Palladium phosphide nanoparticles as highly selective catalysts for the selective hydrogenation of acetylene

Pd₃P and PdP₂ phases of ca. 4 nm were prepared on a TiO₂ support by an impregnation route. Data from the hydrogenation of acetylene under both non-competitive and competitive conditions showed that PdP₂/TiO₂ exhibits enhanced selectivity and stability relative to Pd₃P. Furthermore, the selectivity produced over PdP₂ (84% ethylene selectivity @ 100% acetylene conversion) compares favorably with recently reported materials. XPS and CO-IR measurements reveal that the incorporation of P helps to break up contiguous Pd sites. This in turn is thought to affect the adsorption and desorption of reactants/products and thus improves selectivity. This work reveals that the incorporation of P into Pd materials could be regarded as a promising approach to develop new and improved Pd-based catalyst by creating a means to control the nature of the active sites.