Influence of niobium on carbon nanofibres based Cu/ZrO2 catalysts for liquid phase hydrogenation of CO2 to methanol

Abstract

A series of carbon nanofibres supported Cu/ZrO2/Nb2O5 catalyst synthesized by deposition precipitation method were extensively investigated in relation to their performance in hydrogenation of CO2 to methanol. In order to study the promotion effect of niobium, catalysts were loaded with 0.4, 0.8 and 1.2wt.% of Nb2O5. Incorporation of Nb2O5 facilitated copper reduction by exhibiting a shift of highly reduced copper peak to lower temperature. Likewise, surface enrichment of copper was also enhanced by introduction of Nb2O5 to the catalysts. Activity studies of Nb2O5 doped Cu/ZrO2 catalysts were evaluated in a slurry reactor with a CO2/H2 gas mixture of 1:3 volume ratio, 180oC temperature and 3.0MPa total pressure. The highest activity was achieved with the incorporation of 0.8wt.% of Nb2O5, illustrating the high degree of CuO crystallization on the surface of catalyst are beneficial for the generation of copper catalyst with enhanced activities.