Catalytic performance and characterization of Pt-Co/Al2O3 catalysts for CO2 reforming of CH4 to synthesis gas

Pt-Co/Al2O3 catalyst has been studied for CO2 reforming of CH4 to synthesis gas. It was found that the catalytic performance of the catalyst was sensi tive to calcination temperature. When Co/Al2O3 was calcined at 1473 K prior to adding a small amount of Pt to it, the resulting bimetallic catalyst sh owed high activity, optimal stability and excellent resistance to carbon de position, which was more effective to the reaction than Co/Al2O3 and Pt/Al2 O3 catalysts. At lower metal loading, catalyst activity decreased in the fo llowing order: Pt-Co/ Al2O3 > Pt/Al2O3 >>Co/Al2O3. With 9% Co, the Co/Al2O3 calcined at 923 K was also active for CO2 reforming of CH4, however, its c arbon formation was much more fast than that of the Pt-Co/Al2O3 catalyst. T he XRD results indicated that Pt species well dispersed over the bimetallic catalyst. Its high dispersion was related to the presence of CoAl2O4, form ed during calcining of Co/Al2O3 at high temperature before Pt addition. Pro moted by Pt, CoAl2O4 in the catalyst could be reduced partially even at 923 K, the temperature of pre-reduction for the reaction, confirmed by TPR. Ba sed on these results, it was considered that the zerovalent platinum with h igh dispersion over the catalyst surface and the zerovalent cobalt resultin g from CoAl2O4 reduction are responsible for high activity of the Pt-Co/Al2 O3 catalyst, and the remain CoAl2O4 is beneficial to suppression of carbon deposition over the catalyst.