Improving Low‐Temperature CO2 Methanation by Promoting Ni‐Al LDH‐Derived Catalysts with Alkali Metals

Abstract

AbstractFossil fuel depletion and environmental impacts caused by greenhouse gas emissions such as CO2 are significant issues securing nature preservation within a sustainable economy. CO2 methanation is a promising process to mitigate CO2 emissions and reuse it to produce CH4, serving as fuel, chemical feedstock, and energy source. A series of LDH‐derived Ni‐Al catalysts promoted by Li, Mg, Ca, and La were prepared via co‐precipitation. Characterization by N2 physisorption, X‐ray diffraction (XRD) and photoelectron spectroscopy (XPS), as well as thermal techniques such as temperature programmed reduction (H2‐TPR), desorption (CO2‐TPD, H2‐TPD), and oxidation (TPO) analyses were performed. Low‐temperature catalytic tests (200–400 °C) revealed that alkali metal modification improves performance even at 200 °C, where the Ni55Ca11Al33 catalyst achieved 74 % CO2 conversion with 100 % CH4 selectivity by enhancing basicity and metal‐support interaction, high Ni dispersion and small crystallite sizes, providing proper sites to adsorb and activate CO2. Moreover, the catalysts presented excellent resistance to deactivation, maintaining high stability during 10 h on stream. These results prove that Ni‐Al mixed oxides, LDH‐derived catalysts performances can be further improved by incorporating alkali metals into less energy‐spending, low‐temperature CO2 methanation processes.