Dehydrogenation of ethane and subsequent activation of CO_2 on hierarchically-structured bimetallic FeM@ZSM-5 (M=Ce, Ga, and Sn)

摘要

The catalytic activity for dehydrogenation of C2H6 and successive CO2 activation was studied by using hierarchically-structured bimetallic FeM/ZSM-5 (M=Ce, Ga, and Sn metal) to verify the redox property of the Fe nanoparticles and metal promoters on the acidic ZSM-5. Based on the surface characteristics, the reducibility and oxygen vacant sites of metal oxides on the ZSM-5 largely altered the reduction-oxidation nature and catalytic cracking behavior. The metal-promoted Fe/ZSM-5, especially with CeO2 promoter on the FeCe/ZSM-5, revealed excellent redox cycles and higher steady-state dehydrogenation activity such as a comparable C2H6 conversion of 6.1% as well as C2H4 selectivity of 89.8% at 600 degrees C with a larger CO production with 9.7 mmol/g by CO2 activation at 700 degrees C. This observation was attributed to the incorporated partially reducible CeO2 species by enhancing their interaction with ZSM-5 as well as by easily stabilizing the oxidation states of Ce and Fe metal oxides with its higher thermal stability during C2H6 dehydrogenation through an initial oxidative dehydrogenation followed by a steady-state catalytic cracking and subsequent CO2 activation to CO.