Influence of Ca/Al molar ratio on structure and catalytic reforming performance of Ni/CaO-Al₂O₃ catalyst

CO₂ enhanced sorption methane steam reforming for hydrogen production is a potential approach to economically provide hydrogen and to reduce CO₂ emission. The key point for this process is to develop a composite catalyst with high catalytic and adsorptive capacity. Considering the tunable structure of hydrotalcite-like compounds, co-precipitation method was employed to synthesize Ni/CaO-Al₂O₃ composite catalysts by varying the molar ratio of Ca to Al. The results show that the specific surface area and Ni dispersion of the as-synthesized composite catalysts are greatly influenced by molar ratio of Ca to Al, which derives from the variable interaction between Ni and the support. When the molar ratio of Ca to Al is 3, the composite catalyst obtains a specific surface area of 12.9 m²/g and Ni dispersion of 1.07%. Catalytic evaluation shows that the composite catalyst possesses a H₂ concentration of 95% and a CH₄ conversion of 88%, and H₂ concentration exceeds 93% even after 10 cyclic runs.