Role of active metals Cu, Co, and Ni on ceria towards CO2 thermo-catalytic hydrogenation.

A series of CeO₂ supported Cu, Co, and Ni catalysts have been synthesized by the wet-impregnation method for CO₂ thermo-catalytic hydrogenation from 200 to 400 °C in the fixed bed reactor. All catalysts were characterized by XRD, N₂-isotherms, and H₂ temperature-programmed reduction. XRD results have suggested that the incorporated Cu, Co, and Ni have uniformly distributed on the CeO₂ surface, N₂-isotherm analysis confirmed that the pores of CeO₂ were blocked by incorporated metals and H₂-TPR indicated strong interaction between active metal and CeO₂. The CO₂ consumption rate and product selectivity depend on the type of active metal on CeO₂ and reaction temperature. The order of CO₂ consumption rate for 5 wt.% catalysts was 5Ni/CeO₂ > 5Co/CeO₂ > 5Cu/CeO₂ at 400 °C. The high CO₂ consumption rate for 5Ni/CeO₂ was attributed to the presence of more number of active metallic Ni during the reaction which dissociated H₂ molecule to H-atoms. The formed H-atoms reacted with active CO₂ molecule and formed CH₄ with 100% selectivity. [ABSTRACT FROM AUTHOR]