Improved Catalytic Lifetime of H₂SO₄ for Isobutane Alkylation with Trace Amount of Ionic Liquids Buffer

Abstract

Trace amounts of ionic liquids have been mixed in sulfuric acid to enhance the catalytic performance for the alkylation of isobutane with butene. The experimental results from batch reactors indicated that the reaction efficiency was significantly improved. The effective catalytic lifetime of concentrated H2SO4 mixed with [Bmim][SbF6] was twice compared with pure H2SO4. Under the optimal conditions, the alkylate research octane (RON) reached 98, and the selectivity of C8 was 90%. The ionic liquids with SbF6 anion worked similar to buffer agents, which were in favor of keeping the acid strength of catalytic system, slowing the growth of acid soluble oil, and reducing acid consumption. In conclusion, the new catalytic system of acid and trace amounts of ionic liquids is very promising to substitute the old catalytic system of concentrated H2SO4 alone for the alkylation.