A comparative study of strong metal–support interaction and catalytic behavior of Pd catalysts supported on micron- and nano-sized TiO2 in liquid-phase selective hydrogenation of phenylacetylene

The strong metal–support interaction and catalytic behaviors of Pd catalysts supported on micron(0.1 μm)- and nano-sized (14 nm) TiO2 were investigated in the liquid-phase selective hydrogenation of phenylacetylene to styrene. It was found that when supported on the nano-sized TiO2, the Pd/TiO2 catalyst that reduced by H2 at 500 °C exhibited strong metal–support interaction (SMSI) and much improved catalytic performance in liquid-phase selective hydrogenation of phenylacetylene. However, as revealed by CO pulse chemisorption, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and CO-temperature program desorption, the SMSI effect was not detected for the micron-sized TiO2 supported ones. It is suggested during high-temperature reduction, the inner Ti3+ in large crystallite size TiO2 was more difficult to diffuse to the Pd0 surface than the surface Ti3+ in the smaller crystallite size ones. Sintering of Pd0 metal was observed instead.

Reduction by H2 at 500 °C resulted in strong metal–support interaction for the nano-sized TiO2 supported Pd catalyst, but not for the micron-sized TiO2 supported one. The SMSI effect, however, appeared to be necessary for high catalytic performance of the Pd/TiO2 catalysts in the liquid-phase selective hydrogenation of phenylacetylene to styrene. Figure optionsDownload as PowerPoint slide