Hexagonal BaTiOH Oxyhydride as a Water-Durable Catalyst Support for Chemoselective Hydrogenation.

We present heavily H-doped BaTiOH ( ≈ 1) as an efficient and water-durable catalyst support for Pd nanoparticles applicable to liquid-phase hydrogenation reactions. The BaTiOH oxyhydride with a hexagonal crystal structure (6/) was synthesized by the direct reaction of BaH and TiO at 800 °C under a stream of hydrogen, and the estimated chemical composition was BaTiOH. Density functional theory calculations and magnetic measurements indicated that such heavy H doping results in a metallic nature with delocalized electrons and a low work function. The potential of BaTiOH as a catalyst support was examined for the selective hydrogenation of unsaturated C-C bonds by Pd nanoparticles deposited on BaTiOH. We found that the turnover frequency for phenylacetylene hydrogenation per total amount of Pd in Pd/BaTiOH was the highest among the supported Pd catalysts reported to date. The strong electronic charge transfer between Pd and the support, as confirmed by X-ray photoelectron spectroscopy measurements, can be attributed to be responsible for such high catalytic activity. The combination of the BaTiOH support and Pd nanoparticles provides for the selective hydrogenation of unsaturated C-C bonds and highlights the validity of catalyst design that integrates H in support materials.