EP0208985A2 - Process for coal hydrogenation using as a catalyst an oil soluble metal compound - Google Patents

Abstract

A pasting oil is added to finely pulverised dried coal, the mixture is brought to the process pressure and, after addition of a hydrogen-containing gas and heating, fed to a liquid-phase reactor system at a hydration temperature of about 450 to 500 DEG C. To improve the reaction control, the catalyst is fed in the form of formulations which contain iron phenolate or iron naphthenate and are soluble in the pasting oil. <IMAGE>

Description

The invention relates to a method for coal hydrogenation using an oil-soluble metal compound as a catalyst, the type specified in the preamble of claim 1.

It is known to use in a process for the hydrogenation of hard coal at 700 bar BAYER mass and iron sulfate solution as a catalyst (cf. "The catalytic pressure hydrogenation of coal, tars and mineral oils", Springer-Verlag, Berlin / Göttingen / Heidelberg 1950, page 66).

CA 99: 90818u is a laboratory-scale study on the effectiveness of oil-soluble catalysts in coal liquefaction with molybdenum, cobalt, nickel, manganese and tin as an effective ingredient. In this study, the effectiveness of oil-soluble catalysts based on molybdenum and nickel was determined, whereas the effect of oil-soluble catalysts containing cobalt, manganese and tin was found to be insignificant. In this investigation, the two catalyst metals belonging to the iron group showed cobalt and Nickel has a very different behavior in the catalytic effect, whereas oil-soluble iron compounds were not included in the study. It can be concluded from this that it has not been considered practicable to first produce oil-soluble iron compounds and to consider them as catalysts for the liquefying carbohydrate hydrogenation. Because of the favorable process influence in the sense of a high oil yield as well as for economic reasons, inorganic iron components as catalyst components have proven to be favorable in the prior art.

The invention is based on the problem that when using the compounds of metals from the II. To VIII. Group of the periodic system known to be effective for the carbohydrogenation, these catalysts led to incrustations of the mash heating system because of the pronounced sulfide formation. These sulfide crusts considerably reduce the efficiency of the mash heating, so that the mash heating furnaces had to be operated at higher temperatures in order to achieve the required heating temperatures. There are limits to this measure, however, since the formation of iron sulfide crusts is temperature-dependent and therefore increases as the pipe wall temperature rises, so that the material-determined pipe wall temperature limits are reached relatively quickly, above which there is an increased operating risk or a drastic reduction in operating times.

In order to maintain the desired long-term operation of coal hydrogenation plants, the only thing that has so far been reduced is the reduction of the mash throughput, in order to avoid premature shutdown of the plant with the necessary clearing or removal of the pipes.

The sulfide incrustation described in the preheating system occurs increasingly when using less hydrogenation-active, more carbonized hard coal, which has a higher light-off temperature from the outset and whose mash must be heated up correspondingly more strongly before entering the reaction systems. It has been found that both the catalyst presentation form and the ash content of the charge coal have an influence on the sulfide incrustation.

Although it is already known from the patent specification DRP 648 130 that the finely divided catalysts are only brought into contact with the starting materials after the latter has been heated up, expediently only in the reaction space, the purpose of this was something else, namely the assumed weakening of the effect of To prevent catalysts that were impaired in their effectiveness during the preheating.

The object is achieved in an advantageous manner by the features specified in the characterizing part of claim 1.

It was found that in particular the phenol-rich fractions of the boiling range obtained by distillation of the coal liquefaction products from 160 to 220 ° C, which are returned to the mashing as components of the mashing oil, have an extraordinarily favorable influence on the coal mining behavior when the measures of claim 2 are realized.

The mashing oil cuts mentioned, which contain other arylhydroxy compounds in addition to the base of the phenol series, are abundant in the upper boiling sections of light coal oil with a boiling point of up to 200 ° C, in light medium oil with a boiling range of 200 to 220 ° C and in process waste water. So z. B. a coal-based light oil with an upper boiling point of 210 ° C on an oxygen content of 3.6 wt .-%, the phenol content in this light oil is 6.9 wt .-%, in addition, further substituted phenols and cresols are included .

The method with the features of claim 2 can be carried out so that the aforementioned phenol-rich coal oil cuts are used for the preparation of the iron phenolate catalyst solution. The further option indicated is the arylhydroxy compounds separated in the process water treatment, in particular the phenol in addition to the alkylphenols, naphthol derivatives and the wastewater still present in the process water. Isolate and this after Implement solution in suitable process oils or foreign oils with ferric chloride.

It is also advantageous (claim 3) to use oil-soluble iron catalyst compounds in the form of the naphthenates. Naphthenic acids can be extracted alkaline from petro-derived feedstocks using standard methods and can be released by subsequent acidification. The production of iron naphthenate is carried out in a known manner such. B. in the manufacture of iron naphthenates as siccatives u. the like

For example, with direct injection of iron phenolate and iron naphthenate (0.01% by weight based on iron content and water and ash-free Ruhrstein coal) at 300 bar process pressure and 490 ° C reaction temperature, coal conversion rates of about 93% with oil gains of 53% were based on water and ash-free coal can be achieved.

The reduction in the ash content of the coal to be used can also advantageously contribute to the solution of the task. For example, flotation or washing of the coal to be used are suitable for reducing the ash content.

The oil-soluble iron catalysts obtained can be added directly to the coal mash. The direct injection of the oil-soluble iron catalysts into the reaction system proved to be extremely cheap.

Experiments have shown that the mash heating section can be driven completely free of catalysts without any adverse effects on the reaction.

The direct injection of the oil-soluble iron phenolate or iron arylhydroxy catalysts into the reaction system greatly slows down the sulfide incrustation that otherwise occurs in the mash heating system. In the present process, in which catalyst compounds dissolved in parts of the mashing oil are used, the required amount of catalyst, based on iron, can be preferably 0.1 to 1% by weight of iron, depending on the reactivity of the feed coal, based on water-free, ash-free coal . When adding catalyst in the form of solutions of iron (II) sulfate or BAYER composition sprayed onto the coal, the amount of catalyst required based on iron is significantly higher, namely about 3 to 5% by weight iron based on water-free and ash-free coal .

By reducing the amount of catalyst and injecting the catalyst solution into the reaction system, with the solids content of the mash unchanged, there is an increase in the coal concentration in the mash heating system. This is associated with an increase in the hydrogenable specific amount of coal used in the actual hydrogenation and an additional enthalpy gain at the catalyst injection point by the heating temperature in the mash preheating system can be designed so that the spontaneous rise in the temperature of the mash to the reaction temperature in the reactor at the catalyst injection point is taken into account.

The catalyst can be injected either completely in the mash inlet area or via spigots along the height of the reactor.

The method according to the invention is further described on the basis of the following description of the flow diagram given in FIG.

1.05 t / h of finely ground and dried gas coal from the Ruhr district with an ash content of about 5% by weight based on anhydrous coal are fed via line 1 together with process-based mashing oil from line 2 to the mashing tank 3 and mashed. A distillate oil mixture of the composition 60% by volume with a boiling range> 320 ° C. and 40% by volume with a boiling range from 200 to 325 ° C. was used as the mashing oil.

The resulting mash with a coal content of 44% by weight is fed via line 4 to the pump 5, brought there to a pressure of 300 bar and via line 6 through the heat exchangers 7, 8, 9 and after addition of hydrogen-containing hydrogenation gas via line 30 and after heating in the preheater 10 to 470 ° C in the bottom phase hydrogenation 11, which has three reactors connected in series.

The reaction is conducted through a quench gas feed (not shown) in such a way that an average temperature of 488 ° C. is established in the reactor system.

The reaction products leave the reaction part via line 12 and are separated in the hot separator 13 under process pressure at process temperature or below the temperature into the gaseous reaction products and the liquid constituents containing solids. The gaseous reaction products are fed via line 18 to the heat exchangers 7, 8, 9, in which heat exchange takes place with the fresh mash.

After expansion to atmospheric pressure and separation of the non-condensable portions of the cycle gas, the hot separator top product in the atmospheric column 19 is in light oil with a boiling range of up to 200 ° C, medium oil with a boiling range of 200 to 325 ° C and heavy oil with a boiling range of above 325 ° C separated. When using a cold separator downstream of the hot separator, water is formed together with the coal oil as the liquid phase, which is partly formed from the oxygen chemically bound in the coal and partly consists of injection water (quench water). This quench water is injected into the vapor phase behind the hot separator to avoid blockages caused by crystallizing ammonium salts. The water contains one Part of the tar acids (phenols, cresols, xylenols), which are also formed during the hydrogenation with the participation of the oxygen bound in the coal.

The catalyst solution required for the carbohydrate reaction is kept in the stirred tank 26. For this purpose, for example, about 7 kg / h of the tar acids originating from the process water treatment, in particular containing phenol, are added to the stirred tank 26 via line 25. The iron component is added as a saturated boiling aqueous solution via line 30 with a content of 12 kg / h iron (III) chloride container 26. Before the iron (III) chloride solution is added, the tar acid product, which is introduced into the stirred tank 26 and contains mainly phenol, is taken up at 80 kg / h of process-derived oil with a boiling point of> 325 ° C. fed via line 24.

The catalyst solution prepared in this way is drawn off continuously via line 27 and, after increasing the pressure to the process pressure, is injected into the reactor 11 by means of pump 28 via line 29.

The test operation over several thousand operating hours showed that the sulfide incrustation of the hairpins in the preheater 10, which otherwise clearly occurs after about 500 hours, could be almost completely avoided over the total operating time. Slight incrustation was observed that iron compounds of the coal ash, which still pass through the mash heating system even when the catalyst is injected directly into the reactor. During the test period, neither the heating output nor the amount of mash used to achieve the desired preheater outlet temperature of about 450 ° C had to be reduced.

The catalyst preparation can also be carried out by reacting iron (III) chloride in saturated aqueous solution with special phenol and product boiling sections containing phenol homologs. The phenol enrichment can be further driven by distillative or extractive processes from product light oil with a boiling range up to 200 ^* C and product medium oil with a boiling range from 200 to 325 ° C. In addition, phenol and higher phenol product from the process water treatment can be added for the preparation of the catalyst solution.

Claims (7)

1. A process for the hydrogenation of coal using an oil-soluble metal compound as a catalyst, in which finely ground, dried coal is mixed with a mashing oil, brought to the process pressure of about 150 to 1000 bar and, after the addition of a hydrogen-containing gas and heating by means of heat exchangers and process furnaces to reaction temperature, a bottom phase reactor system consisting of one or more reactors and at a hydrogenation temperature of about 450 to 500 ° C is added, characterized in that the catalyst is supplied in the form of iron phenolate or iron naphthenate-containing formulations in the mashing oil, the amount of catalyst based on iron 0.05 to 5 wt .-%, preferably 0.1 to 1 wt .-% with coal water and ash-free (waf) is the reference basis. 2. The method according to claim 1, characterized in that an iron phenolate catalyst solution by reacting an aqueous solution or a solution in an organic solvent of iron (III) chloride with a phenol mixture originating from the process water treatment of the bottom phase hydrogenation or also by Distillation or extraction obtained phenol-rich product oil boiling cut of the products of the bottom phase hydrogenation, is obtained. 3. The method according to claim 1, characterized in that an iron naphthenate catalyst solution is obtained by reacting an aqueous solution or a solution in an organic solvent of iron (III) chloride with alkaline extracted from petrostatic feedstocks and released by subsequent acidification of naphthenic acids. 4. The method according to claim 1, characterized in that the catalyst is injected directly into the reaction system. 5. The method according to claim 1, characterized in that the injection of the catalyst over 'one or more additional nozzle distributed over the entire height of a reactor. 6. The method according to claim 1, characterized in that the catalyst injection is carried out in all reactors of the bottom phase reaction system. 7. The method according to any one of claims 1 to 6, characterized in that coal is used, the ash content is reduced by known methods to values of 1 or less than 1 wt .-% based on anhydrous coal.

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