Enhanced low-temperature CO2 methanation over a Ni-based catalyst supported on La2O3–Al2O3 composite supports†

Abstract

Despite the substantial efforts in the conversion of carbon dioxide (CO₂) into high value-added products, directly transforming CO₂ into CH₄ at low temperatures still poses a formidable challenge. In this study, we report a bottom-up strategy to synthesize supported Ni catalysts on a doped Al₂O₃ support. LaAl mixed oxide was first synthesized via a co-precipitation method, followed by Ni species loaded using a deposition precipitation method. The CO₂ conversion of the Ni/LaAl catalyst is found to be greatly enhanced, two times higher than that of the Ni/Al₂O₃ catalyst at 250 °C. The characterization results show that the introduction of La promotes the dispersion of Ni, reduces the reduction temperature of NiO and facilitates the adsorption of CO₂ by increasing the basic sites. Temperature-programmed reduction with H₂ demonstrated that La₂O₃ promotes the reducibility of NiO. Furthermore, kinetic analysis, in situ DRIFTS and CO methanation tests evidenced that La₂O₃ promotes the activation of CO₂ and accelerates the CO hydrogenation step.