An ordinary nickel catalyst becomes completely selective for partial hydrogenation of 1,3-butadiene when coated with tributyl(methyl)phosphonium methyl sulfate

Abstract

Performance of an ordinary supported nickel catalyst was tuned to reach an almost complete selectivity for partial hydrogenation of 1,3-butadiene by coating it with a phosphonium-type ionic liquid (IL), tributyl(methyl)phosphonium methyl sulfate, [P4441][MeSO4]. Thanks to high chemical and thermal stability of [P4441][MeSO4], the reaction conditions could be pre-optimized for high partial hydrogenation performance before the deposition of the IL coating. When the catalyst was coated with IL, it provided a total butene selectivity of 99.5 ± 0.2%, a record high partial hydrogenation selectivity ever reported for a nickel-based catalyst. X-ray photoelectron spectroscopy results illustrated that the IL donates electrons to nickel sites and makes them selective for partial hydrogenation. The conductor like screening model for realistic solvents (COSMO-RS) calculations indicated that the IL coating also exerts a filter effect, which helps to maintain this high partial hydrogenation selectivity at all conversion levels.