US1966790A - Process of joint hydrogenolysis and methanolysis - Google Patents

Description

-.C. ELLIS Jufly 17, 1934.

PROCESS OF JOINT HYDROGENOLYS IS AND METHANOLYSIS Fil ed Sept. 20, 1930 Patented July 17, 1934 UNITED STATES PROCESS OF JOINT HYDROGENOLYSIS AND METHANOLYSIS Carleton Ellis, Montclair, N. J., assignor to Standard-I. G. (Zompany Application September 20, 1930, Serial No. 483,383

1 Claim.

This invention relates to the art of treating carbonaceous material with orienting gas composites to form from said carbonaceous material liquid hydrocarbons of a greater range of adaptability as light volatile liquid motor fuels, especially those of desirable anti-knock characteristics; such carbonaceous material including coal and its liquid to solid distillation products, petroleum of liquid to solid character, shale oil and tars from various sources, asphalts and/ or mixtures of certain of these raw materials: the invention being illustrated by examples showing the treatment of liquid petroleum raw material or petroleum oil.

According to the present process I propose preferably to reconstitute specifically liquid petroleum hydrocarbons at high temperatures in a gaseous atmosphere preferably consisting largely of extrinsic hydrogen and a lesser proportion of methane, while creating a pressure of many atmospheres in order to counteract as far as possible the normal tendency exhibited by petroleum hydrocarbons to undergo .dehydrogenation and gas formation at high temperatures.

While it is not apparent that all changes of a dehydrogenating character resulting through the heat treatment of petroleum oils are of a reversible character, a considerable proportion of these may, however, be expected to show such reversibility. In consequence the reaction of a high pressure by the introduction into the heating zone of suitably compressed hydrogen, together with certain other gas or gases, tends by mass action to retard or inhibit dehydrogenation, thereby permitting other and more useful reactions to take place.

When petroleum oil is heated under ordinary conditions of pyrolytic cracking, the break down results in the formation of both lighter and heavier products. These heavierproducts are normally considered to be the result of polymerization or combination of large fragments or residues resulting from the splitting. Polymerization, or whatever the type of reactions are that result in the formation of these heavier-hydrocarbon molecules, is objectionable in that it reduces the yield of light liquid products and also generally progresses unfavorably through various stages, resulting finally in the production of coke and tar. On the other hand, a considerable proportion of hydrocarbons which otherwise might be available in the formation of useful liquid products are converted into gases. The formation of the heavy polymerization products and gases interferes considerably with the 0bjective of the cracking operation as commercially practised.

In one phase of the present invention an object is to obtain from heavier petroleum hydrocarbons a predominating yield of lighter liquid hydrocarbons, especially those within the gasoline range of boiling point by conducting the operation so as to minimize or at least depress the casting off of hydrogen and the formation of polymers.

To accomplish this I introduce hydrogen, pref.- erably with other gases, as an orienting gaseous composite prepared from an outside source, such extrinsic hydrogen and concomitant gases being employed not only for the purpose of hydrogenation, but to prevent or retard objectionable dehydrogenation and gas formation by the petroleum hydrocarbons undergoing treatment. If the molecules of oil which are being submitted to reconstitution are spaced wellapart by interposed molecules of hydrogen and methane, the reactions of polymerization resulting in heavy tars and coke are not prone to occur, especially when the spacing, dilution or whatever the condition established is termed is considerable. The presence of hydrogen of adequate partial pressure may be expected to retard or prevent dehydrogenation in many of these cases where the reaction of dehydrogenation is reversible. This inhibition is more or less effective dependent upon the relative proportion of the hydrogen present in the gaseous composite, that is, on its partial pressure and on certain other conditions. Thus I may on the one hand retard or suppress polymerization and on the other hand reduce the tendency to dehydrogenation and gas formation.

The establishment of such conditions gives rise to a species of hydrogenolysis or specifically hydromethanolysis which permits the heavy oil molecules to become converted into molecules of lower molecular weight, the major part of.

which are of a valuable liquid character, without any net or material absorption of extrinsic hydrogen so far as the liquid products themselves are concerned; such hydrogen as may be required for actual reconstitution possibly even being available as a result of the changes taking place in the oil molecules themselves. It should be noted that the change of hydrocarbons of the parafiin series, CnH2n+2, to those of the naphthene or of the olefin series, CnH2n, and to the aromatic series, CnH2n-6, is accomplished by reduction in the proportion of hydrogen in the molecule. From a mixture of petroleum hydro carbons of various types, including those of the paraflin and naphthene series, the process, so

far as the formation of liquid products is concerned, may be considered to carry through without the consumption of any extrinsic hydrogen and, in fact, in some cases perhaps accompanied by the actual liberation of hydrogen from hydrocarbons which mingles with the extrinsic hydrogen of the reaction zone. On the other hand, any unsaturated gases split off during the reaction, in the presence of hydrogen activated by catalysts or otherwise, will become hydrogenated to an extent dependent upon conditions resulting in many cases in a favorable influence on the reaction particularly desired, namely, the formation of valuable liquid products.

Hydrogen is a costly gas to manufacture on the large scale and this expense is a consideration of importance in the commercial development of the present methods of hydrogenating petroleum hydrocarbons. Since my process does not call for the production of hydrogen in great quantities for actual hydrogen absorption, (except as later noted) but merely requires available a sufficient amount to create the requisite partial pressure, a saving in the cost of operation may be expected.

The process may be carried out in the presence of catalyzers if desired. For hydrogenolysis of this character I preferably employ catalysts which are immune to poisoning by sulphur, oxygen and similar bodies. For this purpose I may use the oxides of molybdenum or tungsten or mixtures of these, preferably incorporated with a bulky carrier and promoter, such as alumina or magnesia. These catalysts are employed not essentially to accomplish hydrogenation through introduction into the molecule of extrinsic hydrogen, but primarily to serve as contact substances to facilitate reconstitution of the petroleum hydrocarbon molecules in the atmosphere of hydrogen. By having present catalysts of this or analogous character complex hydrocarbon molecules may pass through a reconstitution stage involving the formation of simpler mole cules, the trend being in the direction of cyclic compounds containing a diminishing percentage of hydrogen, thereby resulting in light liquid fuels of relatively high anti-knock value. This phase of conversion occurring in the hydrogenolysis may be expressed more specifically as dehydrogenation cyclicyzation.

Catalysts also are useful in enabling the hydrogen given off by the hydrocarbons in excess of the requirements of cyolicyzation to react with the sulphur compounds present and allow the latter to become eliminated as hydrogen sulphide. Hydrogen freshly liberated from the oil molecule may be looked upon as in an active state in which condition its reaction with sulphur to form hydrogen sulphide should occur with comparative ease. As a result I am able by such hydrogenolysis to reduce the sulphur content of thehydrocarbons in considerable measure. This is quite important in the production of hydrunsulphed liquid fuels of good commercial grade.

As a general rule the reconstitution to lighter liquid products serving as motor fuels is optimum at temperatures preferably within the range somewhat above 900 F. and extending to 1000 F. or even higher.

Although pressures of 50 atmospheres or thereabouts may be used, the reaction of reconstitution would progress somewhat too slowly to meet commercial requirements and much higher pressures preferably are employed, including the desirable range 150-250 atmospheres. Pressures even higher may be used in some cases, such as 500 or 1000 atmospheres. By imposing pressure upon temperature an acceleration of reaction results and occurrence of possible unfavorable side reactions may be largely avoided. In the treatment of liquid petroleum raw material I prefer to conduct the evaluating r actions at temperatures and pressures above the critical or at least in that neighborhood. Hence the pressures thus specifically involved are generally above 100 atmospheres and more often above 200 atmospheres. In using such superpressures I do not consider that there is any upper limit except that imposed by cost of compression of the gas.

A desirable method of operation is to preheat the feed oil and orienting gaseous composite which may be done by heat exchange, that is,

the hot products leaving the reaction zone may be brought into heat exchange contact with the feed.

From the heat exchange system the feed may pass through a preheating system and thence to the reaction chamber, where catalysts may be placed arranged in fragmental or other form which permits of free movement through the reaction zone of the entering charge. After the material has left the heat exchange system it is passed to coolers or condensers and to a receiver where the oil is withdrawn and as much of the hydrogen-containing gas as is needed is returned to the reaction zone (recycling). Makeup hydrogen is added as required to create the requisite hydrogen partial pressure. The pressure is released on the oil so withdrawn and the oil is submitted to distillation to separate any particular fractions desired. The hydrunsulphing reactions which progress in the case of petroleum oils containing sulphur compounds result in the formation of hydrogen sulphide and it becomes necessary to discharge a portion of the gases in circulation. These may be vented to the atmosphere or may, if desired, be conveyed to purifiers and treated to produce a fresh supply of hydrogen-containing gas suitable as make-up gas. The release of gas pressure on the oil products also permits the liberation of dissolved gases which may be collected and treated for recovery or discharged as waste, according to local requirements.

Nitrogen compounds present in the oil are usually converted in part at least into ammonia, espe cially in the presence of catalysts of the ammoniaforming type. When the orienting gaseous composite contains nitrogen there exists also the possibility that a part at least of such nitrogen will be converted into ammonia. Owing to the formation of hydrogen sulphide this ammonia will react therewith, forming various ammonium sulphides according to proportions present. The recovery of such ammonium sulphide is contemplated hereunder. The formation of ammonia in this manner also apparently serves another useful purpose in that it aids in the removal of the sulphur from the oil. When an oil of a more refined type low in sulphur is being treated. especially if such oil happens to contain a relatively large proportion of nitrogen compounds, the resulting ammonia may be in excess of that adequate to combine with the sulphur and thereupon ammonium carbonate may be produced, if carbon dioxide is present in the circulating gases. In this case the recovery both of the ammonium sulphide and ammonium car- I the like.

bonate is withinthe purview of the present invention. It should be further noted that nitrogen compounds in the oil appear to stimulate the reaction between nitrogen and hydrogen present in the orienting gaseous composite.

The invention therefore contemplates the recovery of compounds of ammonia according to one phase of operation.

The foregoing has considered chiefly the operation from the standpoint of production of liquid bodies. The invention, however, at least in one phase thereof, involves the simultaneous formation by hydrogenation of certain gaseous products.

Roughly speaking, the stability of hydrocarbons is inversely as the number of carbon atoms present in the molecule, hence methane represents maximum stability, its formation under the conditions imposed herein liberating heat, especially when it is formed through the hydrogenation of oxides of carbon. In carrying on the reaction at the relatively high temperature desirable in the production of anti-knock motor fuels, an evolution of heat in the reaction zone is important. The transmission of heat through metal conducting surfaces is likely to be poor and the intense heat required to be applied often being sumcient to quickly oxidize and distort the metals composing these contacting surfaces.

Hence the evolution of heat in situ is desirable.

With hydrogen seeking to form a hydrocarbon of the greatest stability, namely, methane, there results a pronounced exothermic reaction which is notably great when carbon dioxide and carbon monoxide are thus converted.

If the orienting gaseous composite be made from natural gas by reaction of steam therewith there will be produced in the first instance'a gas containing hydrogen, methane, carbon monoxide, carbon dioxide and nitrogen. The carbon dioxide may be removed by washing with alkaline solutions. In this way a gas may be prepared containing 87 to 88 percent of hydrogen, 5 percent of methane, 4 percent of carbon monoxide and small quantities of nitrogen, the relative proportions of these components varying somewhat from time to time. From the reaction zone in hydromethanolysis there may be obtained a mixture of gases which will contain perhaps percent of hydrogen, 26 or 27 percent of methane, 1 or 2 percent of ethane and less than 1 percent, usually about of 1 percent of carbon monoxide. These proportions are not given as figures whichare constant in actual operation, as variation will result according to conditions of operation, products required, and If the fresh gas is mixed with the recycled gas in the proportion of say one part of fresh gas to 2 parts of recycled gas, or perhaps in the ratio 5:9, an orienting gaseous mixture will be obtained for delivery to the reactor containing a little over one percent of carbon monoxide-perhaps percent of hydrogen, 22 percent of methane and a small amount of ethane. With this equilibrating proportion of methane, that is a proportion adequate to repress or overcome the normal tendency of petroleum hydrocarbons to split to yield this most stable hydrocarbon methane, the tendency of simultaneous formation of higher complexes leading to the production of tars, coke, and the like, is depressed. In hydromethanolysis, therefore, methane is present in such proportions as to secure this equilibrating eifect in greater or lesser degree while at the same time carbon monoxide needed in special cases, this may be accomplished by feeding cold gas at such a point in the reaction zone that adequate reduction of the temperature will take place.

Referring to the drawing, numeral 1 denotes the feed line throu h which the oil is forced by pump 2. The oil is ed with a gaseous treating agent which is supplied under high pressure from line 3, the composition of which is disclosed above, and the mixture flows through a pipe 4 and a heat exchanger 5, thence by line 6 to a fired coil 7 mounted in the furnace setting 8. The pre-heated mixture then flows through a reaction chamber 9 which may be supplied with a suitable catalytic agent indicated at 10, the composition of which is disclosed above.

The products leaving the reaction chamber by l ne 11, flow to the heat exchanger 5 mentioned above, and then pass into a separation drum 12, from which condensed oils flow to storage, not shown, by line 13 and gaseous products are drawn oil by pipe 14 to a purifier 15 which is in the form of a scrubbing tower. By proper adjustment of the quantity of scrubber oil, temperature and other conditions, methane and hydrogen sulfide may be removed from the gas. Fresh gas is added by line 16 and this composition is so adjusted as to control the composition of the total mixture in accordance with the principles outlined above. The gas mixture is compressed by a pump 17 and forced through the pipe 3 mentioned above for circulation through the system.

Example 1.Trea.t a sulphur-containing gasoil in accordance with the foregoing procedure to make light motor fuel, employing a temperature in the reaction zone of 975 F. and a pressure of 200 atmospheres. Use 5000 to 10,000

cubic feet of the gaseous composite (substantially free from carbon monoxide) per 50 gallon barrel of oil used as raw feed. (The volume of gaseous composite is expressed in cubic feet calculated at atmospheric pressure). Condense and separate the light liquid products from the heavier oils. Recycle the latter. Give the light liquid products a slight acid treat and distil to an end point of approximately 400 F. Wash the exit products to remove ammonia compounds as explained above. I

' Example 2.Use gaseous composite containing approximately 3 percent of carbon monoxide and carry the temperature of the reaction zone to 10001020 F. through the additional aid of the exothermic heat thereby generated. As charging stock employ gas oil or heavier oil. Pressure 300- atmospheres. Gaseous composite used at the rate of 4,000 cubic feet per barrel of oil feed. Condense and separate as in Example 1.

The charging stocks of Examples 1 and 2 may contain variable amounts of sulphur. In the following example a charging stock having low sulphur is used in order to obtain ammonium carbonate.

Example 3.Follow the procedure of Example 2, but use as charging stock gas-oil of low sulphur content according to usual standards of sulphur rating. In washings from the condensers and separators collect and refine ammonium carbonate.

Example 4.--Treat a crude naphtha distillate high in sulphur, using a reaction temperature of 980 F. and a pressure of 220 atmospheres. Use 2000 cubic feet of gaseous composite per 50 gallon barrel of raw feed. Condense and separate the light liquid products as anti-knock gasoline stock.

Example 5.-Mix the anti-knock gasoline stock of Example 4 with normal refinery gasoline in proportions to give a blend in which the antiknock stock is present in a proportion ranging from 2.5 to percent, according to the antiknock characteristics desired in the blended fuel.

The hydromethanized motor spirit obtained according to the foregoing procedure may be treated, if desired, by any known refining process, such as sulphuric acid and alkali treatments, and the like. It may be used in the form obtained by the process or may, if desired, be mixed with normal refinery gasoline to produce suitable blends; for example, hydromethanized motor spirit and normal refinery gasoline may be mixed in equal parts. More specifically the process herein involves the step of hydromethanizing petroleum which comprises passing petroleum oil, preferably of a heavy type ordinarily containing sulphur bodies, admixed with a hot highly compressed orienting gaseous composite containing a major proportion of hydrogen, an equilibrating proportion of methane and preferably a few per cent of carbon monoxide into contact with a sulphactive catalyst (that is, one which is active in the presence of sulphur compounds) to convert preferably the major part of said oil into substantially hydrunsulphed liquid products and when carbon monoxide is present to convert the latter substantially into methane with an evolution of heat helpful in the petroleum conversion reaction, condensing the liquid products, preferably recovering compounds of ammonia formed and collecting the methane-enriched gas, preferably mixing a portion of the latter gas with a quantity of fresh gas of higher hydrogen and lower methane content to form said orienting gaseous composite and using this composite for the similar treatment of further quantities of oil. In some cases the remainder of the methane-enriched gas may be treated to recover free and/or combined hydrogen.

It is seen from the foregoing examples that the space-proportioning volume of the orienting gaseous composite varies from 2,000 to 10,000 cubic feet per 50 gallon barrel of raw feed. Such variations are within the range generally required for the reconstituting and dehydrogenating cyclicyzation of petroleum hydrocarbon molecules.

What I claim is:

In the art of treating carbonaceous material with orienting gaseous composites, the step of hydromethanizing petroleum which comprises reacting at a temperature within the approximate range of 900 to 1020 F. and at a pressure above 50 atmospheres on a heavy petroleum oil con-- taining sulphur bodies, in the presence of a sulphactive catalyst with a space proportioning volume of a hot highly compressed orienting gaseous composite containing a major proportion of hydrogen, a lesser equilibrating proportion of methane and a still lower proportion of carbon monoxide, the volume of hydrogen being insufficient to produce saturated liquid products under the conditions impos'ed, for a period adequate to convert the major part of said petroleum into hydrunsulphed liquid products and the carbon monoxide into methane, condensing the liquid products, removing ammonium compounds and collecting the methane-enriched gas, mixing a portion of the latter gas with fresh gas of higher hydrogen and lower methane content and using the composite for the treatment of further quantities of oil.

CARLETON ELLIS.

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