Structural reconstruction of iron oxide induces stable catalytic performance in the oxidative dehydrogenation of n-butane to 1,3-butadiene

Abstract

The CO2-assisted oxidative dehydrogenation of n-butane to 1,3-C4H6 offers a perspective process for producing valuable chemicals while simultaneously utilizing CO2. In this work, iron-based ZnFe2Ox and Fe2O3 catalysts with high 1,3-C4H6 selectivity were prepared and their corresponding structure–activity relationships were investigated in detail. On basis of the in situ spectroscopic characterization, hydrogen-assisted CO2 activation pathway was captured. Kinetic studies show that Fe2O3 catalyst displays a higher reaction order depending on CO2 concentration than that of ZnFe2Ox catalyst. Fe2O3 is evidenced to serve as an effective mediator for oxygen exchange between CO2 and n-butane based on temperature-programmed experiments and deactivation kinetics analysis. Rapid deactivation is observed over ZnFe2Ox due to its strong CO2 adsorption ability, which triggers the reforming reaction accompanied by severe coke deposition. Interestingly, self-healing phenomena for catalytic performance are found on Fe2O3 catalyst after several test cycles. The reaction/regeneration cycles are proved to drive the surface reconstruction which greatly enhance its resistance to over reduction and coking. This study provides a fundamental insight into Fe-based catalysts in the CO2-assisted oxidative dehydrogenation reactions.