Highly efficient steam reforming of ethanol (SRE) over CeO_x grown on the nano Ni_xMg_yO matrix: H₂ production under a high GHSV condition

Steam reforming of ethanol (SRE) over non-noble metal catalysts is normally conducted at high temperature (>600°C) to thermodynamically favour the catalytic process and carbon deposition mitigation. However, high temperature inhibits water-gas shift reaction (WGSR) and therefore restrains the yield of H₂ and leads to the formation of an excessive amount of CO. The modification of non-noble metal catalyst to enhance WGSR is an attractive alternative. In this study, CeO_x was firstly loaded onto a nano-scaled Ni_xMg_yO matrix and subsequently used as the catalyst for hydrogen production via SRE. Morphology of the catalyst materials was characterized by using a series of technologies, while H₂-temperature programmed reduction (H₂-TPR), CO-temperature programmed deposition (CO-TPD), and X-ray photoelectron spectroscopy (XPS), were employed to study the surface nickel, ceria clusters, and their interactions. The catalytic activity and durability of the catalyst were studied in the temperature region of 500°C to 800°C. The CeO_x-coated nano Ni_xMg_yO matrix exhibited an outstanding hydrogen yield of 4.82 mol/mol_ethanol under a high gas hourly space velocity (GHSV) of 200 000 hour⁻¹. It is found that the unique Ni⁰-CeO_x structure facilitates the adsorption of CO on the surface and therefore promotes the effective hydrogen production via WGSR. Moreover, this modified Ni_xMg_yO matrix was found to be a more robust and anticoking nanocatalyst because of reversible switch between Ce⁴⁺ and Ce³⁺.