Effect of strong metal–support interaction on the catalytic performance of Pd/TiO 2 in the liquid-phase semihydrogenation of phenylacetylene

Abstract

Liquid-phase semihydrogenation of phenylacetylene under mild conditions has been investigated on a series of solvothermal-derived nano-TiO 2 supported Pd catalysts with various TiO 2 crystallite sizes in the range of 9–23 nm. As revealed by CO chemisorption and transmission electron microscopy, all the catalysts exhibited strong metal–support interaction (SMSI) when reduced at 500 °C. The catalysts with SMSI show remarkably high catalytic performance in terms of both hydrogenation activities (turnover frequencies (TOFs) 9.1–21.4 s −1) and moderate-high selectivities to styrene (86–90%) at complete conversion of phenylacetylene. Without SMSI effect (the catalysts reduced at 40 °C), styrene selectivity and catalytic activity depended largely on the Pd particle size in which small Pd particles (formed on small crystallite size TiO 2 supports) exhibited lower phenylacetylene conversion and poor styrene selectivity. Moreover, the TOF values of the non-SMSI catalysts were similar to those reported in the literature for other supported Pd catalysts in liquid-phase semihydrogenation of phenylacetylene under mild conditions (TOFs 1.3–2.8 s −1).