US2253607A - Hydrocarbon conversion process - Google Patents

Description

Aug. 26, v1941.

G. A. BOYD ET Al.

HYDRocARBoN CONVERSION PRocEss 2 Sheets-Sheet l Filed June 19. 193'? Aug. 26, 1941. G. A. BOYD Erm.

HYDROCARBON CONVERSION PROCESS Filed Jun 19, 1937 2 sheets-sheet 2 SSN ,Nav

George Aoyd 6'/ ence HSee/qy ATTORNE Patented Aug. 26, 1941 2,253,607 HYDROCARBON CONVERSION PROCESS George A. Boyd, Evanston, and Clarence H. Seeley, Chicago, Ill., assgnors to Standard Oil Company Chicago, Ill., a corporation of Application June 19, 1937, Serial No. 149,104

2 Claims.

This invention relates to hydrocarbon conversion processes and it pertains more particularly to processes for making high quality gasoline out of refinery gases, natural gases and other gaseous hydrocarbons. An object of our invention is to increase the yield of gasoline and other valuable products obtainable from gaseous hydrooarbons by conversion processes. More particularly, our object is to provide a more emcient and eiective method and means for utilizing the so-called xed gases such as hydrogen, methane, ethane .and ethylene in the manufacture of highl quality motor fuel. l

A further object of our invention is to modify and combine hydrocarbon conversion processes in such a way that each process supplements and 'utilizing the so-oalled fixed gases (tail gases) therefrom, converting said gases directly into motor fuel and/or converting them into such form that they may be polymerized or reacted in other parts of our system to form high quality motor fuel.

An object of our invention is to provide a method and means for fractionating gases in various parts of our system andsubsequently combining andutilizing the component parts of said gases. in systems particularly designed for handling them most effectively.

A furtherobject of our invention is to provide new and improved combinations and subcombinations of refinery processes such as desulfurization, polymerization, synthesis, cracking, dehydrogenation, hydrogen production, gas fractionation and olefin concentration systems.

A further object of our invention is to improve the eiiiciency of gas conversion processes by providing unique combinations thereof with other processes, utilizing heat from one process to carry out other processes, using common gas linesv for tying the various processes together so that the various types and fractions of gases may be properly combined or segregated and conveyed to the proper part of the system. A

.19e- 10) 'further object is to provide a combination gas conversion plant whichwill be characterized by maximum exibility of operation and which will be omnivorous as to charging stocks.

Other objects of our invention will be `apparent as the detailed description proceeds.

`We provide a. combination of conversion processes which are so integrated and linterrelated that each supplements theother in the most eicient manner toproduce maximum yields of high quality motor fuel from any and all types of hydrocarbon gases. Our system includes the desulfurizing of diiferent types of feed gases, the catalytic or thermal polymerization or allylation of condensible gases (particularly olens), the

production of carbon monoxide, hydrogen and condensible gases (particularly olens) from iixed gases, natural gas, etc., the utilization of this carbon monoxide and hydrogen fory the synthesis of motor fuel and of condensible gases containing olens, the segregation of gaseous olens from said synthesis step and from other olefin-producing steps, the recycling of the olens to the gas polymerization step and the recycling of xed gases to the hydrogen-carbon monoxideproducing step, the synthesis step and condensible saturates to olefin production steps.

We iirst convert the sulfur compounds in our feed gases into hydrogen sulfide `by treatment withv catalysts and We remove all hydrogen sulfide thus produced so that there will be no sulfur in the gas streams to poison subsequent catalysts. If the desulfurized gases contain polymerizable fractions they may be subjected to catalytic or thermal polymerization. The natural gas is preferably treated with an oxidizing agent such as steam for the production of carbon monoxide and hydrogen which are then catalytically reacted to form motor fuel and condensible gases containing olens, the latter being charged to the polymerization step. The gases from the synthesis step and gases from other parts of the system may be fractionated on the basis of molecular Weight and on the basis of saturates and unsaturates, the unsaturates being polymerized and the saturates being converted into unsaturates bydehydrogenation, cracking or the carbon monoxide-hydrogen synthesis.

The drawing'which forms a part of this disclosure is a iiow diagram of our improved process which because of its size and complexity has been drawn on two sheets which should be placed together and read as a single figure or drawing.

Before describing the details of our system we will give a brief outline which will assist in the understanding of the process as a whole. Refinery gas is passed through catalytic chamber A to convert sulfur compounds to HzS', the HzS is removed in tower B and the desulfurized gases are then passed to catalytic conversion chamber F or thermal conversion coil in furnace P. Natural gas or high line gas is desulfurized by passing through catalytic tower E and ms scrubber D, the scrubbing liquid for towers B and D being regenerated inthe common tower C. The desulfurized natural or high li'ne gases are then passed through a coil in furnace P and reacted in chamber Q with an oxidizing agent for converting said gas into carbon monoxide and hydrogen. This reaction is at a temperature of approximately 1 500 F., and the sensible heat of the reaction products is utilized for furnishing heat to the desulfurizing and catalytic conversion processes which require temperatures of about 750 and 480 F. respectively. The carbon monoxide and hydrogen formed in chamber Q are then reacted in synthesis catalytic chamber chamber S or to olen absorber tower T, the

olens being withdrawn from the absorber liquid in tower U and returned to the catalytic or thermal polymerization process.

Stabilized gasoline from tower H is debutanized in tower J from which butane and light and heavy polymer gasoline are withdrawn. Similarly, scrubbed products from tower N are fractionated in -tower O, from which light and heavy hydrocarbon products are withdrawn, and from which the saturated and unsaturated condensibles are passed to the polymerization systems, dehydrogenation systenr'RS or olefin concentration system TU.

An important feature of our invention is the relation the CO-Hz conversion system LMNO bears to the rest of the system. The initial desulfurizing steps are necessary to protect the catalyst in chamber L. The catalytic conversion process in chamber L not only utilizes the products from catalyst chamber Q, but it utilizes the tail gases from the polymerization system, many of these gases being actually converted in n concentration system TU are likewise converted via the CO-Hz synthesis route and/or the steps of dehydrogenation or gas cracking, into polymerizable gases which can be converted either thermally or catalytically into motor fuels.

. The CO--Hz synthesis step4 therefore acts to tie together the system as a Whole and to utilize the by-products of other conversion processes for the production of feed stocks for the other processes.

Our invention will be described as applied to the conversion of ordinary renery gases into gasoline where there is also a source of natural gas or xed gas. The refinery gases are those which contain appreciable amounts of propane, propylene, butylene, iso-butylene, butane, etc., andixed gases are those which contain hydrogen, methane and perhaps ethane and ethylene. The analyses of these gases may, of course, vary within wide limits and the operation of our system will be Ymodified accordingly, as hereinafter described.

Renery gas from line I0 is passed by pump II through heat exchanger I2 to catalyst chamber I3 wherein it is contacted with a catalyst mixture ofequal parts of copper oxide and lead chromate moistened with a partially hydrolized solution of commercial ethyl ortho-silicate in toluol, ,Here the organic sulfur compounds are converted into hydrogen sulde, the conversion being eiected at about atmospheric pressure and at a temperature of about 700 to r150" F. It should be understood, of course, that we may 'employ other known catalysts for this conversion and other operating conditions known to those skilled in the art for effecting the conversion of organic sulfur into HzS. The hydrocarbons and HzS are then passed through cooler I4 to reduce the mixture to room temperature or higher, after which it is introduced into the base of scrubber tower I5 (B), in which practically all of the HzS is removed from the gases by means of sodium phe- We prefer to reduce the sulnolate or the like. fur content of the gas to less than .1 grain per cu. ft.

The sulfur-free gases are then passed through line I6, compressor I'l and heat exchanger I8 to catalytic polymerization chamber I9 under a pressure of about 100 to 600 or preferably 300 pounds and at `a temperature of about 300 to 600, or preferably 480 F. The catalyst in this chamber is preferably phosphoric acid on kieselguhr, and the time of contact is preferably about 100 seconds. It should be understood, of course, that any other suitable catalyst may be employed for electing the polymerization of the olerins to gasoline, examples of which are sodium-aluminum chloride, boron trifluoride or other metallic halides, sulphuric acid, etc. No claim is made to the use of any of these particular catalysts, per se, because their use and the operating conditions which they require are well-known to those skilled in the art. Polymerization products from catalyst chamber I9 are withdrawn through line 20 to absorber G.

Instead of employing the catalytic polymerization process we may pass the renerygas from compressor I1 thru heat exchanger I8, line I6 and line 2I to thermal-polymerization coils 22 in furnace P, operated at a pressure of about 500 to 3000 pounds and a temperature of about 800 to 1300 F. with a. time of contact of about 20 to 200 seconds. Here again the particular polymerizing conditions for any gas will be dependent upon the composition of that gas, and since these conditions are known to those skilled in the art they will not be described in further detail. Polymerization products from coils 22 are passed through line 23 to line 20 and thence to absorber G. It should also be understood that the conversion products from coils 22 and/or from' catalyst chamber I9 'may be quenched or cooled prior to or at theetime of their introduction into absorber G.

As an absorber liquid in tower Gwe prefer to employ the heavy polymer from a subsequent tower, as will be hereinafter described. 'Ihis or other scrubbing liquid such as gas oil, naphtha, light hydrocarbons down to and including butane, etc., is introduced through line 24 at the upper part of the absorber, and fixed gases. such as hydrogen, methane, ethane and ethylene leave the top of the absorber through line 25. The heavier reaction products and scrubbingliquid leave the base of the absorber through line 25 l such as sodium phenolate or the like removes all of the HzS fromy the gases, the sulfur-free and are passed by pump 2l into stabilizer tower 28. pressure of vabout 240 pounds per square inch, but itv may be operated at full conversion pressure. The stabilizer tower is preferably operated at a pressure of about 325 pounds[sq. in.. a top temperature of about 130 F. and a bottom temperature of about 440 F. The C3 and yC4 fractions Vfrom the top of the stabilizer are withd rawn through line 29 through cooler 30 to collector orreflux drum 3| from whicha part (containing both saturated and unsaturated Cs and C4 fractions) is. withdrawn through line 32. and another part is returned through line 33 and pump 34 as reflux in the top of stabilizer 28 (H).

Stabilized liquid from the base of tower H is withdrawn through line 35 and introduced into the upper part of debutanizer tower 36 (J), which is preferably operated at a top temperature of about 150 F. and pressure of about 100 pounds per square inch and a bottom temperature of about 385 F. The butane fraction from the top of the tower is withdrawn through line 3l, condensed in cooler 38 and introduced into collector 39 from which a part of it may be withdrawn through line 40 for admixture with the fractions in line 32. A portion oi' .the butane fraction is returned through line 4I by pump 42 through line 43 to serve as reiiux in the top of the debutanizer tower. .A part of the butane fraction from collector 39 may also be withdrawn through line 44 for blending with motor fuel or for other purposes. If it is not desired to withdraw a butane fraction as through line 44 then, of course, tower H can be eliminated and line 26 can connect with tower J in the place of line 35. Towers H and J are necessary only when the butane cut is to be withdrawn.

From an intermediate point of the debutanizer tower a side stream of polymer gasoline is withdrawn through line 45 for storage or for further reining treatments with acid, doctor, doctor solution, clay, selective solvents,'etc. Heavy polymer gasoline is withdrawn from the base of the debutanizer tower through line 45 and it is passed by pump 41 to line `48 to line 24 leading to absorber tower G or through line 49 leading to stor. age or to further refining processes, vas hereinabove indicated.v

Returning now to the beginning oi.' our process, we introduce natural gas, high line gas (refinery gas vented at high pressure and containing chiefly hydrogen, methane, ethane-and other diilicult- The absorber .is preferably operated at ay The gases and HzS from the base of chamber 52 are withdrawn through cooler 53 to the lower part of scrubber. 54 wherein a scrubbing liquid gases being removed from the top of the scrubber throughY line 55,. Scrubber liquid from the base of towers 54 and I5 are introduced through lines 56 and 56 respectively to tower 51 wherein the HzS is stripped from the scrubbing liquid by heater 58, the HzS being vented from the system through line 59. The regenerated scrubbing liquid is then returned through coolers 5I and 6|' to the top of towers l5 and 54. While .we employ two separate scrubbing towers, we eiect a marked saving in installation and operating expense vby employing a single regenerating tower which regenerates the scrubbing liquid for both scrubbing towers.

Sulfur-free gases in line are admixed with steam through line 62 and the mixture is passedy through coils 63 in furnace P wherein they are heated to a temperature of about 1200 to 1500 F. The hot gaseous mixture is then passed over a catalyst such as nickel in catalyst chamber 64 (Q), which is operated at atmospheric f pressure or higher. It should also be understood that the catalyst chamber itself may be heated tothe desired temperature and the gases introduced at a temperature below that required for conversion, piclng up the remaining necessary heat in the chamber. lOther suitable catalyst may be employed` for the conversion of hydrocarbons and steam to carbon monoxide and hydrogen. It should also be understood that instead of steam we may employ other oxygencontaining gases or commercially pure oxygen, the catalyst and conditions for operating the CO and H2 generation being varied accordingly. Also, we 4may react the hydrocarbons with metal oxides to produce the carbon monoxide and hydrogen. Our invention is not specific to any particular type of CO and Hz generation and any well-known process may be used for accomly condensible hydrocarbons), or hydrocarbon Y gases not readily polymerizable, said gas being introduced under pressure through line 50 and heat exchanger 5I into catalyst -chamber 52 Y which is substantially a duplicate oi.' catalyst chamber I3 and which operates under the same plishing this result.

The mixture of CO Aand Hz from catalytic chamber 64 is at the high temperature of at least 1200 F., and it is important that the heat of these gases be utilized. We therefore pass the hot gases by line through heat exchangers- 5I, l2 and I3 so that the heat put into the gases for CH--Hz generation is utilized for supplying at least a major part of the heat for the desulfurization catalytic reactions and for the catalytic gas polymerization. It should be understood, of course, that these exchangers may be supplemented by otherV heaters and other heat exchange systems may be employed for obtaining the necessary temperature conditions and desired heat economy.

The mixture 4of' CO and Hz from line 65, after cooling by the heat exchangers, may be supplemented by CO, Hz or a mixture of CO and H2 from line 56. This gas mixture is then passed through line 61 to line 58 wherein it is admixed with tail gases from lines 25 and 59 and/or with condensible gases from lines 32 and 10 also recycled gases through line ll. The mixture of these gases now having about 1 volume of CO to 1.4 volumes of Hz, although the volumetric ratio t may vary from 1:1 to 1:1.8, is introduced into desire to keep them segregated from polymerizcatalyst chamber L which is maintained at a` temperature of about 400 to 700 F., preferably 475 F., and at a pressure of about 1 to 5 atmos' pheres, the time of contact being about 1o to 6o seconds, preferably about 30 seconds, the catalyst in chamber L preferably comprising eighth group metals, particularly cobalt or nickel, or a mixtuer of eighth group metals with metal oxides. Good proportions of metal to oxide are about 1:1 to 1:3,and the oxides may be of chromium, zinc, beryllium, rare earths, uranium, silicon, aluminum, magnesium and manganese. fer to use about 1 part of iron, cobalt or nickel with about 2 parts of chromic oxide.. Combinations with palladium, copper and iron oxide (the latter with nickel and copper) may be used. Nickel on kieselguhr using thorium as a promoter has been found to give excellent results, the ratio of metals to kieselguhr being 1:1, 18% of the metal being thorium; in this case the metals are precipitated as carbonates and then reduced with hydrogen at 450` C. 'A catalyst may be prepared by dissolving aluminum or silicon from alloys to give a so-called Raney alloy skeleton. Raney catalystsof nickel-aluminum, nickel-silicon, cobalt-aluminum, cobalt-silicon and nickelcobalt-silicon have been used in the reduction of carbon monoxide. A very excellent catalyst consists of nickel, manganese and alumina on kieselguhr or on kieselguhr and silica. Sodium or lithium may be used in very small amounts (less than 1%) with the eighth group metals or eighth group metal combinations.

The exact operating conditions and time of contact in catalyst chamber L, which maybe called our catalytic synthesis chamber, will neces-` sarily vary with the dierent gas mixtures charged theret-o and with the diierent catalysts employed. We prefer to maintain the operating conditions so controlled as to yield a large quantity of olens, particularly in the propylenebutylene range, since such olefins are particularly amenable to polymerization in catalytic chamber |9 or thermal coils 22.

The reaction products and gases from the synthesis catalytic chamber L are withdrawn through line 'l2 through cooler 'I3 for condensing Water, and the condensed water is withdrawn from trap M through line 14. Liquid and gaseous products from trap M are withdrawn through line either to the base of .the scrubber tower N or through line 16 to absorber G. Scrubbing liquid, which may be heavy hydrocarbons from the base of tower O, is introduced throughv line 'll near the top of tower N and xed gases are r-el moved from the top of the tower through line 18j.. These gases may contain considerable amounts of CO, H2 and unreacted gas and may therefore be recycled through line 1|, as hereinabove described. Alternatively, they may be passed through line 19 to line 55 for admixture with further amounts of gases and steam for the generation of further amounts of carbon monoxide and hydrogen.

We pre- A side cut of light liquid hydrocarbon product maybe withdrawn from fractionator tower O through line 8l, and if this stream has a low knock rating it may be passed through line 88 and line 8.3 to the gas cracking coil 84 for cracking and/or gas reversion. Heavy liquid from the base of fractionator O is withdrawn through line 89, a portion of it is cooled and introduced through line |'l as a scrubbing medium in tower N and the rest of it is withdrawn through line 90 as a heavy liquid hydrocarbon product, or is passed through line 88 to the gas cracking coils 84 or dehydrogenation furnace R.

As above indicated, lines 32 and 86 lead to olenconcentrator tower T, the gases being in troduced near the bottom of tower T and a scrubbing liquid such as a selected solvent like B, B dichlorethyl ether being introduced through line 9| at vthe top of said tower. Other selective solvents such as liquid sulfur dioxide, benzol, alcohols, ketones, etc., and even gas oil, naphtha or butane may be used as the scrubbing liquid. The scrubbing liquid absorbs most of the olefins and is withdrawn through line 93 to tower 94 where the oleiinsare removed. In tower 94 there is provided a suitable heater in the base thereof and a suitable reux coil at the top for carrying out the olefin regeneration step. Excess. amounts of butane or other hydrocarbon scrubbing liquid may be withdrawn through line 88 to gas cracking feed line 83 or to dehydrogenation feed line 95. Saturates from the top of tower T may be withdrawn through line 96 from which they may be passed through line 91 to the dehydrogenation furnace R, to line 98, to line 83 and the cracking tubes 84, or to line 19 to the carbon monoxide-hydrogen generator unit. Olefins from the top of tower U are withdrawn through line |00 to line 23, and thence to absorber G or through line |0| to line I6 for'charging to either the thermal or catalyticpolymerization system.

As previously indicated, dehydrogenation furnace R may obtain its feed stock or gases from lines 85, 91 or 95 and line 95 is supplied from vline 88 which is connected to lines 44, 8l and 90 so that saturated liquids or condensible gases from all parts of the system may be charged to this dehydrogenation system for conversion to olefins. rfhe conversion is effected in catalytic chamber S which is operated at about 800 to ()u F., preferably 1000 F. at normal pressure or higher, using a chromic oxide catalyst. Other catalysts known to be effective for dehydrogenation may of course be used. Here again the exact operating conditions will depend upon the catalyst employed, and no claim is made to this specific step since it is Well-known in the art.

Conversion products from chamber S are withdrawn through line |02 and line |03 to olen concentrator tower T or through lines |02 and |04 either through line |05 to absorber G or through line |06 to line I6 for admixture with feed stock entering the thermal or catalytic processes.

We have already described the three coils in furnace P and it should be understood that instead of employing a single furnace we may employ a separate furnace for each coil. The hydrogen-carbon monoxide generator and .the thermal polymerization system have been described. Products from the gas cracking coils 84 are led through line |01 to cooler |08 and absorber G or to line may be passed through une m to une tions for any given deiined by the `following claims .oxide and hydrogen thence either through linev A|00 to line 80- and olen concentrator tower T or through line H to line |04 which leads either to line |05 and l |06 for admixture with polymerization feed stock in line |16. y

The saturates and unsaturates from line 32 to the gas cracking coils, through line I I2 leading to line 85 and the dehydrogenation system or to line- 86 leading to the olen concentrator tower T. Wehave also provided. a. line H3 for introducing these gases from line 32 directly to line I6., so that ii' thegse gases contain substantial amounts of polymerizable gas they may be returned directly to the gas polymerization systems.

While a certain number of pumps, valves, heat exchangers, etc., are shown in the drawings, it should be understood that .the drawings are diagrammatic and that further pumps, valves, heat exchangers, connections, etc., will be ,re-

quired in commercial installations; we do notdesire to complicate the already complex drawings by including further details which will be obvious to those skilled in the art. Operating conditions have for the most part been given and where they have been omitted, for instance with respect to oleiin concentrator tower T, it is believed that those skilled in the art are sufciently familiar with the details to arrive at the proper condistock. We prefer, for instance, to operate tower T under la pressure.` of

about 100 pounds absolute and at a temperature of about 180 F., but a wide range of operating conditions is permissible. Similarly,` the conditions ln the scrubber and fractionator N and O may be changed within wide limits and in fact, we may employ a recovery system similar to G, H andJ in-'place of N and O. While we have described in detail a preferred embodiment of our invention it should be understood that we do not limit ourselves toany of saiddetails except as construed as broadly as the prior art will permit.

We claim:

1. The methodof preparing high anti-knock motor fuel which comprises subjecting substantially sulfur-free gaseous hydrocarbons to a controlled oxidation bycontactng with steam and a catalystl comprising nickel at a temperature of 83 leading which should be Y about 1200 to 1500 F. ,to produce carbon mon- Y admixing said carbon monwith substantially unpolymerizable hydrocarbons, subjecting said mixture to a hydrocarbon lsynthesis step including conoxide and hydrogen,

tion to the said metal of the eighth group at a temperature of about 400 F. to synthesize hydrocarbon gases, separating from said thesized hydrocarbon gases a traction contaiiing substantially unpolymerizable xed gases, recycling the recovered xed gases to the mst-mentioned high temperaturecontrolled oxidation to produce additional carbon monoxide and hydrogen, separating from said synthesized hydrocarbon gases a ,second fraction containing polymerizable gaseous hydrocarbons, polymerizing at least a part of said synthesized hydrocarbon gases to form liquid hydrocarbons boiling within the motor fuel boiling range, fractionatng the polymerization product to recover at least unpolymeriz'ed hydrocarbons, admixing said carbon monoxide and hydrogen from the oxidation step with the unpolymerized hydrocarbons from the polymerization step and passing the mixture to the hydrocarbon synthesis step.

2. The method of manufacturing high antiknock motor fuel which comprises subjecting hydrocarbon gases to controlled oxidation at a temperature of between about 1200 F. and 1500 F. in the presence of a catalyst to produce car- -rated condensible hydrocarbons, and a nxed recycling theiiixed gaseous fracgaseous fraction, y

'oxidation step to produce addiand hydrogen. admixing the unpolymerizable saturated condensible hy'- drocarbons and the said carbon monoxide and hydrogen, conducting the said mixture to the hydrocarbon synthesis step to form additional normally gaseous olefins, polymerizingthe normally tional carbon monoxide gaseous o lenns recovered by the lfractionation o! the hydrocarbon synthesis product; separating at least one polymer fraction comprising normally liquid hydrocarbons boiling within the motor fuel range and at least one fraction comprising unpolymerized hydrocarbons and recycling the said unpolymerized hydrocarbons to the hydrocarbon synthesis step with the normally gaseous hydrocarbons recovered from the hydrocarbon synthesis step. Y GEORGE A. BOYD.

CLARENCE H. SEELEY.

one fraction comprising subjecting saidY mixture to a hydrocarbon

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