Diisobutylene process
This invention is a process for producing diisobutylene from isobutylene. The process comprises first passing water through a downflow reactor containing a bed of sulfonic acid resin to produce an effluent stream having a pH of at least 5, then dimerizing isobutylene by contacting the sulfonic acid resin with a reaction feed comprising isobutylene and tertiary butyl alcohol. The downflow reactor comprises a bottom, an inlet located above the resin bed, an outlet located below the resin bed, and inert material in the space from the bottom of the reactor to at least above the outlet.
1 . An isobutylene dimerization process, comprising:
(a) passing water through a downflow reactor containing a bed of sulfonic acid resin to produce an effluent stream having a pH of at least 5; and
(b) dimerizing isobutylene by contacting the sulfonic acid resin with a reaction feed comprising isobutylene and tertiary butyl alcohol to produce a product stream comprising diisobutylene,
wherein the downflow reactor comprises a bottom, an inlet located above the bed of sulfonic acid resin, an outlet located below the bed of sulfonic acid resin, and inert material in the space from the bottom of the reactor to at least above the outlet.
2 . The process of claim 1 wherein the sulfonic acid resin is contacted with the reaction feed at a temperature of 50° C. to 200° C.
3 . The process of claim 1 wherein the isobutylene is produced by dehydration of tertiary butyl alcohol.
4 . The process of claim 1 wherein the reaction feed comprises at least 2 weight percent tertiary butyl alcohol.
5 . The process of claim 1 wherein the reaction feed additionally comprises a C 3 -C 10 hydrocarbon.
6 . The process of claim 5 wherein the C 3 -C 10 hydrocarbon is a C 8 hydrocarbon.
7 . The process of claim 6 wherein the C 8 hydrocarbon is diisobutylene.
8 . The process of claim 7 wherein the reaction feed comprises 25 to 50 weight percent isobutylene, 3 to 8 weight percent tertiary butyl alcohol, and 30 to 60 weight percent diisobutylene.
9 . The process of claim 1 , further comprising hydrogenating the diisobutylene to produce isooctane.
10 . The process of claim 1 wherein the downflow reactor further comprises a drain at the bottom of reactor.
11 . The process of claim 1 wherein the product stream comprises diisobutylene, isobutylene, tertiary butyl alcohol, and water.
12 . The process of claim 11 , further comprising
(c) distilling the product stream to produce a first overhead stream comprising water and isobutylene and a first bottoms stream comprising diisobutylene and tertiary butyl alcohol;
(d) separating at least 30 percent of the water from the first overhead stream to form an isobutylene-enriched stream, and recycling the isobutylene-enriched stream back to step (b); and
(e) distilling the first bottoms stream to produce a bottoms product stream comprising diisobutylene and a second overhead stream comprising tertiary butyl alcohol and diisobutylene.
13 . The process of claim 12 wherein the water is separated from the first overhead stream by decantation.
14 . The process of claim 12 , further comprising recycling the second overhead stream back to step (b).