Alkylated with ionic liquid alkylation with ethylene in ethylene-containing gas streams

An alkylation process which comprises contacting an olefin-containing gas stream in an alkylation zone under alkylation conditions with an isoparaffin in the presence of a catalyst composition in the form of an ionic liquid to provide an alkylate product. In one embodiment, the olefin stream may comprise ethylene-containing offgas together with one or more non-condensable and / or inert gas (s), and the off-gas may be fed in its untreated state to an alkylation reactor containing the catalyst in the form of an ionic liquid, Purposes of alkylating isoparaffins to provide low volatility, high octane gasoline blending ingredients.