Ethane ODH with CO2 over alumina-supported Fe-Ni-O mixed oxides catalysts

Abstract

The dehydrogenation of ethane in the presence of CO₂ on alumina supported Fe-Ni-O catalysts was studied. The Fe/Ni ratio in catalysts strongly influences both the conversion of ethane and CO₂ and the nature of reaction products. Iron species, linked to the hematite phase (α-Fe₃O₄), favors ethane ODH but also the RWGS and dry reforming reactions (as parallel reactions). Nickel oxide has a high catalytic activity due to its capacity to break both C-H and CC bonds in a non-selective way, facilitating the generation of CO. Characterization results show changes in catalysts during the reaction. The H₂-TPR patterns of catalysts suggest a low interaction between the support and the iron particles, and a parallelism between the reducibility of iron particles and the conversion of reactants. In addition, all catalysts suffer important restructuration under reaction conditions, with iron oxide segregates to the catalyst surface together with a partial reduction of Fe³⁺ to Fe²⁺ (as determined by XPS). These changes could be confirmed by XRD, Raman, XPS and UV–vis spectroscopy analyses. Temperature programmed surface reactions (TPSR), under different experimental conditions, indicate an important role of nickel in the bimetallic catalysts, avoiding severe reduction of the catalyst and stabilizing different types of iron oxide species with different selectivity to products.