US2260279A

US2260279A - Catalytic conversion of hydrocarbons

Info

Publication number: US2260279A
Application number: US247132A
Authority: US
Inventors: Ouville Edmond L D; Bernard L Evering; Alex G Oblad
Original assignee: Standard Oil Co
Current assignee: Standard Oil Co
Priority date: 1938-12-21
Filing date: 1938-12-21
Publication date: 1941-10-21
Anticipated expiration: 1958-10-21
Also published as: FR861563A; NL63052C

Description

0ct.21, 1941. v E. L. D'ouvlLLE ETAL 2,260,279l

V CATALYTIC CONVERSION 0F HYDROCARBONS Filed neo. 21, 1938 s sheets-sheet 1 Oct. 2l, 1941. E. L. D'ouvlLLE 'ErAL 2,260,279

CTALYTIC CONVERSION OF HYDROCARBONS' Oct. 2l, 1941. E. D'oUvlLLE ErAL CATALYTIC CONVERSION 0F HYDROCARBONS SQN www

mwN

mSKb

Patented Oct. 21, 1941 UNITED'STATES PATENT ori-ice GATALYTIC CONVERSION 0F HYDRO- CARBONS Edmond L. dOuville, Bernard L. Evering, and Alex G. Oblad, Chicago, Ill., assignors to Standard OilCompany, Chicago, Ill., a corporation of Indiana Application December 21, 1938, Serial No. 247,132

(Cl. ISG-9) 20 Claims.

This invention relates to the preparation of saturated branched-chain hydrocarbons from hydrocarbon mixtures containing aliphatic hydrocarbons, naphthenes and aromatic hydrocar bons. In particular, the 'invention relates to the preparation of 'motor fuel products containing large quantities of branchedchain saturated hydrocarbons and to the preparation of high solvency naphthas.

Saturated branched-chain hydrocarbons are very useful as motor fuels because of their nondetonating properties and high heating values. Furthermore, the saturated branched-chain hyconversion of the aromatic-free residue to prodrocarbons have lower boilingpoints than the corresponding Astraight-chain parafns so that motor fuels containing substantial quantities of 'the former have better starting characteristics than motor fuels containing large quantities of the straight-chain paramns. In addition,

ybranched-chainparaffin hydrocarbons are very useful as raw materials in the preparation of many chemical products.

It is known that normal paraftins can be isomerized to saturated branched-chain hydrocarbons in the presence of suitable catalysts, notably an aluminum halide in the presence of an activator, preferably a hydrogen halide, 'or a compound which will yield .a hydrogen halide.

We have found that the catalytic conversion of normal parafns to saturated branched-chain hydrocarbons is materiallyinhibited by the presence of even small amounts of aromatic hydrocarbons. For example under certain conditions the presence of as little as about 0.4% (by volume) of aromatics in the isomerization feed stock will reduce the ratio of moles of normal paraflins converted to moles of aluminum chloride catalyst used from about 66 to about 10, While about 5% (by volume) of aromatics will further depress the ratio to about 6. Effective conversion of normal parains to saturated- Ybranched-chain hydrocarbons therefore requires a feed stock substantially free of aromatics.

One object of the present invention is' to process an admixture of parafns together with naphthenes and/or aromatics by a series of steps whereby two main products are formed, namely 'a product containing predominantly aromatic hydrocarbons and a product containing predominantly saturated branched-chain hydrocarbons f to be used in motor fuels having high octane numbers. Another object of our invention is to secure improved yields of branched-chain par.-

'ains per pound of catalyst in an aluminum halidecatalytic hydrocarbon conversion process.

lll

duce saturated branched-chain hydrocarbons. Other objects and advantages of the present invention will become apparent from the following description thereof read in conjunction with the accompanying drawings which form a part of the-present specification and in which:

Figure 1 is a general flow diagram of one arrangement for carrying out the invention;

Figure 2 is a schematic flow diagram of a modified method of carrying out the invention;

Figure 3 is a -schematic flow diagram of another modication according to our invention wherein aromatic hydrocarbons4 are removed from the isomerization feed stock by`alkylation followed by fractional distillation.

Since the feed stocks employed generally comprise mixtures containing at least normal paraflins, aromatics and naphthenes, it is advantageous to convert naphthenes to aromaticsby catalytic aromatization in the presence of hydrogen prior to the removal of aromatics from the isomerization feed stock. We therefore will describe and illustrate our invention as applied to a' combination aromatization and isomerization process, although it is to be understood that the invention is not so limited.

For the purpose of clarity several of the terms used in the present specification and claims are definef. as follows; Aromatization means the catalytic conversion of naphthenes, such as cyclohexane and its derivatives, to the corresponding aromatic hydrocarbons; "isomerization means f the catalytic conversion of normal paramns to saturated branched-chain hydrocarbons; space velocity means the volume of cold liquid, per volume of gross space occupied by the catalyst, passed through the catalyst per hour.

Referring to Figure 1 a petroleum fraction `having a boiling range from about 60 F. to about 400 F., preferably from about 150 F. to about .300 F., and containing at least normal paraflins,

naphthenes and aromatic hydrocarbons, is passed through a line l0, a heater Il and a line I2 to black, palladium,

a catalytic reactor I3, hereinafter referred to as aromatizer I3. Hydrogen from aline I4 is passed through the heater II, and lines I5 and I 6 to the aromatizer I3. The aromatizer I3 is packed with a suitable aromatization catalyst, for example 90 AlaOa; 10 CrzOa (a mixture of 90 parts aluminum oxide by weight and parts chromic oxide by weight), platinum on magnesium chromite, nickel on magnesium chromite, platinum nickel or reduced copper suitably supported, or other suitable catalysts. .By maintaining the catalyst in the aromatizerV I3 at a temperature ranging from about 500 F. to about 1000 F., and preferably about 850 F., by suitable means such as the `iacket heater I3A, and passing the feed stock therethrough under a hydrogen pressure of about 0.2 to about 10 atmospheres, at a space velocity of about 0.05 to about 5.0 substantially al1 of the naphthenes capable of aromatization in the feed stock will be converted to aromatics. Under the conditions prevailing in the aromatizer I3 substantially no olens are formed from paraffins', the reaction being almost exclusively a conversion of naphthenes to aromatics. This is of particular advantage in that the absence of olens materially prolongs the life of the aromatization catalyst,

and furthermore permits a more effective separation of the aromatics from the normal parafins in the manner hereinafter described.

The products in the aromatizer I3 are removed therefrom through a line I`1 to a gas separator I8 wherein hydrogen is head through a line I9. to be either-recycled t0 the aromatizer I3 throughv a line 20 or utilized in a subsequent isomerization stage as hereinafter described.

The gas-free stock from the gas separator I8 is removed therefrom through a line 2I,and introduced into an extractor 22 wherein the aromatic hydrocarbons undergo substantially complete removal by countercurrent contact with a suitable selective solvent from a solvent storage tank -23 introduced into the upper portion of the extractor 22 through a line 24. As the selective solvent we may use liquefied SO2, an aluminum chloride-complex, to which further reference will be made hereinafter, other solvents such as furfural, nitrobenzene, nitromethane, or other solvents selected with respect to the distillation characteristics of the feed stock employed and the boiling point of the solvent. The temperature employed in the extraction stage will depend upon the solvent used, but in general this temperature will be between about 40 F. and 120 F.

The extract from the extractor 22 is removed therefrom through a line 25 and introduced into a separator 26. wherein the aromatic hydrocarbons are separated from the solvent. 'I'he separator 26 may be heated by suitable means, such as a steam coil 21. The separated solvent is removed from the separator 26 through a line 28, condensed in cooler 29, and returned to the solvent storage tank 23 through line 30. The aromatic hydrocarbons are removed from the separator 26 through a line 3| to be utilized as a high solvency naphtha o r blended with an isomerized motor fuel as hereinafter described.

-We have described the separation o f the solvent from the aromatic hydrocarbons in which the solvent is removed as an overhead. It will be appreciated by those well versed in the art that, dependent upon the boiling point of the solvent chosen, the solvent will be removed from separated and removed overthe separator 26 either as an overhead or as a bottom, and that the routing of the separated solvent and the separated aromatics must be modied accordingly.

The raffinate from the extractor 22, containing not more than about 2%, and preferably less than 0.5% of aromatic hydrocarbons, is removed therefrom through a line 32 and introduced into a stripper 33, heated by suitable means, such as a heating coil 34, wherein any solvent in the raflnate is separated from it, and returned through condenser 35 and

lines

36 and 30 to solvent storage tank 23. The solvent-free raffinate, comprising substantially paraflnic hydrocarbons, is removed from the stripper 33 through a line 31 and passed through a preheater 38 and a line 39 to a catalytic isomerizer 40 wherein the normal paraffinic hydrocarbons are converted to saturated. branched-chain hydrocarbons as hereinafter described.

While we have shown the removal of solvent from the rallinate in stripper 33, if the solvent employed is the aluminum chloride-hydrocarbon complex, the raflinate may be sent directly to the preheater 38 through the line 32A, since a small amount of the aluminum chloride-hydrocarbon complex in the raffinate is not detrimental to the conversion of normal parafns to the saturated branched-chain hydrocarbons.

We have described the removal of solvent from the raffinate in which the boiling point of the former is lower than that of the latter. It will -be appreciated by those well versed in the artv that, dependent upon the' boiling point of the solvent chosen, the solvent will be recovered from the stripper 33 either as an overhead or as a bottom, and that the routing of the separated solvent and the raflinate must be modified accordingly.

As aforementioned the rainate passes from the stripper 33 through a preheater 38 to a catalytic isomerizer` 40 maintained at the desired temperature by suitable means such as a jacket heater 4I, wherein it is intimately contacted with HCl-activated aluminum chloride, or other aluminum halides activated by a hydrogen halide, introduced into the isomerizer 40 from a catalyst storage tank 42 through a line 43. Contact of the raffinate with the catalyst is preferably made in the presence of hydrogen introduced into the isomerizer 40 through lines 44 and 45. The hydrogen used in the isomerizer 40 may be that obtained from the gas separator I8 and introduced into line 44 through lines I 9 that obtained from the hydrogen storage tank (not shown) and introduced into line 44 through lines I4, I5 and 41. To substantially reduce the degradation of the product formed in the .-somerizer 40 to Ca and/or C4 hydrocarbons, it is desirable to Aintroduce Ca and/or C4 gases, from a fractionator as hereinafter described, into the isomerizer 40.

When the reaction is carried out in the presence of hydrogen the isomerizer 40 is maintained at a temperature within the range of about F. to about 450 F. by suitable means, such as the jacket heater 4I and under a hydrogen pressure from about 800 to about 4000 pounds per square inch. However, at times it may be desirable to carry out the conversion of the raffinate in the absence of extraneous hydrogen or under a relatively low hydrogen pressure, in which case the isomerizer 40 is 'operated within the temperature range of about 180 F. to about and 46, and/or sired the streams may be 450 F. under a pressureranging from about 50 pounds to about 800 pounds per square inch.

Under the conditions prevailing in the isomerizer 40 the normal parafns are converted to saturated branched-chain hydrocarbons. The products from the isomerizer 40, comprising substantialy saturated branched-chain hydrocarbons and an'aiuminum chloride-hydrocarbon complex, are removed therefrom through a line 48 and introduced into a separator 49 wherein the products from the isomerizer are permitted to separate, the aluminum chloride-hydrocarbon complex forming the lower layer. The upper stratum comprising substantially hydrocarbons is removed from the separator 49 through a line 50 and introduced into a fractionator provided with a heating coil 5|'.A wherein by effective fractionation the saturated branched-chain hydrocarbons are separated and removed from the system through lines 52 and 53 as side streams. 'If deblended by lines 54 and 55. Bottoms from the fractionator 5|, comprising substantially partially converted products are removed through a line 53A, and may be recycled to the isomerizer 40 through a line 53B. The

system through line 56A.

The aluminum' chloride-hydrocarbon complex I separated in the separator 49 is removed therefrom through a line 51.. When the complex is employed as the solvent for the removal of varomatic hydrocarbons from the parafns following by way of example,v 90Al203z10Cr2O3 (a mixunconverted low-boiling hydrocarbons, particuthe aromatization stage, it may be transferred from the separator to the extractor 22 through

lines

58, 36, 30, solvent storage tank 23 and line 24. A portion of the complex may also berecycled to the isomerizer 40 through line 59.

If desired the aromatic hydrocarbons, 'or a portion thereof, removed from the separator 26 through the line 3|, may be blendedwith the saturated branched-chain hydrocarbons through a line 00.

The partly spent aluminum chloride catalyst' used in the 'conversion of normal paramns to saturated branched-chain hydrocarbons vforms an aluminum chloride-hydrocarbon complex, hereinafter called aluminum chloride-complex, having substantially the following composition:

Per cent Aluminum 8 to 14 Chlorine 30 to 50 Hydrocarbon i This aluminum chloride complex is substantially immiscible with solvent for aromatics, cellent reagent 4for the removalof aroma-tics from the feedstock going to the isomerizer. In the description of the'process of Figure 1A we have alluded to the use ofthe aluminum chloride complex as the solvent for the removal of aromatic hydrocarbons from the feed stock going to 'the isomerizer. In the following paragraphs we will describe in more detail the embodiment of our invention 'using the aluminum chloridecomplex as the selective solvent.

Referring to Figure 2, a petroleum fraction, containing at least paraillns, and naphthenes, and having a boiling range between about F. and about 400 F., and preferably between about 150 F. and 300 paralns but is an excellent thereby' making it an ex- F., from .a source (not hown) ture of parts aluminum oxide by weight, and

'10 parts chromic oxide by weight) platinum on magnesium chromite, nickel on magnesium chromite, palladium, nickel, and reduced copper suitably supported. The aromatization is carried out at a temperature of -about'500 F. to about 1000 F., and preferably about 850 F. under a hydrogen pressure of4 about 0.2 to about 10 atmospheres and at a space velocity of about 0.05 to about 5.0.

The products from the aromatizer |02 are removed therefrom through a line |05 to a gas separator -|0| wherein the hydrogen is separated from the products from the' aromatizer. The hydrogen separated in the gas separator |06 is 'removed therefrom through a line |01 and either recycled to the aromatizer |02 through line |08a or usedfor the isomerization of the -normal parains as hereinafter described. The 'hydrogen-free products from the gas separator |06 are removed therefrom through a line ||0 and a cooler and introduced into the bottom of an extractor ||2, whereinthey are countercurrently contacted at a'temperature of from about 40 F. to about F. with a descending stream of laluminum chloride-complex, obtained from an isomerization stage as hereinafter described and introduced into the extractor l|2through a spray H3. If desired aluminum chloride complex from an extraneous source may be introduced into the extractor |i2-through spray |3 by means of line ||3a. The aromatics formed in the aromatization stage, together with the aromatics which may be present in the original stock, are dissolved in the aluminum chloride-complex to form an extract phase comprising substantially aromatic hydrocarbons and aluminum chloride-complex and a raffinate phase comprising substantially parailins. The extract from the extractor ||2 is removed therefrom through a line ||4 and introduced into a still I5, wherein the aromatics dissolved therein are removed by distillation and passed through a line ||6 to a condenser ||1 whereinthe vaporized aromatic hydrocarbons are'condensed and `|20 maintained at the desired temperature by a jacket heater|20A, or other suitable means, wherein it is catalytically Vconverted in the presence of a hydrogen halide-activated aluminum halide, but preferably HCl-activated aluminum chloride and/or a mixture of aluminum chloride and aluminum chloride-complex to form satu- -rated branched-chain hydrocarbons. The aluminum chloride catalyst isintroduced from a storage tank |2| through a line |22 into the isomerizer |20. Instead of using fresh aluminum chlo- Aride catalyst we may use in combinationtherewith the aluminum chloride-complex separated from the aromatica in the still H5. The aroa line |00, and a heater |0I matic-free aluminum chloride-complex from the still H5 is removed therefrom through a line |23 which communicates with fresh aluminum chloride catalyst line |22.

The raffinate from the extractor ||2 comprising substantially normal parafflns is converted in the isomerizer |20 in the presence of aluminum chloride and/or aluminum chloride-complex at a temperature of about 180 F. to about 450 F., preferably from about 210 F. to about 250 F., and at a pressure of from about 500 pounds to about 4000 pounds per square inch when hydrogen is employed in the isomerization step. or at a pressure of about 50 pounds to about 500 pounds per square inch when hydrogen is used at low pressures or not at all, in the lsomerization stage. It is preferred, however, to employ hydrogen in the isomerization stage` since we have found that its presence prolongs the catalyst life. Hydrogen for the isomerization stage may be hydrogen from the gas separator |06 which is introduced into the isomerizer |20 through lines |01 and |24 or 'it may be hydrogen obtained from the external source (not shown) through lines |04, |09, |08

and |24.

The products from the isomerizer |20 comprising substantially saturated branched-chain hydrocarbons and aluminum chloride-complex are removed therefrom through aline |25 and introduced into a separator |26 wherein the withdrawn products separate into an upper layer comprising substantially saturated branched-chain hydrocarbons and a lower layer comprising substantially aluminum chloride-complex. The aluminum chloride-complex used to extract the aromatic hydrocarbons from the products obtained from the aromatization stage is Withdrawn from the bottom of the separator |26 through lines |21, |28, cooled in a cooler |29, and introduced into the upper portion of the extractor ||2 through the aforementioned spray H3. A por.

tion of the aluminum chloride-complex from the separator |26 may be by-passed through a line |30 and combined with the aluminum chloridecomplex from the still 5, or if desired, a portion of the aluminum chloride-complex recovered from the still ||5 may be by-passed to the extractor ||2 through the line |30.

The hydrocarbons separated in the separator 26 are removed therefrom through a line 3| and introduced into a fractionator |32 heated by suitable means such as a coil 32A wherein the products from the isomerizer |20 are fractionated from the light paraflns', such as` the C3 and C4 hydrocarbons. The isomerized products are removed as side cuts from fractionator |32 'through lines |33 and |34, and may be blended by means of lines and |36. If desired, a portion of the aromatic hydrocarbons being removed from the system through the line ||6 may be by-passed through a line |31 and blended with the isomerized products itl line |36.

The C3 and C4 hydrocarbons and hydrogen removed as an overhead from the fractionator |32 may be recycled to the isomerizer |20 through line |33 together with partially isomerized products removed from the lower portion of the fractionator |32 through a. line |39. By recycling the C3 and C4 hydrocarbons to the isomerizer degradation of paraflins to C3 .and C4`hyd1'o'carbons is materially inhibited. If desired a "portion of the overhead from the Iractionator |32 Ilnasy be removed from the system through a line The processes just described provide economical stream are passed directly to the isomerizatin and efiicient means of obtaining aromatic rich naphthas which are suitable as a source of high solvency naphthas and naphthas having a high content of saturated branched-chain hydrocarbons which are suitable for high anti-knock motor fuels.

While we have described our invention as applied to an aromatization stage in combination with an isomerization stage it is to be understood that the invention can be applied to installations having no aromatization stage prior to the isomerization stage. In the latter case the isomerization feed stockcontainlng aromatic hydrocarbons will be passed directly by means of line |40 to the extractor ||2 wherein the aromatics are removed from the feed stock by solvent extraction in the manner hereinbefore described,

While we prefer to remove the aromatics from the isomerization feed stock by selective solvent extraction other effective means may be employed. Although it is diflicult to separate mixtures of aromatics, naphthenes and normal paraflins by simple fractionation because of the overlapping boiling points of the constituents we have 'found that an eiective method of separating the constituents by fractionation is to alter the relative boiling points thereof by alkylatlon of the aromatics with low molecular weight olefins, namely the Cz=, Ca= and C4= olens. 'I'heses 10W molecular weight oleflns may be present in the original feed stock or may be added thereto from an extraneous source. This method of alkylation as a means of separation is especially applicable to the separation of aromatics from a narrow boiling range hydrocarbon cut that is 150 to 250 F. in which case the alkylated aromatics formed will distill outside this distillation range. The alkylation takes place at a temperature of from about F. to about 225 F. under a pressure of from about 15 pounds to about 100 pounds per square inch in the presence of a suitable catalyst, such as aluminum 'chloride activated with HC1 or ,the aluminum chloride-complex obtained in the isomerlzation of normal paraiins to saturated branched-chain hydrocarbons. Following the alkylation stage the products are introduced into a fractionating column, wherein the lunreacted oleiins are removed as an overhead.

and recycled to the alkylation stage, the parafilns and naphthenes are removed as a side stream. and the alkylated aromatics removed as bottoms. 'I'he paraflins and naphthenes removed as a side stage wherein the normal parailins are converted to branched-chain parans as hereinabove described.

apparatus suitable for carrying out the modification of our invention last described is schematically shown in Figure 3, to .which reference is now made. A petroleum fraction of the type hereinabove specified containing at least paraln and aromatic hydrocarbons from a source (not shownlis passed through lines |50, |5| and |52 to an alkylation reactor |53 wherein it is contacted with low molecular weight olefins in the presence of a suitable catalyst under conditions such that these oleiins combine with the aromatic hydrocarbons in the charge to form alim/lated aromatics. As stated above, these olens, namely the C2=,l Cs=, and C4= olefins, may be present in the feed stock but may be introduced from an extraneous source, for instance, through lines |54 and |55. The alkylation takes placeat a temperature in the range from about 50 F. to about 225 F. maintained by means of Jacket -bottom of reactor |53 terial withdrawn from reactor lthereof maybe removed from the system through heater |56 or other suitablearrangement and under a pressure in the range from about tol about 100 pounds per square inch. The catalyst, aluminum chloride activated'with HC1 for example, can `be' introduced into reactor 163' through lines |51 and |58, but if the aluminum chloridecomplex obtained in the isomerization stage is used, this is introduced into line |58 through lines |59 and |60.

' The reactionproducts are withdrawn from the through line |6| and introduced' into separator |62 wherein the products are permitted to stratify.

aluminum chloride, the hydrocarbon complex formed in the isomerization reaction or both are the catalytic ma- |53 will be in the form of a fluid hydrocarbon complex and will form a' lower layer in separator |62 which can either be recycled through lines |60 and |58 or removed-from the system through line |63. The upper stratumcomprising unreacted paraffin and naphthene hydrocarbons and alkylated aromatics is removed from separator |62 through line |64 and introduced into fractionator |65 provided with a heating coil |66 wherein by effective fractionation the paraflin hydrocarbons together with the naphthenic hydrocarbons which-may be present in the feed stock are separated as a sidestreaml and withdrawn through line |61. Botused as the alkylation catalyst,

toms from fractionator |65 containing the al-` kylated aromatics are removed through line |68, while the overhead lconsisting largely. of acted gaseous olens is recycled to reactor |53 through lines |69 and |55. A portion of this overhead may be vented through line |16 to prevent inert gases from building up in the system.

The hydrocarbon fraction rich in normal paraihns owing through line |61 is introduced into the isomerization stage, which, as'shown in Figure 3, is similar to that illustrated in Figure 2. This isomerization feed is heated in preheater |1| and introduced through line |1|a into isomerizer |12 maintained at the `desired temperature by jacket heater |13 or other suitable means, wherein the normal paraftln hydrocarbons are catalytically converted to saturated branchedchain hydrocarbons as already described. The alluminum chloride catalyst is introduced into isomerizer |12 from storage tank |14 ,through line |15, and when hydrogen is employed, this is supplied through lines |16, |1.1, |18, |19, |80 and |8|. l

'I'he products from isomerizer |'-12 are removed therefrom by means of line |82 and separated in separator |83 into an upper hydrocarbon layer and a lower layer comprising substantially aluminum chloride complex which, is withdrawn Regardless of whether through line |84. This complex is preferably recycled, at least in part, to isomerizer |12 through line |85, and a portion of it can be used in the alkylation stage as hereinabove set forth by means of line |59. If desired, all or a portion of the complex can be withdrawn from lthe system through line |86.

The upper layer is introduced into fractionator |81 through line |88, and the isomerized products are removed as sidestream cuts through lines |89 and |90. These 'cuts may be blended if desired by means of lines 9| and |92. C4 hydrocarbons and hydrogen removed as an overhead from fractionator |81 may be recycled to isomerizer |12 through lines |93 and |8| to inhibit the degradation of the normally liquid parains to gaseous hydrocarbons, or a portion TheCs and carrying out this modicatlon shown in Figure 3. The

:fresh feed is passed from line |50 through line |98, heater |99 and line 200 to aromatizer 20| which is maintained at the desired reaction temperature by means of jacket 202. Hydrogen from line. |16 is likewise heated in heater |99 and passed to aromatizer 20| through lines 208 and |18. 'I'he conversion of naphthenic to aromatic hydrocarbons takes placel in aromatizer 2||| as already described, and the products pass through line 204 to gas separator 205. The separated hydrogen is removed through line 206 and either returned to aromatizer 20| through lines 201 and |18 or used in the isomerization stage by means of lines 208, and |8|. The liquid layer in separator 205, now relatively free from naphthenes.- and rich in paraflns and aromatics is removed to the alkylation reactor |53 by means of line 209, cooler 2|0 and line |52. Thereafter the aromatics are removed and the remaining parafns are isomerized as previously described, giving a good yield of branched-chain paraillnhydrocarbons.

While we have described Vour inven ion withfrom a hydrocarbon mixture containing straightchain parailin hydrocarbons but not more than 2 per cent by volume of aromatic hydrocarbons,

.and subjecting said hydrocarbon mixture to the.

action of an aluminum halide catalyst and an activator aifording a hydrogen halide under conditions eifective to convert straight-chain parafkfin hydrocarbons to branched-chain parailin hydrocarbons. f

2. The process-of claim l wherein said catalyst is aluminum chloride and said activator is hydrogen chloride. Y I

3. The process of preparing a motor fuel fraction containing a large proportion of branchedchain paraiiin hydrocarbons from a naphtha. containing substantial amounts of aromatic and straight-chain paraiiin hydrocarbons which comprises treating said naphtha to produce therefrom a hydrocarbon mixture containing straightchain paraifln hydrocarbons but substantially free from aromatic hydrocarbons, Aand subjecting said hydrocarbon mixture to the action of an aluminum halide catalyst and an activator affording a hydrogen halide under conditions effective to convert straight-chain parafiln hydrocarbons to branched-cham parailin hydrocarbons.

4. The process of preparing a motor fuel fraction containing aV large proportion of branchednaphthenes therein tov branched-chain paraffin hydrocarbons.

5. The process of claim 4 wherein said selective solvent is liquid sulfur dioxide.

6. 'Ihe process of claim 4 wherein said selective solvent is an aluminum halide-hydrocarbon complex.

7. The process of preparing a motor fuel fraction containing a large proportion of branchedchain paranin hydrocarbons from av naphtha containingsubstantial amounts of aromatic and straight-chain parailin hydrocarbons which comprises treating said naphtha in an extraction zone with an aluminum halide-hydrocarbon complex to remove aromatic hydrocarbons therefrom and produce a raiilnate containing straight-chain parailin hydrocarbons but not more than 2 per cent by volume of aromatic hydrocarbons, subiecting said raillnate in a reaction zone to the action of an aluminum halide catalyst and an activator affording a hydrogen halide under conditions effective to convert straight-chain paraffin hydrocarbons to branched-chain paraflin hydrocarbons, removing said motor fuel fraction and an aluminum halide-hydrocarbon complex from said reaction zone and introducing at least a portion of said complex from said reaction zone into said extraction zone.

8. The process of claim '1 wherein said aluminum halide is aluminum chloride. said aluminum halide-hydrocarbon complex is aluminum chloride-hydrocarbon complex and said activator is hydrogen chloride.

9. 'I'he process of preparing amot'or fuel fraction containing a large proportion of branchedchain paraiiin hydrocarbons from a naphtha containing substantial amounts of aromatic and straight-chain parain hydrocarbons which com- -prises treating said naphtha in an alkylation zone in the presence of oleiins having 2 to 4 carbon atoms per molecule with a catalyst under conditions effective to cause alkylation of the aromatic hydrocarbons in said naphtha bly said oleiins, fractionally distilling the products from said alkylation zone to produce therefrom a hydrocarbon mixture containing straight-chain paraiiin hydrocarbons but not more than 2 per cent by volume of aromatic hydrocarbons, and subjecting said hydrocarbon mixture to the action of an aluminum halide catalyst and an activator aifording a hydrogen halide under conditions effective to convert straight-chain paraffin hydrocarbons to branched-chainparaflin hydrocarbons.

10. The process of preparing al motor fuel fraction containing a large proportion of branchedchain paraihn hydrocarbons from a naphtha containing substantial amounts of aromatic and straight-chain paraiiin hydrocarbons which comprises treating said naphtha in an alkylation zone in the presence of olens having 2 to 4 carbon atoms per molecule with a catalyst comprisy ing an aluminum halide-hydrocarbon complex under conditions effective to cause alkylation of the aromatic hydrocarbons in said naphtha by said oleiins, fractionally distilling the products from said alkylation zone to produce therefrom a hydrocarbon mixture containing straight-chain paraffin hydrocarbons but not more than 2 per l cent by volume'of aromatic hydrocarbons, sub- -lyst-containing portion comprising an aluminum halide-hydrocarbon complex from the products from said isomerization zone, and introducing at least a portion of said'catalyst-containing portion into said alkylation zone. v

11. The process of obtaining a solvent naphtha rich in aromatic hydrocarbons and a motor fuel rich in branched-chain paraihn hydrocarbons from a naphtha feed stock containing substantial amounts of aromatic, naphthenic and straightchain parain hydrocarbons which comprises treating said feed stock in a catalytic aromatization step to convert thenaphtnem'c hydrocarbons .therein to aromatic hydrocarbons, treating the material from said aromatization step to produce therefrom a fraction rich in aromatic hydrocarbons and a fraction rich in straight-chain paraffin hydrocarbons but containing Anot more than 2 per cent by volume of aromatic hydrocarbons, and subjecting said fraction rich in straightchain paraffin hydrocarbons to the action of an aluminum halide catalyst and an activator affording al hydrogen halide under conditions effective to convert straight-chain paraffin hydrocarbons to branched-chain paraffin hydrocarbons.

12. 'I'he process of obtaining a solvent naphtha rich in aromatic hydrocarbons and a motor fuel -rich in branched-chain paraiiin 4hydrocarbons from a naphtha feed stock containing substantial amounts of aromatic, naphthenic and straight-chain paraflin hydrocarbons which comprises treating said feed stock in a catalytic aromatization step in the presence .of hydrogen to convert the naphthenic hydrocarbons therein to aromatic hydrocarbons, contacting the product from said aromatization step with an aluminum halide-hydrocarbon complex to form an extract layer comprising principally aromatic hydrocarbons and aluminum halide-hydrocarbon complex and a raffinate layer rich in straight-chain parafn hydrocarbons and containing not more than about 2 per cent by volume of aromatic hydrocarbons, heating said extract layer to a temperature suilicient to distill the aromatic hydrocarbons therefrom,v and subjecting said raflinate layer to the action of an aluminum halide catalyst and an activator aiording a hydrogen halide under conditions effective to convert straight-chain parailn hydrocarbons to branched-chain paraffin hydrocarbons.

` 13. The process of claim 12 wherein said aluminum halide catalyst is aluminum chloride and said activator is hydrogen chloride.

14. The process of obtaining a solvent naphtha rich in aromatic hydrocarbons and a motor fuel rich in branched-chain paraffin hydrocarbons from a naphtha feed stock containing substantial amounts of aromatic, naphthenic and straightchain parafn hydrocarbons which comprises treating said feed stock in a catalytic aromatization step in the presence of hydrogen at a temperature of about 500 F. to about 1000 F. and

vtor fuel fraction and a under a hydrogen pressure of about 0.2 to about atmospheres to convert the naphthenic hydrocarbons therein to aromatic hydrocarbons, removing hydrogen from the products from said aromatization step, contactingthe substantially hydrogen-free product from said aromatization step with a selective solvent to form an extract layer comprising principally aromatic hydrocarbons and solvent anda rafnate layer rich in straightchain paran hydrocarbons and containing not more than about 2 per cent by volume of aromatic hydrocarbons, heating said extract layer to a temperature suilicient to distill the aromatic hydrocarbons therefrom, vent from said railinate layer, subjecting the rafiinate in an isomerization step to the action of an aluminum halide catalyst and an activator affording a hydrogen halide in the presence of hydrogen under conditions effective to convert straight-chain paraflln hydrocarbons to branched-chain hydrocarbons, separating a mofraction containing hydrogen and normally gaseous hydrocarbons from the products from said isomerization step, and recycling at least a portion of said last-mentioned fraction to s aid isomerization step.

15. The process oi.' obtaining a solvent naphtha rich in aromatic hydrocarbons and a motor fuel rich in branched-chain paramn hydrocarbons from a naphtha feed stock containing substantial amounts of aromatic, naphthenic and straightchain paraffin hydrocarbons which comprises treating said feed stock in a catalytic aromatization step in the presence of hydrogen at a temperature of about 500 F. to about 1000 F. and

removing the solunder a hydrogen pressure of about 0.2 to about 10 atmospheres to convert the naphthenic hydrocarbons therein to aromatic hydrocarbons, removing hydrogen from the products from said aromatization step, contacting the substantially hydrogen-free product from said aromatization step at a temperature of about F. to about F. with an aluminum chloride-hydrocarbon complex in an extraction step to form an extract layer comprising principally aromatic hydrocarbons and aluminum chloride-hydrocarbon complex and. a rainate layer rich in straight-chain paraiiln hydrocarbons and containing not more than about 2 per cent by volume of aromatic hydrocarbons, heating said extract layer todistill aromatic hydrocarbons therefrom, subjecting said ramnate layer in an isomerization step to the action of aluminum chloride and hydrogen chloride in the presence of hydrogen at a temperature of about F. to about 450 F. and a pressure of about 800 to about 4000 pounds per square inch to form branched-chain parallin hydrocarbons and an aluminum chloride-hydrocarbon complex, and using at least a portion 'or said aluminum chloride-hydrocarbon complex as solvent for aromatic hydrocarbons in said extraction step.

16. The process of claim 15 including the steps of separating a fraction comprising propane and butane from the products -from said isomerization step and recycling said fraction to said isomerization step.

17. The process of claim 15 including the step of introducing at least a portion of the hydrogen removed from the products from said aromatization step into said isomerization step.

18. The process of claim 1 which includes subjecting said hydrocarbon mixture to the action of the aluminum halide catalyst and the activator at a temperature of about 180 to 450 F. and in the presence of hydrogen at a pressure of about 500 to 4000 pounds per square inch.

19. The process of claim 1 which includes subjecting said hydrocarbon mixture to the action of the aluminum halide catalyst and the activator' at a temperature of about 210 to 250 F. and in the presence of hydrogen at a pressure o'f about 500 to 4000 pounds per square inch.

'20. The process of preparing a motor fuel fraction containing a large proportion oi branched chain parain hydrocarbons from a naphtha containing substantial amounts of aromatic and straight chain parafn hydrocarbons which comprises removing aromatic hydrocarbons fromsaid naphtha to produce therefrom a hydrocarbon mixture containing straight chain paraffin hydrocarbons with not more than 2% by volume of aromatic hydrocarbons and subjecting said hydrocarbon mixture to the action of an aluminum halide catalyst and an activator affording hydrogen halide at a temperature of about 210 to 250 F. and in the presence of hydrogen at a pressure of about 500 to 4000 pounds per square inch to convert straight chain paraflinhydro-k carbons to branched chain paraiiln hydrocarbons.

EDMOND L. DOUVILLE. BERNARD L. EVERING. ALEX G. OBLAD.