Effect of Ca and Co over Ni-Al Mixed Oxides for Hydrogen Production by Ethanol Steam Reforming

Ni-Al layered double hydroxide-derived catalyst is modified with Ca and Co to improve their properties for ethanol steam reforming (ESR). The catalysts are prepared by coprecipitation and are characterized through N2 adsorption-desorption measurements, X-Ray diffraction, temperature programmed reduction, temperature programmed oxidation, and NH3-temperature programmed desorption. Catalyst activity tests are performed between 400 and 600 degrees C with the calcined catalysts and without reduction using ethanol and water in a 1:3 ratio in a fixed bed reactor with online gas chromatography analysis. The partial substitution of Ni by Co and Ca decreases the acidity of the catalyst. All samples remain stable after the reaction at 600 degrees C for 8 h and present a full ethanol conversion and high hydrogen selectivity, above 90%. The samples modified by Ca or Co are reduced to metallic phase during the reaction and reveal a smaller crystallite size than NiAl. The sample with Ca prepared with a different precipitant results in a catalyst with a more thermally stable active phase, low acidity, and higher specific surface area. This catalyst presents smaller crystallite size and low-carbon formation after the reaction at 600 degrees C for 8 h, demonstrating higher potential for hydrogen production by ESR. Ni-Al mixed oxides modified by Ca or Co are evaluated without reduction for H2 production via ethanol steam reforming. The partial substitution of Ni by Ca decreases the catalyst acidity and increases the resistance to sintering. The sample with Ca prepared with a different precipitant shows smaller crystallite size and low-carbon formation after the reaction at 600 degrees C for 8 h.image (c) 2023 WILEY-VCH GmbH