Maintaining hf solubility in alkylation isobutane recycle

Abstract

In an HF alkylation process it has been found that combining olefin-acting reactant with a recycle stream including isobutane and HF upstream of an alkylation reaction zone is not harmful to alkylate product quality except when the HF is in a free state, i.e., the HF concentration is above the HF solubility level of the recycle stream. Soluble HF in the recycle stream is not harmful to alkylate product quality, therefore, in an embodiment, the overhead vapor stream of an isobutane stripper is condensed, cooled to a separation temperature, and separated into an HF phase and a hydrocarbon phase, a portion of which is withdrawn as an acid saturated recycle stream including isobutane and entrained acid, and heated to a temperature sufficient to place in solution the entrained acid prior to combination of the acid saturated recycle stream with the olefin-acting reactants.