US2971037A - Gamma alumina promoted paraffin alkylation process - Google Patents

Description

1961 R. GILBERT ETI'AL 2,971, 37

GAMMA ALUMINA PROMOTED PARAFFIN ALKYLATION PROCESS Filed Dec. 1, 1958 PPROMOTER LIGHTER I l HYDROCARBON II A '43 ||G- is c 1 I 6b I2 [5 /2| r AIEIr PICKUP) I R\EACT|QN VESSEL ZONE INITIAL -SEPARATION ZONE PRODUCT m SEPARATION ZONE HIGHER PARAFFIN |5J/ HYDROCARB0N FEED GeZrggRMGI'gerf k Jan c arm/c A/an Schr/es/w/m lNVE/VTORS ATTORNEY United States Pater-11:0 F

2 I GAMlVIA ALUMINA PROMOTED PARAFFIN ALKYLATION PROCESS George R. Gilbert, Elizabeth, John E. McCormick, Ro- .;sell,e Park, and Alan Schriesheim,,Fords, N.J., assignors j Esso Research and Engineering Company, a corporation of Delaware Filed Dec. 1, 1958, Ser. No. 717,313 6 Claims. c1. 260-68353) support comprising gamma alumina, under conditions that result in high yields of branched chain parafiin hydrocarbons of from 5 to 7 carbon atoms.

Petroleum, refiners are continuously faced with the problem of supplying better and greater quantities of high octane rating motor fuels to meet the requirements of modern high compression internal combustion engines employed in the automotive industry. Heretofore, the lsupplyof high octane rating gasoline components has been augmented principally by polymerization and alkylation processes using C and C petroleum fractions as Ljstarting materials. These processes have a number disadvantages in that they require severalseparate operations and necessitate the use ofolefin hydrocarbons which are usually in relatively limited supply. It has now been found that, by the use of a promoted aluminum bromidecatalyst, butanes and/ or pentanes can ,be. reacted directly with higher paraifin hydrocarbons to give good yields of C to C branched chain hydrocarbons v of high octane rating, provided certain specific conditions are employed. It has previously been proposed to con-. duct reactions of this type. but yields have been low, ,freaction rates have been uneconomic and satisfactory product distribution has not been obtained.

.In..accordance with the present invention, a paraffin hydrocarbon ,of from 6 to 18 .carbon atoms is reacted with alarge excess of a butane or a pentane, preferably isobutane, employing as a catalyst AlBr supported on or associated with gamma almuina, at. temperatures in the range of from about 30 to about 140 F. and at pres- ,'sures sufiicient to keep thereacting hydrocarbons in the j. liquid phase. The products of the reaction are saturated l branched chain parafiin hydrocarbons predominantly in .the C to C range. The preferredtemperature range is from about 50". to about 120 F.

.The nature and objectsof this invention and the man- ,ner in which the invention can be practiced will be more 'readily understood when reference is made to the ac- "-corhpanying drawings in which the single figure is a schematic flow planof'one process for practicing the iuventiom' r The process will bedescribed with-particular reference 2,971,037 Patented Feb. 7, 1961 to the use of isobutane as the lighter component. Referring to the drawing in detail, a suitable butane feed stream containing at least initially a major proportion of isobutane is obtained by means of line 11 from a suitable source. A portion of the stream is conducted via line 11a through an aluminum bromide pick-up vessel 12 to dissolve aluminum bromide in a portion of the stream that is conducted to the reaction zone. The remainder of the feed stream is combined with the efiluent leaving the pick-up vessel via line 13 and is conducted into a react-ion zone 15. The latter zone contains one or more beds of gamma alumina saturated with aluminum bromide.

A stream of ahigher parafiin hydrocarbon, as for example, heptane, octane, dodecane or cetane, or of mixtures containing the higher parafiins, is conducted into The reaction product leaves the reaction zone through line 18 and is conducted into an initial separation zone 20 wherein light materials, including unreacted isobutane and normal butane are removed overhead and recycled -to the reaction zone by means of line'21. Hydrogen bromide, which is preferably present, will also be recycled via line 21. The heavier material, including C hydrocarbons and higher, is conducted by means of line 22 into a product separation zone 24 wherein C to C hydrocarbons are removed overhead by means of line 25 While heavier material comprising C hydrocarbons and higher as well as any aluminum bromide that has been removed from the reaction zone is recycled to the reaction zone by means of line 26. If desired, conditions can be adjusted in separation zone 24 to include normal heptane in the heavier material recycled through line 26, while including the C branched chain isomers in overhead line 25.

In place of isobutane the feed in line 11 may comprise normal butane, in which case no higher hydrocarbon feed stock will be sent initially to the reaction zonebut the butane will be recycled through line 18, zone 20 and line 21 until a considerable amount of the butane has been isomerized to isobutane. The process may then continue in the manner already described, the recycle f isobutane being suificient to make the desired reaction distribution of the products may be obtained. For example, at temperatures above about 'F. considerable cracking occurs and the principal products are propane and lighter materials. Also it has been established th at aluminum bromide alone or even in the presence of 'conventional hydrogen halide promoters such as hydrogen bromide, in the absence of the support, is very much less active than the catalyst system of the present invention. Furthermore in order for the reaction to proceed-satisfactorily it is necessary that sulficient aluminumbr'dmide be present not only to saturatethe support under the reaction conditions employed but also to leave at least a small amount dissolved in the react ng hydrocarbons.

A mixed catalyst in which a portion of the aluminum of line 17 and is recycled to the reactionzone along with unreacted-butanes by means :ofline 21.

Although the process as described in'conjunction with the drawing COHtGIIlPlfitEStdOWHflOW of the stream=through the catalyst bed, which is preferred, upfiow can also be used. Also in place of a fixed bed process,a moving bed "of catalyst could be used. Alternatively, a slurry type of operation could be employed wherein a suspension of .catalyst is'maintained in the reacting hydrocarbons, the .slurrybeing stirred in :the reactor with suitable mechanical stirring means or recirculated through the reactor by pumping means. Where slurry operation is used, the

slurry is removed from the reactor at the .end of the reaction period, inthe case of batch operation, or as a fraction of the circulating stream in the case of continuous operation, and sent to suitable separation equipment to separate the catalyst :from the .hydrocrabons. separation equipment may comprise a simple settling tank, .a centrifuge, or a filter, for example, or :suitable com- The binations of such means.

It is preferred that the minimum mol ratio of isobutane and/or isopentane to higher parafiin be about :3 to 1 but should preferably beno higher than about 1-2 to .1. If sufiicient iso-C is not present in the reaction zone to effect alkylation of the materials obtained when ahigher -paraflin or other higher product of the reaction is cracked by the catalyst catalyst sludging will result. The feed stock must be essentially free of aromatic hydrocarbons and not more than about 0.02% of such material should be present. An added advantage of the catalysts of the present invention is that naphthene hydrocarbons may be tolerated in the feed stock up to about volume percent.

With increased naphthene content the reaction severity must be increased somewhat --as compared to 'a-reaction in the absence of naphthenes.

This may be accomplished by raising the temperature and/or lowering the feed rate, for example.

Feed rates may vary from about 0.3 to about 2 v./hr./v.

. (liquid volume of total feed per hour per volume .of total catalyst plus support) the higher feed rates being preferred .whenlittle or no naphthenes are present.

To remove aromaticsfrom the .feed stock conventional techniques may be employedsuch as solvent extraction,

. hydrogenatiomacid treating and thelike, .as well as treatment with selective adsorbents such as molecular sieve .zeolites. It is notnecessary that the. higher hydrocarbons used be individual hydrocarbons such as heptane or octane or cetane, for example, but mixtures may be used, such as a petroleum fraction containing paraffinic hydrocarbons in the range of .6 to 18 carbon atoms. Although, as stated, hexane is one of the higher hydrocarbons that may .beused, it .is preferred to employ heptane or higher. Essentially thesame product distribution is obtained-with hexane 'as withheptane but the reaction rate is lower by a factor of about 3.

Other sources of the higher parafiin hydrocarbons for the reaction include light virgin naphthas, and paraffin rafiinates from-the extraction of .hydroformed petroleum fractions.

.-At the start of the process the gamma alumina may be :saturated with aluminum bromide and then placed in the reaction zone, or, alternatively, the gamma alumina alone may be placed in the reaction zone and then satu- "rated :with aluminum bromide carried in with a portion rot'lthefeed. Another method of preparation is to mix considerable yields of C and C isomers.

the aluminum halide with the support and to hear the mixture to effect impregnation. If desired, loosely held aluminum halide may be removed from the catalyst mass by heating the mass and passing through it a gas such as carbon dioxide, methane, hydrogen or nitrogen.

Alternatively the support may be impregnated by dissolving the aluminum halide in a suitable solvent such as ethylene dichloride or dioxane, for example, and the porous carrier impregnated with this solution, followed by heating to remove the solvent and loosely held aluminum halide. Still another alternative is to employ a powdered support or promoter, ,mix the aluminum halide with it, and compress the mixture into pellets.

The following 'examples'serve to illustrate-the practice of the present invention.

EXAMPLB'I Comparative tests were made with'var'ious catalyst systems as shown in Table I. In each instance amixture of 160 cc. (90.5 grams) of isobutane and 40 cc. (27.5 grams) of a normal heptane feed, which consisted of of normal heptaneand 5% of methyl cyclohexane,

was stirred for 3 hours at 72 F. with one of the catalyst systems mentioned above. At the end of each run tion of the product consisted of C hydrocarbon isomers. On the other hand, gamma alumina was a very effective promoter for the aluminum bromide catalyst and gave Still ,greater activity was obtained when -.a small proportion of .hydrogen bromide was employed in addition to the gamma alumina.

The gamma aluminadlsed in these tests was prepared as follows. Aluminum alcoholate was prepared .by reaction of aluminum metal with a 3 to 1 volume ;ratio mixture of mixed amyl alcohols and heavy virgin naphtha, using a trace of mercuric chloride to promote the reaction. The ratio of reactants was about.3 pounds .of aluminum per 7 gallons of the alcohol-naphtha mixture. The aluminum contentof resulting aluminum alcoholate solution was about 94 to 97 grams of alumina per .liter. The aluminumalcoholate was pump-mixed atroom temperature with a diluent (22 volumes of alcoholate per volume of diluent) consisting of mixed amyl alcohols, heavy naphtha and acetic acid in a volumetric ratio of 15 to 15 to 1. This stream was then hydrolyzed with 6.8 volumes of water at room temperature in a-second mixing pump. The mixed product was pumped through .a heat exchanger held at F. outlet temperature.

From the heatexchanger the product went to a separator held at 160 F. The alcohol and solvent layer were continuously withdrawn from the top of the separator while the aqueous layer flowed continuously into a steam jacketed stainless steel sol cooking unit and heated to boiling .for 4 hours. During the heating, alcohol and solvent remaining in the slurry were taken overhead from the cooking unit, together with water. The alcoholsolvent mixture and water were separated and measured, andthe water returned to hold constant volume.

Five [GO-gallon batches of alumina sol were prepared in this .manner and mixed together. Analysis .after mixing indicated an alumina content of 3.1 percent. The entire mixture was spray dried in a tower in a rising stream of flue gas having anentering temperature .of 590-625 F. and an exit temperature of 220-230 F., the entering stream of alumina sol being preheated to F. The 500 gallonsof aluminasol were dried in seven hours to produce 161 pounds of spray dried product containing 32% volatile matter. .About.5'l0 pounds of water were evaporated ,per hour during .this drying operation. The product obtained was gammaalumina. Before using :it as a support or promoter for .aluminum 5 bromide in the't'ests described herein it wasflc'alcined -at 1100 F. for 4hours. I Y Table I Test 1 Test 2 Test 3 Test 4 Catalyst, grams:

AlBri 23. 6 23. 6 23. 6 23. 6 Gamma Alumina 42. 7 42.7 EB: 24 1. 1

Analysis oi Product, Weight 1 Percent:

ISO-C5 0. 4 0. 5 37. 4 41. 8 11-0 0.3 as 5.3 g 6.7

Total 06 0.7 4.1 42.1 48.5

T0151 Ca 0. 5 0. 3 22. 0 24. 1

Total C1 98. 8 95. 6 32. 7 24. 9

EXAMPLE 2 In a manner similar to that employed in Example 1, comparative tests were made with gamma alumina, eta alumina and calcined bauxite. Each of these materials 'was employed with aluminum bromide in 2 different ratios of catalyst to support. The same reaction temperature and time and the same hydrocarbon feed was employed as in Example 1. The gamma alumina was prepared in the manner previously described. The eta alumina and the bauxite were obtained from commercial sources. In each case the support used was calcined for 4 hours at 1100 F. before use. It will be seen from the data presented in Table II that gamma alumina was much more active than either of the other two supports in converting the isobutane and normal heptane into C and C paraffin hydrocarbon isomers.

Gamma alumina prepared from sodium aluminate and obtained commercially showed about the same activity as that reported in Table II. In a similar test, the commercial gamma alumina in the ratio of 47.2 grams to 23.6 grams of AlBr gave, in the 3-hour test, 42.4% C hydrocarbons, 26.0% C hydrocarbons and 30.7% C hydrocarbons.

Table II Promoter Gamma calcined Eta Alumina Bauxite Alumina Promoter, grams 47.2 47.2 47.2 47.2 47.2 47.2

AlBl'a, grams 23.6 35.3 23.6 37.8 23.6 35.4

Analysis of Cr+ Product,

Weight Percent:

EXAMPLE 3 Even greater activity for the desired alkylation reaction was obtained, as measured by conversion of C hydrocarbons to C and C hydrocarbons, by using larger ratios of aluminum bromide to gamma alumina. The test results are shown in Table III. Again the same reaction temperature and time and the same hydrocarbon ilhersamm alumina was prepared as described above.

Table 11 v Gamma Alumina, grams 1 47.2 1 i 45.2 AlBra,grams 47.2 47.2 i HBr,g|-am-z i a I .0 I. 0 7..

Analysis of 0 Product, Wei ht Percent" iso-Cs 48.0 --48.6

. 8.0 7.0 se a 55.6 28. 6 29.4 1.:3 1.s

It has been established in other studies that in order for the reaction to proceed satisfactorily it is necessary to have present in the reaction zone sufficient aluminum bromide so that not only will the total adsorption capacity of the gamma alumina be satisfied but some aluminum bromide will be present in solution in the reacting hydrocarbons. To make sure that such a condition will exist in continuous operation, the gamma alumina in the reaction zone should be saturated with aluminum bromide, and sufiicient aluminum bromide should be dissolved in at least one of the entering streams of reacting hydrocarbons so that a minimum of 0.1 weight percent of aluminum bromide based on feed is sent to the reaction zone.

Although in the illustrative examples given, the higher parafiin hydrocarbon reactant comprised heptane, other studies have shown that with hydrocarbons of greater molecular weight such as octane, cetane, or octadecane, the product distribution is essentially the same as with heptane.

Certain modifications of the process outlined hereinbefore will occur to those skilled in the ant. Such modifications are contemplated within the scope of the pres-' ent invention. For example, if the yield of C hydrocarbons is larger in proportion to the C hydrocarbons than is desired, the product may be distilled to separate a C cut which may then be used in a conventional alkylation step with an olefin. such as ethylene, propylene or a butene, employing the usual alkylation catalysts such as sulfuric acid, phosphoric acid, hydrogen fluoride, or an aluminum halide. Alternatively, the C out can be sent to a second reaction zone of the type herein described for reaction with higher normal parafiin hydrocarbons.

It is to be understood that this invention is not to be limited to the specific embodiments and examples herein described and presented but that its scope is to be determined solely by the claims appended hereto.

What is claimed is:

1. A process for the preparation of high octane naphtha components consisting largely of branched chain paraffin hydrocarbons of 5 to 7 carbon atoms which comprises reacting a minor proportion of a straight chain parafiin hydrocarbon of from 6 to 18 carbon atoms with a major proportion of a lighter hydrocarbon selected from the group consisting of butanes and pentanes, at temperatures no higher than about F., in a reaction zone in the presence of a catalyst comprising aluminum bromide and gamma alumina and maintaining in the reaction zone sufiicient aluminum bromide to furnish aluminum bromide in solution in the reacting hydrocarbons in addition to the quantity required to satisfy the total adsorption capacity of the gamma alumina.

' 2. Process as defined by claim 1 whe-reinfrom about 0.1 to about 8 percent of hydrogen bromide, based on .7 he *re'acting hydrocarbons, :present in :the reactio'n zone.

3. Process as definedrby claim 1 wherein the mol ratio ,of vsaid lighter hydrocarbon selected from the group consisting of butanes and pentanes to said hydrocarbon 10f from 6 to l8pcai'bonatoms in the reactionzone'is in :the range ofifrom about? -to 1 -to-about 1210 :1.

4. Process as defined by claim 11 wherein naphthenic hydrocarbons :are present in-said reaction zone.

' 5. -Process as defined by claim '1 'wherein the temperature "of ;the "reaction is in the range of about 50 10 about 5120 6. Process as defined by claim 1 wherein reacting hydrocarbons are continuously conducted into said reaction zone and reaction products are continuously re- 15 References Citedin the file of this patent UNITED STATES PATENTS 2,349,458 Owen i.. May 23, 1944 2,370,144 Burk Feb. 27; 19,145 2,401,925 Gorin June -11, 1 946 2,41'5; 06'1 De Simoet al. Jan. 28, 1947 ML. A

Claims (1)

1. A PROCESS FOR THE PREPARATION OF HIGH OCTANE NAPHTHA COMPONENTS CONSISTING LARGELY OF BRANCHED CHAIN PARAFFIN HYDROCARBONS OF 5 TO 7 CARBON ATOMS WHICH COMPRISES REACTING A MONOR PROPORTION OF A STRAIGHT CHAIN PARAFFIN HYDROCARBON OF FROM 6 TO 18 CARBON ATOMS WITH A MAJOR PROPORTION OF A LIGHTER HYDROCARBON SELECTED FROM THE GROUP CONSISTING OF BUSTANES AND PENTANES, AT TEMPERATURES NO HIGHER THAN ABOUT 140*F. IN A REACTION ZONE IN THE PRESENCE OF A CATALYST COMPRISING ALUMINUM BROMIDE AND GAMMA ALUMINA AND MAINTAINING IN THE REACTION ZONE SUFFICIENT ALUMINUM BROMIDE TO FURNISH ALUMINUM BROMIDE IN SOLUTION IN THE REACTING HY-

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