Control of coordinatively unsaturated Zr sites in ZrO₂ for efficient C-H bond activation.

Abstract

Due to the complexity of heterogeneous catalysts, identification of active sites and the ways for their experimental design are not inherently straightforward but important for tailored catalyst preparation. The present study reveals the active sites for efficient C-H bond activation in C₁-C₄ alkanes over ZrO₂ free of any metals or metal oxides usually catalysing this reaction. Quantum chemical calculations suggest that two Zr cations located at an oxygen vacancy are responsible for the homolytic C-H bond dissociation. This pathway differs from that reported for other metal oxides used for alkane activation, where metal cation and neighbouring lattice oxygen form the active site. The concentration of anion vacancies in ZrO₂ can be controlled through adjusting the crystallite size. Accordingly designed ZrO₂ shows industrially relevant activity and durability in non-oxidative propane dehydrogenation and performs superior to state-of-the-art catalysts possessing Pt, CrO_x, GaO_x or VO_x species.