Catalytic Performance of γ-Al2O3–ZrO2–TiO2–CeO2 Composite Oxide Supported Ni-Based Catalysts for CO2 Methanation

Composite oxide supported Ni-based catalysts were prepared by a wet impregnation technique and applied to the methanation of carbon dioxide. The composite oxide supports were prepared by an impregnation–precipitation method using commercial γ-Al2O3 powder as a host with variation of the percentage of loading of ZrO2, TiO2, and CeO2 promoters from their respective salt precursors. NH4OH was used as the precipitating agent. The as-prepared catalysts were characterized by Brunauer–Emmet–Teller surface area analysis, atomic absorption spectroscopy, X-ray diffraction, temperature-programmed reduction by H2 (H2-TPR), and CO chemisorption. Catalytic activity of the newly synthesized catalysts was investigated toward hydrogenation of CO2 at atmospheric pressure by varying reaction temperature between 250 and 400 °C (with increasing step equal to 25 °C). Experimental results revealed that the composite oxide supported Ni-based catalysts showed performance superior to that of the γ-Al2O3 only supported Ni-based catalyst (which was synthesized using the same procedure for comparison). Among the investigated catalysts, the Ni/C15 catalyst with composite oxide support (55% of γ-Al2O3 loading and 15% equivalent loading of ZrO2, TiO2, and CeO2) showed the best activity: 81.4% conversion of CO2 to CH4 at 300 °C. Better performance of the composite oxide supported Ni-based catalysts was achieved because of the improvements in the reducibility nature of the catalysts (investigated using H2-TPR).