US1917324A - Production of low boiling hydrocarbon products - Google Patents

Description

July 11, 1933. M. PIER El AL 7,

PRODUCTION OF LOW BOILING HYDROCARBON PRODUCTS Original Filed June 7, 1929 Mucheus Pier Kai l Winkler Wolrcr 5(mon I NVENTORS ORNEY-S.

Patented July 11, 1933 UNITED STATES PATENT OFFICE MATH'IAS IPIER, OF EEIDELBERG, KARL WINKLER AND WALTER SIMON, OF LUDWIGS- BLAFEN-ON-THE-RHINE, GERMANY, ASSIGNORS, BY MESNE ASSIGNMENTS, TO

STANDARD-I. G. COMPANY, OF LINDEN WARE PRODUCTION OF LOW BOILING HYDROCARBON PRODUCTS Application filed June 7, 1929, Serial No. 369,258,

This invention relates to improvements in the manufacture and production of low boiling hydrocarbon products.

A method according to. which pastes of coal of all varieties in oils, tars, mineral oils and the like are treated with hydrogen or gases supplying the same, first in the liquld state under such conditions of pressure and temperature that generally speaking only the sulphur and oxygen compounds present in the said materials are completely .or rjor the most part eliminated, and that only incipient or no substantial destructive hydrogenation of the oil occurs, the products obtained then being subjected without any further addition of hydrogen to a cracking treatment, with or without the employment of catalysts has already been proposed.

We have now found that low boiling products, and in particular hydrocarbons, such as have the character of benzines, can be obtained from carbonaceous materials, which are liquid at room temperature, as for example, pastes of coal of all varieties in oils, tars, mineral oils and the like, in a very good yield without formation of coke and incrustation of the apparatus and without any substantial gasification taking place, if the said initial materials or middle oils of any origin are treated in the fluid state, namely in the liquid or vapour phase with hydrogen or gases containing or supplying hydrogen at an elevated pressure and temperature, under such conditions that products rich in hydrogen, especially those of the nature of middle oils are obtained, and subjecting these to acracking treatment in the presence or absence of other gases, as for example reducing or protective gases. If middle oils be employed as the initial materials the said treatment furnishes middle oils which are more highly saturated. Such reducing or protective .gases are, for example, hydrogen,

hydrocarbons, of low boiling point, nitrogen, carbon monoxide and carbon dioxide or mixtures of these gases. The cracking treat,- ment may be carried out under any known conditions. The method of working described and claimed in the present case is of great economical importance, especially and in Germany June 15, 1928. Renewed November 19,

pounds as for example high temperature tars, high boiling crude oils, residues from cracking treatments and so on, the direct cracking of which is very diflicult because these products cannot be decomposed at a moderate temperature, whereas at high temperatures a considerable separation of coke takes place, a continuous and economic working thus being made impossible. If, however, the products are first enriched in hydrogen, a cracking operation can be carried out successfully and without loss. The enrich-' ment in hydrogen is principally effected by giving the hydrogen a high partial pressure, for example such that the partial pressure of the reaction products therein is 10 per cent or less. It is also advantageous to employ catalysts immune from sulphur poisoning, for example such containing the elements of the 6th. group of the periodic system, preferably together with such selected from the second to the fourth group. As specific examples of such hydrogenatin catalysts immune from poisoning by su phur may be mentioned, a catalyst prepared from the oxides of molybdenum zinc and magnesium, or from tungstic and zinc oxide, or from the oxides of molybdenum and zinc, if desired, to ether with kaolin or from the oxides of moly denum and aluminium, or from molybdic acid, chromic acid and kaolin, or from tungstic acid, or chromic acid with manganese dioxide and zinc sulphide, or from molybdic acid, chromic acid and Florida earth (aluminium hydrosilicate), or from tungstic acid, chromic acid and thorium oxide, or from chromic acid, nickel sulphide and aluminium hydrosilicate. The treatment in the first stage of the process is in any case relatively more strenuous than the already proposed treatment of the initial .materials with hydrogen for the purpose of completely or for the most part eliminating NEW JERSEY, A CORPORATION OF DELA- are preferably separated by distillation and tion takes place. Thus, for example, according to the present process the duration of the treatment may be longer than that required for the aforesaid already proposed treatment or higher temperatures or higher pressures may be employed. Moreover, as a rule, the higher are the temperatures employed in the enrichment with hydrogen, the higher must be the pressures. be rendered relatively more strenuous by the employment of more active catalysts. Apart from this fact the relative rigorosity of the treatment is also dependent on the nature of the initial materials. Thus, for example, if an initial material, which is not very readily prone to the action of destructive hydrogenation, be treated under otherwise the same conditions as a material which is more susceptible to the said treatment, the treatment in the latter case will be relatively more strenuous than in the former case. As examples of elevated temperatures, which may advantageously be employed for the enrichment with hydrogen may be mentioned such ranging between about 300 and 550 C. but preferably such of between about 350 and 480 C.

The pressures employed will in most cases be above atmospheric, those of 5,10, 20, but preferably of 50, 100, 200 atmospheres or even more being suitable.

The hydrogenating gases may be passed 1n circulation.

From the products resulting from such enrichment in hydrogen, in case they do not consist entirely of middle oils usually boiling between about 200 and 350 C. these latter then the middle oils are subjected to the cracking treatment. Cracking may be effected in the presence or absence of gases, for example reducing gases. If. hydrogen be employed in both stages, it is necessary to work in the presence of said catalysts, at least in the first stage of the process or in other words, when enriching the products in hydrogen.

The cracking treatment in the second stage of the products enriched in hydrogen, ob tained in the first stage of the process, may also be so modified as to become a destructive hydrogenation having such conditions of working, as principally lead to splitting without complete saturation with hydrogen. In order to increase the tendency towards the formation of aromatic compounds, if such be desired, the content of methane in the gases must be kept at a minimum. For example, strongly splitting catalysts and preferably higher temperatures than in the first stage may be employed simultaneously for said purpose, for exam le, temperatures of up to about 700 C. s examples of suitable catalysts having mainly a cracking action may be mentioned mixtures of compounds and particularly oxides of the solid The conditions may also' elements of the 2nd, 3rd or 4th group of the periodic system or of the 6th and 3rd group of the periodic system. As examples of such catalysts may be further mentioned bauxite, kaolin, Florida earth, bentonite, zinc oxide, manganese dioxide, silica, calcium aluminate, oil shale residues, anh drous halides of metals and solid metal oids, such as aluminium chloride, ferric chloride, Y boron fluoride and the like.

Fractions of lower boiling point, for example such having the character of middle oils may also be distilled at the beginning from the initial materials, and then enriched in hydrogen in the vaporous state-as hereinbefore described and subsequently cracked. The remaining higher boiling fraction of the initial materials is treated by itself with hydrogen under pressure, in the liquid form in order to convert it into a product rich in' .hydrogen, which is then cracked. From the high boiling distillation residues obtained after each cracking treatment, products rich in hydrogen are formed again, from which by a renewed cracking treatment, hydrocarbons of a low boiling point, having the character of benzines are obtained in a good yield, and so on.

When middle oils are emplo ed as the initial materials it is also very a vantageous to carry out the cracking treatment of the products enriched in hydrogen obtained in the first stage under such conditions that mainly low-boiling unsaturated hydrocarbons are formed. When employing initial materials of the nature of 'coal tar, it is advantageous to carry out the second stage of the treatment under such conditions that mainly unsaturated gaseous hydrocarbons are obtained.

The second stage of the process namely the cracking treatment may be carried out at atmospheric pressure or at elevated pressures, for example, at pressures of up to 50 atmospheres, but of course, where practicable, even higher pressures, for example, 100, 200 atmospheres or even more may be employed. The employment ofhigher pressures is articularly advantageous when the crac ing treatment takes the form of a destructive hydrogenation under conditions leading mainly to splitting of the molecule.

The process according to this invention may be applied both when starting from such initial materials as are practically free from oxygen and sulphur and from such initial materials containing these elements.

The present invention will be further described with reference to the accompanying drawing diagrammatically showing a front elevation partly in section of a plant which is very suitable for carrying out the process according to the invention.

Referring to the drawing in detail hydro gen is introduced at 1 and supplied by means of pump 2 to the heating coil 4, where it is heated to the reaction temperature together with the oil to be hydrogenated introduced at 3. The mixture of hydrogen and oil is then passed into the reaction vessel 5 where it is subjected to destructive hydrogenation. The mixture of the resulting product rich in hydrogen and hydrogen not converted leaving the vessel 5 is led into the condenser 6, the condensed portions being collected in vessel 7. The non-condensable gases are withdrawn at 8 and may be returned to the process by way of pump 2 or may be set free by valve 9. The liquid products collected in vessel 7 pass, by way of valve 10 into the cracking tubes 11 which are externally heated by hot gases. The cracked mixture is then subjected to condensation in vessel 12 wherefrom the uncondensable gases are withdrawn at 13 while the liquid portions are pumped by pump 14 into pipe 15, and after being mixed with fresh hydrogen introduced at 16 and circulated by pump 17, they are heated in coils 18 to the reaction temperature prevailing in the second hydrogenating vessel 19. The products leavmg vessel 19 are cooled in condenser 20, the condensed portions being collected in "vessel 21 while the uncondensable portions are either recycled by way of pipe 23 and pump 17 or withdrawn by valve 24. The liquids collected in vessel 21 are withdrawn by valve 22.

The following examples will further illustrate the nature of this invention, but the invention is not restricted to these examples.

E temple 1 A viscous producer tar containing 30 per cent of a fraction boiling up to 350 C. is treated in the liquid form with hydrogen at from 430 to 450 C. and under a pressure of about 200 atmospheres in the presense of a catalyst prepared from the oxides of molybdenum, zinc and magnesium. The product obtained contains about from 10 to 15 per cent of a fraction boiling up to 200 C. and about per cent of a fraction boiling from 200 to 350 C. These products, from which the fractions boiling below 200 C. may be separated, if so desired, are subjected to a cracking treatment, 50 to 60 per cent of a very valuable motor fuel thus being formed. The residue which is no longer suited for a cracking treatment, is again subjected to the above described destructive hydrogenation and is again cracked alone or together with the hydrogenated crude product. \Vhen working according to this method the cracking treatment proceeds without any substantial troublesome formation of coke, whilst cracking the tar, without the preceding hydrogenation is practically impossible because of a large deposition of coke.

Example 2 Tar from mineral coal as obtained in illuminating gas works, on being subjected to destructive hydrogenation 'in the liquid under a pressure of 200 atmospheres and at a temperature of 400 to 420 C. together with hydrogen over a hydrogenating catalyst, containing for example molybdic acid, zinc oxide and magnesia. The resulting product containing more hydrogen than prior to the said treatment is then subjected to a cracking treatment at the same pressure and a higher temperature than that employed in the first stage, for example at about 480 C. in the presence of hydrogen and'of a catalyst prepared for example from molybdic acid and china clay. On cooling, a product is obtained containing up to between 50 and 60 per cent of a non-knocking benzine rich in aromatic compounds. A benzine of such a character is also suited to render knocking fuels non-knocking. Theremainder is composed of aromatic middle oils.

An oil containing sulphur or free from both, oxygen and sulphur, can be treated in the same manner as the middle oil containing oxygen. According to the working conditions it is also possible to transform middle oils, which are free from aromatic hydrocarbons, or contain only small amounts thereof, either completely or partly into aromatic hydrocarbons, such as benzene and its homologues so that products of any desired composition are formed which may serve, for example, directly as motor fuels or as additions toothers which give rise to knocking, when used without such additions.

tar containing aromatic hydrocarbons, for

example of a high temperature tar, are hydrogen with hydrogen at about 430 C. under a pressure of 200 atmospheres in the presence of a catalyst containing molybdenum and chromium. The reaction product obtained is contacted in the presence of steam at about from 550 to 600 C. and under a pressure of 200 atmospheres with a catalyst contain ing calcium oxide and iron, in order to effect cracking.

The final reaction product obtained when compared with the initial material, shows a considerable increase in the fractions boiling up to 200 C. Besides, a gas is obtained in a very good yield containing from about 30 to 50 per cent of olefines and diolefines.

The liquid reaction product obtained in the above treatment may, after the benzine has been distilled ofi', be subjected alone or mixed with new initial material, to a second hydrogenation followed by a cracking treatment.

Instead of employing the catalyst containing calcium oxide and iron mentioned in this example other catalysts may be used, as for example the elements or their compounds of the second group of the periodic system, together with the elements or their [compounds of the third or fourth group, or with manganese or its compounds. It may also be advantageous under certain conditions to work under pressures below 200 atmospheres or in the presence of diluent gases, such as nitrogen, methane and the like.

Eazample 4 50 parts of ground coal are made into a paste with 50 parts of a residual oil, obtained by destructive hydrogenation of the same coal; the mixture is preheated to a temperature of about 360 to 380 C. and is forced by means of a pump into the lower part of a high pressure reaction vessel where hydrogen, having nearly the reaction temperature is mixed with the coal paste, by forcing it in through porous plates. The resulting emulsion of coal paste and hydrogen is passed through a high pressure reaction vessel at temperatures from 440 to 460 C. under a pressure of 200 atmospherers. In'the upper part of the reaction vessel the main portion of the gas together with the vapourized hydrocarbons separates from the coal paste while the remainder of the latter is removed together with small amounts of hydrogen and low boiling hydrocarbons dissolved therein. The gaseous and vaporous products leaving the upper part of the reaction vessel are cooled down in stages under pressure, after they have given up their sensible heat in regenerators, for preheating fresh gases in a counter-current, the hydro-carbons separating out as fractions.

From 6 to 10 per cent of the hydrocarbons thus obtained have the nature of benzlne boiling up to 180 C. The rest boils up to 325 C. and is cracked without any addition of hydrogen.

This oil yields about 50 to 60 per cent of low boiling motor fuels, having no tendency to knock, which fuels may also be employed as additions to knocking benzines, in order to render them non-knocking.

What we claim is:

1. The process of obtaining low boiling hydrocarbons from bituminous materials of an aromatic nature which comprises treating said materials with hydrogen at a temperature between 300 and 550 C. and a pressure of the order of those employed in destructive hydrogenation, the partial pressure of the hydrogen being at least about 90% of the total pressure and the total pressure increasing as the temperature increases, to thereby extensively hydrogenate said materials, and then subjecting the high boiling fractions of the resulting product to a cracking treatment at a temperature substantially higher than that in the first stage treatment to efiect a splitting of said fractions, without a substantial hydrogenation, into low boiling hydrocarbons.

2. A process as defined in claim 1 wherein the first stage of the process is effected in the presence of a catalyst immune to sulfur poisoning and having predominantly a hydrogenating action.

'3. A process as defined in claim 1 wherein the first stage is effected in the presence of a hydrogenating catalyst immune to poisoning by sulfur and the second stage is effected in the presence of a catalyst having predominantly a splitting action.

4;. The process of producing low boiling hydrocarbons from high boiling bituminous materials rich in aromatic compounds which comprises treating said materials with hydrogen at a temperature ranging from 300 to. 550 C. and a pressure of the order of those employed in destructivehydrogenation in the presence of a catalyst comprising an element of the 6th group of the periodic system, the partial pressure of the hydrogen being at least about 90% of the total pressure and the total pressure increasing with an increase in temperature, to thereby effect an extensive hydrogenation of said materials, and then subjecting the high boiling fractions of the resulting product to a cracking treatment in the presence of a splitting catalyst at a temperature substantially higher than that of the first stage to effect a splitting of said fractions, without substantial hydrogenation, to low boiling hydrocarbons.

5. A process as defined in claim 4 wherein said initial materials comprise a product selected from the class consisting of middle oils, producer tar and coal tar.

6. A process as defined in claim 1 wherein the cracking treatment is carried out at a temperature above 550 C.

7. A process for the production of low boiling hydrocarbon products from carbonaceous materials, which are liquid at room temperature, which comprises treating a producer tar in the liquid form with hydrogen at from 430 to 450 under a pressure of about 200 atmospheres in the presence of a catalyst prepared from the oxide of molybdenum, zinc and magnesium, the partial pres sure of the hydrogen being at least about 00% of the total pressure, and then subjecting the high boiling fractions of the resulting product to a cracking treatment at a temperature substantially higher than that of'thc first stage to effect a splitting of said fractions, without substantial hydrogenation, into low boiling hydrocarbons.

In testimony whereof We have hereunto set our hands.

MATHIAS PIER.

KARL VVINKLER.

WALTER SIMON.

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