US2250410A - Catalytic treatment of hydrocarbons - Google Patents

Description

-Patented 1941 I CATALYTIC TREATMENT or uroaooannons I Adrianus Johannes van Peski, Neth erlands, assignor to Shell Development Company, San Francisco, Call! a corporation of Delaware No Drawing. Application April as, 1939, Serial No. 270,655. In the Netherlands May 21, ms

3 Claims.

This invention relates to the catalytic isomerization of saturated hydrocarbons.

A principal object of the invention is to provide a practical and economical-process for the production of commercially valuable branched or more highly branched chain paraflin hydrocarbons from normal or only slightly branched chain paraflln hydrocarbon-s containing at least five.

carbon atoms per molecule and boiling at a temperature not substantially greater than about r60" 0.

The process of the invention is of great'com- .mercial importance in that it provides a direct method for the production, via catalytic isomerization, of isoparafiln hydrocarbons from the more available and less valuable normal paraflln hydrocarbons such as normal pentane, normal hexane, normal heptane, normal octane, etc. The

isoparailins which contain at least flve carbon atoms are useful as motor fuels and as components of. anti-knock motor fuel compositions. In addition, the lower isoparaflins such as isopentane and the isohex-anes are valuable starting materials in the production of tertiary oleflnes which in turn are valuable starting materials for.

the production of highly branched chain paraifin hydrocarbon motor fuels and motor fuel constituents via polymerization and hydrogenation or by direct coupling or alkylation with an iso- -pa-raflin. The process of the invention can he applied to the individual normal or slightly branched chain paraiiln hydrocarbons to increase their anti-knock value or it may be applied didrocarbon molecule of amore condensed type;

rectly to hydrocarbon fuel mixtures, such as straight-run gasolines, containing relatively high.

percentages of normal or only slightly branched chain paraflin hydrocarbons to isomerize said hydrocarbons and thus increase the total antiknock value of the fuel mixture with a minimum or treatment and loss of the treated material.

The process of this invention comprises contacting the hydrocarbon to be treated, or a mixture or such hydrocarbons, with a catalyst consisting of or essentially comprising an acid-acting halide at a temperature not greater than about 150 C. under a pressure sufliclently high to ensure the presence of a liquid phase in the system and in the presence of such an amount of a hydrogen halide that the partial pressure of the hydrogen halide in the system is equal to at least three atmospheres.

The treatment of normally liquid paraflin hydrocarbons boiling up to about 160 C. in accordance withthe process of the invention has the apparent efiect oi displacing the end groups of the hydrocarbon molecule toward the center of the carbon chain; consequently, the process may be applied to the treatment of any such saturated hydrocarbon possessing a structure capable of modification in such a way as to result in a hy- The process can be applied to theisomerizatlon to isoparattin hydrocarbons oi anyoi the normal paraiiin hydrocarbons higher than butane. Suitable normal parailin hydrocarbons are normal pentane, normal hexane, normal heptane, nor- .mal octane, normal ncnanes, etc. The hydrocarbons treated are preferably those which boil at a temperature not greater than about 160 C.

The process may be applied to the treatment of a suitable pure or substantially pure normal hydrocarbon or to a mixture consisting of or comprising one or a plurality of such hydrocarbons.

For example, a suitable starting material may comprise, besldes'a substantial amount of a suitable normal or slightly-branched chain 'paraflin hydrocarbon, one or a plurality of other hydrocarbons which may not be capable of isomerization under the conditions of operation, and/orone or more non-aqueous inert diluent materials.

.If desired, relatively inert diluent gases such as hydrogen, nitrogen, carbon dioxide, methane,

ethane, etc., may be introduced into the reaction zone to aid in establishibg and/or maintaining the desired operating pressure.

The process is executed in the presence of a catalyst consisting of or essentially comprising an acid-acting halide. The term acid-acting hallde"'is used herein and in the appended claims to designate those active'metal or non-metal halides (other than' the hydrogen halides) which will give an acid reaction in water. Representative acid-acting halides are the halides oi aiuml-- num, zinc, iron, arsenic, antimony, molybdenum, tungsten, cadmium, beryllium, tin, boron, and the like. The metal halides, particularly the chic "rides of the'above-listed metals, form a preferred upon the particular catalyst or catalyst mixture selected, upon the material to be treated and, to a certain extent, upon the conditions of operation, and may vary 'over a wide range. In general, the catalyst may be advantageously emis set by th isomerization will take place at a practical rate ter ' halide in the system being equal to at least three atmospheres. The

is a catalyst for has failed to provide any bons because of that .by operating under a reactions usually occur to an undesired extent. The lower limit of the practical operating range temperature at which the desired and will depend upon the particular hydrocarbon material treated, the particular catalyst employed, the total pressure in the system, and the partial pressure of the hydrogen halide in the system. A favorable conversion of the treate hydrocarbon material is sometimes obtained at room temperature or only slightly elevated temperatures. For example, when is treated, conversion to isopentane can be eiiected at a practical rate at temperatures below 50 C. and even as low as 20 C.

The process is executed under a superatmospheric pressure, the total pressure in the system being sumcientlyhigh to ensure the presence of a liquid phase of hydrocarbon inthe sysand the partial. pressure of a hydrogen total pressure inthe system will in all cases be equal to at least three atmospheres and will depend upon the surev oi the hydrogen haifde under which it is desired to operate, upon the temperature of operation, and upon the vapor pressure of the other components or the reaction system at the operating temperature. Total pressures as high as 20 atmospheres, and. higher, may be conveniently employed. In general, total pressures o! from about 3 to about 15 atmospheres are preierred. v

The partial pressure of the hydrogen halide in the system should'in all cases be equal to at least three atmospheres and be as high as 20 atmospheres or higher. In general, the process is preferably operated with a partial pressure of a hydrogen halide in, the system of from 3 to about 15 atmospheres. Since the actual partial pressure or hydrogen halide under the reaction conditions depends upon several factors such as the temperature, solubility, etc., and is diflicult to determine accurately, the partial pressures of hydrogen halide herein referred to are those measured when the reaction mixture is first brought to a temperature of 20 C.

It is known that aluminum chloride in the presence of a small amount of hydrogen chloride the isomerization of the normal However, this knowledge technically feasible process for the conversion of the liquid normal parailin hydrocarbons to isoparamn hydrocarthe fact that the isomerization reaction proceeds at a prohibitively low rate at the low temperatures necessary to avoid excessive cracking of the treated and resultant hydrocarbon. I have made the unexpected discovery total pressure in the reaction system sufllci'ent to maintain a liquid phase therein and increasing the partial presparaflin hydrocarbons.

about 150 (3., losses of material due to cracking.and"other degradation normal pentane sions characteristic of 1 atmosphere appears tome the minimum prac. tical operating partial pressure or the hydrogen halide at which the highand selective converthe process areobtained. As the partial pressure or the the system is increased from about 1 atmosphere to about 20 atmospheres, other conditions being the same, higher conversions of the desired isoparafllns are obtained per time. -In general, I prefer to operate with a partial .pressure of a hydrogen halide in the system of from about 3 to about atmospheres.

The term hydrogen halide" as used herein Y and in the appended claims embraces hydrogen chloride, hydrogen bromide, hydrogen iodide and hydrogen fluoride. In most cases hydrogen chloride is suitable, and, due to its availability and cheapness, its use is preierre'd. halide from any source is suitable. Since the process is preferably executed in the substantial absence or water, care should be taken to avoid introduction of water into the system with the partial presit may, if desired,

from the unreacted material is constituents of the reaction mixture.

One oi the practical advantages or the process of the invention is that the desired conversion or the treated hydrocarbon material to branched or more branched chain hydrocarbon material can be effected with the use of relatively shorter treatment times than are'required by the known methods without the necessity of increasing the temperature and thereby increasing the extent 0! occurrence of undesired degradation reactions. The time or treatment will depend upon the particular hydrocarbon material treated, upon the particular catalyst employed, upon the partial pressure of the hydrogen halide in the system,

and upon the temperature and other conditions of operation.

The process of the invention may be executed in a'batch, intermittent or continuous manner.,

When separation of desired, such separation maybe effected inany suitable manner as by fractional distillation, etc., and the unreacted material returned to the reaction zone for further treatment.

The following modes of executing the process examples illustrate suitable oi the invention.

The invention is not to be regarded as restricted to the particular catalyst, the particular modes of operation, the particular h y d r o c a r b o n s treated, or the particular operating conditions pheres specified in the examples.

Example I A hydrocarbon mixture consisting of about 91.5% normal pentane and about 8.5% of iso-. pentane was charged to an autoclave along with about 10% of its weight of anhydrous aluminum chloride. Hydrogen chloride gas was forced into the autoclave until the total pressure therein at about room temperature was about 5' atmos- (g'auge) and the partial pressure oi the hydrogen chloride therein was about 4.5 atmospheres; The mixture in the autoclave was kept at about 20". C. for about 18 hours during which time. it was agitated by revolution of the autosure of the hydrogen halide to at least threeatmospheres results in materially increasing the rate of isomerization while permitting the use of temperatures at which undesired degradation reactions can be substantially obviated. About At the end of 16 hours, the mixture was discharged from the autoclave, the hydrogen chloride and the aluminum chloride removed. and the hydrocarbon material analyzed. It was found to consist of 38% by weight or isop'entane, 11% by weight of isobutane, 44% by weight of n-pentane and about 7% or higher boiling constituents.

hydrogen halide inv time unit or treatment A hydrogen the isomerized hydrocarbon" Example II The same hydrocarbon material was treated with the same catalyst and under substantially 'the same conditions of temperature and reaction However, the operation was effected under time.

a total gauge pressure of about 3.5 atmospheres,

. Example III ,A hydrocarbon mixture consisting of about 91.5% by weight of normal pentane and about 8.5% by weight of isopentane was treated with about of its weight of aluminum chloride -at about C. for a period of about 17hours under a hydrogen chloride partial pressure of about 0.5 atmosphere. The reaction product was found to consist of'about 9.5% by weight of isopentane and about90.5% by weight of nor,- mal pentane. Only about 1% of the treated normal pentane was converted to isopentane.

It was found that keeping other conditions" substantially the same and'increasing the partial pressure of hydrogen chloride resulted in a materially} increased conversion of normal pentane to isoparaffin (principally isopentane) after a partial was reached.

When a partial pressure of hydrogen chloride of 1.5 atmospheres was used, the resulting hy drocarbon product contained. about 19% .by weight-of isoparafiin hydrocarbons (isopentane pressure of at least 1 atmosphere and isobutane, with the latter present in only' small amount), and about 81% of normal pentane. At a hydrogen chloride partial pressure of 5.5 atmospheres, about 53% of the treated normal pentane was converted to isoparafiin hydrocarbons (primarily isopentane) with the formation of no hydrocarbons lower than butane. At a hydrogen chloride partial pressure of about 7.5 atmospheres, about 66% of the treated normal pentane wasconverted to iso-' parafiin hydrocarbons (primarily isopentane) with the formation of no hydrocarbons lower than butane. At a partial hydrogen chloride pressure of about 10.5 atmospheres, about 92% of the treated normal pentane was converted to terially predominating, and with the formation of no hydrocarbons containing less than four carbon atoms.

Example I V Amout 100 parts of normal hexane were charged to a suitable pressure reaction vessel along with about 5% of its weight of aluminum chloride. Hydrogen chloride gas was added in an amount sufficient to provide a partial pressure of hydrogen chloride of about 10 atmospheres .in the system. The reaction mixture was maintained at about 80 C. for about 16 hours. At the end of this time, the hydrogen chloride. and aluminum chloride were separated from the hydrocarbon material and the hydrocarbon 'material analyzed. It consisted of 8% by weight isohexane, 5% by weight isopentane, 10% by weight isobutane, about 1% by weight propane, the .remainder being unchanged normal hexane.

WhileI have described my invention in a detailed, manner and provided specific examples illustrating suitable modes of executing the same, it is to be understood that'modificatlons may be made and that noJimitations other than those imposed by the scope of the.appended claims are intended.

I claim as my invention: 7

1. A process for the conversion of normal hexane to isoparafiin hydrocarbons which comprises contacting normal hexane in the liquid isopentane and isobutane, with the former maphase with an aluminum chloride catalyst at a temperature. of from 20 C. to C. for a time not exceeding 17 hours under a pressure of hy- 'drogen chloride equivalent to from three totwenty atmospheres when measured at 20 C.

2. A process for the conversion of normal I pentane predominantly to isopentane which comprises contacting normal pentane in the liquid phase with an aluminum chloride catalyst at a temperature of from 20 C. to 150 C. for a time not exceeding 17 hours under a pressure of hydrogen chloride equivalent" to from three to twenty atmospheres when measured at 20 C. v Y

3: A process for the conversion of a normal parafiin hydrocarbon to an isoparaflin hydrocarbon which comprises contacting a normally liquid normal parafiin hydrocarbon which boils at a temperature not greater than about C. with an acid-acting halide catalyst in the liquid phase at a conversion temperature of from 20 C. to 150 C. for a time not exceeding 17 hours under a pressure of a hydrogen halide equivalent to from three to twenty atmospheres when measured at 20 ,C.

ADRIANUS JOHANNES VAN PESKL'