Mechanism of biogas reforming for hydrogen production over Ni-Co bimetallic catalyst

Abstract

Ni-Co bimetallic catalysts supported on commercial γ-Al2O3 modified with La2O3 were prepared by conventional incipient wetness impregnation for biogas reforming. The catalysts were characterized using temperature-programmed hydrogenation (TPH), temperature-programmed oxygenation (TPO), temperature-programmed surface reaction (TPSR), temperature-programmed desorption (TPD), and a pulse experiment. During biogas reforming the surface carbon species on Ni-Co/La2O3-γ-Al2O3 originated mainly from the cracking of CH4 and the contribution of CO2 was insignificant. Cracking of CH4 results in three carbon species of Cα, Cβ, and Cγ, which have different reaction activities. During the reaction, the amount of Cα decreased but Cβ and Cγ increased. In addition, Cγ could be changed into inactive graphite carbon. The activation of CH4 and CO2 was mutually promoted in the reforming reaction. It was revealed that the controlling step for biogas reforming over the Ni-Co/La2O3-γ-Al2O3 catalyst could be the reaction of the surface species of O with C to form CO or with CHx to give CHxO followed by the formation of CO and adsorbed H. © Editorial office of Acta Physico-Chimica Sinica.