Highly Active and Stable Isolated Ir^δ+ Sites in Iridium Phosphide for Propane Dehydrogenation

Abstract

Developing highly stable catalysts at high temperatures while maintaining high activity and selectivity has been a focus of research for propane dehydrogenation (PDH). Herein, we report the catalytic properties of Ir δ+ sites isolated by phosphorus in iridium phosphide (IrP 2 ) as ultrastable and active catalysts for PDH. Like other transition and main group single-site catalysts, the IrP 2 catalysts exhibit remarkable propylene selectivity (99%). Notably, the optimized IrP 2 catalyst has a PDH rate of 0.418 mol C 3 H 6 per mole of Ir per second, which represents an approximately 400-fold increase compared to that of Ir NPs and is significantly higher than that of conventional, ionic singlesite catalysts. Furthermore, it exhibited a robust stability up to a week with little deactivation. A series of advanced characterizations, including in situ X-ray absorption spectroscopy, scanning transmission electron microscopy, and in situ X-ray photoelectron spectroscopy, elucidated that the isolated Ir δ+ ions are the active sites for PDH.