Oxidative dehydrogenation of ethane with carbon dioxide over the Cr-based catalysts prepared by sol-gel method

A series of Cr/SiO₂-G catalysts with different chromium contents were prepared by sol-gel method using chromium nitrate as the chromium source and tetraethyl orthosilicate (TEOS) as the silica source. The catalysts were characterized by XRD, BET, SEM and TPR. The catalytic performances of Cr/SiO₂-G for the oxidative dehydrogenation of ethane to ethylene with CO₂ were evaluated in a fixed-bed micro-reactor. XRD results indicated that Cr species were presented in Cr₂O₃ phase when the Cr content exceeded 5%, while the Cr species was not observed in the XRD patterns of the catalyst with a lower Cr content. The pore diameter of the catalyst was 2nm, irrelevant to the Cr content. The Cr/SiO₂-G with 5% Cr exhibited largest surface area and highest catalytic activity; at 750℃, the conversions of ethane and CO₂ are 79.29% and 23.74%, respectively, with the yield of ethylene being 67.91%. The catalyst containing 5% Cr exhibits appropriate redox properties, which may be relevant to its high catalytic activity for the ethane dehydrogenation with CO₂.