Selective reduction of CO2 to CO over alumina-supported catalysts of group 5 transition metal carbides

Abstract

We show the applicability of a preparation method, previously reported for obtaining tailored bulk VCx catalysts, for alumina-supported G5TMCs. The characteristics of the G5TMCs/Al2O3 catalysts and their behaviour in the selective reduction of CO2 to CO through the RWGS reaction is reported. VCx/Al2O3 catalysts were active, stable and highly selective; meanwhile NbC/Al2O3 and TaC/Al2O3 were not active. VCx/Al2O3 catalysts exhibited selectivity to CO over 99.5 % at temperature above 773 K. The characteristics of alumina-supported vanadium carbide particles depended on the vanadium precursor and on the atmosphere used during the catalyst preparation. XPS characterization of VCx/Al2O3 catalysts revealed the presence of carbide species on surface before and after RWGS reaction. The catalytic behaviour of VCx/Al2O3 is analysed in the light of their characteristics and compared with bulk VCx counterparts. The most performant catalyst, VC(Pr)/Al2O3, was stable over 4 days at 723 K, with ∼100 % selectivity to CO and CO2 conversion of ∼11 %.