Patent ID: 8123913

Claim:
A process for separating diisopropylbenzene (DIPB) and triisopropylbenzene (TIPB) from a feed comprising DIPB, TIPB, and polyalkylate heavies, the process comprising: introducing the feed into a distillation column operating at a column top pressure of less than 5 psia, a column bottoms pressure of less than 3 psi above the column top pressure and a bottoms temperature ranging from about 435° F. to about 465° F.; and taking off a side draw comprising at least 99.8 wt % of the DIPB and at least 50 wt % of the TIPB present in the feed and a bottoms stream comprising at least 95 wt % of the heavies contained in the feed, wherein the side draw is taken off from the column at a side draw point, the DIPB, TIPB and heavies are introduced into the column at a feed point, the column having a number of theoretical stages X, wherein X is an integer that is greater than 40 and an uppermost stage is numbered 1 and a lowermost stage is numbered X, the side draw point being disposed at a stage integrally numbered from about 0.26·X to about 0.40·X from the uppermost stage and the feed point being disposed at a stage integrally numbered from about 0.31·X to about 0.62·X from the uppermost stage.