US2963526A - Paraffin alkylation reactions promoted with fluoroalcohol - Google Patents

Description

9 1960 G. M. KRAMER ETAL 2,963,526

PARAFFIN ALKYLATION REACTIONS PROMOTED WITH FLUOROALCOHOL Filed D80. 1. 1959 I llu llb REACTION 25 a ZONE 1 'l5 l2 2e, AIBr3 PICK UP 2o ZONE ,24

PRODUCT SEPARATION- ZONE George M. Kramer George R. Gilbert Inventors fi m W PofenfAtforne United States Patent Q 2,963,526 PARAFFIN ALKYLATION REACTIONS PRO- MOTED WITH FLUOROALCOHOL George M. Kramer, Berkeley Heights, and George R. Gilbert, Elizabeth, N.J., assignors to Esso Research and Engineering Company, a corporation of Delaware Filed Dec. 1, 1959, Ser. No. 856,400 6 Claims. (Cl. 260-68353) The present invention relates to the alkylation of certain paratfinic hydrocarbons with other paraffinic hydrocarbons to produce branched chain hydrocarbons intermediate in chain length between the chain lengths ofthe reacting materials. In particular, the invention in volves the reaction of a butane or a pentane, preferably isob'utane, with paraffinic hydrocarbons of from 6 to 18 carbon atoms to produce high octane rating components for motor fuels. The process employs a promoted catalyst comprising aluminum bromide and yields a product that predominates in branched chain parafiin hydrocarbons of from 5 to 7 carbon atoms. The process is known as a pa'raffin alkylation process.

Modern high compression gasoline engines require fuels that have high antiknockqualities. Heretoiore, the supply of components for such fuels has been augmerited principally of polymerization and alkylation processes using C and C petroleum fractions as starting materials. Because processes of the latter types require that a supply of olefins be available, and also because such processes usually involve a number of separate operations, they leave much to be desired.

It has recently been found that by the use of a promoted aluminum bromide catalyst, butanes and/or pentanes can be reacted directly with higher paraffin hydrocarbons of from 6 to 18 carbon atoms to give good yields of C to C branched chain saturated paratlin hydrocarbons of high octane rating. employed are those that favor simultaneous cracking, isomerization and alkylation reactions. The. quantity of the butane or pentane in the reaction is considerably greater than the quantity of the higher paraiiin hydrocarbon and there is a net consumption of the lower hydrocarbon. Most desirably, conditions are such that the products of the reaction predominate in C and C parafiin isomers with smaller proportions of C isomers. Since there is a net consumption of the lower boiling and higher boiling reactants and a net production of intermediate hydrocarbons, in effect, one paraffin hydrocarbon is alkylated with another paraffin hydrocarbon. Accordingly, the process may be termed a paraifin alkylation process.

The reaction conditions that are favorable for obtaining the desired products, in a paraiiin alkylation reaction of the type described, include reaction temperatures in the range of about 30 to 140 F. and pressures sufficiently high to maintain the reacting hydrocarbons in the liquid phase. At temperatures above about 140 F. excessive cracking occurs and the principal products obtained are propane and lighter materials. The preferred temperature range is from about 50 to about 120 F.

Regardless of the particular heavier parafiin hydrocarbon that is used in the range of from 6 to 18 carbon atoms, the product obtained predominates in C and C isomers along with lesser amounts of'C isomers. It is generally preferred that heptane or a higher hydrocarbon be employed rather than hexane.

The catalyst employed in the present invention is one that comprises a complex of aluminum bromide, a fluoroalcohol of from 3 to 7 carbon atoms and having from -4 t 2 .flPQfiaaatw tes al a i monohydric The conditions r4 ice alcohol of from 1 to 3 carbon atoms. Among the specific fluoroalco-hols that may be used are included ncr cr cn on, HCF CF CF CF CH OH and H(CF CH OH. The fluoroalcohols are made via a reaction of the type x H XCHZOH where x=l, 2, 3 The mole ratio of fluoroalcohol to aluminum bromide in the complex should be at least 0.05 to' 1 but should not exceed about 0.5 to 1. Mole ratios of aliphatic alcohol to fluoroalcohol may range from 1:2 to about 2:1. A particularly active catalyst comprises aluminum bromide, methanol and 2,2,3,3-tetrafluoroprop anol-l.

The nature and objects of the invention and the manner in which it may be practiced may be more readily understood when reference is made to the ensuing description and the accompanying drawing in which the single figure constitutes a schematic flow plan of the process.

The process may be particularly described with reference to the use of isob-utane as the lower hydrocarbon entering the reaction. Referring now to the drawing in detail, isobutane from a suitable source is conducted by means of line 11 into a stirred reaction zone 15 which contains a catalyst complex of the present invention, i.e., a complex comprising aluminum bromide, a lower fluoroalcohol, and a lower aliphatic alcohol. Because of the high solubility of aluminum bromide in hydrocarbons, a small proportion of the aluminum bromide may tend to be lost from the system by solution in the product stream. To replace this loss, a small fraction of the isobutane stream may be diverted by means of lines 11a and 11b through an aluminum bromide pick-up zone containing a body of aluminum bromide. This diverted stream will dissolve the aluminum bromide and conduct it into the reaction zone.

A stream of the higher parafiin hydrocarbon involved in the reaction, for example, heptane, octane, or cetane,

or a mixture containing two or more of the higher paraffin hydrocarbons, is conducted into the reaction zone by means of line 16. The two reacting hydro-carbon streams are intimately contacted with the catalyst with the aid of the stirring means, and conditions are maintained to bring about the desired reaction. In some cases, the reaction may be promoted with a hydrogen halide, such as HBr. If such is used, it is conducted into the reaction zone through line 13. If the promoter is HBr, it may be employed in proportions of from about 0.2 to about 8 weight percent, based on the reacting hydrocarbons. I

The reaction product and catalyst leave the reaction zone through line 17 and are conducted into a settling zone 18 where separation of catalyst from the products of the reaction is effected. Separation in zone 18 may be by simple settling or it may be aided by centrifuges, for example. The separated catalyst complex is returned to the reaction zone through line 21.

The' reaction products, which have now been separated from the catalyst complex, are conducted by means of line 19 into stripping zone 20 where conditions are maintained to remove hydrogen halide promoter and unreacted isobutan-e overhead to be recycled to the reaction zone via line 22. The stripped p'roduct'is then conducted through line 23 into a product separation zone wherein conditions are maintained to fractio-nate the product. The various fractions including C to C hydrocarbons may be removed overhead or as side streams through lines 25 and 26. Heavier product matterials comprising C hydrocarbons and higher may be recycled if desired by means of line 28. The product S9133.

ration step may also be conducted in such manner that the C hydrocarbons are recycled through line 28. If any dissolved aluminum bromide has been carried out of the reaction zone with the products, this will also be methylcyclohexane (1.7 grams), using a reaction temperature of 75 F. and a reaction period of three hours. The mixed hydrocarbon feed was added directly to the premixed catalyst complex in a vigorously shaken reactor,

present in the bottoms that are recycled from zone 24 5 and the products of the reaction were separated from the to the reaction zone. catalyst and analyzed at the end of the three-hour reaction In place of isobutane the feed in line 11 may comprise period. The results of the various tests are shown in normal butane, in which case no higher hydrocarbon feed Table I.

Table 1 Test A B o D E F o H J Catalyst. Grams:

111B 23.6 23. 6 23. 6 23. 6 23.6 23.6 23. e 23. a 23. a Fluoroalcohol. 9. 0 6. 75 4. 1. 58 0. 75 0. 37 Methyl Alcoho 0 3. 0 2. 25 1. 5 .0. 52 0. 25 0.13 1. 42 2. s4 Mole Ratio:

Fluoroaloohol to AlBr; 0.75 0.56 0. 33 0.13 0. 07 1.03 MeOH to Alan.-. 1. 04 0. 78 0. 52 0.15 0.09 0. 04 0.5 1. 0 Analysis of 0 Product Weight Percent:

isoO 0.4 0 0. s 13.8 21. 5 14. 4 2. 7 0. 9 0. 3 nC 0. 3 0 0.1 1.5 2. 1. 5 0.3 0.1 0.1

Total 0. 7 0 0. 9 15.4 30.0 15. 9 3. 0 1. 0 0. 7

iso-O, 0. 5 o 0. 5 10.0 11. e 8.8 1. s 0. 7 0. 4 no.,-- 0 o o 0. 5 0. 5 0. 4 0 0.1 0

Total 0.5 0 0.5 10. 5 12. 2 9. 2 1. 8 0. a 0. 4

iso-C 45. 2 0 2. 3 62.6 41. 1 51. 1 46. 2 29.6 13. 4 11-0 52. s 100.0 92. 2 10.4 15. 2 22. 0 47. a 68. 9 s5. 4

Total as. s 100. 0 94. 5 73. 0 5s. 3 73. 1 94. 0 9s. 5 35. 8

stock will be sent initially to the reaction zone, but the butane will be recycled through line 22 until a considerable amount of the butane has been isomerized to isobutane. The process may then continue in the manner already described, the recycle isobutane being suflicient for the reaction to proceed while the fresh butane feed becomes isomerized to isobutane in the reaction zone.

As a minimum it is preferred that the mole ratio of isobutane to higher paraffin be at least 3 to 1, but should preferably be no higher than about 10 to 1. If sulficient iso-C is not present in the reaction zone to elfect alkylation of the materials obtained when a higher paraifin or other higher product of the reaction is cracked by the catalyst, catalyst sludging will result. Feed rates may vary from about 0.5 to about 5 w./hr./w. (weight of total hydrocarbon per hour per weight of AlBr in the complex), while rates of from about 1 to about 3 w./hr./w. are preferred. The feed stock should preferably be low in aromatic hydrocarbon content. Naphthene hydrocarbons may be tolerated in the feed stock up to about volume percent. With increased naphthene content the reaction temperature for equivalent activity mus-t be increased somewhat as compared to a reaction in the absence of naphthenes.

Conventional procedures may be used for removing aromatics from the feed stocks. These include solvent extraction, acid treating, hydrogenation and selective adsorption, as with molecular sieve zeolites, for example. It is not necessary that the higher hydrocarbons used in the reaction be individual hydrocarbons such as heptane, octane, cetane, etc., but they may include mixtures. Thus, various petroleum fractions may be used such as virgin naphthas, and parafiin raffinates from the solvent extraction of hydroformed petroleum fractions.

The invention is illustrated by the following examples.

EXAMPLE 1 Comparative tests were made with aluminum bromide alone, and with a catalyst complexes comprising either aluminum bromide plus methyl alcohol or aluminum bromide plus a mixture of a fiuoroalcohol (2,2,3,3'- tetrafluoropropanol-l) and methyl alcohol. In each case thecatalyst was used to eifect the reaction of 80 volume percent of isobutane (87.4 grams), 19 volume percent of normal beptane (27.4 grams), and 1 volume percent of It will be noted from the results obtained that aluminum bromide alone had essentially no activity for the desired reaction. Furthermore, the reaction was not promoted by the catalyst complex consisting of aluminum bromide and methanol with no fiuoroalcohol present. Other tests have established that complexes containing aluminum bromide and fluoroalcohols of from 3 to 11 carbon atoms but with no added aliphatic alcohol were likewise unsatisfactory for the paraffin alkylation reaction. Only the 3-component complexes were active. Ap-

' preciable conversion to C and C hydrocarbons was obtained in the tests of Example 1 when the fiuoroalcohol was present in the catalyst complex in a mole ratio range of fiuoroalcohol to aluminum bromide of from 0.07 to 1 to 0.38 to 1.

EXAMPLE 2 In the same manner as in Example 1 catalyst complexes comprising aluminum bromide, a C fiuoroalcohol, H(CF CH OH, and methyl alcohol in one case and ethyl alcohol in the other, were tested for the reaction described in Example 1. The results obtained are shown It will be understood that this invention is not to be limited by any theory regarding its operation nor by the specific examples herein presented by way of illustration of the invention. Numerous modifications within the spirit and scope of the invention will occur to those skilled in the art. The invention is defined by the appended claims.

What is claimed is:

1. A process for the preparation of high octane naphtha components which comprises reacting a minor proportion of a paraflin hydrocarbon of from 6 to 18 carbon atoms With a major proportion of a hydrocarbon selected from the group consisting of butanes and pentanes, in the presence of a catalyst complex comprising aluminum bromide, a fiuoroalcohol of from 3 to 7 carbon atoms and an aliphatic alcohol of from 1 to 3 carbon atoms, the mole ratio of said aliphatic alcohol to said fiuoroalcohol being in the range of from about 1 to 2 to about 2 to 1.

2. Process as defined by claim 1 wherein the mole ratio of fiuoroalcohol to aluminum bromide in the complex is in the range of from about 0.05 to 1 to about 0.5 to 1.

H(CF CH- 0H 6. A catalyst complex for the isomerization and alkylation of paraflinic hydrocarbons of from 4 to 18 carbon atoms which comprises aluminum bromide, a fiuoroalcohol of from 3 to 7 carbon atoms and an aliphatic alcohol of from 1 to 3 carbon atoms, the mole ratio of fluoroalcohol to aluminum bromide in the complex being in the range of from about 0.05 to 1 to about 0.5 to 1, and the mole ratio of aliphatic alcohol to fiuoroalcohol being 20 in the range of from about 1 to 2 to about 2 to 1.

No references cited.

Claims (1)

1. A PROCESS FOR THE PREPARATION OF HIGH OCTANE NAPHTHA COMPONENTS WHICH COMPRISES REACTING A MINOR PROPORTION OF A PARAFFIN HYDROCARBON OF FROM 6 TO 18 CARBON ATOMS WITH A MAJOR PROPORTION OF A HYDROCARBON SELECTED FROM THE GROUP CONSISTING OF BUTANES AND PENTANES, IN THE PRESENCE OF A CATALYST COMPLEX COMPRISING ALUMINUM BROMIDE, A FLUOROALCOHOL OF FROM 3 TO 7 CARBON ATOMS

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