Proximity-Dependent Oxide–Support Interactions in Cobalt/Ceria-Based Catalysts for Propane Dehydrogenation

Abstract

The CoO_x-based catalyst has attracted extensive research interest for propane dehydrogenation. However, enhancing its performance has been challenged by uncertainties surrounding the valence states of cobalt. This paper describes the pivotal role of proximity-dependent Co²⁺ in cobalt/ceria-based catalysts for nonoxidative propane dehydrogenation. By combining transmission electron microscopy and in situ spectroscopies, we discovered that Co²⁺, stabilized by the cooperative CoO_x–CeO_x interface, rather than metallic Co⁰, is responsible for activating the C–H bonds of propane. For the 1Co/20CeAl catalyst, where CoO_x and CeO_x are in intimate contact at the nanoscale, the highest Co²⁺ content was achieved, leading to the highest space–time yield (STY) of propylene with a high selectivity of 86%. Kinetic studies indicate that the proximity-dependent oxide–support interaction mediates the Co⁰/Co²⁺ ratios, resulting in a shift in the rate-determining step from the first C–H bond activation in 1Co/Al to the second C–H bond activation in 1Co/20CeAl. This study emphasizes the utilization of oxide-support interactions to optimize catalytic performance.