Alkylate is produced by supplying iso-C4+ hydrocarbon feed to an alkylation reactor, and by further selectively supplying to the alkylation reactor an olefin selected from the group consisting of refinery grade propylene (RGP) and polymer grade propylene (PGP), and combinations thereof. The olefin feed is controlled such that the proportion of PGP supplied through the olefin feed inlet exceeds that of RGP for a predetermined time interval, using a special purpose computer programmed to optimize the allocation of PGP between alkylation production and a commodity market in order to increase total net profit margin.