Preparation and characterization of Ni/CeO2-SiO2 catalysts and their performance in catalytic partial oxidation of methane to syngas

Abstract

Hexahydrated cerium(III) nitrate (Ce(NO3)3·6H2O) and tetraethyl orthosilicate (C8H20O4Si) were used as the precursors for the synthesis of a series of xCeO2-(1-x)SiO2 (x = 0, 0.25, 0.5, 0.75, 1) composite oxides using a sol-gel process under acidic conditions. The active component, Ni, was loaded on the as-synthesized composite oxides, producing supported Ni catalysts for catalytic partial oxidation of methane to syngas. The properties of the as-synthesized products, such as textural structure, reduction behavior, surface acidity, and carbon deposition, were determined using N2 physical adsorption/desorption, X-ray diffraction, scanning electron microscopy, ultraviolet-visible diffuse reflectance spectroscopy, temperature-programmed reduction by H2, temperature-programmed desorption of NH3, and thermogravimetric analysis. The effects of catalyst composition, calcination temperature, and reaction time on the catalytic performance were investigated. The characterization results showed that these Ni/CeO2-SiO2 catalysts have large surface area, small CeO2 crystals, weak acidity, and low carbon deposition. Highly dispersed NiO is present and is easy to be reduced. The Ni/CeO2-SiO2 catalyst with a Ce/Si molar ratio of 1:1, w(Ni) = 10%, and calcined at 700 °C exhibited good stability and the highest CH4 conversion (∼84%) and CO and H2 selectivity (> 87%).