Modulating Lattice Oxygen through an Alkaline Earth\nMetal Promoter for Chemical Looping Oxidative Dehydrogenation of Propane

Rational design of metal oxide-type\nredox catalysts for selective\npropylene production is of paramount importance, yet remains challenging.\nThis paper describes the structural and electronic effect of an alkaline\nearth metal promoter on lattice oxygen reactivity for chemical looping\noxidative dehydrogenation (CL-ODH) of propane through the configuration\nof core–shell-type redox catalysts, which consist of a redox-active\nFeVO<sub>4</sub> core and a selective mixed alkaline earth metal oxide\nshell. A systematic study demonstrates that Mg is the optimal promoter\namong all alkali and alkaline earth metals investigated, and the formed\nMg<sub>2</sub>V<sub>2</sub>O<sub>7</sub> outer shell provides a catalytic\nsurface for C–H activation while blocking the nonselective\nsites for FeVO<sub>4</sub>, typically as an oxygen carrier. The core–shell\nredox catalyst with a higher coverage of the Mg<sub>2</sub>V<sub>2</sub>O<sub>7</sub> layer achieves an enhanced propylene selectivity of\n80.8% at an operation temperature of 550 °C. The design strategy\nhighlights the exploration of alkaline earth metals in redox catalysts\nfor chemical looping processes.