Processes and apparatuses for separating diisopropylbenzene (DIPB) and triisopropylbenzene (TIPB) from a feed (21) comprising DIPB, TIBP, and polyalkylate heavies are disclosed. The disclosed processes include introducing the feed (21) into a distillation column (22) having a column top (24) pressure of less than 35 kPa (5 psia), a column bottoms (25) pressure of less than 21 kPa (3 psi), and preferably 14 kPa (2 psi) or less above the column top pressure with a bottoms temperature ranging from 224° to 241°C (435° to 465°F). The processes also include taking off a side draw (28) comprising at least 99.8 wt% of the DIPB and at least 50 wt% of the TIPB present in the feed (21) and a bottoms stream (41) comprising at least 95 wt% of the heavies contained in the distillation feed (21). The low temperature bottoms temperature enables high pressure steam to be used as the bottoms reboiler (38) heat source.
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