knock, combustible pressuring compounds are incorporated.

A specific object is the provision of a combination process for manufacturing from petroleum gasoline fractions ethylene, butadiene and other unsaturated or aromatic products and a high anti-knock gasoline having excellent volatility characteristics for use as a motor fuel.

These and other objects of the invention will become more apparent from the following detailed discussion thereof.

In one preferred form, this invention involves .a process wherein a mixed hydrocarbon or petroleum feed stock boiling within the gasoline boiling range is subjected to fractionation to remove C4 and lighter hydrocarbons, an isopentane out and a C5 to C6 aliphatic hydrocarbon cut containing at least most of the normal pentane and saturated aliphatic heXanes from the feed stock and to provide a higher boiling gasoline fraction for use as a reforming feed. The reforming feed is subjected to suitable reforming conditions, preferably in the presence of a dehydrogenation or aromatization catalyst, to effect conversion to a reformed product containing gasoline of increased anti-knock rating. The reformed product is subjected to fractionation to effect removal therefrom of C4 and lighter hydrocarbons, an isopentane cut and a C5 to C5 aliphatic hydrocarbon cut containing at least most of the normal pentane and saturated aliphatic hexanes from the reformed product and to provide a higher boiling reformate gasoline. The C5 to C6 aliphatic hydrocarbon out recovered from the original feed stock and the reforming products is subjected to cracking at elevated temperatures and under conditions controlled to effect conversion to a product rich in unsaturated gaseous hydrocarbons. The product may also contain appreciable amounts of aromatic hydrocarbons. The cracked product is subjected to a separation operation to recover therefrom ethylene as a product and an olefin-rich fraction containing principally hydrocarbons in the C3 to C4 hydrocarbon range (i.e., unsaturated C3 hydrocarbons or unsaturated C4 hydrocarbons or .a mixture of both). The olefin-rich fraction is alkylated with isoparainic material, such as isobutane, or with other alkylatable hydrocarbons boiling in the gasoline range, under conditions suitable for conversion to an alkylate rich in branched chain aliphatic or aromatic hydrocarbons. An alkylate gasoline of high anti-knock value is separated from said alkylate. At least a substantial portion of said alkylate is blended together v vith at least a substantial portion of the reformate gasoline and preferably but not necessarily also with at least a substantial portion of the isopentane recovered from the original feed stock and from said reformed product. Sufhcient C4 hydrocarbons, preferably normal butane or isobutane, if available, are added to the blend to provide a Reid Vapor Pressure within the range of about 6 to 16 pounds per square inch gauge.

In some cases, gasoline resulting from thermal or catalytic cracking of petroleum fractions boiling above the gasoline reformer feed may lbe added either to the reformer feed or to the linal gasoline blend, depending upon required octane rating of the blended gasoline products. Also, additional products may be recovered from the product resulting from cracking the C5 to C6 aliphatic hydrocarbons, such as butadiene and other diolens, propane, propylene, acetylenes, fuel gas, aromatic gasoline and higher boiling aromatic distillate. The aromatic gasoline may be added to the nal gasoline blend. In one form of the invention, C7 and heavier aliphatic hydrocarbons, preferably straight chain hydrocarbons boiling within the gasoline range, may be separated from the reformer feed stock or product or both and subjected to cracking along with the C5 to C5 aliphatic hydrocarbons.

In one of its broader aspects, this invention involves a combination process for manufacturing from a low octane gasoline feed stock a high anti-knock engine fuel and ethylene. In accordance with this process, at least most of the gasoline feed stock is subjected to reforming to provide a reformed product containing gasoline of improved anti-knock rating. At least most of at least one of the aliphatic hydrocarbon materials within the range of C5 to C7 hydrocarbons contained in either or both of the gasoline feed stock and reformed product is separated by distillation or other means and subjected to pyrolytic cracking at temperatures Within the range of about 1,300 to l,750 F. The separated .aliphatic material may be cracked alone or along With other hydrocarbon material from other sources. The cracking conditions are controlied so that the separated aliphatic material is converted to a cracked product made up principally of hydrocarbons having less than five carbon atoms per molecule and containing substantial amounts of gaseous olens, including ethylene. Ethylene and, if desired, other olens such as butadiene and acetylenes are separated from the cracked products as essentially pure petrochemical products. A gaseous feed stock rich in either or both of C3 and C4 oleiins is also separated from the cracked product and subjected to a combining reaction in which the constituents of said gaseous feed stock constitute at least a substantial portion of the reactants to form a gasoline product having a lower average volatility and higher antiknock rating than said separated aliphatic hydrocarbon material.

In another broad aspect, this invention provides certain improvements in an overall refining operation wherein fractions of mixed hydrocarbons of differing boiling points are subjected to a plurality of refining process steps to prepare a plurality of products, including a plurality of refinery pool gasoline fractions, each of which is ultimately utilized as a component in at least one final gasoline product and wherein one of said refining process steps involves reforming of a gasoline feed of relatively 10W anti-knock rating to form a reformed product of improved anti-knock rating. ln accordance with this aspect of the invention, at least most of at least one of the aliphatic hydrocarbon materials selected from the group consisting of straight chain C5 hydrocarbons, straight chain C6 hydrocarbons, branched chain C5 hydrocarbons, straight chain C7 hydrocarbons and branched chain C7 hydrocarbons, contained in the crude fraction containing reformer gasoline at elevated temperatures to form a gaseous product rich At least a substantial portion of the resulting gaseous oleiins, for example, the C3 and C4 olet'ins, is subjected to a combining operation to form a gasoline product of lower average volatility and higher anti-knock rating than the separated aliphatic hydrocarbon material. The combining reaction may comprise alkylation of the gaseous olens with isobutane or benzene, for example. Alternatively, the combining reaction may comprise catalytic polymerization to form polygasoline or some other reaction, such as hydration, to form isopropyl and tertiary butyl alcohols. The high anti-knock gasoline resulting from the combining operation is utilized as one of the relinery pool gasoline fractions. At least one and usually two or more different grades of engine gasoline are prepared by blending together selected refinery pool gasoline fractions, which, to some extent, may have been separately stored. The reformate gasoline is one of the important components of at least one of these blended engine gasolines. The gasoline from the combining operation and usually aromatic gasoline also formed in the cracking reaction are also important components of at least one .of the blended engine gasolines. Preferably, substantial amounts of the reformate and alkylate are blended together in at least one of the final engine gasoline blends. Usually, although not always, a combustible, high antiknock pressuring compound, such as normal or isobutane, isopentane or C3 hydrocarbons, is added to the engine gasoline blends in sufficient amounts to pressure them to a suitable Reid Vapor Pressure Within the range of about 6 to 16 pounds per square inch gauge. lf desired7 an isopentane, fraction which has been bypassed around the reformer or isopentane from another source may also be added to one or more of the engine gasolines blended from the refinery gasoline pool fractions.

The fractionation of the original feed stock and the reformer products may be conducted separately. However, in the preferred form of this invention, the original feed stock and reformate product are separately fractionated to remove C3 and lighter hydrocarbons and to provide fractions boiling in the range of C4 hydrocarbons through about 160 to 200 F. ASTM end point or, alternatively, up to about 210 F. ASTM end point and heavier reformer feed and product gasolines, respectively. The C4 to 160 to 200 F. light gasoline fractions so obtained are fractionated toether to recover therefrom an isopentane fraction and a light cracking feed stock of aliphatic hydrocarbons boiling above isopentane but below C7 hydrocarbons and containing at least most of the normal pentane and saturated aliphatic hexanes from said light gasoline. In the case of the C4 to 210 F. fraction, the light cracking feed stock obtained upon separation boils above isopentane and below C3 hydrocarbons.

'The invention may be more fully understood from the following description read in connection with the accompanying drawings in which:

FIGURE l is a schematic iioW diagram of a preferred arrangement for carrying out the invention; and

FIGURE 2 is a schematic ow diagram showing in greater detail a preferred form of the system for cracking C5 to C3 aliphatic hydrocarbons and for recovery of valuable products therefrom.

lt is contemplated that the hydrocarbon feed stock for the process of this invention may, in some cases, be derived from sources other than petroleum, for example, mixed hydrocarbons recovered by roasting shale or by destructive hydrogenation of coal. Preferably, the feed stock is of petroleum origin, and the invention Will be described as applied to such stocks, although it is to be understood that the invention is not so limited.

Turning now to FIGURE l, a Wide boiling range petroleum crude stock containing `gasoline components suitable for reforming feed is subjected to fractionation in conventional topping, fractional distillation and tar separation equipment Well known to the art at to remove C3 and lighter hydrocarbons and to recover `a light gasoline fraction containing essentially all of the C4 to C5 or C4 to C6 or C4 to C7 aliphatic hydrocarbons from the crude and being essentially free of C3 and lighter hydrocarbons. Preferably, the light gasoline fraction contains essentially all of the C4 to C5 aliphatic hydrocarbons from the crude and is essentially free of C3 and lighter hydrocarbons, benzene and C7 and heavier or higher boiling hydrocarbons. In this case, the light gasoline fraction will have an ASTM 10% point Within the range of about 100 to 140 F. and an end point Within the range of about 160 to 200 F. lt will be understood that the terms essentially all and essentially free of, as employed in the above connection and hereinafter in describing and claiming the invention in connection with various specified cuts or fractions, are intended to mean that the fraction mentioned contains or is free of the specified hydrocarbon material within the usual limits of practical commercial fractional distillation equipment.

Also recovered from the crude are a higher boiling gasoline fraction essentially free of C4 to C6 aliphatic and lighter hydrocarbons in the preferred form of the invention or essentially free of C4 and lighter hydrocarbons and of the particular aliphatic hydrocarbon or hydrocarbons selected for cracking charge in the broader forms of the invention. ln addition, a Virgin gas oil fraction and a residuum fraction, including tar, are recovered from the crude. All or a portion of the residuum may be subjected at 1l to thermal viscosity cracking at elevated temperatures and pressures to produce some thermal gasoline and gas oil or fuel oil suitable as charge stock to a thermal or catalytic cracking operation. Thermal cracking is conducted at temperatures of the order of 800 to 1,100" F., usually under superatmospheric pressures, in equipment Well known to the art and requiring no further description here. The products from the thermal cracking unit lll are subjected to fractionation at 12 to provide gasoline, cycle stock or gas oil, fuel oil and tar fractions. If desired, a light gasoline fraction of boiling range and content similar to that separated from the crude, for example, a fraction containing C., to Cs hydrocarbons, and boiling up to about to 200 F. end point (as determined by ASTM distillation) may be recovered from the thermal cracking products, and this may be added with the fraction of similar boiling range obtained from the crude to the distillation system ll'7. Higher boiling thermal gasoline may be added in limited quantities to the final motor gasoline blend at 25, to be further discussed hereinafter. Preferably, the higher boiling thermal gasoline is subjected to reforming either separately or together With the straight run gasoline fraction of similar boiling range recovered from the crude.

The virgin gas oil obtained from the crude is subjected to catalytic cracking at temperatures of the order of 800 to 1,05 0 F. and pressures of the order of 5 to 100 pounds per square inch gauge over a suitable catalyst at 13 to effect conversion to catalytic gasoline, C3 and lighter hydrocarbons and cycle stock boiling in the fuel oil and heavy gas oil range. These products are recovered in suitable conventional fractional distillation equipment at 14. The cycle stock may be further cracked or further distilled to provide light and heavy domestic fuel oils. The catalytic gasoline may be employed as a separate motor fuel alone or together with the thermal gasoline from 12 or it may be added to the final motor gasoline blend at 25, to be described hereinafter. Since the C4, to 160 to 200 F. end point fraction of the catalytic gasoline is of a relatively high anti-knock value, itis preferred to employ this `fraction in final gasoline blends. However, this is not intended to preclude the possibility in some operations of adding this fraction or a fraction of similar boiling range and content to the light gasoline fraction recovered from the crude to the latter for the further processing described hereinafter. If desired, a cycle oil or gas oil obtained from the thermal cracking products may also be subjected to catalytic cracking at 13.

The higher boiling straight run gasoline fraction recovered from the crude stock usually contains less than about 10% by Weight of the highest boiling and lighter aliphatic hydrocarbon separated from the crude for inclusion in the cracking feed. Thus, when the light gasoline recovered from the crude is C4 to C6 aliphatic hydrocarbons, the higher boiling straight run gasoline fraction Will usually contain less than about 10% by weight of C6 or lighter aliphatic hydrocarbons. It is subjected in part or in whole to reforming for the purpose of improving its antiknock rating and other characteristics for use in motor or aviation fuels. For example, the reformer feed may consist of the entire fraction boiling above the 160 to 200 F. end point (ASTM) light gasoline fraction and having an end point within the range of about 300 to 410or F. (ASTM distillation). Alternatively, only a portion of this material may be reformed or different portions, i.e., light and heavy naphtha portions, may be separately reformed under different conditions. The reforming may be conducted at 15 in conventional equipment and under conventional processing conditions, lboth Well known to the art. In less preferred forms of the invention, the reformer feed gasoline fraction may be subjected to thermal reforming at temperatures of the order of 900 to l,150 F. and pressures of the order of 200 to 1,000 pounds per Square inch gauge to form a gasoline of increased antiknock value. Residence time at reforming temperature is in the range of about to 30 seconds. The thermal gasoline Will contain considerable amounts of unsaturated hydrocarbons as Well as aromatics and unconverted paranic hydrocarbons. It is preferred in this invention to subject the reformer feed gasoline to catalytic reforming over a suitable catalyst having a dehydrogenation or aromatization activity, particularly an activity for promoting aromatization of naphthenes to aromatics and desirably for aromatization of paraihnic hydrocarbons to aromatics through what has become known as a dehydrocyclization reaction. Examples of suitable catalysts are group VI metal Suldes or oxides such as molybdenum oxide, chromium oxide, tungsten or vanadium oxides or the like or mixtures of the same on suitable carriers such as activated alumina, bauxite, zinc aluminate or the like. A preferred reforming catalyst is comprised of about 0.3 to 1.5% by Weight platinum or palladium deposited on a carrier such as alumina or a mixture of silica and alumina. In some cases, the catalyst may contain small amounts of a halogen or a halogen compound. A number of these catalysts have been described in the literature, and their composition and method of manufacture are now Well known to the art. In general, the catalytic reforming operation may be conducted at temperatures of the order of 850 to 1,050 F. and preferably 875 to l,000 F., pressures of the order of 50 to 1,500 and preferably 100 to 700 pounds per square inch gauge, space velocities of the order of 0.5 to and preferably 0.5 to 3 volumes of oil feed (measured as a liquid at 60 F.) per hour per total volume of catalyst in the reforming reactor or reactors, and hydrogen to hydrocarbon mol ratios of the order of 2 to 20 and preferably 4 to 10. The reforming product is subjected to fractionation at 16 to remove hydrogen, C3 and lighter hydrocarbons and, in the preferred operation, a light reformate fraction made up of hydrocarbons 4boiling in the range of C4 hydrocarbons to about 160 to 200 F. end point (ASTM) and to provide a stabilized, higher lboiling reformate gasoline. The light reformate gasoline fraction, in the preferred form of the invention, is essentially free of C5 and lighter and C7 and heavier hydrocarbons and of benzene, While the higher boiling reformate gasoline is essentially -free of C5 and lighter aliphatic hydrocarbons. This fraction contains at least most of the normal pentane and saturated aliphatic hexanes from the reformate gasoline. Alternatively, the light reformate fraction recovered from the reforming product may contain C., to C5 or C4 to C7 aliphatic hydrocarbons. The ASTM end point of the reformed gasoline may be within the range of about 300 to 410 F. All or a substantial portion of this gasoline is added to the nal motor gasoline blend at 25. In some cases, a portion of the reformate may be employed in an aviation gasoline blend at 26.

The light gasolines containing the aliphatic hydrocarbons removed from sources above indicated, including the light reformate gasoline from 16, for example, the C4 to 160 to 200 F. end point gasoline fractions, are subjected to further fractionation at 17 to provide a normal butane fraction, a butylene-isobutane fraction containing some normal butane, an isopentane fraction and a light cracking feed cut. In the preferred form of the invention, the latter cut may be made up particularly of normal pentane and saturated aliphatic hexanes. In this case, the normal butane fraction may contain small amounts of C5 hydrocarbons and of lighter hydrocarbons, principally C3 hydrocarbons not entirely removed in previous fractionation steps. This fraction may be removed from the system as such or it may be added in Whole or in part to the final motor gasoline blend at 25. IIn some cases, the C4 fraction may be subjected to further suitable treatment to eliminate any C5 hydrocarbons before addition to the gasoline blend. The butylene-isobutane-butano fraction will, depending upon the effectiveness of the fractionation, contain relatively minor amounts of C3 and C5 hydrocarbons. This fraction may be Withdrawn from the process, but preferably it is employed as a portion of an alkylation feed stock as hereinafter discussed. In some operations, particularly where the amount of butylene and isobutane in the feed to the distillation system is small, these materials may be included in the recovered normal butane fraction and added to the nal gasoline blend.

When the light C4 to 160' to 200 F. end point gasoline is derived exclusively from crude plus catalytic reformate, the olefin content is low and the light cracking feed stock recovered at 17 is made up very largely (55 to 80% by Weight) of normal pentane and saturated aliphatic hexanes, although it does, in this case, contain relatively small amounts of other hydrocarbons, such as cycloparafins, aromatics and olefins, which Would remain due to practical eciency limitations of commercial fractional distillation equipment. When light thermal gasoline is also supplied to the distillation system at 17, the light cracking feed stock will contain certain amounts of oleiinic C5 to C5 hydrocarbons. As a general rule, in the preferred form of the invention, the light cracking feed stock will contain not in excess of 10% by weight isopentane and lower boiling hydrocarbons and not more than 10% by Weight C7 and higher boiling hydrocarbons. ln some operations, particularly when the isopentane content of the light gasoline supplied to the distillation system at 17 is insufficient to warrant additional cost to effect its separation, the isopentane may be included in the light cracking feed stock. In accordance With the preferred form of the invention, the light cracking feed stock contains at least most of the normal pentane and saturated aliphatic hexanes from the original crude or reformer feed stock and reformer product. In this case, the fraction has an ASTM end point in the range of about 160 to 200 F. On the other hand, when it is desired only to subject the straight chain C5 hydrocarbons to cracking, the fraction will have an ASTM e-nd point of about 100 F. or slightly higher. When it is desired to crack the normal pentane and alihpatic C5 and C7 hydrocarbons from the reformer feed stock and product, the fraction will have an ASTM end point of about 210 F. In this case, the cracking fed stock will contain about to 100% by weight normal C5 and saturated, aliphatic C5 and C7 hydrocarbons and not more than about 15% C5 and heavier hydrocarbons.

In accordance with the preferred form of this invention and in accordance with that broader phase of the invention involving the provision in a refining operation in which gasoline is subjected to reforming of a method for decreasing the overall low octane volatility as Well as increasing the anti-knock value of the total liquid gasoline produced, it is important to remove, for cracking, the selected low octane aliphatic hydrocarbons, both from the stock containing the reformer feed gasoline and from the reformed product. In the broader forms of the invention, the selected aliphatic hydrocarbon material should be at least most of at least one of the materials in the group: straight chain C5 hydrocarbons, particularly normal pentane; aliphatic C5 hydrocarbons, particularly saturated, straight chain C6 hydrocarbons; and aliphatic C7 hydrocarbons, particularly saturated, straight chain C7 hydrocarbons. When only the straight chain C5 hydrocarbons are cracked, it is preferred to also at least remove the straight chain C5 hydrocarbons from the reformer feed and product in order to achieve overall maximum anti-knock rating in the refinery pool gasolines. In this acse, the removed straight chain C6 hydrocarbons or the removed aliphatic C hydrocarbons may be upgraded by isomerization or sold separately as a jet fuel component.

On the other hand, in that broad aspect of this invention involving a combination process for improving a gasoline manufacturing operation with simultaneous manufacture of ethylene and other petrochemical products by pyrolytic cracking of selected aliphatic hydrocarbon fed stocks under speciahy controlled conditions, it is contemplated that the light cracking feed stock may be derived from either the stock containing the reformer feed gasoline or from the reformed product, or both. However, even in this aspect of the invention, it is preferable to obtain the cracking feed stock at least from the reformate and more preferably from both the reformate and the reformer feed source stock.

The aliphatic hydrocarbon material separated from the reformer feed source stock and from the reformed product may be subjected to cracking either alone or in admixture with other similar hydrocarbon materials derived, for example, from catalytic or thermal gas oil cracking operations, natural or casing-head gasolines. Also, the cracking feed stock may include higher boiling, straight chain hydrocarbons from the stock containing reformer feed gasoline or from the reformer product or both in addition to the aliphatic hydrocarbon material within the range of C5 to C7 hydrocarbons.

The light cracking feed stock is subjected to an initial cracking reaction at 1S at elevated temperatures, under conditions controlled to effect conversion to a cracked product rich in gaseous oleiins and also containing diolens, aromatics and some unconverted parainic hydrocarbons, as well as lower boiling parains. While the cracking of the light feed stock may be conducted in the presence of suitable cracking catalysts, for example, silicaalumina catalysts or mixtures of cracking and dehydrogenation catalysts, it is preferred to conduct the conversion thermally in the absence of catalysts. In general7 the thermal cracking is conducted at temperatures in the range of about 1,200 to 1,800 F. or higher and preferably 1,400 to l,600 F., furnace outlet pressures ranging broadly from slightly below to 2 atmospheres above atmospheric and preferably l5 to 25 pounds per square inch gauge, and residence periods at reaction temperature in the range of 0.1 to 3 and preferably 0.6 to 1.3 seconds. In general, the higher the reaction temperature employed, the lower the residence period required. It is preferred to add steam with the feed to the cracking reactor, the amount of steam added ranging broadly from 30 to 150% and preferably from 75 to 125% by weight of the hydrocarbon feed. The cracked products issuing from the pyrolytic cracking unitv are immediately quenched to a temperature below the decomposition ternperature of the products by injection of a suitable quench liquid, such as water, into the product stream at 29. The temperature is reduced below about 1,300c F. to 1,350 F. at this point. The temperature may be further reduced to about 700 to 900 F. by passage of the products through a waste heat boiler, not shown. The products then pass to a scrubber 19, where certain impurities are removed and the temperature further reduced. The quench liquid injected into the scrubber may be water or some other suitable liquid, such as light virgin gas oil, light or heavy gas oil from a catalytic cracking operation or an aromatic gas oil fraction. It will be understood that the quench step may be accomplished by other suitable means well known to the art, for example, contact of the reactant product with cool, solid, heat transfer particles. The quenched, cracked product passes to a product treating and recovery system 20, which system is described in further detail hereinafter in connection with FIGURE 2.

An intermediate gaseous product fraction rich in ethane is recovered as well as other products in the product recovery system. Because of practical limitations on the fractionation equipment, the ethane fraction may contain minor amounts of higher and lower boiling hydrocarbons and some ethylene. The ethane fraction is passed to a separate cracking system 21 to effect conversion to ethylene. In reaction system 21, it is preferred to subject the ethane to thermal cracking at temperatures broadly within the range of 1,300 to 1,800o F. and preferably 1,450 to 1,600 F., furnace outlet pressures ranging from slightly below to about 2 atmospheres above atmospheric and preferably 15 to 25 pounds per square inch 4gauge and residence times at reaction ternperatures in the range of about 0.2 to 3 and preferably about 0.5 to 1.5 seconds. Steam in amounts ranging from 20 to 50% of the feed may be added to the reactor at 2i along with the ethane fraction.

It is contemplated that alternatively the ethane fraction may be subjected to catalytic rather than thermal conversion to form an ethylene-rich product at 21. For example, the ethane fraction may be subjected to a cracking reaction at high temperatures over a silica-alumina cracking catalyst. Alternatively, the ethane fraction may be subjected to catalytic dehydrogenation over a suitable dehydrogenation catalyst at temperatures in the range of about 850 to 1,300" F., pressures ranging from subatrnospheric to a few atmospheres, and residence periods at reaction temperatures of the order of 0.5 to 6 seconds. Such catalytic cracking and dehydrogenation operations and the conditions and catalysts employed therein are well known in the art. Exemplary of suitable dehydrogenation catalysts are those comprising minor amounts of group VI metal oxides, such as chromia and molybdena on carriers such as alumina and silica and magnesium oxide. Another suitable catalyst cornprises a mixture of vanadium and aluminum oxides. In such operations, steam or small amounts of oxygen may be added with the feed. It is to be understood that, unless otherwise stated to the contrary in claiming this invention, it is intended that the term cracking as applied to the conversion of the C5 to C6 hydrocarbon cracking feed stock shall include, as well as the initial cracking step at 18, the catalytic or thermal conversion of the intermediate ethane fraction to an ethylene-rich product at 21.

The reaction product stream from 21 is immediately quenched to a temperature below the decomposition temperature of the products by injection of a suitable quench liquid, such as water, into the product stream at 28. The products are quenched to a temperature below about 1,400 F. at this point. The product stream is further cooled by passage through a waste heat boiler to about 700 to 900 F. The products then pass to a scrubber, where certain impurities are removed and the temperature further reduced. The quench liquid at 22 may be similar to that used in scrubber 19. The quenched product is returned to the product recovery system 20 for recovery of ethylene and other products along with those formed in the initial cracking reaction at 18. Unconverted ethane may be recycled to extinction to the `cracking system at 2.1. Alternatively, the products from 2,1, after passage through the Waste heat boiler, may be passed to scrubber 19 along with products from 18.

In addition to ethylene, other products recovered in system 20 are fuel gas consisting principally of methane and containing some hydrogen and carbon monoxide and dioxide, butadiene, aromatic gasoline, aromatic distillate boiling above the gasoline range (i.e., above about 300 to 410 F.ASTM), a propane-propylene fraction and a butane-butylene fraction. The propane-propylene fraction may be further fractionated to provide propane and propylene as additional products. The aromatic gasoline may contain of the order of 75 to 95% aromatics and have a Research Octane with 3 ccs. of TEL of the order of 104. This may be treated to remove diolens 11:* and other unstable materials, after which the Research Octane with 3 ccs. of TEL may be of the order of 110 to 115. -It will be understood that Research Octanes referred to herein are determined according to the ASTM Test Method No. D-908-55. The aromatic gasoline may be cut to a suitable end point in the range of 300 to 410 F. (ASTM) and added in part or in entirety to the final motor or aviation gasoline blends at 25 and 26, respectively, or in part to both. The aromatic distillate may be sold as such as a valuable petrochemical raw material Which may be further processed for recovery of pure aromatic compounds or used as a solvent material. In addition to the above products, diolens, such as propadiene, and acetylenes, such as methyl acetylene, may be recovered as product.

While, as indicated above, some liquid aromatic gasoline and aromatic distillate may be obtained in the products from the cracking operation, the conditions for the cracking operation when controlled as disclosed above are such `that the cracked product is made up principally of hydrocarbons having less than live carbon atoms per molecule and containing substantial amounts of normally gaseous, unsaturated hydrocarbons. Preferably, a major portion of the cracked product consists of normally gaseous, unsaturated hydrocarbons.

The propane-propylene and butane-butylene fractions from the cracked product contain principally propylene and butylene With only minor amounts of propane and normal butane, the diolelins and acetylenic materials having been removed. These fractions may be recovered separately or together as a single fraction in system 20. When recovered together or mixed, they constitute a suitable olen-rich alkylation feed fraction made up principally of C3 to C4 hydrocarbons but containing minor amounts of C2 and C5 to C5 hydrocarbons. .In general, the olefin-rich C3 to C4 fraction contains at least 70% by volume of unsaturated C3 to C4 hydrocarbons. This fraction is subjected to alkylation in unit 23 with suitable alkylatable hydrocarbon material, yielding upon alkylation high anti-knock alkylate gasoline. Examples of such alkylatable materials are isobutane and aromatics or side chain aromatics boiling in the gasoline range, such as benzene. The alkylation step results in formation of an alkylate rich in branched chain aliphatic or aromatic hydrocarbons boiling principally in the gasoline range. When it is desired to recover propylene as a Separate product, the olefinic material subjected to alkylation may comprise C4 oleinic hydrocarbons. The alkylation unit may be of any of the conventional types Well known in the art, for example, sulfuric acid, aluminum chloride or hydroiiuoric Aacid alkylation units. In the sulfuric acid-type process, the reaction temperature is preferably of the order of 401 to 70 F., and the pressure is of the order of 5 to 5() pounds per square inch gauge. About 50 to 70% by volume of sulfuric acid is used. This acid may range from 98 to 100% concentration at the start of the operation to about 90% concentration when it is discarded. Suiicient isoparafiinic hydrocarbon is added to the unit to maintain an isoparaflinic to oletinic hydrocarbon molecular ratio within the range of about 4 to 10, unconverted isobutane being recovered and recycled to the unit. In the case of hydrouoric acid alkylation, the reaction temperature is maintained in the range of about 75 to 100 F. Isobutane for the alkylation step may be supplied entirely from outside sources, and also additional butylenes may be recovered from the original light gasoline feed and from light reformate gasoline in the fractionation system at 17. Thus, the isobutane-butylene-normal butane fraction from 17 may form part of the feed to the alkylation unit.

The alkylate produced in unit 23 is subjected to fractionation at 24 to remove C3 and, if desired, C4 hydrocarbons so as to provide a stabilized, high anti-knock alkylate gasoline having an ASTM end point in the range of about 300 to 410 F. and a heavy alkylate boiling above the alkylate gasoline. The alkylate gasoline may be added in part or in entirety to either the final motor or aviation gasoline blends at 25 and 26, respectively, or in part to both. Propane, butane and heavy alkylate are withdrawn as separate products from the product recovery system `24.

While, in the preferred form of this invention, the unsaturated hydrocarbons resulting from the cracking operation are subjected to alkylation, in accordance with the broader aspects of this invention, the unsaturated hydrocarbons may be subjected to other suitable combining reactions, in which the unsaturated hydrocarbons constitute at least a substantial portion of the reactants and are converted under controlled conditions to form a gasoline product of lower average volatility and higher anti-knock rating than the aliphatic hydrocarbon material separated from the reformer feed and product streams as cracking feed stock. For example, the oleiinic C3 to C4 fraction may be subjected to thermal polymerization at 1,100 to 1,150 F. and 60 to 1,200 pounds per square inch gauge to form a 400 F. end point polymer gasoline, which, after percolation through fullers earth to remove gums, has a Reasearch Octane Number of the order of 89 clear. Alternatively, catalytic polymerization over sulfuric acid or phosphoric acid-type catalysts may be employed. For example, in the selective catalytic polymerization of the butylene fraction obtained from the cracked products With 65% sulfuric acid at 165 to 212 F., with 10 to 15 minutes contact time, a conversion of about to a polymer ygasoline containing predominantly octenes is obtained. This gasoline is hydrogenated at 200 C. over platinum on charcoal to provide a gasoline having a Research Octane Number of about 99. Alternatively, olenic C3 and C4 hydrocarbons from the cracking products may be converted to isopropyl and tertiary butyl alcohol, respectively. Thus, for example, the liquid propylene combined with recycle hydrocarbons from the hydration process may be absorbed in 75% sulfuric acid (hydrocarbon to acid ratio about 1.5). Sulfation of the propylene occurs at a ternperature of about 85 F. The mixture is diluted with Water to about 35% acid concentration, and hydration is eected at about 200 F. isopropyl alcohol is recovered by steam stripping; and, upon further distillation, diisopropyl ether is also recovered. Both compounds constitute valuable, high anti-knock blending components for engine fuels. By appropriate adjustment of acid concentration and temperature, the relative proportions of di-isopropyl ether and isopropyl alcohol in the product may be varied. Alternatively, the propylene in the cracking products may be converted to the same products by direct catalytic hydration of propylene in the presence of steam over a tungsten oxide catalyst. The isobutenes in the cracking products may be converted to tertiary butyl alcohol by a process similar to the one described above. Alternatively, the isobutylenes may be converted to tertiary butyl acetate by suitable combining reactions well known in the art. Tertiary butyl acetate is a valuable blending component for leaded gasolines when employed in small quantities. For example, when by volume of tertiary butyl acetate is added to a catalytic reformate having a Research Octane Number of With 3 mls. TEL, the Research Octane Number is increased by about 1.5 numbers. The Research Blending Octane for di-isopropyl ether, isopropyl alcohol and tertiary butyl alcohol, when blended in the amount of 10% by volume with 100 Research Octane (with 3 mls. TEL), catalytic reformate gasoline Was found to be 120.7, 113.7 and 111.7, respectively. In accordance with one broad aspect of the invention, unsaturated C2 hydrocarbons may also be subjected to the combining operation as Well as C3 to C4 hydrocarbons. It Will be understood that the term combining reaction, as employed herein in describing and claiming 13 this invention, is intended to cover any reaction in which the specified unsaturated hydrocarbon feed stock is subjected to conversion, in one or more steps, either alone or with suitable added reactants, to form a higher boiling, normally liquid product boiling within the gasoline range and having a high anti-knock value and a composition otherwise suitable for use as a blending component in high anti-knock engine gasolines. The term is intended to include any of the alternative processes discussed above, including alkylation.

It will be understood that the exact distillation sequence by which the light cracking feed stock is isolated from the reformer feed source stock and from the reformate may differ somewhat from that specifically described hereinabove. For example, the source stock containing reformer feed gasoline may be subjected to one or more separation operations to remove therefrom C3 and lighter hydrocarbons and to provide a reformer gasoline feed. Similarly, the reformate product may be separately subjected to one or more separation operations to remove C3 and lighter hydrocarbons and to provide a stabilized, reformed gasoline. The aliphatic hydrocarbon or hydrocarbons selected for cracking may be removed from the reformer feed source stock or from the reformate product or both in one of the above-mentioned separation operations. C4 hydrocarbons may also be separately removed from the reformer feed source stock or from the reformate product, preferably both, in the above-mentioned separation operations. Also, the aliphatic cracking feed material may be separated from the reformer `gasoline feed source stock and from the reformed product by means other than distillation alone, such as by solvent extraction or by the use of molecular sieves or by a combination of these latter methods with distillation. Such alternative separation methods are well known in the art.

While, in most operations in accordance with this invention, the cracking feed stock consists essentially entirely of hydrocarbon material boiling within the range of C5 to C7 aliphatic hydrocarbons, it is contemplated that, in some cases, hydrocarbon material boiling outside of this range may also be subjected to cracking in admixture with the C5 to C7 hydrocarbons. For example, essentially lall of the C5 and heavier straight chain hydrocarbons may be removed from the reformer feed gasoline stock or from the reformate `or from lboth and employed as cracking feed stock. This separation may be accomplished by means of solvent extraction or by use of molecular sieves, such `as naturally occurring chabazite, selective synthetic zeolite or `alumina silicate selective adsorbents. For example, C5 to 380 F. end point straight run naphtha may be contacted in the vapor phase at about 450 F. with granular calcium alumina silicate made up of porous crystals of about 5 angstrom units pore diameter. The adsorbent acts to selectively adsorb essentially `all of the normally liquid, straight chain hydrocarbons, i.e., C5 and heavier hydrocarbons in the gasoline. The straight chain hydrocarbons are stripped from the adsorbent at 550 F. with steam. The full straight cha-in hydrocarbon fraction is employed as charge stock to pyrolytic cracking, while the remaining gasoline not adsorbed by the molecular sieve is subjected to reforming to improve its anti-knock value.

It will be noted that FIGURE l, in one sense, depicts a general flow scheme for an `overall refining operation on a petroleum crude yor -a petroleum crude fraction. The crude fraction entering at is converted by a plurality of process steps, including fractional distillation, thermal and catalytic cracking of heavier than gasoline components, and catalytic reforming of straight run gasoline components with or without cracked gasolines over aromatization-type catalysts. A number of products result, such as C3 and lighter hydrocarbons going to fuel gas, normal lbutane, thermal and catalytic gas `oils and fuel oils, tar and a plurality of gasoline fractions. The

total of these gasoline fractions from any or all of cat-alytic cracking, thermal cracking, reforming, isomerization, alkylation, gas polymerization and other gasolineforming reactions, together with isopentane and C4 hydrocarbons and other high anti-knock value pressuring compounds, go to make up what is known as the overall refinery gasoline pool. Relatively small amounts of straight run gasoline or absorption gasoline recovered from refinery gas streams may comprise one or more of the refinery pool gasoline fractions. While, for the purpose of simplicity, the various gasoline streams are shown in FIGURE l as running directly into either a motor or aviation gasoline blend at 2S and 26, respectively, it will be understood that the various components comprising the refinery gasoline pool may be stored separately or blended together in part prior to blending into finished gasoline products. Instead of two blends Of engine gasoline, the refinery may make up several blends from the gasoline pool components. For example, two or more motor gasolines of different octane ratings and possibly different boiling ranges may be blended. In addition, the refinery may blend an aviation fuel of a higher anti-knock rating and a still different boiling range.

In accordance with the method of this invention, relatively low octane, normal pentane or straight chain pentanes and saturated, aliphatic C6 hydrocarbons or straight chain C6 hydrocarbons, particularly normal hexane and, if desired, saturated, aliphatic C7 hydrocarbons or straight chain C7 hydrocarbons, particularly normal heptane from the stock or stocks containing reformer feed gasoline `and from the reformate (or, in one broad aspect of the invention, from either of these stocks), are diverted from the gasoline pool. These hydrocarbons are converted as described above to `gaseous olefins which can be combined, preferably alkylated, to form more desirable refinery pool gasoline fractions of higher antiknock value and lower average volatility than the hydrocarbons so diverted from the gasoline pool. At the same time, a number of valuable chemical raw material products, such as ethylene, butadiene and aromatic distillates, are manufactured. It will be noted that, by the process of this invention, the overall content in the total refinery pool gasoline fractions of relatively volatile, low octane, straight chain, aliphatic hydrocarbons within the range of C5 to C7 hydrocarbons is reduced, i.e., the overall low octane volatility -of such gasoline fractions is reduced below what it would be in the case of ordinary reforming operations. More particularly, the volatility of the liquid reformate gasoline produced is substantially less than it would be in conventional reforming operations. The resulting low volatility reformate gasoline is particularly useful for low volatility, high anti-knock aviation gasolines. For example, a `desirable low volatility aviation gasoline may consist of 50% by volume of such a reformate gasoline which is essentially free of normal pentane and straight chain hexanes and 50% of alkylate gasoline resulting from alkylation of C3 to C4 oleflns with isobutane. In the case of final gasolines requirmg pressuring, this invention permits incorporation in the final blends of greater Aamounts of high lanti-knock rating pressuring materials, such as butanes or isopentane, than would otherwise be possible within the limits of gasoline volatility specifications. By the method of this invention, the overall octane rating of the total of the refinery pool gasoline fractions is increased without excessive loss in total gasoline volume. It is usually preferable to blend together in at least one of the finished gasoline blends at least a substantial portion of the reformate and alkylate gasolines formed in the abovedescribed combination process. However, within the broader scope of the invention, the reformate and alkylate components of the gasoline pool may be employed entirely as components of separate and different engine gasoline blends.

While, in accordance with this invention, it is preferred 'l5' to remove ethylene formed in the cracking operation from the system as a product, in one broad aspect of the invention, a substantial part of the ethylene may also :be converted to high anti-lcnock Igasoline by a suitable oombining reaction. This 'ability to utilize the ethylene for manufacture of an alternate, valuable product during periods `when market demand for ethylenes is low is one of the attractive features of the combination ethylene and gasoline manufacturing process of this invention.

The process of this invention is applicable to renery operations involving manufacture of either a single final gasoline blend or two or more gasoline blends. For example, there may be provided a regular motor gasoline and a higher antilinock rating special blend, or there may be provided a single motor gasoline and an aviation gasoline or two or more motor gasolines of different octane rating and, in addition, an aviation gasoline. In the event an aviation gasoline blend is provided, it will have a lower end point than the motor gasoline, e.g., as ASTM end point in the neighborhood of 290 to 338 F. Also, base stock from a source outside the process of this invention may be added to the aviation gasoline blend in addition to certain of the intermediate product fractions from the process of this invention, as discussed hereinabove.

It will be noted that, in a preferred form, this invention involves an improvement to a gasoline reforming process in which the stock containing the reforming feed and the reforming product is fractionated to remove at least the normal aliphatic C and the saturated aliphatic C5 hydrocarbons contained therein. rl`hese C5 to C6 hydrocarbons are cracked at elevated temperatures to form a product rich in gaseous olens, a substantial portion of which is alkylated with isoparaiiinic material or other alkylatable material to produce a product containing high anti-knock alkylate gasoline. At least a substantial portion of the alkylate gasoline is blended together with at least a substantial portion of the product from reforming after removal of the C5 to C5 hydrocarbons.` Preferably, at least a substantial portion of an isopentane fraction also recovered from the reformer feed and product and at least a substantial portion of the aromatic gasoline formed in the C5 to C5 cracking reaction are also added to the final gasoline blend. In addition, C., hydrocarbons, particularly paratinic C., hydrocarbons, are added to the blend to pressure it to a level suitable for use as an engine or motor fuel.

In general, the vapor pressure most suitable for motor gasoline varies with climatic and seasonal conditions within the range of 6 to 16 pounds per square inch gauge` Reid Vapor Pressure (R.V.P.). For example, at essentially sea level altitudes, vapor pressures found satisfactory for current automobiles during the summer months range from about 6 to 10, whereas, during the winter months, vapor pressures in the range of 10 to 16 are satisfactory. It has been found that, during the summer months, the factor which usually limits the maximum allowable R.V.P. is vapor lock inthe automobile and in the gasoline dispensing pumps. During the cooler seasons, the limiting factor is usually the problem of ice formation in the automobile carburetor. Carburetor icing may be encountered during relatively cool periods when the humidity is relatively high and when the gasoline has a high volatility. It has been found that, other things being the same, carburetor icing diculties increase with increasing R.V.P. and also with decreasing gasoline mid boiling point. Since the straight chain C5 and C5 hydrocarbons contribute somewhat to gasoline volatility, their elimination from the nal gasoline blend permits incorporation of greater amounts of C4 hydrocarbons for the same nal R.V.P. Moreover, since elimination of the straight chain hydrocarbons from the nal blend results in an increase in the ASTM mid boiling point of the gasoline, it has been found that higher gasoline R.V.P.s and, thus, still greater amounts of C4 hydrocarbons may be utilized at least during the non-summer months Without increase in carburei6 tor icing tendencies. Moreover, during the summer months, the overall volatility characteristics of the gasoline are improved.

It has been known heretofore that gasoline blends made up of components boiling at opposite ends of the volatility limits of motor gasoline give unsatisfactory engine performance, particularly from the standpoint of engine starting and warm-up. Such fuels have been called dumbbell fuels, since there is little or no hydrocarbon boiling between the two dissimilar components. It has been discovered that, due to the fact that gasoline reforming, particularly catalytic reforming, results in an overall downward shift in the gasoline boiling range, C4 hydrocarbons may be substituted for the C5 to C5 hydrocarbons in accordance With the process of this invention without giving rise to the unsatisfactory engine performance characteristic of dumbbell fuels. This is particularly true when alkylate gasoline produced in accordance with this invention is also added to the iinal gasoline blend.

Further, it will be noted that, by the process of this invention, components of relatively high octane blending value are substituted for components of low blending value in the nal gasoline blend. Wheras, the blending values of normal pentane and normal hexane in catalytic reformates containing benzene and C7 and heavier hydrocarbons have been found to be of the order of 83 and 49 (Research Method Octanes), the y'blending values of isobutanes and normal butanes were found to be in excess of 100. In addition, by elimination of the straight chain C5 to C5 or of the straight chain C5 to C7 hydrocarbons from the reformer charge, hydrocracking of these components to form methane, ethane and hydrogen is avoided, and they are converted separately under proper conditions to valuable unsaturated petrochemical products, alkylation feed stocks and high octane aromatic gasoline.

While, as has been indicated above, isopentane may be included in the light gasoline cracking feed stock, it is preferred, in View of the relatively high anti-knock value of isopentane, to add this material to at least one of the final gasoline blends. In the case of the aviation gasoline blend, isopentane is employed to the exclusion of C4 hydrocarbons for the purpose of providing the desired Reid Vapor Pressure. In some cases, it may be necessary to supply additional isopentane from an outside source to provide the required vapor pressure for the aviation gasoline.

It is contemplated that materials other than butanes may be employed as gasoline blend pressuring materials. In general, the pressuring material employed in accordance with the method of this invention should be a volatile, combustible material having a substantially higher antiknock rating than the straight chain hydrocarbon material which is removed from the reformer gasoline feed source stock and from the reformate for cracking. Exemplary of suitable pressuring materials other than normal and isobutane and other C4 hydrocarbons are C3 hydrocarbons, particularly propanes, and isopentane. While it is usually desirable to pressure most engine gasolines, this is not always the case, as has been indicated hereinabove. This invention is, therefore, not considered to be restricted in its broader aspects to the use of added pressuring materials in the final gasoline blends.

It will be noted that, in one broad aspect, this invention provides an integrated combination process for simultaneously manufacturing ethylene and other petrochemical products and for improving the anti-knock value and decreasing the low octane volatility of engine gasoline. As pointed out hereinabove, both the usual processes for manufacture of ethylene and processes for upgrading C5 to C7 straight chain hydrocarbon material are separately so costly as regards installation and operation that they are often considered marginal operations from the standpoint of economics. In accordance with this invention, the low octane, aliphatic hydrocarbon material Within the range of C5 to C7 hydrocarbons is removed from the reformer gasoline feed source stock or from the gasoline reformate or preferably from both and subjected to pyrolytic cracking at temperatures within the range of 1,300 to 1,750 F. and under conditions controlled to convert the material to a cracked product made up principally of hydrocarbons having less than five carbon atoms per molecule and containing substantial quantities of gaseous olefins, including ethylene. Thus, large quantites of ethylene are produced as petrochemical product, and large quantities of other gaseous oleflns are produced which may be combined by suitable reaction to high octane value gasoline which constitutes a very valuable added refinery pool gasoline fraction. As contrasted with separate processes for manufacturing ethylene land for isomerizing or otherwise upgrading such straight chain hydrocarbons as normal pentane and normal hexane, the combination process of this invention is surprisingly attractive from standpoints of overall product results and economies. The high grade alkylate or comparable gasoline is substituted in the refinery gasoline pool in place of low octane, volatile C to C7 aliphatics without excessive loss in gasoline production, while, at the same time, substantial quantities of ethylene and other petrochemicals are produced as products. The type of cracking reaction involved in the process of this invention and the products derived therefrom are illustrated in the following examples, in which two light gasoline cracking charges are subjected to pyrolytic cracking with a peak furnace tube temperature of about 1,460 F. (tube outlet), pressure of 20 pounds per square inch gauge, steam to hydrocarbon weight ratio of 1:1 and residence time within the cracking zone within the range mentioned hereinabove. The light gasoline feed A has an API gravity of 78.0, and ASTM initial, and end point of 108, 123 and 185 F., respectively. Light gasoline feed B has an API gravity'of 75.3 and ASTM initial, 10% and end point of 130, 145 and 235 F., respectively. The compositions of the light gasoline feed stocks are presented in Table I.

TABLE I Composition of Typical Light Cracking Feed Stocks Gasoline feed, weight percent Component Propylene Isobut-ane Normal butane Isopent'me C5 to C@ olefin Normal he "um 2,'2-tlimet-hyl butane B-methyl pent-ane Ztl-dimethyl butane ,fz-methyl penttme Methyl cyclopert-me Cyclopenttme Oyclohexane C5 to Ca cyelo-oleins, Benzene Normal hept me C1 paraims .f-methyl he "me C3 parathns 3methyll1c 'me C9 parailins Cm paratrns 2,2-dimethyl pan tane 2,3-dimethyl pent'me 2 ,gt-dimethyl pntwne C7 and lighter eycloparaffins 2. 3ethyl pentane Toluene 0. C3 alkyl ben:ene 0. Cr alkyl beurette O Unidentitied 0 Total The product distributions from the cracking operation are shown in Table II.

Referring now to FIGURE 2, there is presented a flow plan showing in greater detail a preferred arrangement of the light gasoline cracking system and the feed preparation and product recovery and treatment system used in connection therewith. The towers employed for the distillation system shown at 17 in FIGURE 1 are shown at 3th, 31 and 32 of FIGURE Z. The light cracking feed stock consisting principally of C4 to C6 aliphatic hydrocarbons enters the debutanizer 30 via conduit 33. C4 and lighter hydrocarbons pass overhead from tower 30 via conduit 34 to deisobutanizer 31, a portion of the overhead material being reuxed via conduit 35 after being condensed in condenser 36. Isobutane and butylenes are withdrawn from the top of tower 31 via conduit 38 and may be supplied to the alkylation unit as discused hereinabove. Normal butane is withdrawn from the bottom of tower 31 via conduit 39 and may be employed for pressuring the iinal gasoline blends at 25 and 26 of FIGURE 1. In some operations, the deisobutanizer may be eliminated and the entire C4 hydrocarbon fraction recovered from the top of the debutanizer tower 30. A fraction made up principally of C5 to C5 hydrocarbons but containing minor quantities of lighter and heavier hydrocarbons passes .from the bottom of'tower 30 to the deisopentanizer 32. An isopentane fraction is withdrawn from the top of tower 32 via conduit 40, while a portionv of the overhead material is reuxed via conduit 41 after condensation in condenser 42. The bottoms from tower 32 discharge via conduit 43 and are pumped by pump 44 to the thermal cracking system 18.

While only one cracking furnace is disclosed at 18 in FIGURE 2, it will be understood that the thermal cracking system may involve use of a number of tubular-type reaction furnaces usually arranged in parallel. For example, the reactant may be passed in parallel through 17 tubular-type furnaces. The furnaces are designed in such av manner that the temperature of the reactant gradually increases and approaches the maximum desired temperature at a point near the outlet of each reactor. In order to avoid excessive secondary reactions leading to tar and coke formation, it is important to prevent the -reactant from reaching the maximum temperature or to incur a temperature drop at an intermediate point in the reactor system. In furnaces that require shut-down to permit removal of coke deposits from the tubes at periodic intervals, e.g., once every 30 to 60 days, in order to permit removal of the coke from the furnace tubes without interruption in the continuous operation, an additional furnace may be provided which will be operated in conjunction with the 17 furnaces in a staggered, swing-type operation involving use of 17 reactors for the cracking reaction while the coke is being removed from the tubes in the remaining reactor. The cracked products from the cracking reactors 18 are quenched by water injection to a 19 temperature below 1,350 F. and pass to one or more quench boilers 120, in whichV the temperature is further reduced to 700 to 900 F. by steam generation. The cracked products then pass through conduit 45 to a gas scrubber 19, where the gases are scrubbed with a countercurrent flow of hydrocarbon having a boiling range of 450 to 650 F. The 450 to 650 F. boiling range hydrocarbon is recirculated and functions to further cool the furnace eftiuent, absorb resinous materials formed by polymerization and remove carbonaceous materials carried over from the reactors. If desired, water may be employed as the scrubbing liquid in tower 19 instead of gas oil. The scrubbed gases are passed via conduit 47 through condenser 48 to separator 49. Heavy hydrocarbon condensate from the separator 49 passes through conduit 50 to stripper S1. The condensate is steam stripped to remove butane and lighter materials, and the stripped liquid is passed via conduit 52 to the rerun tower 106. Vapor from separator 49 leaves via conduit 53 and is joined via conduit 54 by vapors from stripper S1. The gas is compressed in one or more stages at 55. The purpose of the compression is to raise the pressure level on the volatile products to that required for their separation by high pressure-low temperature fractional distillation. Multistage compression of the gaseous material from the gas scrubber 19 with cooling and separation (not shown) between stages is desirable in order to avoid high temperatures whichl would produce polymers. Water recovered lfrom the intermediate separators is discarded. Hydrocarbon condensate recovered from the intermediate separators is pumped to the outlet piping from the next compression stage, where its sponge effect is utilized. The compressed material, including condensate from the iinal compression stage, passes through cooler 56, in which it is cooled to about 65 F., and then to the separator 57. The pur- 3 pose of the cooling step at 56 is to condense as much propylene and heavier hydrocarbon material as possible, thereby excluding it from demethanizer 69. The condensate made up principally of propylene and heavier hydrocarbons passes via conduit 58 to caustic and water Wash at one or more drums 59. The liquid hydrocarbons are washed with aqueous sodium hydroxide solution and then with water for the purpose of removing hydrogen suliide and other acidic materials. The washed hydrocarbons are passed via conduit 60 to prefractionator 61, where ethane and lighter materials are removed overhead via conduit 62 to the suction of compressor 55. The prefractionator bottoms containing propylene and heavier hydrocarbons pass via conduit 63 to debutanizer 896. The prefractionator pressure is set at about 285 pounds per square inch gauge.V VThe top temperature is not permitted to fall below about 60 F. .in order to avoid hydrate formation. The bottom temperature in the prefractionator is maintained below 260 F. in order to avoid polymerization of butadiene in the reactants. Deethanizer bottoms are supplied to the prefractionator via conduit 84 at a rate suicient to permit proper control of the bottom temperature. The overhead from separator 57 passes via conduit 64 to a caustic and water wash tower 65, where the vapors are caustic washed and water washed and delivered via conduit 66 to one or more driers 67. The hydrocarbons are passed through a suitable desiccant, such as synthetic alumina bead desiccant, bauxite or activated alumina. The function of the driers is to lower the dew point of the gas suiciently to prevent hydrate formation in the low temperature equipment which follows the driers. The dried stream is passed via conduit 68 to a series of coolers not shown in the drawings and cooled to a temperature of the order of 80 F. and to a demethanizer 69. This tower is designed to minimize ethylene loss to tail gas while removing substantially all the methane and lighter hydrocarbons from the bottom product. The overhead from demethanizer 69 is cooled by evaporating ethylene at 150 F., and the tower is reboiled by condensing propylene. The demethanizer pressure may be about 495 pounds per square inch gauge and the bottom temperature ofthe order of 60 F. Fuel gas consisting primarily of methane and hydrogen is withdrawn via conduit 70 from the top of demethanizer 69, and this gas may be employed as fuel in the cracking furnaces. Bottoms from the demethanizer consist primarily of ethylene, ethane, C3 and C4 hydrocarbons with a small quantity ot C5 and heavier hydrocarbons. Bottoms from the demethanizer tower 69 pass via conduit 71 to the de-ethanizer 72, which may operate at a pressure of the order of 400 pounds per square inch gauge, with an overhead temperature of the order of 15 to 24 F. and bottoms temperature of the order of 171 F. The overhead from tower 72 consisting primarily of ethylene and ethane with some impurities passes Via conduit 73 to an ethaneethylene splitter tower 74, which may operate at a pressure on the order of 98 pounds per square inch gauge, with an overhead temperature of the order of 77 F. and a bottoms temperature of the order of 40 F. Tower reboiling and condensing functions may be combined in a heat pump arrangement in which the overhead vapor is compressed at 127 to a pressure of about 295 pounds per square inch gauge and condensed in the reboiler 129 to provide reboiler heat. The overhead product leaves tower 74 via

conduits

75 and 134 to an acety- Iene conversion step 76. The acetylene conversion may be a conventional type known to the art. The hydrocarbon stream is subjected to mild hydrogenation over suitable catalyst to effect selective hydrogenation of the acetylene content of the stream without substantial hydrogenation of the olens and diolefins. Catalysts known in the prior art which are suitable for this operation are nickel, platinum, iron, cobalt and noble metal oxides on suitable supports such as silica, pumice, charcoal and alumina. Examples are catalysts comprising 3 to 10% of cobalt molybdate on activated alumina or 3 to 10% of a mixture of nickel and iron on pumice. Suitable operating conditions vary With the catalyst within the range of about to 600 F., pressures of from 0 to 1,500 pounds per square inch gauge and usually less than 200 pounds per square inch gauge and space velocities of the order of 300 to 1,500 volumes of gas (measured at standard conditions) per hour per volume of catalyst. The reactant feed should contain about l0 to 50% by volume of hydrogen. If the cracked gas does not contain suicient hydrogen, this may be added via conduit 133. In some operations, small amounts of water vapor may be supplied to the hydrogenation reactor with the feed. If desired, some other means for removal of the acetylene from the cracked gases may be substituted for the hydrogenation unit. For example, the mixed gas may be subjected to selected oxidation by passage together with sufficient oxygen to oxidize contained hydrogen and acetylene over a catalyst such as activated alumina at temperatures of the order of 650 to 750 F. and pressures near atmospheric.

Eluent from the acetylene conversion step 76 is cooled to 27 F. and fed via conduit 135 to topping still 77 for removal of methane and lower boiling contaminants from the ethylene product. The topping still 77 may operate at a pressure of the order of 335 pounds per square inch gauge with a bottoms temperature of the order of 5 to 0"V F. and an overhead temperature of the order of l5 to 20 F. Reboiler heat is supplied by condensing propylene and the overhead condenser is cooled by propylene refrigerant. Overhead from tower 77 containing methane, ethylene and lower boiling material passes via conduit 78 to the suction of process gas compressor 55. The bottoms from tower 77 pass via conduit 79 to tailing still 80 for removal of heavy contaminants from the ethylene product. The tailing still 30 may operate at a pressure of the order of 275 pounds per square inch gauge, with a bottoms temperature of the order of to .-10 F. and an overhead temperature of the order of to -25 F. Rebcler heat is supplied by condensing propylene and the overhead condenser is cooled by propylene refrigerant. The overhead from the tailing still Si) is essentially pure ethylene, which is withdrawn from the system via conduit 81. The bottoms from the tower 80 containing a mixture of ethylene and ethane are returned via conduit S2 to the ethane-ethylene splitter tower 7d. An ethane fraction is withdrawn from the bottom of tower 74 via conduit S3, and this is passed to the ethane cracking system 21.

The ethane cracking system may be comprised of one or more tube-type furnace reactors. For example, the ethane may pass through three tubular furnaces in par* allel, with a fourth furnace being provided for staggered, swing-type operation to permit continuous operation during periods of coke removal from the furnace tubes. Reaction products from furnace 21 are quenched 'by Water injection at 28 immediately on leaving the furnace to reduce the temperature below 1,3 50 F. and pass to one or more quench boilers 12S, in which the temperature is further reduced to 700 to 900 F. by steam generation. The cracked products then join the cracked products from the naphtha cracking section and pass to the gas scrubber 19, where they are scrubbed and further cooled.

The bottoms from the de-ethanizer 72 consisting primarily of C3 and C4 hydrocarbons with minor amounts of C5 and heavier hydrocarbons pass via conduit Sd to the debutanizer 86. Also supplied to the debutanizer is the prefractionator Ibottoms stream, which is of similar composition. A portion of the de-ethanizer bottoms passes via conduit 85 to the prefractionator tower 61. This light material is routed through the prefractionator 61 to lower the prefractionator reboiler temperature and prevent the formation of polymers caused by high temperatures. The debutanizer effects a sharp separation between butadiene and pentadiene components of the feed streams. The debutanizer S6 may operate at a pressure of the order of 195 pounds per square inch gauge with a bottoms temperature of the order of 335 to 340 F. and an overhead temperature of the `order of 125 to 130 F. Reboiler heat is supplied by steam, and the overhead is condensed in a water cooled condenser. Overhead from tower 86, which is essentially free of C5 and heavier hydrocarbons, passes via conduit S7 to depropanizer 8S, which may be operated at a pressure 4of the order of 250 pounds per square inch gauge with a bottoms temperature of the order of 210 to 215 F. and an overhead temperature ofthe order of 110 to 115 F. The depropanizer effects a split between the methyl acetylene and butadiene components of the feed stream. The depropanizer overhead condenser uses water as a cooling medium, and reboiler heat is supplied by steam. The overhead principally made up of propane and propylene and containing relatively small amounts of impurities, such as methyl acetylene and propadiene, is withdrawn via conduit 89. rl`his stream is passed to a methyl acetylene and propadiene removal step. As an example, the stream may pass through hydrogenation reactor 92, where the methyl acetylene and propadiene are selectively hydrogenated. Hydrogen for the conversion is passed through the deoxygenation reactor 90, where a platinum catalyst promotes a reaction between hydrogen and small amounts of oxygen and carbon monoxide present. The oxygen and carbon monoxide conversion step may be a conventional type well known to the art. Temperature in this step may be about 250 F. and the pressure about 350 pounds per square inch gauge. The conversion process may be of conventional type well known to the art and the same process as described for the acetylene conversion step 76. If desired, some other means for removal of the methyl acetylene and propadiene may be substituted for the hydrogenation unit. For example, the methyl acetylene and propadiene can be removed by absorption or extraction. Eluent from the conversion step 92 passes via conduit 93 through condenser 94'to propylene topping still 95. Light contaminants introduced with the hydrogen stream, such as methane and ethane, are withdrawn from the top of tower 95 via conduit 96 and pass to compressor 55. The propylene topping still 95 may be yoperated at a pressure of the order of 345 pounds per square inch gauge, having a temperature at its top of about 109i F. and a temperature at its bottom of about 139 F. The propane-propylene fraction Withdrawn from the bottom of tower 95 may be withdrawn from the system at this point and employed ultimately as part of the charge to the alkylation unit or further fractionated to produce an essentially pure propylene stream and a propane-propylene stream as shown in FIGURE 2. The bottoms from tower 95 are passed via conduit 97 to the propane-propylene splitter 9S. The propane-propylene splitter 9S may be operated at a pressure of the order of 298 pounds per square inch gauge with a bottoms temperature of the order of 130 F. and a top temperature of the order of 120 F. Reboiler heat is supplied by steam, and the overhead is condensed in a water cooled condenser. An overhead of essentially pure propylene is Withdrawn via conduit 99. A bott-oms fraction of propane and propylene is withdrawn via conduit 10d and is ultimately employed as alkylation unit charge. The propylene may be Withdrawn as one of the cracking products. If desired, the C3 splitter may be omitted and the entire propane-propylene stream employed as an alkylation feed stock. The bottoms fraction from depropanizer 88, principally made up of butylene and butadiene, is passed via conduit 101 to butadiene reco-very 102. The C4 fraction is passed through a butadiene extraction unit, from which are recovered butadiene as a product, which is withdrawn via conduit 103, and a butane-butylene fraction, which is withdrawn via conduit 104, and employed as a portion of the charge to the alkylation unit. The butadiene extraction unit may be of the conventional type well known to the art. For example, extraction may be accomplished by means of aqueous amm-oniacal cuprous acetate solution or by use of furfural as the extractiva solvent. The bottoms product from the debutanizer 86 containing C5 and C6 and higher boiling hydrocarbons is passed via conduit 105 to rerun tower 106. The rerun tower may be operated at a pressure of the order of 7 pounds per square inch gauge with a top temperature of about 216 F. Steam is injected into the reboiler inlet line to keep the bottoms temperature down to about 420 F. A 400 F. plus fraction of an aromatic distillate is Withdrawn via conduit 107. The overhead from tower 106 passes via conduit 108 to heater 109, where it is heated to a temperature of about 350 to 400 F. and vaporized. The vaporized furnace eiuent passes via conduit 110 to clay treating tower 111. Tower 111 is maintained at a pressure of about 40 to 50 pounds per square inch gauge and a temperature of the order of 300 to 400 F. Diolefins present in the rerun tower 106 overhead are polymerized in tower 111 in a manner well known to the art. The contact material in tower 111 may consist of Attapulgus clay or bauxite. The treated stream is passed via conduit 112 to rerun tower 113 for the purpose of recovering an aromatic gasoline, which is Withdrawn loverhead via conduit 114, and an aromatic distillate, which is withdrawn via 115. The rerun tower may be operated at a pressure of about 7 pounds per square inch gauge, having a top temperature of the order of 260 F. and a bottom ternperature of the order of 392 F.

EXAMPLE 1 As an example `of the operation in accordance with the combination process of this invention, the processing of 20,500 barrels (42-gallon barrels) per calendar day of a mixture of parafnic, mixed base and naphthenic crudes may be considered in connection with FIGURE 1. The crude is fractionated in distillation system 10 to remove C3 and lighter hydrocarbons and to provide 4,900 barrels of residual tar, 3,900 barrels of virgin gas oil, 1,250 barrels of a cut boiling in the range C4 to 175 F. and 3,830 barrels of 175 to 370 F. end point heavier reformer charge gasoline. The virgin and thermal gas oil having a boiling range of about 460 to l,000 F. is subjected to catalytic cracking under conventional conditions in a moving bed catalytic cracking unit at 13. About 2,850 barrels of catalytic gasoline having the properties indicated in Table V are recovered from the catalytic cracking products by distillation at 14 This gasoline is added to the final motor gasoline blend at 25.

The residuum is subjected to thermal viscosity breaking at 11 to produce additional catalytic cracking stock. About 270 barrels of l175 to 370 F. end point thermal gasoline are also formed, and this gasoline is added, along with the heavier reformer charge gasoline, to the reforming unit 15. In addition, about 95 barrels of light thermal gasoline are formed, which are added to the distillation system 17 along with C4 to 175 F. cuts from the crude and gasoline reformate.

The resulting 4,100 barrels of thermal and straight run gasoline available as reforming feed boil Within the range 175 to 370 F. by ASTM distillation and are essentially free of aliphatic C to C6 hydrocarbons, containing less than about by Weight thereof. This stabilized gasoline has a Research Octane with 3 ccs. TEL of 70. This gasoline feed is reformed over an aromatiZation-type catalyst comprising about 0.6% by weight platinum impregnated on alumina. Reforming conditions include: 500 pounds per square inch gauge pressure, hydrogen to hydrocarbon mol ratio of 9, space velocity-temperature relationship maintained in the range of 0.5 to 2 (Volume of oil per hour per volume of catalyst) and 850 to 980 F. forming a reformate containing a 380 F end point gasoline, which, at a Reid Vapor Pressure or l0 pounds per square inch gauge, woud have a Research Octane with 3 ccs. TEL of about 102. The reformates are subjected to fractional distillation to remove C3 and lighter hydrocarbons and an aliphatic hydrocarbon fraction boiling in the range of C4 hydrocarbons to about 175 F. Also recovered from the distillation of the high pressure reformate are about 2,620 barrels of 160 to 380 F. end point, 40.0 API, stabilized reformate gasoline having a Research Octane with 3 ccs. TEL of 103.3. The stabilized reformate gasolines are essentially free of aliphatic C5 to C6 hydrocarbons, containing less than 10% by weight thereof. The stabilized reformate gasolines are aided to the motor gasoline blend at 25.

The C4 to 175 F. light reformate gasoline fractions from the high pressure reforming step amount to about 790 barrels. The light reformate fractions are subjected to fractional distillation in system 17, together with 95 barrels of C4 to 175 F. thermal gasoline and 1,250 barrels of light straight run gasoline. Recovered from the distillation system 17 are:

The isopentaue and normal butane fractions are added to the motor gasoline blend at 2'5. The butylene-isobutane fraction is added to the alkylation reactor at 23. The normal pentane-hexane fraction contains less than about 5% by fweight C4 and lighter hydrocarbons and less than about 10% by weight benzene and C7 and heavier aliphatic hydrocarbons. Equal parts by Weight of this fraction and steam are supplied to the initial pyrolytic cracking reactors at 18. Operating conditions in the cracking reactor include: inlet ternperature, 300 F., and maximum temperature reached near coil outlet, 1,525" F.; inlet and outlet pressures, and 20 pounds per square inch gauge, respectively; and reactant residence time within the reactor at temperatures in the range of 300 to l,525 F. about l second. The cracked product is quenched to a temperature of about 1,350 F. by Water injection at 19 and then cooled in a waste heat boiler to 700 to 900 F. The cracked products are passed to the product recovery system 20, in which about 1,295 barrels of an ethane fraction (including recycle at a rate of 555 barrels) are recovered and subjected to pyrolytic cracking in the cracking reactors at 21. Steam is added with the ethane to the extent of' about 30% by Weight of the hydrocarbon feed. Operating conditions in the ethane reactor include: inlet temperature, 60 F., and 1,570 F. reached near coil outlet; inlet and outlet pressures, 55 and 20 pounds per square inch gauge, respectively; reactant residence time in reactor within temperature range of 60 to 1,570 F., about l second.

Approximately 425 barrels of propane-propylene and butano-butylene hydrocarbons are recovered from product recovery system 20. The olefin content of these fractions is approximately by volume. This material is supplied to Athe alkylation unit 23 along with 170 barrels of butylene-isobutane fraction recovered in distillation system 17. Approximately 370 barrels of isobutane from an outside source are also supplied to the alkylation unit. The alkylation is conducted at a temperature of about 55 F. and a pressure of about 50 pounds per square inch gauge in the presence of about 50 to 55% by volume of 99 to 89% sulfuric acid catalyst. The alkylation products are subjected to fractionation at 24 to recover alkylate gasoline, heavier alkylate, propane and butane as products. if desired, the amount of alkylate gasoline may be increased by also alkylating unsaturated C3 to C4 hydrocarbons from the catalytic cracking products. This fraction may be alkylated separately or together with the unsaturated C3 to C4 hydrocarbons from the pyrolytic cracking products.

The product recovery system 20 is operated in the manner hereinabove described to recover the several products indicated on FIGURE l. Products resulting from the combined light gasoline cracking and alkylation operations are as follows:

Fuel gas pounds 49,90() Propane barrels 7 Butane do 3 Ethylene (99.8% pure) pounds 87,400 Butadiene (99.5% pure) do 12,200 Aromatic gasoline barrels-- 245 Aromatic distillate do 70 Alkylate gasoline do 760 The aromatic gasoline and alkylate gasoline are added to the motor gasoline blend at 25, and their properties, together with the properties of the other components of the final gasoline blend, are shown in Table III.

TABLE -II-l Components of Motor Gasolzne Blend Cnta- High Aro- C4 Absorp- Component lyticallgvv press. matic Alkylate Isohydrotion Total cracked reformate gasoline gasoline pentane carbone gasoline blend gasoline gasoline Amount in blend, bbls 2,850 2, 620 245 1 1,100 300 935 250 8, 300 Properties A P.I 58.0 40. 38. 4 71. 95. 7 76.0 58.0 108 105 105 160 130 125 238 165 210 270 230 303 286 310 375 R.V.P 6.4 10.0 12.3 Research octan lear 103. 6 95.0 93. 0 95.0 73.0 94. 5 t. 3 ecs. TEL 104. 2 104.0 102.0 103.0 88.0 100. 4 2.6 ccs. TFT; 100.0

1 Includes 340 bmrels of aklylate rulting from alkylation of unsaturated C3 to C4 hydrocarbons from the catalytic cracking step.

A small amount of absorption gasoline is recovered by treating the Wet gas streams from the renery gas producing units, such as the gas oil catalytic and thermal cracking units. The absorption gasoline may be conveniently added to the final gasoline blend, although this is not essential.

In addition to the C4 hydrocarbon fraction recovered in distillation system 17, about 635 barrels of C4 hydrocarbone (about 96% normal butane) from an outside source are added to -the nal gasoline blend at 26 to provide a Reid Vapor Pressure of 12.3 pounds per square inch gauge. This is an average of Reid Vapor Pressures considered satisfactory for yearly gasoline production. Quantity and properties of the final gasoline blend resulting from the combination process example above described are shown in Table Ill,

EXAALIPLE 2 In another example, 20,500 barrels of the crude mentioned in Example l are separated into the same fractions mentioned in Example 1, except that, instead of the C4 to 175 F. cut, a C4 to 200 F. cut is taken, which amounts to about 1,670 barrels, leaving 3,410 barrels of 200 to 370 F. end point heavier reformer charge gasoline. From the products resulting from viscosity breaking of the residuum fraction, about 241 barrels of 200 to 370 F. end point thermal gasoline are separated and added to the heavier reformer charge gasoline, and about 124 barrels of C4 to 200 F. light thermal gasoline are separated and added to the distillation system 17 along with the C4 to 200 F. cut from the crude.

The resulting 200 to 370 F. thermal and straight run reformer charge is essentially free of C5 to C7 aliphatic hydrocarbons, containing less than about by weight thereof, and amounts to 3,651 barrels. This charge is reformed under the same conditions as given in Example 1 to provide about 2,855 barrels of C3-free reformate gasoline, in this case including the C5 to C7 hydrocarbons.

The total feed to distillation system i7 consists of 1,670 barrels of C4 to 200 F. light straight run gasoline and 124 barrels of C4 to 200 F. thermal gasoline. Recov ered from distillation system 17 are:

Barrels Normal C4 fraction 175 Iso-C4-i-C4 `fraction (of which 40 barrels are iso- C4) 70 Iso-C5 fraction 195 Normal-C5--saturated aliphatic hexanes and heptanes 1,230

The normal pentane-heptane fraction, comprising light straight run and thermal gasolines, is subjected to pyrolytic cracking under the same conditions as given in Example l. Ethane recovered from product recovery system 20 is cracked in reactors 21. Fropane-propy-lene and butanehutylene fractions recovered from system 20 amount to 364 barrels and are alkylated in unit 23 with 70 barrels of butylene-isobutane fraction recovered from distillation system 117 together with sutlicient outside isobutaue to effect the desired alkylation. Products resulting from the combined light gasoline cracking and alkylation oper-V ation are recovered from system 20 as follows:

The aromatic gasoline and alkylate gasoline are added to the final gasoline blend at 25. Absorption gasoline is also added as in Example l, and sucient butanes are added to pressure the iinal blend to about 12.3 Reid Vapor Pressure. The components of the tinal gasoline blend are indicated in Table 1V.

TABLE 1V Components of Final Gasoline Blend From Example 2 Research octane Component R.V.P. Amount,

barrels Clear 3 ec. TEL

Oatalvtically cracked gaso- I me 5.3 89.3 96 0 2, 850 High pressure reiormate e 5. 5 95.0 102.0 2,855 6. 4 103. 6 104. 2 226 4. 0 95.0 104.0 l, 090 20. 0 93.0 102.0 195 C4 hydrocarbons 50. 5 95. 0 103. 0 990 Absorption gasoline 10. 0 73.0 88. 0 250 Total blend 12. 3 92. 6 100.0 8, 456

EXAMPLE 3 As a further example of the advantages of the process of this invention over previous methods, processing of a gasoline feed stock consisting of about 93% straight run and 7% thermal gasoline is considered. This gasoline has an A.P.l. gravity of 60 and boils in the range of C3 to 370 F. This Vfeed stock is processed in the following different Ways:

(A) The gasoline feed stock is fractionated to remove C3 and lighter hydrocarbons and to provide about 1,345 barrels per calendar day of a C4 to 175 F. light gasoline fraction and about 4,100 barrels per calendar day of a heavier to 370 F. gasoline fraction. The latter fraction, which has a Research Octane with 3 ccs. TEL of about 70, is subjected -to catalytic reforming in the manner described in Example 1. About 105 barrels of isopentane and 2,620 barrels of 160 to 380 F. end point stabilized reformate gasoline are recovered from the reformate and blended together with the C4 to 175 F. light gasoline fraction in the final motor gasoline blend. Also, 225 barrels of C4 hydrocarbons are recovered from the reforming products, but only 70 barrels of this can be added to the iinal motor gasoline blend Within the carburetor icing limits set for the finished gasoline.

(B) The gasoline feed is fractionated to remove C and lighter hydrocarbons and to recover about 245 barrels per calendar day of a C4 hydrocarbon fraction, 195 barrels per calendar day of an isopentane fraction, 905 barrels per calendar day of a C5 to C5 fraction containing aliphatic hydrocarbons 'other than isopentane `and 4,100 barrels per calendar lday of a he-avier 175 to 370 F. end point gasoline fraction. The latter fraction is reformed under the same conditions as in A above. The C5 to C5 fraction from the straight run gasoline and light reformate recycle is subjected to isomerization over a noble metal catalyst at about 750 fF., 250 pounds per square inch gauge and 2.0 volumes per hour per volume of catalyst space velocity to produce about 1,360 barrels of light gasoline product containing about 70% isomers. The light gasoline product from isomerization, the original `isopentane fraction and the 150 to 380 F. end point catalytic reformate (including isopentane formed in reforming) are blended together in the iinal gasoline blend. Also, about 205 barrels of the original C4 hydrocarbon `fraction are added to the final blend. This is all that can be used Within the set carburetor icing limit.

(C) The gasoline feed stock is fractionated -to `remove C3 and lighter hydrocarbons and to provide 245 barrels of a C4 lhydrocarbon fraction, 195 barrels of an isopentane fraction, 905 barrels of a fraction containing aliphatic C5 to C5 hydrocarbons other than isopentane and 4,100 barrels of 175 to 370 F. reformer charge gasoline. These fractions are processed in the manner indicated in Example l of this invention, the reforming conditions being the same as in A above. The charge to pyrolytic cracking consists of the 905 Ibarrels of the aliphatic C5 to C6 hydrocarbons other than isopentane from the gasoline feed stock kand 460 barrels of a similar fraction from the catalytic reformate. Conditions for the light gasoline cracking and alkylation operations are the same as for the above examples of operation in accordance with the method of this invention. In this case, gasoline resulting from thermal or catalytic cracking of the gas oil and residual portions of the crude are not added to the linal gasoline blend. The components of the iinal gasoline blend are:

i60-380 F. reformate 2,620 Alkylate (13G-400 F.) 760 Isopentane 300 Aromatic gasoline (S-286 F.) 245 C4 hydrocarbons 620 Total 4,545

In the case of each gasoline blend, sufficient C4 hydrocarbons were added from sources Within and outside the process to provide a final gasoline having the same volatility characteristics from the standpoint of carburetor icing. Because of the fact that gasoline blend C had Ia higher 50% mid boiling point, it was possible to blend to a lhigher Reid Vapor Pressure while still providing a motor gasoline of satisfactory volatility characteristics than in the case of gasolines A and B. Product yields and properties resulting form methods A, B and C Vare summarized in Table V.

TABLE V Properties and Yields of F z'nal Motor Gasoline Process Method A B C Quantity of final gasoline blend, bbl/CD 4, 600 4, 490 4, 545 Amount outside C4 hydrocarbons in blend,

bbl/CD 0 0 23H 315 205 620 l0. 7 10. 7 13. 4 98. 7 101. 5 103. 3

lt should be understood that the specific examples of operating conditions, apparatus arrangement 4and applications of this invention are exemplary in character and are not to be construed as limiting the scope of the invention thereto.

We claim:

l. A combination process for manufacturing from a gasoline-containing feed stock a high anti-knock engine fuel and ethylene which comprises: separating a gasoline reformer feed from said feed stock and subjecting it to a reforming operation under conditions controlled to provide a reformed product containing gasoline of improved anti-knock value, separating from at least one of said feed stock and reformed product a fraction including at least most of at least one of the contained straight chain, aliphatic hydrocarbon materials Within the range of C5 to C7 hydrocarbons; subjecting the fraction so separated to cracking under conditions controlled to convert it to a cracked product made up principally of hydrocarbons having less than five carbon atoms per molecule and rich in gaseous oleiins, including a substantial amount of ethylene, subjecting the cracked product to a separation operation to recover therefrom essentially pure ethylene as a product and withdrawing said ethylene product, and subjecting at least a substantial portion of the gaseous oleiins from said cracked product remaining after recovery of said ethylene product to a combining reaction in which said gaseous oleiins constitute at least a substantial portion of the reactants under conditions controlled to form a gasoline product of lower average volatility and higher anti-knock rating than said separated fraction which was subjected to cracking as aforesaid.

2. A process according to claim 1 further characterized in that said fraction, including said straight chain, aliphatic hydrocarbon materials Within the range of C5 to C7 hydrocarbons, is removed from both said feed stock and reformed product.

3. In a refining operation wherein a gasoline feed is subjected to a reforming operation under conditions controlled to provide a reformate gasoline product of improved anti-knock value, the improvement which comprises: separating from the stock containing reforming feed gasoline and from the reformate product at least most of at least one of the contained straight chain, aliphatic hydrocarbon materials Within the range of C5 to C7 hydrocarbons; subjecting said separated aliphatic hydrocarbon material to cracking at elevated temperatures to convert it into a product rich in gaseous oletins; subjecting at least a substantial portion of said gaseous oleiins to a combining reaction in which said gaseous olefns constitute at least a substantial portion of the reactants under conditions controlled to form a gasoline product of lower average volatility and higher average anti-knock rating than said separated aliphatic material; recovering said gasoline product and blending at least a substantial portion thereof With at least a substantial portion of the reformate gasoline from which said aliphatic hydrocarbon material has been separated and adding to the blend a volatile, combustible pressuring material to pressure the blend to a Reid Vapor Pressure Within the range of about 6 to 16 pounds per square inch gauge satisfactory for engine gasoline, said pressuring material having an anti-knock rating substantially higher than said separated aliphatic hydrocarbon material, the amount of pressuring material so t9 added to said blend being suiicient to provide a Reid Vapor Pressure substantially in excess of that which would cause engine carburetor icin:v in a blend of said reformate gasoline containing said separated, aliphatic material instead of the gasoline product from said combining operation.

4. In a process for manufacture of a gasoline of high anti-knock value by subjecting a petroleum gasoline feed to a reforming operation under conditions controlled to provide a gasoline product of improved anti-knock value, the improvement in combination therewith which cornprises: subjecting the stock containing the reforming feed gasoline and the reforming product to fractionation to effect removal therefrom of at least most of the normal pentane and saturated, aliphatic hexanes contained therein to provide a cracking feed stock made up principally of aliphatic C to C5 hydrocarbons; subjecting said cracking feed stock to cracking at an elevated temperature controlled to convert .it to a product rich in gaseous olens; subjecting at least a substantial portion of said olens to alkylation with suitable alkylatable hydrocarbon material yielding high octane gasoline boiling range hydrocarbons upon alkylation, whereby an alkylate is formed; separating a high anti-knock alkylate gasoline fraction from said alkylate; blending at least a substantial portion of said alkylate gasoline fraction with at least a substantial portion of the gasoline product from said reforming which remains after removal of said C5 to C5 hydrocarbons; and adding sufficient C4 hydrocarbons to the resulting blend to pressure Vit to a suitable Reid Vapor Pressure within the range of 6 to 16 pounds per square inch gauge, the amount of C4 hydrocarbons so added to said blend being sufficient to provide a Reid Vapor Pressure substantially in excess of that which would cause engine carburetor icing `in a blend of said reformer gasoline product containing said separated, aliphatic, C5 to C6 hydrocarbons instead of said alkylate gasoline.

5. A combination process for manufacturing from a gasoline feed stock a high anti-knock engine fuel and ethylene, which comprises: subjecting at least most of said gasoline feed stock to reforming under conditions controlled to form a reformed product containing reformate gasoline of improved anti-knock rating; separating from at least one of said gasoline feed stock and reformed product at least most of at least one of the contained aliphatic hydrocarbon materials within the range of C5 to Cf, hydrocarbons; subjecting the aliphatic hydrocarbon materials so separated to pyrolytic cracking at temperatures within the range of about 1,300 to 1,750" F. and under conditions controlled to convert said material to a cracked product made up principally of hydrocarbons having less than tive carbon atoms per molecule and containing substantial amounts of gaseous olefins, including ethylene; subjecting said cracked product to a separation operation to recover essentially pure ethylene therefrom as a product and to recover a gaseous feed stock rich in at least one olefin within the range of C5 to C4 olelns; subjecting said last-named feed stock to a combining reaction, in which the constituents of said lastnamed feed stock constitute at least a substantial portion of the reactants, to form a gasoline product having a lower average volatility and higher anti-knock rating than said separated aliphatic hydrocarbon material.

6. 1n a refining operation wherein fractions of mixed hydrocarbons of differing boiling points are subjected to a plurality of refining process steps to prepare a plurality of refinery pool gasoline fractions, each of which is ultimately utilized as a component in at least one nal gasoline product, and wherein one of said process steps involves reforming of a gasoline feed fraction of relatively low anti-knock rating at an elevated temperature to form a reformed gasoline product of improved anti-knock rating, a method for increasing the overall anti-knock rating and decreasing the overall low octane volatility of the total of said renery pool gasoline fractions, while also manufacturing ethylene as a product, which method comprises: subjecting the hydrocarbon fraction containing said gasoline reformer feed to at least one separation operation to provide a reformer gasoline feed; subjecting said reformer feed, at an elevated temperature, to reforming under conditions controlled to effect conversion to a reformed product containing gasoline of substantially improved anti-knock rating; subjecting said reformed product to at least one separation operation to remove therefrom at least the C5 and lighter hydrocarbons and to provide a stabilized reformate gasoline; separating from the material being processed in at least one of said separation operations at least most of at least one of the contained aliphatic hydrocarbon materials within the range of C5 to C7 hydrocarbons; subjecting the hydrocarbon material so separated to pyrolytic cracking at temperatures within the range of about 1,300 to 1,750 F. and under conditions controlled to convert said material to a cracked product made up principally of hydrocarbons having less than five carbon atoms per molecule and containing substantial amounts of gaseous oleiins, including ethylene; subjecting said cracked product to a separation operation to recover essentially pure ethylene therefrom as a product and to recover an alkylation feed stock rich in at least one olefin within the range of C3 to C4 olens; subjecting said last-named feed stock to alkylation with a suitable alkylatable material to form an alkylate gasoline of high anti-knock rating; recovering said alkylate gasoline, and utilizing the same as one of said refinery pool gasoline fractions, and utilizing the remaining stabilized reformate as another of said refinery pool gasoline fractions.

7. A combination process for manufacturing from a gasoline-containing feed stock a high anti-knock engine fuel and gaseous oleiin product which comprises: separating a gasoline reformer feed from said feed stock and subjecting it to a reforming operation under conditions controlled to provide a reformed product containing reformed gasoline of improved anti-knock value, separating from said feed stock and from said reformed product at least most of at least one of the contained straight chain, aliphatic hydrocarbon materials within the range C5 to C7 hydrocarbons, subjecting the so separated aliphatic hydrocarbon material to cracking under conditions controlled to convert it to a cracked product made up principally of hydrocarbons having less than five carbon atoms per molecule and rich in gaseous oleiins, including substantial amounts of olens in the range C2 to C3 oleiins, recovering from the cracked product by separation at least one essentially pure olefin within the range C2 to C3 oleiins as product, and withdrawing said separated olefin as product, treating at least a portion of the remaining cracked product to derive therefrom at least one hydrocarbon material boiling in the gasoline range and having a higher anti-knock rating than said separated straight chain aliphatic material, preparing a Ifinal gasoline blend containing at least most of the gasoline from said reformed product remaining after separation of said aliphatic hydrocarbon material and adding to the blend a volatile, combustible, pressuring material to pressure the blend to a Reid Vapor Pressure within the range of about 6 to 16 pounds per square inch gauge satisfactory for engine gasoline, said pressuring material having an anti-knock rating substantially higher than said separated, straight chain, aliphatic material, the amount of pressuring material so added to said blend being sufficient to provide a Reid Vapor Pressure substantially in excess of that which would cause engine carburetor icing in a blend of said reformed gasoline containing said separated aliphatic material.

8. In a refining operation wherein petroleum crude fractions are subjected to a plurality of refining process steps to prepare a plurality of refinery pool gasoline fractions, each of which is ultimately used as a component in blending at least one nal blended gasoline, and wherein one of said process steps involves reforming of a gasoline feed fraction at elevated temperature in the presence of a reforming catalyst to form a reformed gasoline product of improved anti-knock rating, a method for increasing the overall anti-knock rating and decreasing the overall low octane volatility of the total of said refinery pool gasoline fractions so as to permit inclusion of an increased total amount of said pressuring material in the tota-l of the final blended gasolines requiring pressuring and, at the same time, manufacturing ethylene as a product, which method comprises: separating from said reformed gasoline product at least most of at least one of the contained low octane, straight chain aliphatic hydrocarbon materials selected from the group consisting of normal pentane, straight chain C6 hydrocarbons, branched chain C6 hydrocarbons, straight chain C7 hydrocarbons and branched chain C7 hydrocarbons; subjecting the so separated aliphatic hydrocarbon material to cracking at an elevated temperature under conditions controlled to convert it to a product made up principally of hydrocarbons having less than tive carbon atoms per molecule, said product being rich in gaseous oletins, including a substantial amount of ethylene; subjecting said cracked product to a separation operation to recover ethylene therefrom as a product and to recover a gaseous feed stock rich in at least one olefin within the range of C3 to C4 oletins; withdrawing the separated ethylene as essentially pure product, subjecting at least a substantial portion of said feed stock to a combining reaction in which the constituents of said last-named feed stock constitute at least a substantial portion of the reactants to form a gasoline product having a lower average volatility and higher anti-knock rating than said separated aliphatic material; recovering the gasoline from said combining reaction, and utilizing the same as one of said reiinery pool gasoline fractions.

9. A combination process for manufacturing from a gasoline-containing feed stock a high anti-knock engine fuel and gaseous olen product which comprises: separating a gasoline reformer feed from said feed stock and subjecting it to a reforming operation under conditions controlled to provide a reformed product containing gasoline of improved anti-knock value, separating from at least one of said feed stock and reformed product a fraction including at least most of at least one of the contained straight chain, aliphatic hydrocarbon materials within the range C to C, hydrocarbons, subjecting the fraction so separated to cracking under conditions controlled to convert it to a cracked product made up principally of hydrocarbons having less than tive carbon atoms per molecule and rich in gaseous oleiins, including substantial amounts of oleiins in the range C2 to C3 oleiins, subjecting the cracked product to a separation operation to recover therefrom at least one essentially pure olelin within the range C2 to C3 oleiins as a product and withdrawing said separated oleiin as a product, subjecting at least a substantial portion of the gaseous oleinic material from said cracked product remaining after recovery of said essentially pure olefin to a combining reaction in which said gaseous olefinic material constitutes at least a substantial portion of the reactants under conditions controlled to form a gasoline product of lower average volatility and higher anti-knock rating than said separated fraction which was subjected to cracking as aforesaid, selectively adjusting the amount of at least one pure olefin Within the range C2 to C3 olens which is separated from said cracked product as product, depending upon requirements for said pure olefin product, and including at least a substantial portion of said lastnamed olen which is unrecovered as product in the gaseous oletinic material which is subjected to said com,- bining reaction.

10. A combination process for manufacturing from a gasoline-containing feed stock a high anti-knock engine fuel and gaseous oleiin product which comprises: separating a gasoline reformer feed from said feed stock and subjecting it to a reforming operation under conditions controlled to provide a reformed product containing gasoline of improved anti-knock value, separating from at least one of said feed stock and reformed product a fraction including at least most of at least one of the contained straight chain, aliphatic hydrocarbon materials within the range C5 to C7 hydrocarbons, subjecting the fraction so separated to cracking under conditions controlled to convert it to a cracked product .made up principally of hydrocarbons having less than tive carbon atoms per molecule and rich in gaseous oletins, including substantial amounts of oletins in the range C2 to C3 oleiins, subjecting the cracked product to a separation operation to recover therefrom at least one essentially pure olefin within the range C2 to C3 olens as product, and withdrawing said separated olen as a product, selectively adjusting the amount of at least one pure olefin within the range C2 to C3 oletius which is withdrawn as product as aforesaid, depending upon requirements for said pure olefin product, whereby, during periods of low product requirement, there is an excess of said olefin, and subjecting at least a substantial portion of any such excess to a combining reaction in which said olefin constitutes at least a substantial portion of the reactants under conditions controlled to form a gasoline product of lower average volatility and higher anti-knock rating than said separated fraction which was subjected to crackin-g as aforesaid.

ll. In a process wherein a petroleum gasoline fraction is subjected to reforming at elevated temperatures in the presence of hydrogen under pressure over a catalyst having a substantial aromatization activity to form a reforming product containing high anti-knock gasoline, the improvement in lcombination therewith which comprises: subjecting a petroleum reforming feed stock to fractionation to essentially remove C3 and lighter hydrocarbons and a light gasoline fraction made up of hydrocarbons boiling in the range of C4 hydrocarbons to about 160 to 200 F. and to provide a higher boiling gasoline fraction as a feed for said reforming; subjecting said reforming product to fractionation to remove C3 and lighter hydrocarbons and a light re-formate fraction made up of hydrocarbons boiling in the range of C4 hydrocarbons to about 16() to 200 F, and to provide a higher boiling reformate gasoline; subjecting said light gasoline and light reformate fractions to fractionation to effect recovery therefrom of an isopentane fraction and a cracking feed stock boiling essentially in the range of aliphatic hydrocarbons above isopentane and below C7 hydrocarbons and containing at least most of the normal pentane and hexane from said light gasoline fractions; subjecting said cracking feed stock to cracking at elevated temperatures to convert the same into a cracked product made up principally of hydrocarbons having less than five carbon atoms per molecule, said product being rich in unsaturated gaseous hydrocarbons, including a substantial amount of ethylene; subjecting said product to a separation operation to recover therefrom ethylene as a product and an alkylation feed made up of oleiinic hydrocarbon material having a number of ycarbon atoms per molecule within the range of 3 to 4; withdraw-ing the separated ethylene as an essentially pure product, alkylating said alkylation feed with an alkylatable material suitable to yield upon alkylation with said feed an alkylate containing substantial amounts of high anti-knock gasoline boiling range material, recovering the high anti-knock alkylate gasoline from said alkylate and blending at least a substantial portion of said alkylate gasoline together with at least a substantial portion of said isopentane fraction and at least a substantial portion of said heavier reformate gasoline; and adding C4 hydrocarbons to the resulting blend in suticient amount to provide a blend Reid Vapor Pressure Within the range of about 6 to 16 pounds per square inch gauge; whereby normal pentane and hexane from the reforming feed and products are converted to more valuable products, while relatively large am unts of C4 hydrocarbons are incorporated into the final gasoline blend, which is of high anti-knock value and good Volatility characteristics for use in gasoline engines.

12. A combination process for manufacturing from a mixed hydrocarbon feed stock unsaturated, gaseous hydrocarbons and a high anti-knock gasoline having satisfactory volatility characteristics for use as a motor gasoline, which comprises: subjecting said feed stock to a fractionation operation to remove therefrom C4 and lighter hydrocarbons, an isopentane cut and an aliphatic C5 to C6 hydrocarbon cut containing at least most of the normal pentane and saturated aliphatic hexanes from said feed stock and to provide a reformer feed fraction boiling essentially below about 410 F.; reforming said reformer feed fraction under conditions controlled to form a reformate-containing gasoline of substantially increased anti-knock value; subjecting said reformate to fractionation to remove therefrom C4 and lighter hydrocarbons, an isopentane cut and an aliphatic C5 to C6 hydrocarbon cut containing at least most of the normal pentane and saturated aliphatic hexanes from said reformate and to provide a stabilized, reformed gasoline which is substantially free of at least normal pentane and saturated, aliphatic hexanes; subjecting at least the normal pentane and saturated, aliphatic heXanes recovered from said feed stock and said reformate to cracking at an elevated temperature level under conditions controlled to effect substantial conversion to a cracked product made up principally of hydrocarbons having less than five carbon atoms per molecule, said cracked product containing substantial amounts of gaseous, olelinic hydrocarbons, including a substantial amount of ethylene; subjecting said cracked product to a separation operation to provide therefrom ethylene as a product and an olefin-rich fraction containing principally hydrocarbons falling in the range of C3 to C4 hydrocarbons; withdrawing the separated ethylene as an essentially pure product, subjecting said olefin-rich fraction to alkylation with alkylatable hydrocarbon material suitable to yield, when alkylated with said olefin-rich fraction, an alkylate containing substantial amounts of high anti-knock, branched chain hydrocarbons in the gasoline boiling range; separating an alkylate gasoline of high anti-knock Value from said `alkylate; blending together at least a substantial portion of said alkylate gasoline with at least a substantial portion of said stabilized, reformed gasoline and at least a substantial portion of the isopentane recovered from said feed stock and said reformate; and adding C4 hydrocarbon material to the blend to pressure it to a Reid Vapor Pressure within the range of 6 to 16 pounds per square inch gauge, satisfactory for motor gasoline; whereby there is provided a high anti-knock value motor gasoline having Volatility characteristics suitable `for use as motor gasoline.

13. A process according to claim 12 further characterized in that said higher boiling reformer feed fraction is reformed over a reforming catalyst suitable for promoting conversion of naphthenes to aromatics at elevated temperatures within the range of about 850 to 1,100 F. and pressures within the range of about 50 to 1,000 pounds per square inch gauge, in the presence of hydrogen in the amount of about 0.5 to 20 mois of hydrogen per mol of hydrocarbon feed, and said cracking of the C5 to C6 aliphatic hydrocarbons is conducted at temperatures within the range of about 1,300 to 1,750 F. and under conditions controlled to convert said material to a cracked product made up principally of hydrocarbons having less than five carbon atoms per molecule.

14. A process according to claim l2 further characterized in that said normal pentane and saturatedaliphatic hexanes recovered from said feed stock and said reformate are subjected to pyrolytic cracking at temperatures within the range of about 1,300 to 1,750 F. and under conditions controlled to convert said material to a cracked product containing some normally liquid aromatics but made up principally of hydrocarbons having less than live carbon atoms per molecule and containing substantial amonnts of gaseous clelins, including substantial amounts of ethylene and butadiene, and said cracked product is subjected to a separation step to recover as products ethylene, butadiene, an aromatic gasoline, an aromatic distillate boiling above the motor gasoline range and an olefin-rich fraction containing substantial amounts of propylenes and butylenes, Which latter fraction is alkylated as aforesaid with isoparafinic material, said isoparafnic material being made up principally of isobutane, and said aromatic gasoline is added to said blend of stabilized, reformed gasoline, alkylate gasoline, isopentane and C4 hydrocarbon material.

15. A process according to claim 6 further characterized in that butadiene is separated from said cracked product as a separate product in addition to ethylene and in that said olefin-rich alkylation -feed is subjected to alkylation with added isobutane.

16. A process according to claim 6 further characterized in that, in the fractionation of said hydrocarbon fraction containing the gasoline reformer feed, C3 and lighter hydrocarbons are removed and a light gasoline fraction boiling in the range of C4 hydrocarbons to about to 210 F. end point is recovered in addition to said reformer gasoline feed and said light gasoline fraction is further fractionated together with a light reformate fraction to separate C4 hydrocarbons from materia-l boiling thereabove, which latter are subjected to cracking; and, in the fractionation of said reformed product, C3 and lighter hydrocarbons are removed and a light reformate fraction boiling in the range of C4 hydrocarbons to about 160 to 210 F. end point is recovered in addition to said stabilized reformate gasoline, said light reformate being further fractionated together with said light gasoline fraction as aforesaid.

17. A combination process for manufacturing from a petroleum gasoline feed stock petrochemical products and a high anti-knock motor fuel of suitable volatility `characteristics, which comprises: subjecting said feed stock to fractionation to remove C3 and lighter hydrocarbons and to provide a light gasoline fraction containing hydrocarbons boiling Within the range of C4 hydrocarbons to about 160 to 200 F. and a heavier gasoline fraction boiling above about 160 to 200 F. and having an ASTM end point within the range of about 300 to 410 F; subjecting said light gasoline fraction along with a light reformate to fractionation to provide a normal butane fraction, a butylene-isobutane fraction, an isopentane fraction and a light cracking feed cut made up principally of straight chain C5 to C6 hydrocarbons; reforming said heavier gasoline over a catalyst having an aromatization activity at temperatures within the range of about 850 to 1,100 F. and in the presence of hydrogen under pressure to form a reformate containing a high anti-'knock gasoline; fractionating said reformate to remove C3 and lighter hydrocarbons and to provide a light reformate boiling within the range of `C4 hydrocarbons to about 160 to 200 F. and a reformate gasoline boiling above about 160 to 200 F. and having an ASTM end point Within the range of about 300 to 410 F., said reformate gasoline being substantially `free of CG and lighter aliphatic hydrocarbons; subjecting said light reformate to spedite rfractionation along with said light gasoline fraction as aforesaid; subjecting said lightcrackihg feed cut to pyrolytic cracking at temperatures within the range of about 1,300 to 1,750 F. and under conditions controlled to convert said material to la cracked product containing some aromatics but made up principally of hydrocarbons having less than lfive carbon atoms per molecule, including substantial amounts of ethylene; subjecting said cracked product to a separation operation to provide an ethylene fraction, a butadiene fraction, an aromatic gasoline fraction and a C3 to C4 hydrocarbon fraction rich in propylenes and butylenes; subjecting said latter fraction together with said butylene-isobutane fraction and added isobutane to alkylation under conditions controlled to provide an alkylate rich in branched chain hydrocarbons; separating a high anti-knock, alkylate gasoline from said alkylate; blending said alky-late gasoline together with said normal butane fraction, said isopentane fraction, said reformate gasoline and said aromatic gasoline; and adding to the blend sulicient additional C4 hydrocarbon material to provide a Reid Vapor Pressure within the range of about 6 to 16 pounds per square inch gauge.

18. A combination process for manufacturing from a petroleum lfeed stock of broad boiling range unsaturated, gaseous hydrocarbons and a high anti-knock gasoline having satisfactory volatility characteristics for use as a motor gasoline, which comprises: fractionating said feed Stock to remove therefrom C4 and lighter hydrocarbons, an isopentane cut, light gasoline comprised principally of C to C6 aliphatic hydrocarbons other than isopentane, a higher boiling gasoline fraction essentially free of saturated aliphatic hexanes and lower boiling aliphatic hydrocarbons and a distillate boiling above motor gasoline; subjecting said distillate to cracking at elevated temperatures to provide a rst cracked product containing cracked gasoline; subjecting said product to fractionation to recover therefrom a stabilized, cracked gasoline essentially free of C3 and lighter hydrocarbons; reforming said higher boiling gasoline fraction at temperatures within the range of about 850 to l,100 F. in the presence of hydrogen over a catalyst suitable for effecting aromatization of naphthenes to aromatics so as to form a reformate containing gasoline of substantially increased anti-knock value; fractionating said reformate to remove therefrom C4 and lighter hydrocarbons, an isopentane cut and light reformate made up principally of C5 to C5 aliphatic hydrocarbons other than isopentane and to provide a stabilized, reformed gasoline which is substantially free of at least the normal pentane and saturated, aliphatic hexanes; subjecting said light reformate and said light gasoline to pyrolytic cracking at temperatures within the range of `1,300 to l,750 F. under conditions controlled to effect substantial conversion to a second cracked product made up principally of hydrocarbons having less than five carbon atoms per molecule and containing substantial amounts of gaseous, olefinic hydrocarbons, including substantial amounts of ethylene; subjecting said second cracked product to a separation operation to provide therefrom at least ethylene as a product and an oleinrich fraction containing principally hydrocarbons having Within the range of 3 to 4 carbon atoms per molecule; subjecting said olefin-rich fraction to alkylation with alkylatable hydrocarbon material suitable to yield upon alkylation with said `fraction an alkylate rich in branched chain hydrocarbons within the gasoline boiling range; separating an alkylate gasoline of high anti-knock value from said alkylate; blending at least a substantial portion of said alkylate gasoline with at least a substantial portion of said stabilized, reformed gasoline and said stabilized, cracked gasoline and at least a substantial portion 36 of the isopentane recovered from said feed stock and said reforrnate; and adding C4 hydrocarbon material to the blend to pressure it to a Reid Vapor Pressure within the range of 6 to 16 pounds per square inch gauge, satisfactory for motor gasoline.

19. A combination process for manufacturing from a gasoline-containing feed stock a high anti-knock engine fuel and ethylene which comprises: separating a gasoline reformer feed from said feed stock and subjecting it to a reforming operation under conditions controlled to provide a reformed product containing gasoline of improved antiknock value, separating from at least one of said feed stock and reformed product a fraction including at least most of at least one of the contained straight chain, aliphatic hydrocarbon materials within the range of C5 to C7 hydrocarbons; subjecting the fraction so separated to pyrolytic cracking at temperatures within the range of about 1300 to l750 F. and under conditions controlled to convert said material to a cracked product made up principally of hydrocarbons having less than tive carbon atoms per molecule and containing substantial amounts of gaseous olefins, including substantial amounts of ethylene, separating essentially pure ethylene from said cracked product and withdrawing said ethylene as a product, treating at least a portion of the remaining cracked product to derive therefrom at least one hydrocarbon material boiling in the gasoline range and having a higher antiknock rating than said separated straight chain aliphatic material, preparing a final gasoline blend containing at least most of the gasoline from said reformed product and adding to the blend a volatile, combustible, pressuring material to pressure the blend to a Reid Vapor Pressure within the range of about 6 to 16 pounds per square inch gauge satisfactory for engine gasoline, said pressuring material having an anti-knock rating substantially higher than said separated straight chain, aliphatic material.

20. A process according to claim 18 further characterized in that a fraction made up principally of C5 to C6 aliphatic hydrocarbons is separated from said Ifirst cracked product and is subjected to pyrolytic cracking along with said light gasoline fraction and said light reformate.

Z1. ln a refining operation wherein a gasoline feed is subjected to a reforming operation under conditions controlled to provide a reformate gasoline product of improved anti-knock value, the improvement which com.- prises: separating from the stock containing reforming feed gasoline and from the reformate product C4 and lighter hydrocarbons and at least most of the normally liquid, straight chain hydrocarbons boiling within the gasoline boiling range, including C5 to C7 straight chain hydrocarbons; subjecting said normally liquid hydrocarbons to cracking at elevated temperatures to convert the same into a product rich in gaseous olefins; subjecting at least a substantial portion of said gaseous oleflns to a combining reaction in which said gaseous oleiins constitute at least a substantial part of the reactants, under conditions controlled to form a gasoline product of substantially higher anti-knock rating than said separated, normally liquid hydrocarbons; and blending at least a substantial portion of said gasoline product with the reformate gasoline remaining after separation of said normally liquid hydrocarbons to provide a high anti-knock gasoline blend.

22. A combination process for manufacturing from a gasoline feed stock a high anti-knock engine fuel and ethylene, which comprises: subjecting at least most of said gasoline feed stock to reforming under conditions controlled to form a reformed product containing reformate gasoline of improved anti-knock rating; separating

Claims

6. IN A REFINING OPERATION WHEREIN FRACTIONS OF MIXED HYDROCARBONS OF DIFFERING BOILING POINTS ARE SUBJECTED TO A PLURALITY OF REFINING PROCESS STEPS TO PREPARE A PLURALITY OF REFINEY POOL GASOLINE FRACTIONS, EACH OF WHICH IS ULTIMATELY UTILIZED AS A COMPONENT IN AT LEAST ONE FINAL GASOLINE PRODUCT, AND WHEREIN ONE OF SAID PROCESS STEPS INVOLVES REFORMING OF A GASOLINE FEED FRACTION OF RELATIVELY LOW ANTI-KNOCK RATING AT AN ELEVATED TEMPERATURE TO FORM A REFORMED GASOLINE PRODUCT OF IMPROVED ANTI-KNOCK RATING, A METHOD FOR INCREASING THE OVERALL ANTI-KNOCK RATING AND DECREASING THE OVERALL LOW OCTANE VOLATILITY OF THE TOTAL OF SAID REFINERY POOL GASOLINE FRACTIONS, WHILE ALSO MANUFACTURING ETHYLENE AS A PRODUCT, WHICH METHOD COMPRISES; SUBJECTING THE HYDROCARBON FRACTION CONTAINING SAID GASOLINE REFORMER FEED TO AT LEAST ONE SEPARATION OPERATION TO PROVIDE A REFORMER GASOLINE FEED; SUBJECTING SAID REFORMER FEED, AT AN ELEVATED TEMPERATURE, TO REFORMING UNDER CONDITIONS CONTROLLED TO EFFECT CONVERSION TO A REFORMED PRODUCT CONTAINING GASOLINE OF SUBSTANTIALLY IMPROVED ANTI-KNOCK RATING; SUBJECTING SAID REFORMED PRODUCT TO AT LEAST ONE SEPARATION OPERATION TO REMOVE THEREFROM AT LEAST THE C3 AND LIGHTER HYDROCARBONS AND TO PROVIDE A STABILIZED REFORMATE GASOLINE; SEPARATING FROM THE MATERIAL BEING PROCESSED IN AT LEAST ONE OF SAID SEPARATION OPERATIONS AT LEAST MOST OF AT LEAST ONE OF THE CONTAINED ALIPHATIC HYDROCARBON MATERIALS WITHIN THE RANGE OF C5 TO C7 HYDROCARBONS; SUBJECTING THE HYDROCARBON MATERIAL SO SEPARATED TO PYROLYTIC CRACKING AT TEMPERATURES WITHIN THE RANGE OF ABOUT 1,300 TO 1,750*F. AND UNDER CONDITIONS CONTROLLED TO CONVERT SAID MATERIALS TO A CRACKED PRODUCT MADE UP PRINCIPALLY OF HYDROCARBONS HAVING LESS THAN FIVE CARBON ATOMS PER MOLECULE AND CONTAINING SUBSTANTIAL AMOUNTS OF GASEOUS OLEFINS, INCLUDING ETHYLENE; SUBJECTING SAID CRACKED PRODUCT TO A SEPARATION OPERATION TO RECOVER ESSENTIALLY PURE ETHYLENE THEREFROM AS A PRODUCT AND TO RECOVER AN ALKYLATION FEED STOCK RICH IN AT LEAST ONE OLEFIN WITHIN RANGE OF C3 TO C4 OLEFINS; SUBJECTING SAID LAST-NAMED FEED STOCK TO ALKYLATION WITH A SUITABLE ALKYLATABLE MATERIAL TO FORM AN ALKYLATE GASOLINE OF HIGH ANTI-KNOCK RATING; RECOVERING SAID ALKYLATE GASOLINE OF HIGH UTILIZING THE SAME AS ONE OF SAID REFINERY POOL GASOLINE FRACTIONS, AND UTILIZING THE REMAINING STABILIZED REFORMATE AS ANOTHER OF SAID REFINERY POOL GASOLINE FRACTIONS.