US2220091A

US2220091A - Conversion of hydrocarbon products

Info

Publication number: US2220091A
Application number: US176288A
Authority: US
Inventors: Bernard L Evering; George G Lamb
Original assignee: Standard Oil Co
Current assignee: Standard Oil Co
Priority date: 1937-11-24
Filing date: 1937-11-24
Publication date: 1940-11-05
Anticipated expiration: 1957-11-05

Description

Nov. 5, 1940. B. L. EVERING- ET AL 2,220,091

CONVERSION OF HYDROCARBON PRODUCTS Filed Nov. 24, 1957 2 Shets-Sheet 1 Producf' sum/25k ACCUMULAI'OR FRACTION/170R 3nventors George 6. Lamb Berna/'0 L. E var/n9 (Ittorneg Nov. 5, 1940. B. L E'VERING ET AL 2,220 091 CONVERSION OF HYDROCARBON PRODUCTS Filed Nov. 24, 1937 2 Sheets-Sheet 2 .u R" 6 :1 W a h g u a Q \q I w N 4 m N w h N 43 q Snnentors George 6. Lamb Gttorneg N Bern dLEl/ ring Patented Nov. 5, 1940 UNITED STATES PATENT (OFFICE--- CONVERSIQN OF HYDBOOABBON PRODUCTS Bernard L. Everlng and George G. Lamb, Chicago,

Ill., assignors to Standard OiiCompany, Chicago, 111., a corporation of Indiana- Application November 24, 1937, Serial No. 176,288 '2 Claims. (01. 196-9) V This invention relates to the preparation of a high antiknock motor fuel from an admixture of propane and straight run petroleum naphtha with the aid of catalysts. In particular, our invention relates to the preparationof a motor fuel product containing large quantities of branchedchain saturated hydrocarbons. I

Saturated branched-chain hydrocarbons, and particularly mixtures of them, are very useful as motor fuels on account of their antiknock properties and high heating value. Also, the saturated branched-chain hydrocarbons have lower boiling points than the corresponding straight-chain paraflin and, consequently, motor fuels containing substantial quantities of the former have better starting characteristics than motor fuels containing large quantities of the latter. In addition, branched-chain paraffin hydrocarbons, such as the iso-hydrocarbons, are very useful as starting materials in the prepara tion of many chemical products.

One of the principal objects of our invention is to convert an admixture of propane and straight run naphtha of low antiknock value into a motor fuel fraction of high antiknock value. Examples of the paraflinic straight run naphtha which may be used in our process are Mt. Pleasant naphtha, Pennsylvania naphtha, Mid- Continent naphthas and the like. This conversion or branching of the admixture of hydrocarbons is efiected without substantial formation of fixed gases such as hydrogen and methane. Following the conversion of the hydrocarbons into a motor fuel product of high antiknock value, the

products from the reaction zone may be fractionated by any ofthe methods hereinafter described to give a motor fuel product of desired volatility and antiknock properties. I

Other objects, advantages and methods of utio lizing our process will become apparent from the description hereinafter- In the drawings, attached to and forming a part of the specification Figure 1 is a diagrammmatic illustration of one arrangement of the apparatus which may be used in practicing our process. Figure 2 is a diagrammatic illustration of the types of reaction zones which may be used in our process.

Our embddiment of our process will be described witl i reference to the conversion of saturated straight run petroleum naphtha. in the presence of a parafiinic gas consisting almost entirely of propane. The naphtha used in this example boils within the range of 150 to 400 F.,

however, our process may be used with petroleum naphthas having end boiling points within the range of 230-500 F. The straight run petroleum naphtha enters the system through conduit A and is forced by pump [0 into the manifold ll. Propane enters the system through line B and is forced by compressor l2 into-the manifold II where it is mixed with the other products therein. Also, a slurry or solution of aluminum chloride in light mineral oil is prepared in the catalyst mixer I3 and passed by pump l4 through line IE to line It and then introduced into the mani- 10 fold II. A promoter or activator, namely, hydrogen chloride, hydrogen bromide, carbon tetrachloride, the alkyl halides such as methyl chloride or bromide, ethyl chloride or bromide, propyl chloride or bromide, butyl chloride or 15 bromide, or any compound which in the presence of an aluminum halide yields a hydrogen halide is added to the reaction zone I! through conduit C with the aid of pump or compressor 29. Also,

in the place of aluminum chloride we may use 20 other aluminum halides such as aluminum bromide. The naphtha, gas, catalyst "and promoter are continuously fed to the system as above indicated and the admixture of materials is then passed through the e1ongated.reaction 25 zone or coil II which is maintained at a temperature within the range of 150-600 F., but pref-- erably within the range of 200-500" F. or 300-475 F. At temperatures below about 475 F., substantially no fixed gases are produced during the con- 30 version of the materials in zone ll, however, at temperatures above about 475 F. very small or negligible amounts of fixed gases may be formed. The pressure maintained in the coil or reaction zone I! may vary over a wide range, that is, -35 from atmospheric pressure to 6,000 pounds per square inch. In some cases the pressure may be even higher. We prefer to use a pressure within the range of about 200-4000 pounds per square inch. The time of contact employed in the reac- 40 tion zone I! may vary considerably, ranging from 1 to 150 minutes. When the naphtha in the reaction zone I1 is mostly in the liquid phase, we

may use a reaction time of from 1 to 120 minutes, but preferably from 2 to 30 minutes. But when 45 the hydrocarbon components, naphtha and feed gases, are mostly in the vapor phase, the reaction may be effected in a shorter period, namely, from 5 to 300 seconds. Any suitable heating medium, such as steam, hot oil, or thermally stable liquids, may be passed around the coil or heating zone I! with the aid of conduits l8 and Is to effect the desired heating or reaction between the hydrocarbon components'in zone ll. Also, any suitable mixing means may be used in the reac- 55 tion zone to effect better contact between the hydrocarbons, catalyst and halide promoter. By keeping the materials in the reaction zone thoroughly mixed, the reaction time will be consider- 5 ably reduced. Figure 2 shows three modified forms of the reaction zone I! and these modified forms effect intimate contact between the hydrocarbons and catalysts and thereby reduce the time of contact to the lower parts of the above ranges. The propane used in our process may be derived from any source, and the term propane is used herein to define a fraction of hydrocarbon gas containing no olefin's and from 75 to 100% 5 C3Ha. The other hydrocarbons which may be present in the propane consist almost entirely of the butanes.

As pointed out hereinafter, an aluminum halide-hydrocarbon complex, in the form of a solution, is formed in the system and it may be used as the catalyst in the reaction zone I'I. Alternatively, additional amounts of fresh aluminum halide may be added to this aluminum halidehydrocarbon complex and the admixture used as the catalyst in the reaction zone ll. When aluminum chloride is used as the catalyst this complex is called an aluminum chloride-hydrocarbon complex. g I

The converted products pass from the reaction zone through the transfer line 20 and valved conduit 2| and are introduced into the separator22 where liquid phase separationiseflected between the aluminum chloride-hydrocarbon complex on the one hand and the reacted and unre- 5 acted products on the other. Alternatively, the products in the transfer line may be passed through the cooler 23 before being introduced into the separtor 22. The cooler is usually employed when the higher temperatures are used 40 in the reactor II. To assist further in the cooling of the products in the transfer line and thereby control the character of the reaction, all or a part of the naphtha feed stock may be used as a quenching medium and introduced into the 5 transfer line through valved conduit 24. Also, oils heavier than the feed stock may be used as the quenching medium. The quenching step may be used with or without the assistance of the cooler 23.

50 An aluminum chloride-hydrocarbon complex settles to the lower part of the separator 22 in the form of a heavy liquid. This complex appears to be some kind of a loose combination between the aluminum chloride and a product of 55 the aluminum chloride-hydrocarbon reactions. This solution is withdrawn from the bottom of the separator 22 through line 25 and passed by pump 26 through line 21 and check valve 28 to conduit l6 where it is returned to the reactor to 0 serve as the catalyst for effecting the alteration of saturated chain hydrocarbons into branchedstraight-chain parafiins or iso-hydrocarbons. When the aluminum chloride-hydrocarbon complex is recycled and used as the catalyst, hydro- 135 gen chloride or other hydrogen halides -may be introduced into the system through line C with the aid of compressor 29 to serve as the promoter for the reaction. By recycling the aluminum chloride-hydrocarbon complex and adding small 70 or large amounts of hydrogen chloride, as above described, only small amounts of the fresh catalyst need be added from time to time through line I5 to make up for losses. We have observed, however, that the presence of large amounts of 75 hydrogen chloride or a promoter which liberates a halogen acid in the presence of an aluminum halide retards the formation of excessive amounts of aluminum halide-hydrocarbon complex in the reaction zone and thereby keeps the aluminum halide in a highly reactive state 5 for the purposes of our process. Intermittently or continuously all or a part of the aluminum halide-hydrocarbon complex may be withdrawn through valved conduit 30 and discarded or revivified and re-used by intro- 10 ducing it into line I6. As another method of handling the aluminum chloride-hydrocarbon complex withdrawn from the bottom of separator 22, it may be passed through line 25, pump 26 and valved conduit 30a to the catalyst mixer l3 1 where small amounts of aluminum chloride are added thereto. This admixture is then passed from the bottom of the catalyst mixer l3 and introduced into line I6 as hereinbefore described.

If desired, small amounts of hydrogen halides 0 such as hydrogen chloride and hydrogen bromide may be added to the catalyst in the catalyst mixer l3 by means of valved line l3a or introduced into the system through line C. In the operation of our process we prefer to add the promoter to 25 the process through conduit C rather than through the mixer l3.

The reacted and unreacted hydrocarbon products in separator 22 which are above the liquid level of the aluminum chloride-hydrocarbon complex as shown by line 3! are withdrawn through line 32 with the assistance of pressure regulator 33 and introduced into the fractionator 34. The pressure regulator 33 effects the desired reduction in pressure on the products before they enter the fractionator 34.

Fractionator 34 effects, as hereinafter indicated, the degree of fractionation desired. The temperature and pressure conditions, number of plates, and reflux ratio employed in the fraction-' ator 34 may be varied to give the desired fractionation. The hydrocarbon products withdrawn from the top of the fractionator 34 contain the added unreacted propane, branched-chain parafilnic hydrocarbons produced in the process and controlled amounts of the naphthas charged to the system. This overhead fraction from tower 34 is passed through line 35' to the cooler 36 and thence into the reflux drum 31. Of course, the hydrogen halide promoter will be in the overhead from. tower'34, The heavy hydrocarbon products in the bottom of fractionator 34 are withdrawn therefrom through line 38 and passed to the accumulator tank 39 where they may be recycled through conduit 40 with the aid of pump 4| to the inlet side of the system.

The degree of fractionation effected in tower 34 will determine to a large extent the composition of the final motor fuel product recovered from the bottom of tower 50. In one embodiment of our invention, the overhead products from tower 34 may consist of unreacted feed gas, and the fraction of hydrocarbons boiling within the gasoline range. For example, the overhead fraction from tower 34 may consist of the feed gas,- and heavier hydrocarbons boiling up to about 390 to 430 F. In a second embodiment of our invention, the fractionator 34 may be operated so that end boiling point of the overhead will not exceed the end point of the motor fuel product desired. In either of these modifications, the low boiling constituents in the overhead from fractionator34 are removed in the stabilizer 50 to give a high antiknock motor fuel 7 containing a large portion of branched-chain sist of propane and a naphtha having an initial boiling point of about 200 F. and an end boiling point of about 460 F., the overhead from fractionator 34 may be cut at a point to exclude hydrocarbons boiling above about 390 to 410 F. Other naphthas may be used in this embodiment and the other embodiments of our invention, for example, straight run petroleum naphthas having initial boiling points within the range of 150- 300" F. and end boiling points within the range of 440- 500- F.

If desired, the fractionator 34 may be operated so that the end boiling point of the overhead therefrom does not overlap the initial boiling point of the feed naphtha to the extent indicated above. The end boiling point of the overhead from tower 34 may be cut at a point where the content of normally liquid straight-chain paraffins therein (excluding the gases, namely'those boiling below 55 F.) will not exceed about 5 to 15% by volume. When the fractioriator 34 is operated in this manner, the overhead therefrom will contain a very high concentration of saturated branched-chain hydrocarbons.

As a fourth modification of the method for operating fractionator 34, the end boiling point of the overhead therefrom may be cut at a point below the initial boiling point of the feed naphtha. For example, if the feed naphtha charged to the process, along with propane, has an initial boiling point within the range of 260 to 350 F., the end boiling point of the overhead fraction from tower 34 may be out at a point slightly below the initial boiling point of the particular-naphtha charged to the system. I

The efiect of the fractionation employed in tower 34 upon the final motor fuel product produced by our process will be discussed hereinafter in connection with the stabilizer 50.

Bubble trays 42 are placed in the tower 34 to assist in the fractionation. A portion of the heavy products in the bottom of tower 34 are withdrawn from trap-out plate 45, passed through line 46 to the reboiler 41 and then returned to the tower to supply heat for the fractionation of the products therein.

The liquefied products in the bottom of reflux drum 3'! are recycled through line 48 with the aid of pump 49 to the top of the bubble tower or fractionator 34 and used as reflux. The overhead from th reflux drum, is introduced into the stabilizer 50 where the desired fractionation is made between the normally gaseous hydrocarbons on the one hand and the higher boiling products on the other. The normally gaseous hyydrocarbons in tower 50 consist almost entirely of the added unreacted propane and the isobutane produced by the catalytic reaction in the reaction zone IT.

The product withdrawn from the bottom of stabilizer 50 through valved conduit 5| contains converted naphtha which has a much higher antiknock value than the original feed naphtha.

This increase in antiknock value is due, primarily,

to the presence of branched-chain paraflins produced by the interaction of the feed naphtha and gases in reactor I'I. These branched-chain parafiins are isobutane, branched-chain pentanes, branched-chain hexanes, branched-chain heptanes, branched-chain octanes and branchedchain paraflins containing 9 or more carbon atoms in the molecule. From the foregoing description of our process, it is apparent that the product removed from the bottom of tower 50 through valved conduit 5| contains a very large amount of branched-chain saturated hydrocarbons and, in addition, this fraction may be characterized as follows: (a) containing a substantial portion of the isobutane produced in the process and having an end point below or substantially,

equal to the end boiling point of the naphtha charged to the system; (b) containing a substantial portion of isobutane and having an end boiling point commensurate with that of commercial gasoline, that is, between 380 and 420 E; (0) containing substantially no isobutane and having an end point below or substantially commensurate with the end boiling point of the feed naphtha; and (d) containing substantially no isobutane and having an end boiling point commensuvapor pressure but which is deficient in high antiknock components such as the branched-chain parafiins. Also, it is particularly advantageous to blend the product referred to in (b) above with a partly debutanized or completely debutanized cracked gasoline to give a high antiknook motor fuel of desired volatility. The motor fuels produced by our process which have an end boiling point of about 390? F. or lower are particularly desirable as aviation motor fuel because of their anti-detonating and volatility characteristics, and high heating value.

The unreacted propane passes from the top of the stabilizer through line 52- to condenser 53 and thence into the reflux drum 54. If the isobutane produced in the reaction zone I! is not removed from the bottom of tower 50 along with the high antiknock motor fuel fraction, it will pass overhead along with the propane. Bubble trays 55 or other fractionating means are placed in the stabilizer 50 to assist in the fractionation therein. A portion of the product in thebottom of the stabilizer may be withdrawn from trap-out plate 56 and passed through line 51 to the reboiler or heating means 58 and thence introduced into the bottom of the stabilizer. The heat added by the reboiler is usually suflicient to effect the desired fractionation in tower 50. It should be understood that other heating means may be used to condense a, part of the vapors therein for use as reflux. A portion of the liquefied hydrocarbon product in line 59 may be passed through valved conduit 62 and introduced into the manifold H 5 for further use in the process of converting straight-chain paraffins into branched-chain paraffins. By employing an efliclent cooler at 53, substantially all of the products in reflux drum 54 will be in the liquid phase'and the portion thereof that is not used as reflux may be recycled through line 62 to the reactor ll-thereby avoiding the necessity of compressing the gases that are removed from the overhead of drum 54. As previously stated, the halogen-containing promoter which is employed in the reaction zone I! will pass along with the overhead from

towers

34 and 50 and consequently-a substantial portion of this promoter will be present in the products recycled from drum 54 to the reactor II. If de-.:

sired, the draw-ofi line 63 may be used to withdraw from the system a portion of the liquefied hydrocarbon product in line 59.

The uncondensed gas in reflux drum 54, assuming that all of the products in drum 54 are 2 not recycled in the liquid phase as previously indicated, is recycled to the inlet side of the system through valved conduit 64. Also, a portion of the hydrogen halide promoter used in the process will pass along with this overhead product. If

30 desired,- all of the hydrocarbons withdrawn from the top of reflux drum 54 may be passed through valved conduit 65 and introduced into the absorber 66 where the hydrogen halide such as hydrogen chloride is separated from these gases. Water, hydrochloric acid or any other suitable solvent may be introduced into the top of the absorber through line 67 and withdrawn through the bottom thereof through line 68 with the dissolved promoter. The thus washed gases may be 50 drocarbons, containing the isobutane and propane, withdrawn from the bottom of reflux drum 54 may be recycled through line 52 to the reaction zone. Alternatively, or in combination with this step, a portion of or all of the liquefied fraction 55 and all or a substantial part of the gases removed from the top of reflux drum 54 may be recycled to the reaction zone. In carrying out any of the hereinbefore described embodiments of our process, the pressure and temperature maintained in 60 separator-54 may be regulated so that the liquid product withdrawn through line 63 will consist largely of isobutane. Of course, when it is desired to remove substantially all of the isobutane 6 from the liquid products in separator 54 the liquid products in the bottom of separator 54 may be passed to a fractionator (not shown) whereby a sharp fractionation is made between propane on the one hand and isobutane on the other. 70 When the separator 54 or the fractionator (not shown) are used to make a sharp separation between the propane fraction and isobutane, the liquid products from the bottom of separator 54 or the fractionator (not shown) are not recycled but all or substantially all of the gases removed from the top of the separator 54 or the fractionator are recycled.

As another embodiment of our process, the feed gases introduced through line B may consist almost entirely of propane and the naphtha introducedthrough line A may have an initial boiling point above about 260 F. When these materials are used as'the charging stock and subjected to the action of aluminum chloride or the aluminum only the branched-chain hydrocarbons containing from 5 to 8 carbon atoms are withdrawn from the bottom thereof through line 5| and the propane and isobutane recycled by any of the methods hereinbefore described.-

The temperature employed in the tops and bottoms of towers 34- and 50 as well as the pressures maintained therein may be varied in order to eifect the desired type of fractionation. When tower 34 is operated at a pressure of about 210 pounds per square inch, a top temperature of about 440 F. and a bottom temperature of about 600 F., the products withdrawn from the bottom thereof through line 38 will consist mostly of hydrocarbonsboiling above about 410 to 430 F. whereas the products taken overhead from tower 34 will consist mostly of the lower molecular weight hydrocarbons. When tower 50 is operated at a pressure of about 200 pounds per square inch, a top temperature of about 200 F. and a bottom temperature of about 500 F., the products withdrawn through line 5! will be substantially free of propane and isobutane, however, if tower 50 is operated at a pressure of, about 200 pounds per square inch, a top temperature of about 110 F. and a bottom temperature of about 400 F., a substantial portion of isobutane produced by the process will be retained in the product withdrawn from the bottom of the tower.

In carrying out our herein described process, the portions of products charged to the reaction chamber l'l may vary somewhat. For example, for one part by weight of naphtha charged to the reactor, the parts by weight of gas, catalyst and promoter may be from 0.1 to 1; 0.01 to 1; and 0.03 to 0.3 respectively. The proportion of gas referred to above applies to the use of propane per se or the admixture of propane and isobutane.

In any of the modifications hereinbefore set forth, we may withdraw a part of the oil from accumulator tank 39 through valved conduit II instead of recycling it to the reaction zone. Alternatively, a once-through operation may be used wherein the heavy products in the accumulator tank 39 are not recycled. However, in this once-through conversion of the naphtha we do recycle the gases by any of the methods hereinbefore described.

As stated hereinbefore, Figure 2 shows some of the modified forms of the reaction zone which may be used to efiect intimate liquid phase con tact as Well as vapor phase contact between the hydrocarbon reactants and catalysts. In describing the three modifications of the reaction zone, the same numerals will be used, whenever possible, as are used on Figure 1.

Modification A illustrates the use of a mixer mounted within the reactionzone II. This modification is used preferably for liquid phase operations. The feed naphtha, gases, catalyst and promoter enter the reactor I1 through the manifold II and pass into the reactor through line Ila. If desired, a part or all of the catalyst and/or promoter may be added to the reactor through line IIb. As the hydrocarbon, catalyst and promoter pass up through the reactor, they are thoroughly mixed by the revolving blades I2 which are mounted'on the shaft driven by the motor- I3. A packing is placed around the shaft at I4 to prevent the escape of gases and liquids from the reaction zone, A closed steam coil I5 is placed inside the reactor to provide the necessary heat for the reaction, however, the products in line I I may be heated by any conventional means before entering the reactor II. The converted products pass from the reaction zone through the transfer line 20, valved conduit 2| and are introduced into the separator 22 where liquid phase 'separation is eflectedbetween'the aluminum halide-hydrocarbon complex on the one hand and the reacted and unreacted products on the other. Alternatively, the products in the transfer line may be passed to the cooler 23 being introduced into the separator 22. The feed stock may be introduced through valved conduit 24. The aluminum halide-hydrocarbon complex is withdrawn from the lower part of the separator 22 and passed by line 25, pump 26, line 21 and check valve 28 to the inlet of the reaction zone. Intermittently or continuously all or a part of the aluminum halide-hydrocarbon complex may be withdrawn through valved conduit 30 and treated as hereinbefore described. The reacted and unreacted hydrocarbon products in separator 22 which are above the liquid level of the complex as shown by line 3 I' are 'withdrawn through line 32 with the assistance of pressure regulator 33 and introduced into the fractionator 34. In brief, this modification of the reaction zone is very easily adapted to the process hereinbefore described with reference to Figure 1.

Modification C illustrates the use of a mixer mounted within the reaction zone, similarto that shown in modification A, with the improvement of permitting the recycling of gases within the reaction zone before the reacted and unreacted products are passed to the fractionating system. The reacted products pass from the top of the reaction zone through line 20 and are introduced into separator 16 where the unreacted gases are withdrawn from the top thereof through valved conduit I1 and returned with the aid 01' the compressor 18 to the bottom of the reactor I1. This step of recycling the unreacted gases in combination with the turbo-mixer provides an excellent Way of obtaining thorough contact between the gases and promoter on the one hand and the liquid feednaphtha and aluminum chloride catalyst on the other. The liquid products in the bottom of separator I6, including the aluminum halide-hydrocarbon complex as well as liquid hydrocarbons, are withdrawn from the bottom thereof through line 19 and introduced into the separator 22. The separation effected in separator 22 and the method of handling the aluminum halide-hydrocarbon complex and hydrocarbon products are the same as described with reference to modification A and also Figure 1. To prevent the building up of unreacted hydrocarbons within reaction zone I1, a valved by-pass 'I'Iais provided'for venting some of the gases in separator I6 into conduit i2 so that they will pass into the fractionating system. as described in Figure 1.

In either of the above two modifications, we may use a turbo-mixer in the place of the mixing device shown. Modification B illustrates the use of a vapor phase reaction chamber. The feed naphtha, gases and promoter enter the reactor II through the manifold I I and pass into the reactor through line Ila. If desired, a part or all of the promoter may be added to the reactor through line IIb. Theproducts in line a are sprayed or atomized into the bottom of the reaction zone II. We prefer to heat the hydrocarbons in manifold II before they enter zone I'I so that they will vaporize when introduced therein. A closed steam coil I5 is provided in the chamber to maintain the desired temperature therein. The catalyst comprising a mineral oil slurry of the aluminum halide is sprayed into the top of the chamber I'l through conduit I5. This slurry of catalyst may be prepared in the mixer as shown by Figure 1. The counter-current contact between the descending catalyst and ascending hydrocarbon vapors and promoter insures intimate contact between the products in the reaction zone II. The aluminum halide-hydrocarbon complex falls to the bottom of the chamber I1 and is withdrawn through line 80. If desired, the liquid level of the aluminum halide-hydrocarbon complex or catalyst solution in zone Il may be permitted to rise a short distance above the level of the nozzle on line Ila so that the feed products in line II will be, atomized into the liquid catalyst or catalyst slurry. This complex or liquid catalyst may be recycled directly to line I5 or it may be mixed with additional quantities of the aluminum halide and/or promoter and returned to line I5. The reacted and unreacted hydrocarbon constituents in zone I! are withdrawn from the top thereof through line 8| with the assistance of the pressure reducing valve 82 and introduced into the fractionator 34 as shown in Figure l.

' The pressure and temperature conditions maintained in modifications A, B and C of the reaction zone may be the same as those described in connection with Figure 1. Also, it has already been pointed out that the time of contact may vary over a relatively wide range and that thorough mixing or agitation of the constituents in the reaction zone I! materially shortens this time of contact. a

While we have described our invention with reference to specific examples by way of illustration, it is apparent that other modifications may be employed.

We claim:

1.v In a process for converting substantial amounts of the straight-chain parailln hydrocarbons in a low antiknock straight run petroleum naphtha into saturated branched-chain hydrocarbons whereby a motor fuel fraction having a relatively high antiknock value is obtained, the steps comprising contacting in a reaction zone an admixture of said petroleum naphtha, pro- I pane, a conversion catalyst selected from the part of the straight-chain paraffin hydrocarbons in said petroleum naphtha into saturated branched-chain hydrocarbons without substantial formation of hydrogen and methane, withdrawing the products from said reaction zone and separating said motor fuel fraction from said products.

2. In a process for converting substantial amounts of the straight-chain-paraffln hydrocarbons in a low antiknock straight run petroleum naphtha into saturated branched-chain hydrocarbons whereby a motor fuel fractionhaving a relatively high antiknock value is obtained, the steps comprising contacting in a reaction zone an admixture of said petroleum naphtha, pro-.

pane, aluminum chloride and a hydrogen halide, the reacting hydrocarbon gases present being largely propane and substantially free of unsaturated hydrocarbons, at a temperature within the range from about 150F. to about 600 F. and under superatmospheric pressure, whereby substantially no hydrogen and methane are formed, withdrawing the products from said reaction zone and separating said motor fuel fraction from said products.

3. The process of claim 2 wherein said temperature is in the range from about 200 F. to about 500 F. and said pressure is in the range from about 200 to about 4000 pounds per square inch.

4. In a continuous process for converting substantial amounts of the straight-chain paramn hydrocarbons in a low antiknock straight run petroleum naphtha into saturated branchedchain hydrocarbons whereby a motor fuel fraction having a relatively high antiknock value is obtained, the steps comprising contacting in a reaction zone an admixture of said petroleum naphtha, propane, a conversion catalyst selected from the group consisting of aluminum chloride,

aluminum bromide and their hydrocarbon complexes, and a halogen-containing promoter for said catalyst, the reacting hydrocarbon gases present being largely propane and substantially free of unsaturated hydrocarbons, at an elevated temperature and pressure sufficient to convert a substantial part of the straight-chain para-flin hydrocarbonsin said petroleum naphtha into saturated branched-chain hydrocarbons without substantial formation of hydrogen and methane,

withdrawing the products from said reaction zone and separating therefrom an aluminum halidehydrocarbon complex, fractionating the remaining hydrocarbon products to produce said motor fuel fraction and a gaseous fraction consisting largely of propane and substantially free of unsaturated hydrocarbons, and recycling at least a portion of'said gaseous fraction to said reaction-zone.

5. In a continuous process for converting substantial amounts of the straight-chain paraffin hydrocarbons in a low antiknock straight run petroleum naphtha into saturated branchedchain hydrocarbons whereby a motor fuel fraction having a relatively high antiknock value is obtained, the steps comprising contacting in a reaction zone an admixture of, said petroleum naphtha, propane, aluminum chloride and a hydrogen halide, the reacting hydrocarbon gases present being largely propane and substantially free of unsaturated hydrocarbons, at. a temperature within the range from about 150 F. to about,

600 F. and under superatmospheric pressure. whereby substantially no hydrogen and methane are formed, withdrawing the products from said reaction zone and separating therefrom an aluminum chloride-hydrocarbon complex, fractionating the remaining hydrocarbon products to product said motor fuel fraction and a gaseous fraction consisting largely of propane and substantially free of unsaturated hydrocarbons. and recycling at least a portion of said gaseous fraction to said reactionzone. I

6. In a process for converting substantial amounts of the straight-chain paraffln hydrocarbons in a low antiknock straight run petroleum naphtha into saturated branched-chain hydrocarbons whereby a motor fuel fraction havinga relatively high antiknock value is obtained, the steps comprising contacting in a reaction zone an admixture of said petroleum naphtha, propane, aluminum chloride and a. hydrogen halide, the-reacting hydrocarbon gases present being largely propane and substantially free of unsaturated hydrocarbons, at a. temperature within the range from about 200 F. to. about 500 F. and under a pressure in the range from about 200 to about 4000 pounds per square inch, whereby substantially no hydrogen and methane are formed, withdrawing the products from said reaction zone and separating therefrom an aluminum chloridehydrocarbon complex, subjecting the remaining hydrocarbon products to stabilization, whereby substantially all of the isobutane is removed from said hydrocarbon products, and said motor fuel fraction and a gaseous fraction consisting largely of propane and isobutane and substantially free of unsaturated hydrocarbons are produced, and recycling at least a portion of said gaseous fraction to said reaction zone. 7

7. In a continuous process for converting straight-run petroleum naphtha containing substantial amounts of straight-chain paraflin hydrocarbons and a fraction of substantially completely saturated gases containing at least 85% of propane into a motor fuel product containing relatively large amounts of saturated branchedchain hydrocarbons, the steps comprising contacting in a reaction zone an admixture of said straight-run petroleum naphtha, said fraction f saturated hydrpcarbon gases containing at least 85% propane, an aluminum halide and a halogen promoter, at an elevated temperature and pressure suflicient to convert a part of the hydrocarbon components therein into saturated branchedchain hydrocarbons without substantial formation of hydrogen and methane, withdrawing the products from the reaction zone and separating therefrom an aluminum halide-hydrocarbon complex, subjecting the remaining hydrocarbon products to stabilization, thus removing from said remaining hydrocarbon products substantially all of the normally gaseous hydrocarbons and there- ,by forming a motor fuel product of lower vapor pressure than commercial gasoline but containing relatively large amounts of branched-chain hydrocarbons and recycling at least a portion of the normally gaseous hydrocarbons separated by the stabilization to the reaction zone for further use.

BERNARD L. EVER1NG.- GEORGE G. LAMB.