Synthesis and characterization of Cu-Zn/TiO2 for the photocatalytic conversion of CO2 to methane

Different Cu-Zn/TiO2 catalysts were synthesized by using the wet impregnation method. The prepared catalysts were used for the conversion of CO2 into methane by photocatalysis. Various characterization techniques were used to observe the surface morphology, crystalline phase, Brunauer-Emmett-Teller (BET) surface area, presence of impregnated Cu and Zn, and functional group. Scanning electron microscope analysis showed spherical morphology, and slight agglomeration of catalyst particles was observed. BET analysis revealed that the surface area of the catalyst was decreased from 10 to 8.5 m(2)/g after impregnation of Cu and Zn over TiO2 support. Synergetic effect of Cu and Zn over TiO2 support (Cu-2.6/TiO2, Zn-0.5/TiO2 and Cu-2.6-Zn-0.5/TiO2) and the effects of Cu loading (0, 1.8, 2.1, 2.6 and 2.9 wt%) were also investigated at different feed molar ratios of H-2/CO2 (2:1 and 4:1). The Cu-2.6-Zn-0.5/TiO2 catalyst showed a maximum conversion of 14.3% at a feed molar ratio of 4. The addition of Zn over the catalyst surface increased the conversion of CO2 from 10% to 14.3% which might be due to synergy of Cu and Zn over TiO2 support.