Facile in situ synthesis of highly dispersed chromium oxide incorporated into mesoporous ZrO2 for the dehydrogenation of propane with CO2

Highly dispersed chromium oxide-modified mesoporous ZrO2 (xCr-ZrO2) was prepared via an acid-base pair pathway and evaporation-induced self-assembly method for the dehydrogenation of propane reaction with CO2. The resulting materials exhibit mesoporous structure and different zirconia crystals with doped chromium species. Catalytic performance results revealed that the 7Cr-ZrO2 catalyst with abundant dispersed oligomeric Cr6+ species and isolated Cr6+ species showed the highest catalytic activity among the catalysts studied; initial conversion 68% and yield 40.5% were obtained. The following conclusions were drawn by utilizing the in situ/operando Raman spectroscopy and discrete Fourier transform calculations to investigate the structure of chromium species, the redox reaction path, and the formation of coke under real reaction conditions. The oligomeric and isolated Cr3+ species with activated oxygen are denoted as active oxidative chromium species, which are the main active sites of redox reaction. The foremost effect of CO2 is inhibiting rather than eliminating coke. Moreover, a possible new coke formation route is proposed. (C) 2019 Elsevier Inc. All rights reserved.