CrOx/Ce1−xZrxO2 for chemical looping propane oxidative dehydrogenation: The redox interaction between CrOx and the support
Propane dehydrogenation is an attractive alternative for propylene production to petroleum-based routes. However, overcoming deactivation and toxicity of catalysts in propane direct dehydrogenation (PDH), and over oxidation in oxidative dehydrogenation (ODHP) remain challenging. Here, a chromium-based catalyst supported on a Ce-Zr solid solution is constructed for chemical looping oxidative propane dehydrogenation (CL-ODHP). A dual modulation of oxygen species by Zr doping was unraveled by characterizations and DFT calculation: the oxygen of surface CrO x was constrained while the oxygen mobility of the Ce-Zr support was promoted. Based on these properties, the interaction between surface CrO x and the support further enables an oxygen “donor–acceptor”, which potentially functions as in situ activation and regeneration of redox CrO x species as well as blockage of non-selective oxygen released from the Ce-Zr support. The optimized material (7.5Cr/Ce 0.8 Zr 0.2 O 2 ) achieves propane conversion up to 50% and propylene yield of 31% at 600 °C, and has the lowest Cr content among previously reported Cr-based catalysts that have comparable performance. These results provide insights for the design of highly active and selective redox catalysts for chemical looping as a reaction engineering strategy for the upgrading of propane dehydrogenation processes.
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