N2O Assisted Ethane Transformation into Ethylene Using NiO--CeO2--ZrO2 Catalysts

Abstract

NiO--CeO2 and NiO--CeO2--ZrO2 catalysts have been synthesized, electrochemically characterized (Mott-Schottky (MS) measurements and Electrochemical Impedance Spectroscopy), physicochemically characterized (by N2 adsorption, XRD, Transmission Electron Microscopy and XPS) and tested in the N2O assisted ethane oxydehydrogenation. The use of low Zr-loadings (Zr/ Ce=0.1 at. ratio) has led to the optimal results in the ethylene production, improving those obtained by the Zr-free NiO--CeO2 catalyst. However, high Zr-loadings have meant a decrease in the olefin production. The catalytic results obtained have been explained considering the amount of oxygen vacancies, the crystalline phases formed and, especially, the nature of the surface Ni species. Importantly, the use of N2O as an oxidizing agent leads to a remarkable improvement in the selectivity to the olefin compared to that obtained employing molecular O2. Then, for a given ethane conversion the selectivity to ethylene is ca. 15 points higher using N2O than using O2. Another additional positive aspect of this NiO--CeO2--ZrO2 catalyst is its high catalytic stability.