Influence of Metal Particle Size on Oxidative CO2 Reforming of Methane over Supported Nickel Catalysts: Effects of Second-Metal Addition

Abstract

Oxidative CO2 reforming of methane is studied over Ni/AlCeZrOx catalyst with addition of a second metal element (Mg, Co, La, Mn, or Fe) aiming to improve the performance of the catalyst and increase their resistance to coking. Addition of Mg produces the best catalyst showing high CH4 and CO2 conversions as well as high selectivities to synthesis gas with no severe coke deposition. Addition of Co, La, and Mn also exhibits significant improvement, whereas Fe brings only a moderate improvement. The high activity is accompanied by high stability and low amount of deposited coke. The high activity and stability are attributed mainly to nanosized metallic particles, which accompany high amounts of available surface oxygen, and high basicity of the surface. The basicity of the catalyst promotes adsorption and dissociation of CO2, and surface oxygen can oxidize surface carbon intermediates to regenerate active metal sites before they turn to coke to sustain catalytic cycle.