CO₂ Methanation: Nickel-Alumina Catalyst Prepared by Solid-State Combustion

The development of solvent-free methods for the synthesis of catalysts is one of the main tasks of green chemistry. A nickel-alumina catalyst for CO₂ methanation was synthesized by solid-state combustion method using hexakis-(imidazole) nickel (II) nitrate complex. Using X-ray Powder Diffraction (XRD), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Hydrogen temperature-programmed reduction (H₂-TPR), it was shown that the synthesized catalyst is characterized by the localization of easily reduced nickel oxide on alumina surface. This provided low-temperature activation of the catalyst in the reaction mixture containing 4 vol% CO₂. In addition, the synthesized catalyst had higher activity in low-temperature CO₂ methanation compared to industrial NIAP-07-01 catalyst, which contained almost three times more hard-to-reduce nickel-aluminum spinel. Thus, the proposed approaches to the synthesis and activation of the catalyst make it possible to simplify the catalyst preparation procedure and to abandon the use of solvents, which must be disposed of later on.