Activity and characterization of modified Cr2O3/ZrO2 nano-composite catalysts for oxidative dehydrogenation of ethane to ethylene with CO2

Cr2O3/ZrO2 nano-composite catalysts modified with Ni, Fe, Co, Mn oxides respectively were synthesized by coupling co-precipitation with azeotropic distillation method. The effect of modifiers on the catalytic activity in the dehydrogenation of ethane with CO2 was investigated. The modifiers exhibited different effects on catalytic behavior. Fe, Co and Mn oxides markedly increased ethylene selectivity, but the Ni-5-Cr-10/Zr nano-composite catalyst mainly favored side reactions-the reforming and cracking reactions. The Fe-5-Cr-10/Zr nano-composite catalyst exhibited an excellent performance in this reaction, producing 50.05% ethylene yield at 53.72% ethane conversion at 650 degrees C. The modified Cr2O3/ZrO2 nanocomposite catalysts were characterized by BET, TEM, XRD, XPS, CO2-TPD and NH3-TPD techniques. The characterization indicated that weak acid sites are involved in ethane activation, and strong acid-base pairs promote the reforming and cracking reactions. The distribution of chromium species, oxygen species and base/acid property on the surface of catalyst cooperatively determined the catalytic activity in dehydrogenations of ethane to ethylene using CO2 as an oxidant. (c) 2007 Elsevier B.V. All rights reserved.