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

Abstract

Abstract Fossil fuel depletion and environmental impacts caused by greenhouse gas emissions such as CO 2 are significant issues securing nature preservation within a sustainable economy. CO 2 methanation is a promising process to mitigate CO 2 emissions and reuse it to produce CH 4 , 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 N 2 physisorption, X‐ray diffraction (XRD) and photoelectron spectroscopy (XPS), as well as thermal techniques such as temperature programmed reduction (H 2 ‐TPR), desorption (CO 2 ‐TPD, H 2 ‐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 % CO 2 conversion with 100 % CH 4 selectivity by enhancing basicity and metal‐support interaction, high Ni dispersion and small crystallite sizes, providing proper sites to adsorb and activate CO 2 . 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 CO 2 methanation processes.