Alkylation of Isobutane with C₃−C₅ Olefins:  Feedstock Consumption, Acid Usage, and Alkylate Quality for Different Processes

Commercial processes for alkylating isobutane with C3−C5 olefins often consume significantly different amounts of isobutane and olefin feeds when equal amounts of alkylate product are formed. Undesired byproducts, including light (C3−C5) paraffins and isoparaffins, acid-soluble oils (ASOs or conjunct polymers), and pseudo-alkylates (mixtures of C5−C16 isoparaffins having low octane numbers), are produced in variable amounts. About 0.6−3.0% of the olefins often reacts to produce ASOs and pseudo-alkylates. For alkylations with HF as the catalyst, isobutane consumptions are often 6−15% higher for production of a given amount of alkylate than for those with sulfuric acid. Several details pertaining to feedstock consumption are reported for what is thought to be the first time. Recent improvements that reduce feedstock demands, reduce byproduct formation, and increase the quality (or octane number) of the alkylate product are discussed.