Coupling acid catalysis and selective oxidation over MoO<sub>3</sub>-Fe<sub>2</sub>O<sub>3</sub> for chemical looping oxidative dehydrogenation of propane.

Wang, Xianhui; Pei, Chunlei; Zhao, Zhi-Jian; Chen, Sai; Li, Xinyu; Sun, Jiachen; Song, Hongbo; Sun, Guodong et al. · Nat Commun · 2023

basic_science · Level V

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Abstract

Redox catalysts play a vital role in chemical looping oxidative dehydrogenation processes, which have recently been considered to be a promising prospect for propylene production. This work describes the coupling of surface acid catalysis and selective oxidation from lattice oxygen over MoO<sub>3</sub>-Fe<sub>2</sub>O<sub>3</sub> redox catalysts for promoted propylene production. Atomically dispersed Mo species over γ-Fe<sub>2</sub>O<sub>3</sub> introduce effective acid sites for the promotion of propane conversion. In addition, Mo could also regulate the lattice oxygen activity, which makes the oxygen species from the reduction of γ-Fe<sub>2</sub>O<sub>3</sub> to Fe<sub>3</sub>O<sub>4</sub> contribute to selectively oxidative dehydrogenation instead of over-oxidation in pristine γ-Fe<sub>2</sub>O<sub>3</sub>. The enhanced surface acidity, coupled with proper lattice oxygen activity, leads to a higher surface reaction rate and moderate oxygen diffusion rate. Consequently, this coupling strategy achieves a robust performance with 49% of propane conversion and 90% of propylene selectivity for at least 300 redox cycles and ultimately demonstrates a potential design strategy for more advanced redox catalysts.