US2354652A - Hydrocarbon conversion - Google Patents

Description

Aug. 1, 1944.

D. R. CARMODY l' AL HYDROCARBONv CONVERSION Filed July 28, 1939 paraflins with olens.

Patented Aug. l, i944 HYDROCARBON CONVERSION Don B. Carmody, Whiting, Ind., Aand Bernard L. Evering and Edmond L. dOuville, Chicago, Ill., assignors to Standard Oil Company, Chicago, lll., a corporation of Indiana Application Juiy 2s, 1939, serial No. 287,039

1o claims. (o1. 26o-essa) This invention relates tothe production of hydrocarbons boiling within the gasoline boiling range. 'particularly hydrocarbons having high antlknock characteristics. More particularly this invention relates to a unitary process for the production of high antiknock motor fuel wherein a catalyst spent for one reaction is utilized as the catalyst, inv another reaction. v

The isomerization of naphthas to branchedchain hydrocarbons by the use of an anhydrous aluminum chloride catalyst is known in the art. We have discovered that the catalyst when spent' for promoting the isomerization of naphtha is still an active catalyst for the alkylation of iso- Moreoven during the isomerization reaction varying quantities of isoparaiilns are formed which are useful as a feed for the alkylation process.

It is an object of this invention to .provide an improved process for the production of high antiknock motor fuels characterized by the presence of large quantities of branched-chain paramns. Another object of this invention is to provide a process in which the catalyst spent from one reaction is used as a catalyst in another reaction whereby further quantities of antiknock gasoline are produced. A still vfurther object of this invention is to provide a process in which a catalyst may beeifectively utilized for the production of high antiknock motor fuelsuntil completely spent.

l Further objects will become apparent as the description of this invention proceeds.

The accompanying drawing is a schematic iiow diagram which illustrates one preferred embodiment of this invention.

Referring now to the drawing a naphtha boiling Within the range of from about 60 F. to about 400 F. enters through line I0. A paraiiinic straight-run; naphtha from the distillation of crude oils is particularly suitable. Since the presence of aromatics in the naphtha has been found to be deleterious in carrying out the isomerization reaction we prefer to remove these aromatics. If a straight-run naphtha having an endpoint of about 150 to 160 F. is used as feed, such feed will be free of aromatics and hence a preliminary solvent extraction step is not necessary and thenaphtha will be introduced directly into line 28 via valved line I0'. Ifla naphtha of higher boiling range containing aromatics is used, thevnaphtha can be introduced into tower II where it is contacted with solvent from line I2.

selective solvent may be a liquefied sulfur dioxide, an aluminum chloride-hydrocarbon complex (to which further reference will be made hereinafter) or other suitable solvent selected with respect tothe character of the feed sto'ck employed and the boiling point of the solvent. The mixture of -solvent and naphtha in the `tower II is allowed to separate, the raftinate passing overhead through line I3 to stripper I4 wherein aromatic-free naphtha is distilled from the sol- `vent by heating means I5. The separated solvent through line 2l, to be utilized as a high solvency naphtha or for any other desirable purpose. The aromaticfree solvent is withdrawn through line 22 and may be discarded through valved line 23 or recycled to the extraction tower through valved line 24 which leads to line I2. Pump 25 in line 22 aids in the withdrawal of the solvent.

The separation of the solvent from the aro- `matic-free naphtha and from the aromatic hyx drocarbons has been described as permitting the hydrocarbons to pass overhead and solvent to be withdrawn from the bottom of strippers I4 and I9. It will be appreciated by those skilled in the art, however, that this may be reversed (depending upon the boiling point of the solvent chosen) and the solvent taken overhead-the hydrocarbons being removed as a bottom product. In the event that the solvent distills overhead the routingof the respective streams from strippers I4 and I9 will be reversed. K l

The aromatic free naphtha from stripper I4 is withdrawn through line 26 and directed through preheater 21 by means of pump 28. In preheater 21 the naphtha is heated to a temperature 4of 'about 250 F. and directed through line 29 to catalytic isomerizer 30. Anhydrous aluminum chloride is introduced into isomerizer 30 through line 3l (from a source not shown) while hydrogen chloride, which functions as an activator, is introduced through line 32. The naphtha is preferably contacted with the aluminum chloride in the presence of hydrogen which is introduced from any suitable source through line 33. The temperature of isomerizer 30 is controlled by suitable means such as jacket heater 34 and intimate contact between the catalyst andthe naphtha can be obtained by means of stirrer 35 or any other suitable means which will distribute the catalyst throughout the naphtha ln a manner adequate for promoting proper catalytic contact.

The reaction is carried out under a hydrogen partial pressure of from about 100 pounds per square inch to 1000 pounds per square inch pref- Y erably 450 to 650 pounds per square inch, at temperatures of from about 100 F. to about 250 F. with hydrogen chloride as a promoter. The contact time required varies from 1 to 120 minutes, depending upon the other conditions of the reaction. As the reaction progresses a liquid complex forms which is withdrawn with the hydrocarbons through line 36 and directed to separator,

the following analysis:

, Weight per cent Aluminum 12.5 Chlorine 44 Carbon+hydrogen 43.5 Atomic ratio Cl/Al e 2.7

In an effort to ascertain the chemical structure of the complex, a portion of it was carefully decomposed by adding water drop by drop with constant stirring. 'Ihe products were collected in a water reflux condenser, a solid carbon dioxideacetone tower, a gas absorption tube to remove HCl, and a permanent gas collector. The hydrocarbon layer was extracted with ether and the ether distilled from the hydrocarbon layer. The

45 volume overhead from the distillation of hydrocarbons had the following characteristics:

Boiling range F 142-553 Refractive index "/D 1.3820-153'17 The distillation revealed plateaus at 300 F. and again at 440 F., which fractions were characterized by pronounced terpene odors.v The fractions showed varying degrees of unsaturation.

From the ratio of chlorine to aluminum it will be seen that the chlorine atoms have not been replaced by hydrocarbon radicals, since otherwise the ratio of chlorine to aluminum would have been of the order of 2:1 to 1:1. Moreover, from the analysis of the hydrocarbon from the complex after hydrolysis, it is obvious that the hydrocarbons are not present in the form in which they originally were found in the light distillate rafnnate. In place of aluminum chloride, aluminum bromide can be substituted. Throughout this specification and claim, the terms AlCh-saturated hydrocarbon complex, lAlCla-paraflin complex" and AlCl-naphthene complex, are used to indicate the product of the reaction between the aluminum chloride and the hydrocarbon referred to, and not indicate that the hydrocarbon is present in the complex in the form of a saturated hydrocarbon, a paramn or a naphthene.

The above complex has-been found to be very effective as a catalyst in an alkylation reaction. In case the catalyst is not entirely spent for promoting the isomerization reaction due to the conditions used, a part of it may be recycled to isomerizer Il through valved line 30 which joins .'ine Il. This complex is also effective for the solvent extraction of aromatics from a mixture containing aromatic, naphthenic 'and paramnic hydrocarbons; therefore, apart may also be directed to extraction tower Il through valved line 40 which joins line I2 to be used as the solvent for the extraction of aromatics. The remainder of the complex is directed through valved line 4l to the alkylation reaction which will be described in more detail later. Pump 42 assists in the removal of the complex. Under the conditions described for isomerizer 30 the normal parafiins in the aromatic-free naphtha are converted to saturated branched-chain hydrocarbons boiling chiefly within the gasoline boiling range. Quantities of isobutane are also formed during thereaction.

The hydrocarbons are withdrawn from separator 31 and forced by pump 43 through line 44 to fractionator 45 wherein a separation is made between the normally gaseous hydrocarbons, the isomeric paraiiins of gasoline boiling range and the remaining heavier hydrocarbons. Included with the hydrocarbons will be the hydrogen and the gaseous hydrogen chloride from the lsomerization reaction. The isomers of gasoline boiling range are withdrawn through line 46 for storage or for blending with low antiknock gasoline or with other products of gasoline boiling range from our process. The hydrocarbons heavier than gasoline are Withdrawn through line 41. The normally gaseous hydrocarbons including those having four carbon atoms per molecule, plus the hydrogen and gaseous hydrogen chloride are taken overhead through line 48, cooled in cooler 49 and separated in reflux drum 50. The hydrogen and gaseous hydrogen chloride pass overhead through line 5| and may be discarded from thesystem through valved line 52 or returned to the lsomerization reaction through valved line 53 which Joins line 33. Compressor 54 aids in increasing the pressure to a point suitable for maintaining the hydrogen partial pressure in isomerlzer 30. Bottoms from reflux drum 50 comprising chiefly C4 hydrocarbons are withdrawn through line 55. A portion of them may be recycled to fractionator 45 through valved line 56 to act as reflux. The remaining butanes may be discarded through line 51 but preferably are directed through valved line 58, pump 55, and heater 60 to the alkylation reactor. Bottom heating means 6I in fractionator 45 aids in the fractionation of the products.

Asv the isoparainic feed stock for the alky1ation reaction we prefer'to use lsobutane. This may be obtained as a by-product from the isomerlzation reaction as has been pointed out or may be obtained from anyvsuitable source. In the debutanization of gasolines, particularly gasolines prepared by the thermal or catalytic cracking of hydrocarbons of the gas oil type there is produced a butane fraction which contains large quantities of normal and isobutane as well as normal and isobutylene, together with small quantities of C3 and C5 hydrocarbons due to imperfect frac-v tionation. Such a butane fraction is a suitable source of isobutane for our process, Since this butane cut contains quantities of olefins having four carbon atoms per molecule it is often advis'- able to subject this cut to a polymerization reaction so that the butylenes are converted to the dimers which on hydrogenation yield so-called iso-octane (2,2,4-trimethyl pentane) which is valuable as an aviation fuel. The unconverted parailinic hydrocarbons from such a polymerization process arel also suitable for an alkylation feed stock. Natural gas also contains large quantites of butane 'and is therefore suitable for our process although it is preferable, since the greater self -reffr' t 2,354,565: v part of the butane content oi' natural gas is in the form of normal butane, that it be subjected to isomer-ization to increase the amount of isobutane available. The isoparailinic hydrocarbon may be introduced through valved line l2 where it may join the isobutane from the isomerization reaction or where it may supplant the lsobutane from that som-ce.

Olefln containing gases from 'any suitable source enter through line 88. These may be gaseous oleilns containing 2, 3 or 4 carbon atoms tion we may also use ethylene to great advantage which with the isobutane will produce isohexanes. This, having a lower boiling point than iso-octane is valuable as a blending'fuel Atoincrease `the volatility of an iso-octane aviation fuel while at the same timemaintaining high antiknock characteristics. Gaseous hydrogen chloride as a promoter may be added through line 64 'although this is not essential for the alkylation reaction. The alkylation reaction is carried out at from about F. to about 212 F. depending on the olens used, and under pressures of from about 0 to 1000 pounds per square inch. The isoparaillnic hydrocarbons are present in amounts equal to, and preferably in excess of the oleiinic hydrocarbons.

The ratio of isoparailin to olefin may vary from 3:1 to about 4:1 to insure as complete utilization of the olefinic material as possible without polymerization. Intimate contact between the aluminum chloride-hydrocarbon complex and the hydrocarbon feed stocks is obtained by means of rapid stirring with stirrer 65 or by any other suitable means, such as orifice mixers, etc., whereby the catalyst and reactants are brought into sufficiently intimate contact to insure the promotion of the alkylation reaction. Cooling jacket B6 serves' maintain the proper temperature control y ther equally effective means, for example g coils within the alkylator 61 or ation by evaporation of the hydro- H j yaybe substituted. Theyreaction mixture is withdrawn from allater in which event it will be withdrawn'throuh valved line 1l.

' The hydrocarbon product of the alleviation reaction, which will be referred to hereinafter as the alkymer,` is withdrawn from separator I8 through line 18 in which is located pump 11 and directed to fractionator 18 having bottom heating means 18 to assist in the fractionation. In fractionator 18 a separation is made between the normally gaseous hydrocarbons, the alkymer: of gasoline boiling range andthe alkymers heavier than gasoline. The gasoline alkymer is withdrawn through line I8 and may be sent to storage or may be blended with the products from the isomerization .reaction or with low or high antiknock fuels of any other source to increase the overall octane number of volatility.

The normally gaseous hydrocarbons are taken overhead through line 8|, cooled in condenser l! .and separated in reflux drum 88.' Gases lighter than butane pass overhead through line 84. The butane fraction is withdrawn through line 8l in which is located pump B6 and part may be recycled to fractionator 18 through valved line 81 to act as reflux. In the event that there is available in the butane cut a considerable portion of `isobutane it may be recycled to the alkylation process through valved lines 88 and 89 which join line 62 prior to preheater 80. If-there are present in the butane cut large amounts of unreacted olens these may be recycled to alkylator 81 through lines 88 and 90 which joins line 63. In the event that the bottoms from reflux drum consist primarily of normal butanes these may be withdrawn through valved line 9| and may be used for blending with gasolines deficient in butanes or may be directed to an isomerization reactor (not shown) for conversion intov isobutanes which may then be returned to the alkylation reaction.

The products from the alkylation reaction which are of higher boiling range than is suitable kylatr l81 through line S8 and directed to separator 69 wherein4 the complex is separated from the hydrocarbons. Since the catalyst may not be spent as regards alkylation it may be withdrawn through .line 10 by pump 12 and recycles through valved line 1| to alkylator 61 through line 4I. It is possible to restore a part of the activity of the complex by introducing at a care- .fully controlled optimum rate during the oncompletely spent for alkylation it can be'withdrawn through valved line 14 and discarded or it can be utilized otherwise as will be described for use in ordinary aviation gasoline or in motor fuel are withdrawn from near the bottom of fraction'ator 18 through line 92 in which is inserted pump 93. Since in the alkylation reaction some polymerization may have occurred it i:

quite possible that these heavier products wili contain some unsaturates. It is therefore 'desirable to recycle these to the alkylation reaction,

present, are of higher boiling range than the usual aviation fuels which generally are made up oi so-called iso-octane (2,2,4-trimethylpentane).

The lower volatility of the safety fuels` makes them desirable `when dumping the gas tanks in emergencies, since there is a greatly decreased tendency for the fuel to ilash and burn. 'Ihe recycle may be accomplished by withdrawing the polymers from fractionator 18 by pump v98 through line 94 which joins line 63 entering the alkylation reactor 61. The safety fuel, in the form of heavy alkymers may be withdrawn through valved line 95.

On.- the other hand, if a larger quantity of safety fuel is desired, a part or all of the gasoline alkymer may be diverted through valved line a and recycled to alkylator 61 for further alkylation with fresh olefin gases whereby the molecular weight is increased and the previously described characteristics of "safety fuel acquired.

The catalyst from the alkylation reaction may no longer be eective for promoting the reaction between an oleiin and an isoparailln and yet may not be spent as regards further catalytic activity. For this reason it may be withdrawn from separator 88 and directed via line 15 and heater 96 to a polymerization reactor 91 wherein oleiins are polymerized to form hydrocarbons suitable for use as gasoline or as lube oil depending upon the conditions maintained in the polymerizer. 'I'he olefin polymerization is claimed in our copending application S. N. 510,112, led November 13, 1943.

Normally gaseous oleiins from any source (which may be the same source as that which provided olefins for the alkylation reaction) enter polymerizer 91 through line 08. The conditions in polymerizer 91 may be varied depending upon the type of oleiln charged and the products desired. In the polymerization of these gaseous olefln's to gasoline type or lubricating oil type fractions, temperatures of about to 450 F., and

pressure suillcient to keep the reactants in the liquid phase will be used. Predominantly gaso line type fractions will be produced at the higher temperatures and heavier lubricating oil fractions will predominate in the product when the lower temperatures are used. Intimate contact between the oleflnic feed gas and the catalyst may be obtained by the use of a mechanical stirrer 00 or any other suitable means for obtaining adequate contact between the reactants and the catalyst. The temperature may be maintained by the use of jacket |00 or by any other suitable means, such as internal coils.

The aluminum chloride complex and the polymerized hydrocarbons are withdrawn through line |0| and allowed to separate -in separator |02. 'I'he complex is withdrawn through line |01 in which is inserted pump |04, and i! still active,

isobutane. This is not useful in the polymerization reaction but is a valuable feed for the alkylation reaction. Therefore, the bottoms from reflux-drum i il may be directed through line |20 and valved line |2| to line 50 which leads to alkylator 61. It there are any considerable amounts' of olefins which pass through the polymerization reaction unchanged these may be returned to polymerizer 01 via line |20 and valved line |22.

The bottoms from fractionator |09 may be withdrawn through line |22, pump |24 and directed to alkylator 61 for conversion to safety fuel through valved line |25'or withdrawn for hymay be recycled through valved line |05. If the catalyst is spent for polymerization, however, it may bediscarded through valved line |06.

The polymerized hydrocarbons together with any unreacted feed gases are withdrawn from separator |02 through line |01 in which is inserted pump |'08 and directed to fractionator |09 having bottom heating means H0. In the event that polymerizer 91 has been used for the production of gasoline the polymers of gasoline boiling range will .be withdrawn through line l Il and directed to a hydrogenation unit (not shown) for conversion into saturated hydrocarbons. Normally gaseous hydrocarbons are taken overheadthrough line |I2, cooled in condenser ||3 and separated in reflux drum Ill. The lighter hydrocarbons may be taken overhead through line H5 and discarded while the heavier hydrocarbons up to and including the butanes" are withdrawn through line ||6 in which is inserted pump ||1. A portion` of the bottoms is returned to fractionator |03 through valved line ||8 to act as reflux. The remainder may be withdrawn through valved line H9 and discarded, used for 'blending with butane deficient gasolines, directed to a'dehydrogenation unit (not shown) for the production of further oleiinic feed gases for either the alkylation or polymerization processes or, in the event that the bottoms are compartial pressure of hydrogen of 500 pounds per.

square inch to 2000 pounds per square' inch. By this process the catalyst is completely spent as regards isomerization as it is carried out in isomerize`r 30 and as regards alkylation as it is carried out in alkylator 01'. The separation of the products will follow closely that described in connection with isomerizer 30.

ByA our process we are able to utilize completely a catalyst so that it is no longer eifective for cattalytic reactions. We have also described a unitary process in which the catalystl from one process is used as the catalyst for another process,the first process at the same time being capable of supplying a part of the reactants for the second process.

We claim:

1'. A process for the production of high anti-- of AlCl and AlBra to form normally liquid isomposed primarily of normal butanes, these may be erized hydrocarbons, normally gaseous hydrocarbons and an aluminum halide-hydrocarbon complex, separating said complex from said hydrocarbons and reacting isoparaiiinic hydrocarbons with oleflnic hydrocarbons in the presence of said complex as a catalyst.

` 2. A process for the production of high antiknock motor fuels which comprises subjecting a predominantly saturated hydrocarbon to isomerization in the presence of aluminum chloride whereby an aluminum chloride saturated hydrocarbon complex is `formed, separating said complex from the hydrocarbon reaction products, and reacting isoparaiiinic hydrocarbons with oleiinic hydrocarbons in the presence of said complex as avcatalyst.

3. The method of producing quality motor fuel which comprises isomerizing a substantially saturated naphtha with an aluminum halide of the class consisting of AlCl; and AlBra to form normally liquid isomers, normally gaseous hydrocarbons including isobutane. and an aluminum halide complex, alkylating saidisobutane with an oleflnic hydrocarbon by means of said aluminum halide complex, and recovering alkylation v products of the gasoline boiling range from the lighter and heavier' products of the alkylation reaction.

4. The method of claim 3 which includes the step of eiecting the isomerization with hydrogen under a partial pressure of about 100 to 1000 pounds per square inch.

. 5. The method of claim 3 wherein the alumi-` num halide is aluminum chloride.

6. The method of claim 3 which includes the previous step of removing aromatics from the naphtha prior to the isomerization step.

7. The method of utilizing aluminum chloride in catalytic hydrocarbon reactions -which comprises rst contacting it withv a substantially aromatic free normally liquid saturated hydro- I carbon fraction under conditions` for effecting isomerization of said hydrocarbon fraction and the formation of an aluminum chloride complex,

separating said aluminum chloride complex from isomerized hydrocarbons, and subsequently treating a, mixture of isop'arains with olens in the presence of said aluminum chloride complex under conditions for effecting alkylation.

6. The method of utilizing aluminum chloride in hydrocarbon conversion processes which comprises contacting aluminum chloride with substantially aromatic free normally liquid saturated hydrocarbons under isomerization conditions to form isomer-ized hydrocarbons and an aluminum chloride complex, separating said complex from said hydrocarbons, admixing isoparaflinic hydrocarbons and olenic hydrocarbons with said separated complex under alkylation conditions to convert the isoparaiilnic hydrocarbons into hydrocarbons of higher molecular weight, and addisobutane and an aluminum chloride complex,`

reacting at least a part of said isobutane with said olen-containing hydrocarbons in the pres- -ence of said aluminum chloride complex under alkylationv conditions to form hydrocarbonsof the gasoline boiling range, and separating the products of the gasoline boiling range from the aluminum chloride complex and lighter and heavier hydrocarbons.

l0. The method of claim 9 which includes the further step of reacting straight chainhydrocarbons with the aluminum chloride complex separated from the alkylation step under isomerization conditions at higher temperatures than said rst isomerization step lto form branched chain hydrocarbons.

DON R. CARMODY. BERNARD L. EVERING. EDMOND L. DOUVILLE.

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