Effect of the Structural and Electronic Properties of Rh/CeXZr1-XO2 Catalysts on the Low-temperature Ethanol Steam-reforming

Rh catalysts supported on CexZr1-xO2 (with x=0-1) materials were synthesized by precipitation method. The influence of the two different cerium salt precursors, ammonium cerium(IV) nitrate and cerium(III) nitrate hexahydrate, over the structure and catalytic activity in steam reforming reaction was investigated. The synthesized catalysts were characterized by various techniques, such as N-2 adsorption-desorption, temperature-programmed desorption, X-ray diffraction, Raman spectroscopy, diffuse reflectance UV-Vis, and X-ray photoelectron spectroscopy. The use of ammonium cerium (IV) nitrate as a cerium precursor resulted in solid CexZr1-xO2 solutions with improved oxygen mobility and specific surface area. The catalytic evaluation exhibited the support composition and structure impact on its activity and product yield. The Rh supported on Ce0.5Zr0.5O2 solid solution rendered the higher activity and H-2 and CO2 yields among both series, related to improved oxygen mobility and greater Rh-0 dispersion. The formation of surface defects adjacent to Rh clusters by strong metal-support interaction effect was suggested by Raman analysis. The close contact between the Rh-0 site and oxygen vacancy could be favoring cyclic-like ethanol adsorption and favored the breaking of the C-C bond and further oxidation of adsorbed CO and CHX species.