US1960794A - Production of useful hydrocarbons - Google Patents

Description

May 29, 1934. M PlER PRODUCTION OF USEFUL HYDRQCARBONS Filed Aug. 21 1930 Patented May Z9, `-1934 PRODUCTION 0F USEFUL HYDROCARBONS Mathias Pier, Heidelberg, Germany, assignor to Standard-I. G. Company, Linden,`N. J., a corporation oi.` Delaware Application August 21, 1930, SerialNo. 476,938` In Germany August 27, 1929 9 Claims. (Cl. ISB-53) r1`his invention relates to improvements lin the manufacture and production of useful hydrocarbons.

In the production of useful liquid hydrocarbons by the destructive hydrogenation of carbonaceous materials, such as coals of all varieties, high boilf ing hydrocarbon mixtureatars, bitumens, pitches, the distillation, extraction or conversion products of the said materials by treatment with hydrogen or gases containing or supplying hydrogen at elevated temperatures and under pressure in the presence of catalysts, it 'is desirable that the par-l tial pressure of the improved products in the reac- 'tion vessel should be maintained as high as possible since in this manner a very high throughput for a reaction vessel of given capacity can be attained. V

Hitherto, however, diiiiculties have been encountered in practice, when operating with such high partial pressures, 'since the yield vof the de-r sired valuable hydrocarbons especially gasolines when working in one operation often proved unsatisfactory. In .many cases larger or smaller amounts of inferior products were formed, which were unsuitable for further treatment, or which could onlyv be improved with diiculty and at undesirable expense. In particular the formation of highly viscous, difcultly volatilizable products tending to form deposits on the catalysts and thus reducing their activity and also the deposition of carbon and the formation of methane was very disadvantageous, the latter causing undesirable local superheating and great loss of hydrogen whereby the economy of the process was impaired. Moreover, the working temperature in the reaction chamber was diiiicult to regulate.

It has been proposed to avoid these disadvantages by operating with flowing gases, preferably in closed circulation and maintaining a large excess of hydrogen, so that the partial pressure, of the resulting improved'products must not exceed 10 per cent of the total pressure in the reaction chamber, and is preferably maintained at .from l to 5 per cent. But'operation in this manner is attended by the disadvantage that a large apparatus is required for a given throughput.

I have now found that the destructive hydrogenation of liquid hydrocarbon mixtures in the presence of catalysts for the production of low boiling hydrocarbons, especially such as are low in hydrogen, as, for instance; non-knocking ben- Zines or aromatic hydrocarbons like benzene can be carried out while keeping the partial pressure, in th'e reaction vessel, of those improved products formed which boil below 200 C. as high as possible and in any case at more than 10 per cent of the total pressure, without any of the said disadvan tages occurring, if benzines or light oils i. e. hydrocarbons usually boiling to .the extent of at least per cent above about 60 C., preferably above C., and practically completely below 325 C., be employed as the initial material and the operation be carried out in the gaseous phase', which expressicnbincludes the vaporous phase, and if the presence of products which do not remain vaporous at the working temperature and which ,may be deposited on vthe catalysts 'l is avoided. The amount of hydrogen present will, however, always be in excess of the hydrocarbon vapors present at the temperature and pressure employed. Generally, the partial pressure of the hydrogen is adjusted so that it is suiciently high to prevent the formation of coke and yet so low as to prevent the formation of substantially large quantities of saturates. The quantity of hydrogen to parent oil necessary to produce the above desired partial pressures will of course vary considerably depending upon the nature and boiling point range of the oil. Usually, however, from .about 1500to 3000 cubic ft. of hydrogen is used C. -or more, but below 650 C. For example a partial pressure of the resulting improved products boiling-below 20.0 C. of 30 or 50 atmospheres and more may be employed when the total pressure is 200 atmospheres. Thus, a product boiling up to 220 C., rich in aromatic hydrocarbons and containing` up to 40 per cent of constituents, boiling up to C. has been obtained from a heavy benzine fraction boiling between 150 and 200 C. when working with a partial pressure of the improved products boiling below 200 C. of 45 per cent of the total pressure. The partial pressure chosen may generally speaking be higher the more rich in hydrogen the initial materials are or the lower their boiling points lie. When treating initial materials of comparatively high boiling point and keepingvthe partial pressure of the improved products boiling below 200 C. in the reactionvessel at more than 10 per cent of the total pressure, the partial pressure of all the` hydrocarbons present in the reaction vessel will as a rule, amount to at least 20 per cent of the total pressure, though of course it may be much In order to convert the initial materials completely into motor fuels poor in hydrogen and proof against compression it is preferable to return the incompletely improved fractions of the treated materials, especially the constituents boiling above 200 C., to theyreactiori vessel, if desired after previousy releasing the pressure, or further to work them up-in one or more reaction vessels arranged one behind each other under conditions suited to the particular product, and only to withdraw the constituents of low boiling point formed. For example by cooling the gases and vapors leaving the reaction Avessel in a separating vessel maintained at about 200 C. the constituents boiling above 200 C., especially the middle oils, are condensed and are again supplied under pressure to the reaction vessel, if desired after treatment with scavenging gases for the purpose of removing the remaining low boiling constituents. During the heating up of the middle oil, whichis to be returned, a further fractionation may be carried outin the neighborhood of the working temperature in order to remove any gaseous constituents injurious to the reaction which are present in a dissolved form or which have been newly formed during the heating. Working with a high partial pressure of the improved products boiling. below 200 C. while returning the incompletely improved products to the reaction .vessel has the advantage contrasted with the processes hitherto known that the resulting` nal product is poorer in hydrogen, and therefore the benzines are nonknocking. 'Ihe consumption of hydrogen is correspondingly less and at the same time, under the said conditions, the undesirable formation of methane is to a great extent suppressed while the higher molecular gases as for example propane, butane'and the like, and the nal product are obtained in greater concentration. The constituents boiling above 200 C. returned againI/to the reaction vessel are for the most part converted into aromatic hydrocarbons, that is' the dehydrogenation is mainly exerted on these higher boiling constituents. In case of a too strong formation of aromatic hydrocarbons it may be advantageous not to return all constituents boiling above 200 C., but onlya part thereof. In order` as far as possible to avoid a toofar reaching dehydrogenation at the tempera- `tures concerned, the employment of catalysts `having a strong' hydrogenating action is of importance. As catalysts may be mentioned those immune from poisoning by sulphur. Compounds, and especially oxides of the metals of thev 5th to the 8th groups of the periodic system either alone or iri admixture with each other or with elements of the 2nd to 4th groups of the periodic system or their compounds are for example suitable. As examples may be mentioned mixtures of molybdic acid-zinc oxide-magnesium oxide, tungstic acid-magnesium oxide, and tungstic acid-molybdic acid-zinc oxide. Catalysts comprising a metal 'of the 6th group of the periodic system are particularly suitable, especially whenv these metals are present in the form of their oxides. Moreover, the hydrocarbons boiling above 200 C. which areto be returned, may, before being returned'into the reaction chamber, be subjected at low partial pressure .of the improved products formed and at-suitable temperatures to a treatment with hydrogen, either in a" special reaction vessel or within the circulating systeml during the heating up, in order to supply them to the reaction chamber again at elevated temperatures. The constituents of the reaction product boiling above 200 C. may also be Worked up in some other Way, for example, they may be supplied to another destructive hydrogenation process in which, for example, high boiling hydrocarbons are treated in the liquid phase, whereby a hydrogenation of these constituents then takes place. If it is desired by treatment of the said constituents to obtain anaromatic middle oil for use for other piuposes Ithan asa motor fuel, as for example as a gas oil or as a solvent or diluent in coal liquefaction processes, this may 'bevelected by the employment of a catalyst having a splitting action, as for example cobalt silicide or metallic chro'rnium, whereby the whole or a part of th'e `eliluent products which boil above 200 C. may be Withdrawn from the circulating system and replaced by fresh material.

'In cases when the final products have been X and the like, on the amount 'employed and on the working temperature. For example, with initial materials whichhave a low boiling point 0r which are already comparatively poor inhydrogen it is preferable to employ av higher linear' velocity of flow or a shorter time during unich the materials are present in the. reaction cham. ber than with initial materials rich in hydrogen and of high boiling point. In order to maintain the velocity of ow at the desired rate without altering the partial pressure of the initial material the hydrogen may be replaced to a greater or less extent by an inert gas.

The process according to the present invention renders it possible; with high efficiency, .to convert all initial materials which arecapable of being treated in the gaseous phase to a great extent into final products having the desired hydrogen concentration. I

As has been pointed out above, the initial materials used according to the present invention are benzines and light middle oils. They may be o1?v any desired origin andv may be obtained for example by distillation or cracking of hydrocarbon oils such as for example, mineraloils or tars, or by destructive hydrogenation of coal, tars, mineral oils, distillation products, conversion. products and residues thereof.

When employing benzines as the initial materials, it is preferable to separate the benzines into fractions having a comparatively' narrow boiling point' range, as for example of not more than 50 C., andjto subject these fractions singly to the treatment in Iaccordance with the present invention. It is preferable to start with fractions which boil above `100" C. and preferably those having a boiling point range of only from 20 to 30 C. By appropriate selection of the reaction conditions, especially as regards the'temperatur'e and pressure,"f`the fraction (or fractions) to be treated may beyconverted either to of low boiling point, or else mainly into aromatic hydrocarbons of higher boiling point. Generally speaking under otherwise equal conditions higher temperatures, for example 600 to 620 C., tendvto promote the formation of large amounts of benzene and its nearest homologues, whereas at lower temperatures, such as about 550 C., the tendency of the reaction is towards the formation of aromatic hydrocarbons of higher boiling point. The employment of fractions having a narrow boiling point range has the advantage that the undesirable formation of gas is to a large extent suppressed and a good yield is obtained.

Middle oils may directly be treated by the process according tothis invention. Generally speaking, however, it is more advisable first to convert them into benzines by destructive hydrogenation or cracking, if necessary after enriching them in hydrogen by a treatment with hydrogen under, appropriate conditions of temperature and pressure and preferably with the aid of strongly hydrogenating catalysts; these manner of working has the advantage that the presence of products which do not remain vaporous at the working temperature and which may be deposited on the catalysts, isavoided in a particularly reliable manner. According to this manner of working, middle oils are first converted for example by destructive hydrogenation linto products similar to benzine which boil mainly above 100 C. Of these, a suitable fraction of higher boiling point, as for example that which boils from 140 to 160 C., is then subjected in a secondA treatment to destructive hydrogenation at elevated temperature, i. e. aromatized, whereby at the same time large amounts of light constituents boiling below 100 C. are formed. when mixed with the previously separated benzine fraction which has not been subjected to destructive hydr'ogenation, yields a correctboiling non-knocking benzine. The aromatized partial fraction may also be used alone orin admixture with other benzines from any source as a motor fuel.

Since with initial materials containing large lamounts of sulphur the formation of high boiling condensation products is favored, it is advantageous first to subject them to a purification and this may be effected by gentle destructive hydrogenationor other chemical treatment.

Various pressures may be employed inthe process according to the present invention, such as a pressure of 20 atmospheres, but usually high pressures of 50, 100, 200, 500 or even' 1000 atmospheres or'more are employed.

The invention will be further explained with reference to the accompanying drawing showing in a somewhat diagrammatic fashion an elevation, partly in section, of a plant in which the process according to this invention may be carried out. It is, however, to be understood that the invention is not restricted to the particular arrangement shown in this drawing.

Referring to this drawing in detail letter A `denotesthe store-vessel from which initial oil,

The resulting product,

after conjunction at AD with hydrogen similarly compressed in pump E and supplied in amounts measured by gauge F, into the prehea'tcr G in which it is heated together with hydrogen above a temperature at which the highest boiling por tions of said oil are vaporized. TheA hot mixture of hydrogen and oil vapours arev then introduced at H into the-high pressure vessel J which is, lled with an irregularly arranged catalyst preferably present in the form of small cubes and which is kept at a temperature above 500 C. In this vessel the oil undergoes partial conversion into lower boiling products containing considerable amounts of aromatic hydrocarbons. The vapours issuing at K from vessel I are then conveyed into the heat-exchanger L in which the heavier boiling unconverted constituents are condensed. The mixture of the condensate and the uncondensed lower boiling portions are separated in vessel M at'the bottom of which the said condensate may be withdrawn. The latter is then recycled by way of pump N and gauge O and combined with the initial oil issuing from pump C. The uncondensed lower boiling portions leave vessel M at the top and enter a second heatexchanger P in which the hydrocarbons of the boiling point range of benzine are condensed. The mixture of this condensate and the uncondensed gases are led into the Yseparator Q wherefrom the said condensate is withdrawn at the bottom in an amount measured by gauge Z. The uncondensed gases, after passage through gauge R and cooling vessel S are introduced to the tower T in which they are washed with middle oil supplied at U and sprayed in at the top of the said tower. By this washing treatment theuncondensed gaseous hydrocarbons as well as any uncondensed low boiling hydrocarbons and impuri- .ties, such ashydrogen sulphide, if any, are absorbed by the washing oil. This oil is then passed' into vessel V in which it is released from pressure and thereby freed from the absorbed gases. The oil is then recycled by means of pump W into 4the tower T. The unabsorbed gas leaving the tower at X mainly consists of hydrogen. It is pumped by means of pump Y successively into the yheat-exchangers I and L in which it acts as the cooling medium and then combined with fresh hydrogen leaving pump E.

The various gauges included in the described arrangement serve for determining the ratio of the single partial pressures. The amounts of hydrogenv introduced into the reaction vessel J is measured by gauge F, those of the materials to be converted by gauges B and O. The amounts f of gas and converted products leaving the said reaction vessel are measured by gauges R and Z respectively. Since the nature of the initial material as well as that of the converted products may be easily determined by analysis the amounts of hydrogen and initial products requisite for maintaining the desired partial pressures may be easily adjusted. Y

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

Example 1 y From a middle oil prepared by the destructive hydrogenation of brown coal a product is ob- L zine be led inthe Vapor phase at from 540 to 570 C. with a partial pressureof 60 atmospheres (the total pressure being 200 atmospheres) together with hydrogen over a catalyst prepared from tungstic acid with an addition of magnesia,

a hydrocarbon mixture is formed which begins to" I `v boil at about 60C. and which consists to the extent of about one half of aromatic hydrocarbons. The relative quantity of hydrogen to oil ucts in a separating vessel arranged behind the reaction vessel; it can easily be determined from the amount of the improved product condensed; under the conditions specified in the foregoing it amounts to about 25 per cent of the total pressure.

If initial materials containing large amounts of sulphur, as for example fractions of American crude oil which contain up to 2 per cent or more of sulphur, be subjected to the manner of lworking hereinbefore described; it is preferable, in Aorder to avoid coking 'phenomena in the preheating zone and on the catalyst which result in an abatement of the catalytic action,l to remove the sulphur in a suitable manner; thisl may be effected for example by leadingthe initial material at 400 C. under a' pressure of 20d atmospheres together with hydrogen over a catalyst consisting of the oxides of molybdenum, zinc and magnesium, whereby the sulphur content of the product is reduced to below 0.1 per cent.

Example 2 An American heating oil yields a low boiling product which is strongly saturated by treatment in .the liquid phase with hydrogen under pressure. A fraction-of this product boiling beeluent gases an'd vapors, and after the addition of a correspondingamount of fresh initial tween 200 and 275 C. is treated with a partial pressure of 50 atmospheres at a temperature-of about 510 C. at a total pressure of 200 atmospheres with hydrogen in the presence of a catalyst which contains about 9 0 parts of silicon and 10 parts of cobalt. The constituents boiling above 200 C. are separated from the material are again subjected to the said treatment. and the constituents boiling above 200 C. are returned to the process and lso on. From the efiluent constituents whichl boil below 200 C., the parta-1 pressure of which in the reaction vessel is about 15 per cent of the total pressure, and which in addition to about 40 per cent of aromatic hydrocarbons still contain up to 15 per cent of'unsaturated hydrocarbons, a benzine of correct boiling point may be condensed which,

even in motors of high compression, shows no tendency to knock. According to this mode of operation, the relative amount of hydrogen to oil present in the reaction space in vapor form approximates 2200 cubic ft. of hydrogen for each barrel of oil. f Example 3 A fraction .boilingbetween 140 and 160 is -distilled off from a benzine which has been obtained from petroleum by distillation, and the said fraction is led at a temperature of 550 C. together with hydrogen under a pressure of 200 atmospheres overa catalyst prepared from tungstic 'acid and magnesia, the partial pressure of the product formed insofar as it boils below 200 C. being kept at about 30 atmospheres.

A product rich in aromatic hydrocarbons is thus obtained the final boiling temperature of which is 170 C. If this product be mixedwith a benzine which is not non-knocking in motors with high compression, an excellent non-knockingV motor fuel is obtained.

Example 4 -being 50 .-atmospheres. The resultingA product consists of up to 50 per cent of benzene and its homologues and is very suitable for correcting knocking motor fuels.

'Ihis application is a continuation in part of application 198,304 which was filed in the Patent Omce onJune 1l, 1927.

1. The process of producing liquid hydrocarbons which comprises destructively hydrogenating in thevapor phase liquid hydrocarbon materials essentially comprising constituents boiling substantially below `325 C; at a pressure Vof at least 20 atmospheres and a temperature in the upper half of the destructive hydrogenation range with an amount vof hydrogen in excess of the amount of hydrocarbon vapors present at the pressure and temperature employed,

the partial pressure of the' hydrogen being chosen so low as to-'prevent the formation of saturates and so high as to prevent the formation of coke,

this treatment giving rise to the formationA of unsaturated hydrocarbon mixtures boiling below 200 C.4 and possessing a high value.

2. The process as defined in claim 1 wherein thetemperature employed ranges from 500 to 650 C.

3. The process as defined in claim 1 wherein a catalyst immume to poisoning by sulphur is utilized. y

4. 'Ihe process of producing liquid hydrocarbons which comprises destructively hydrogenating in the vapor 'phase liquid hydrocarbon materails essentially comprising constituents boiling substantially below 325 C. at a temperature of from about 500 lto 650.C., in the presence of a catalyst immune to poisoning by sulphur, with an amount of hydrogen in excess of the amount of hydrocarbon vapors present at the pressure and temperature employed, the partial pressure of .the hydrogen being chosen so low'as to prevent the formation of saturates and so high as to prevent the formation of coke and the partial pressure of the improved products formed which boil below 200 C. being maintained of the total pressure, this treatment giving rise to the formation of unsaturated hydrocarbon mixtures boiling below 200 C. and possessing a high anti-knock fuel value.

anti-knock fuel above 10% 5. The process of producing liquid hydrocarbons which comprises destructively hydrogenating in the vapor phase a liquid hydrocarbon mixture boiling to the extent of at least 75% above C. and practically completely below 325 C. at a pressure of at least 20 atmospheres and a temperature of from about 500 to 650 C., in the presence of a catalyst mmume to poisoning by sulphur, with an amount of hydrogen in excess of the amount of hydrocarbon vapors present at the pressure and temperature employed, the partial pressure of the hydrogen being chosen so low as to prevent the formation of saturates and so high as to prevent the formation of coke and the partial pressure of the improved products formed which boil below 200 C. being maintained above 10% of the total pressure, this treatment giving rise to the formation of unsaturated hydrocarbon mixtures boiling below 200 C. and possessing a high anti-knock fuel value.

6. The process as dened in c1aim'5 wherein a parent hydrocarbon mixture is employed which boils to the extent of at least 75% above 80 C., and practically completely below 180 C.

7. The process as defined in claim 4 wherein the partial pressure of the products formed which boil below 200 C. is adjusted so as to be higher the richer is the initial hydrocarbon mixture in hydrogen.

8. The process as defined in claim l wherein the products formed which boil above 200 C. are condensed from the gases issuing from the reaction vessel and'returned to the reaction vessel.

9. The process as defined in claim 4 wherein the parent hydrocarbon material comprises a heavy benzine boiling substantially between 130 and 200 C., the temperature is one selected from a range of from 540 to 570 C., the partial pressure of the parent material is about 60 atmospheres, the total pressure is about 200 atmospheres and the catalyst comprises a mixture ofv

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