One exemplary embodiment can be an alkylation unit. The alkylation unit can include at least one alkylation reaction zone having an alkylation catalyst, at least one cooler communicating with the at least one alkylation reaction zone, a settler communicating with the at least one alkylation reaction zone and the at least one cooler, a fractionation zone receiving an effluent from the settler passing through a line, and a boot coupled to a substantially horizontal portion of the line. Generally, the boot receives an effluent portion rich in the alkylation catalyst.