Dehydrogenation of ethane and subsequent activation of CO₂ on hierarchically-structured bimetallic FeM@ZSM-5 (M=Ce, Ga, and Sn)

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 °C with a larger CO production with 9.7 mmol/g by CO₂ activation at 700 °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.