Alkylation

Alkylation is a petroleum refining process that combines light olefin gases, such as propylene and butylene, with isobutane over an acid catalyst, typically sulfuric acid or hydrofluoric acid, to produce a high-octane liquid called alkylate used for blending into gasoline. The process was developed and scaled up by refiners in the United States in the late 1930s, and wartime demand for high-octane aviation fuel during the Second World War drove rapid expansion of alkylation capacity, since alkylate burns more cleanly and resists engine knock better than many other gasoline components. Alkylation remains a standard refinery process today, valued for producing a clean-burning, low-sulfur, low-aromatic gasoline blending component.