The Combination of Calcium Oxide and Cu/ZrO2 Catalyst and their Selective Products for CO2 Hydrogenation

The catalytic activities of Cu/ZrO2_CaO catalysts were investigated on CO2 hydrogenation.The CO2 hydrogenations were carried out over combination of calcium oxide and Cu/ZrO2 catalyst.Two calcination temperatures were chosen at 300 and 650 o C according to thermal decomposition results.The catalysts were characterized by means of N2 adsorption-desorption, H2 temperature programmed reduction and X-ray diffraction.The CO2 hydrogenation under atmospheric pressure and at 250 o C was carried out over copper-based catalysts combined with calcium oxide namely i.e.Cu/ZrO 2 _CaO300, Cu/ZrO 2 _CaO650, Cu/ZrO2_Cu/CaO and Cu/ZrO2+CaO.The catalytic activities over all catalysts were consistent for 4 hours.The catalytic reaction rates over copper-based catalysts were in the range of 21.8 -47.4 mol L -1 s -1 g cat -1 .The modification of calcium oxide can improve the catalytic activity of copper-based catalysts to 47.4 mol L -1 s -1 g cat -1 .The calcination temperature can cause a difference in active species that impact on product selectivity.The CaO consisting in copper-based catalysts, i.e.Cu/ZrO 2 _CaO650, facilitate the growth of long chain hydrocarbon, whereas Cu/ZrO 2 _CaO300 favors the formation of carbon monoxide plausibly arising from reverse water gas shift reaction.Directly combined calcium oxide with Cu/ZrO 2 via physically mixing, i.e.Cu/ZrO2+CaO, can impr ove the r ate of methanol production.