Pt-promoted α-Al2O3-supported Ni catalysts: Effect of preparation conditions on oxi-reduction and catalytic properties for hydrogen production by steam reforming of methane

Abstract

The effect of Pt addition on the oxi-reduction properties of α-Al2O3-supported Ni catalysts, with different degrees of interaction between NiO and the α-Al2O3 support, was studied using atmospheres of H2, H2/H2O, and CH4/H2O. The effect of Pt promotion on the reduction of NiO with H2 was significant for NiO species that interacted more strongly with the alumina surface, but was much lower when a NiAl2O4-like bulk phase was formed. For samples activated with H2, although metal dispersion decreased with increasing Pt content, the activity was maintained constant by the presence of Pt sites. For samples activated with a CH4/H2O mixture, the activity increased with increasing Pt content, due to the higher reducibility of Ni in the Pt-promoted catalysts. The Pt promotion effect was stable; there was no important decrease in the influence of Pt on NiO reduction, even after high temperature re-oxidation of the catalysts.