US2378200A - Catalytic cracking of hydrocarbons - Google Patents

Description

.Paten'ted June 12,.' 1945 2,378,200 CATALYTIC CRACKING OF HYDROCARBONS Joseph D. Danforth, Riverside, Ill., assignor to Universal Oil Products Company,` Chicago, Ill., a corporation of Delaware v Application November 9, 1942, Serial No. 464Q984 (Cl. ISG-'54) 14 Claims.

This appiicauonis a continuation in part of my copending application Serial No. 412,715 filed September 29, 1941.

This invention relates to the treatment of hydrocarbons for the conversion thereof into lower boiling hydrocarbons suitable for use in motor fuel and particularly to the .production of individually lower boiling hydrocarbons of a branched chain structure which can be used as a starting 'material insynthetic processes or directly as high antiknock constituents of motor fuel blends of gasoline boiling range. More specifically, the invention is concerned with improvements in a catalytic 4cracking process wherein a metallic halide catalyst of the Friedel-Crafts type is introduced into the reaction zone by a liquid carrying medium. i

It has been recognized for some time that there is a distinct limitation both' as vlto quality and yield. of product obtainable from strictly thermal cracking processes aimed at the production of optimum yields of high antiknock value gasoline. Even though cracking .plants have been developed which are more or less perfect mechanically and where individual fractions of hydrocarbon charges and intermediately insuciently converted products are subjected individually to conditions of temperature and pressure best suited for effective conversion; it has been found that high antiknock value materials useful as gasoline boiling range motor fuels are difficult to obtain without sacrificing yields due to losses by the formation of fixed gases on one hand and production of heavy carbonaceous residual` materials on the other. It has further been found that gasoline produced by thermal cracking contains a substantial quantity of unsaturated hydrocarbons which have a tendency to decrease the effectiveness of added antiknock compounds such as tetraethyl-lead.- To overcome these limitations, many catalytic processes have been tried with varying degreesy of success. Substantially saturated .gasolines having comparatively high octane numbers have been produced by cracking .high boiling hydrocarbon oils in the presence ofimetallic halide catalysts of the Friedel-Crafts type such as aluminum chloride. The major drawback to this operation has beenthe excessive catalyst consumption due-primarily to the production of heavy hydrocarbon catalyst complexes by the reactionvbetween the .fragmental -unsaturated hydrocarbons formed during the cracking operation and the catalyst material. v

vThis invention is directed to an improved process'for cracking highk boiling hydrocarbons in the presence of a metallic-.halide catalyst of the -Friedel-.Crafts type. The improvements are primarily a novel method of introducing the catalyst into the reaction zone and the presence of a diluent in the reaction mixture. In the process herein disclosed, the dilu'ent is also utilized asa means for the introduction of the catalyst. One

of the essential features ofthe improved -operation is the conduction of the cracking reaction in the presence of a small amount of catalyst and the continuous addition of catalyst to the reaction zone, in a liquid hydrocarbon carrying medium. Inthe ordinary operation, theC reaction is conducted in the presence of the bulk of the catalytic agent. As a result, a large portion of the catalyst is contaminated and consumed without being electively used In conducting the operationin the manner hereinafter more fully described only a small portion of the catalyst is contacted with the hydrocarbons to be cracked While the major portion is maintained in a separate catalyst supply tower through which the liquid hydrocarbon carrying medium is passed.

The presence of a liquid diluent in the reaction mixture reduces the concentration of the reactive hydrocarbon, decreases the time of said hydrocarbon within the reaction zone and eliminates to a considerable extent the further decomposition, Y of the desiredV products and the formation of heavy 'hydrocarbon vcatalyst complexes. This diluent also has a washing effect and removes A the sludge-like materials which tend to coat the catalyst thereby presenting an active catalyst surface for contact with the incoming hydrocarbon reactant. Under some conditions, the diluentv may also undergo conversion. For examplefif normal butane is used as a carrying medium under A conditions of temperature and pressure at which the operation is conducted a substantial amount of isobutane is produced. vAlthough the concentration of active catalysts within the reaction zone is continually being decreased by the formation of hydrocarbon catalyst complexes', this de- Jpletion is compensated by the introduction of fresh catalysts in solution with the liquidv carrying medium thereby maintaining the `active catalyst concentration within the reaction zone substantiallyconstant throughout the entire operation.

The ,amount of l'liquid hydrocarbon introduced' into the reaction zone as a carrying medium is dependentupon the particular type of hydrocarbon used-for this purpose, but will ordinarily be within the range of approximately 40 to 90% by volume of the hydrocarbon oil being cracked. Byloperating inthis manner, the catalyst will b'e more eiiiciently utilized and the amount of hydrocarbon oil, converted per pound of catalyst consumed substantially increased. Under certain conditions of operation, it may be desirable to add hydrogen and/or hydrogen chloride in amounts not exceeding mol of the reaction mixture.

In one specific embodiment, the present invention comprises a process for converting relatively high boiling hydrocarbon oils into substantial yields of lower boiling hydrocarbons 'by subjecting said hydrocarbon oil in a substantially liquid phase to contact Within a reaction zone with aluminum chloride introduced to said reaction zone by a liquid 'carrying medium.

By the process of this invention, a metallic halide catalyst of the Friedel-Crafts type and particularly aluminum chloride is; introduced into the reaction zone 'by means of a liquid hydrocarbon carrying medium. This liquid hydrocarbon carrying medium may be normal or isobutane formed in the process or introduced from I an outside source, relatively low boiling normallyA liquid parail'ins or naphthenic hydrocarbons, boiling within the gasoline boiling range, for example the approximate range of from about 10 to about 350 F. at atmospheric pressure. The liquidcarrying medium is passed through a chamber containing a metallic halide catalyst maintained at such a temperature and pressure that the desired amount of catalyst is carried therefrom by the carrying medium. The actual amount of catalyst removed from the catalyst chamber is dependent upon the solubility of the aluminum chloride or other metallic halide catalysts in the particular hydrocarbon hosenl as a carrying' medium. 'I'he solubility, of course, will be controlled-primarily by the temperature at which the solved therein sufcient to promote the cracking of a hydrocarbon oil when introduced in a subsequent reaction zone. The particular temper ature at which catalyst tower 3 is maintained is dependentupon the type of hydrocarbon being used as a carrying medium. With butane ther temperature is ordinarily within the range of approximately 140 to about 250 F. and under a pressure sufficient to maintain the butane in a substantially liquid phase. With various other hydrocarbons, the temperature may be lowered to approximately 100 F.' or raised to about 350 F. The catalyst disposed within tower. 3 may comprise aluminum chloride, zirconium chloride, zinc chloride, iron chloride, or mixtures'thereof. However, for purposes of simplification, the descriptionof this drawing relates to the use of aluminum chloride as the catalyst agent.

The butane containing the desired amount of aluminum chloride leaves catalyst tower 3 through line l containingvalve 5 and is intro-v duced into reactor 6 wherein it is contacted with a hydrocarbon charging stock, comprising either a kerosene or gas oil fraction from the primary distillation of a crude oil, introducedthrough line 36 containing valve 31 into pump 38 which discharges through line 24 4containing Valve 25 into reactor 6. As previously pointed out, in the preferred mode of operation reactor G shall be a packed chamber containing any solid granular packingeither porous ornon-porous which does git deleteriously affect the activityoi. the catacarrying medium is maintained. The catalyst carrying medium and the hydrocarbon oil to be cracked are introduced to a reaction zone wherein a substantial portion of the high boiling hydro- 'carbone are converted into gasoline boiling range hydrocarbons. "Although the reaction chamber may be a large empty chamber providing suili- I cient reaction time to produce' the desired conversion, it is preferablypacked with any well known granular porousV or non-porous-packing material which has no harmful effect upon the activity of the metalhalide cracking catalyst. The particular material employed in any given reaction is dependent upon the hydrocarbons being treated, the temperature and pressure employed, the amount of catalyst used and other v The features and advantages of the present inventicn will be further evidentA from the consideration of the following description of acharacteristic operation in connectionwith the attached drawing whichshows diagrammatically in general side elevation one type of apparatus in which the process of the invention may be carried out. For simplication, .such units as furnaces, condensers, reboilers, etc. not essential st. The temperature within reactor 6 `is ordinarily maintained within the range of approximately 200 to 750 F., but preferably within the,

range of 200 toabout'500" F. This temperature will be controlled somewhat by the particular'v hydrocarbon chosen as the carrying medium, since one of the essential features of this invention is that a substantial portion of the carrying medium be. dissolved.E within .the hydrocarbon oil being cracked to act as a diluent. The pressure will be controlled by the temperature and the amount of carrying medium dissolved in the reaction products desired, but will ordinarily be within the range of 150 to 2000 pounds.

As shown in the drawing,l the aluminum chloride containing stream and the hydrocarbon oil to be cracked are in parallel flow. However, this invention is not limited to any particular ow in- -the reaction'zone. The aluminum chloride containing stream may also be introduced counter current to the gasoil stream and eil'ective results obtained.

Although only one catalyst supply tower and onereaction tower areshown in the attached diagrammatic drawing, more than vone may be employed simultaneously or intermittently either in parallel or series now. Y

The reaction .products leave reactor 6 through line 1 containing valve 8 and are introduced into fractionator 9 wherein the isobutane and normal butane charged to the process orl formed during the operation in adm ixture with any light hydrocarbon gases' formed are separated from the heavier hydrocarbons. The butane stream is withdrawn through line I0 containing valve Il and is introduced into fractionator -I2 wherein Athe isobutane and lighter hydrocarbons are sepf arated from the normal butane and recovered through line I6 containing valve l1 as a product of the reaction.' The normal butane is withdrawn from fractionator l2 through line I8 containing valve I9 and recycled through pump 30 which discharges through line 3 [containing valve 2,378,200 3 32 into line 34. '.I'he excess normal butane formed during the ,reaction is withdrawn through line 39 containing valve 40 and recovered as a. product I* of the reaction.

The hydrocarbons boiling higher than.butane are withdrawn from fractionator 9 Ithrough line I3 containing valve H to fractionator l5 wherein the gasoline boiling range hydrocarbons formed during the reaction are separated from the insufllciently converted hydrocarbons. These gasoline boiling range hydrocarbons are withdrawn through line 20 containing valve 2I, cooled and condensed, and recovered as a product of thereaction. The insuiiicientlyconverted hydrocarbons are withdrawn through line 22 containing valve .23 into the suction of pump 26 which recycles these hydrocarbons through line 21 containing valve 28 hito .reactor 6.

If it is desired to have hydrogen or hydrogen chloride present within reactor- 6, they may be introduced either singly or together through line 4I containing valve 42 into line l which directs them in admixture with the butane catalyst so- -lution into reactor E.

The following examples are introduced to illust-,rate the improved results obtained from the process, although they are presented with no'intention of limiting the scope of the invention in exact correspondence with the examples given.

`since some latitude is possible in the type lof packing material used in the reaction zone, the

amount of catalyst introduced to said zone, the

conditions of operation, etc.

' Example I A butane fraction comprising essentially normal butane is heated to 200? F. under a 'pressure of 250 pounds per square inch and -passed through a bed of granular aluminum chloride disposed within a catalyst supply tower. The elliuent from the tower is commingled with a 31.0 A. P. I. kerosene fraction in a packed reaction zone maintained at 250 F. under a pressure of 500 pounds to the volumes of kerosene is maintained at about 1:1. A once through yield of 34% by volume of 400 F. endpoint gasolineof 78 octane number I persquare inch.l` A ratio of volumesof butane and 2 bromine number is obtained. 'The actual aluminum chloride consumption is approximately two pounds per barrel of kerosene charge. About 23 mol of the normal butane charge is converted into isobutane.

` Example II For comparative purposes, the same kerosene charging stock is heated to 250 Ffand introduced under 500 pounds persquare inch pressure into a reaction zone containing granular aluminum chloride. A once throughyield of 32% byvolume of 400 F. endpoint gasoline with a 77.4

octane vnumber is obtained. While the once through yield of gasoline is only slightly less than that obtained when operating in accordance withl the improved method shown vin Example I, the

consumption of aluminum chloride is increased approximatelytwo fold to about 4 pounds'per barrel of charge. f f l Iclaimasmyinvention: 1. A process for producing lower-boiling hydrocarbons from higher boiling hydrocarbons which comprises passing said higher boiling hydrocarbons through Aa reaction'zone containing asclid packing material capable of retaining 'a deposit of metal halide catalyst, passing a separate stream of liquid hydrocarbons boiling within the approximate range of 10 to 350 F: under atmospheric pressure in contact with a body of a metallic halide catalystof the Friedel-Crafts type under. conditions such as to dissolve catalyst therein, commingling the catalyst containing stream with the stream oi higher boiling hyf drocarbons within the reaction zone,l and maintaining the reaction zone at acracking ,temperature to therein convert a substantial -portion of the hydrocarbons into lower boiling products.

v2. A process for producing gasoline boiling range hydrocarbons from higher boiling hydrocarbons which comprises passing a streamof said higher boilinghydrocarbons through 'a reaction l5 zone containing afsolid packing material capable oi' retaininga deposit of an aluminum halide catalyst, passing a separate stream of a liquid lyst containing stream with a stream of the higher boiling hydrocarbons .within the reaction zone,

and maintaining' the .reaction zone at a cracking temperature to therein convert a substantial portion of the hydrocarbons into lower boiling products.

' h her boiling hydrocarbons through a reaction z ne containing a'solid packingy material capable of retaining a deposit of an aluminum halide 35- catalyst, passing a separate stream of a liquid hydrocarbon boiling within the approximate range'of 10 to 350 F. at atmospheric pressure in contact with 'a bodyof aluminum halidecatalyst under conditions such as to dissolve cata- 40 lyst therein, commingling the resultant catalyst containing stream with the higher boiling hydrocarbon stream in the presence of hydrogen halide within the reaction zone, maintaining the reaction zone at a cracking temperature to therein convert a substantial portion o f the, hydrocarbons into lower boiling products and separating the latter from the efuent of the reaction zone.

4. A process for producing lower boiling hy:

drocarbons from higher boiling hydrocarbons hydrocarbons through a reaction zone `containconditions suchas to dissolve therein aluminum halide from said body, commingling 4the resultant catalystl containing butane :stream with the stream of higher boiling hydrocarbons' in the u presence of hydrogen halide Within the reaction zone, maintaining said reaction zone at a crack-l lng temperature to therein convert ansulistantial portion of the hydrocarbons to lower boiling l .products and separating the latter from the eilluentof 'the reactionzone. i

5. A conversion process which comprises introducing hydrocarbons into a reaction zone-containing a body of solid packing material; supplying to `said reaction zone a separate streaml of 0 liquid substantially saturated hydrocarbons con-- taining a dissolved metal halide catalyst, and

eiecting' conversion cfa substantial portion ci the hydrocarbons into lower boiling hydrocarbons in said zone in the presence of the catalyst introduced in said separate stream. i

3. A process for producing' gasoline boilingv 30 range hydrocarbons fromhigherboiling hydrocarbons which comprises passing a 4stream of said which comprises passing a stream of theheavi'er 6. A conversion process .which comprises introducing a stream of hydrocarbons into a reaction zone containing a body of solid packing material, subjecting a separate stream of liquid substantially satuated hydrocarbons to contact with a metal halide catalyst under conditions such that said separate stream dissolves at least a portion of the metal halide catalyst, introducing the resultant solution into said reaction zone, and effecting conversion of a substantial portion of the hydrocarbons into lower boiling hydrocarbons in said zone in the presence of the catalyst introduced in said separate stream.

7. The process of claim 6 further characterized in that said liquidhydrocarbons comprise liquid butane.

8. The process of claim' 6 further characterized in that conversion of the hydrocarbons is,

accomplished in the presence of a 'hydrogen halide.

` 9. A conversion process which comprises introa hydrogen halide to said zone and maintaining the reaction zone at cracking conditions to eiiect conversion of the hydrocarbons in the presence or the catalyst introduced in said separate stream..`

10. The process of claim 9 further characterizedin that said aluminum halide comprises aluminum chloride and said hydrogen halide comprises hydrogen chloride.

11. The process of claim v9 further characterized in that the cracking reaction is accomplished in the presence of. hydrogen.

12. A cracking process which comprises introducing a hydrocarbon oil heavier than gasoline to a reaction zone containing a body of solid packing material and maintained at cracking temperature, simultaneously introducing to said zone a, stream of paraflinic hydrocarbon liquid containing a dissolved aluminum halide catalyst, and cracking the oil in said zone in the presence of the catalyst introduced thereto in said paraiiinic liquid. y

13. fIhe process as defined in claim 12 further characterized in that hydrogen is introduced to said zone during the cracking of the oil therein.

14. 'Ihe process as dened in claim 12 further characterized in that said parafilnic liquid comprises a butane. l

. JOSEPH D. DAN'FORTH.

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