A high-loading catalyst of highly dispersed nickel species on acid-treated mesoporous clay layers for efficient CO and CO2 methanation†

The catalytic performance of a nickel catalyst in the methanation reaction is strongly influenced by the nickel loading in the catalyst. However, a high nickel content in the catalyst can result in significant nickel agglomeration and sintering, leading to reduction in the number of the active sites available for the methanation reaction, ultimately resulting in poor catalytic performance. Herein, an efficient nickel catalyst with up to 20 wt% of highly dispersed nickel species was successfully synthesized by a straightforward wet chemical method. The optimal composition of the catalyst was selected by using an orthogonal experimental scheme and range analysis method. During the preparation process, acid-treated clay was used as the support, and amino acids were employed as ligands for nickel ions. The amino groups in amino acids can coordinate with the nickel ions, forming nickel-amino acid framework nanocrystals on the clay layers and thus obtaining a catalyst with a high content of highly dispersed nickel species on the clay layers. The catalyst demonstrated an impressive single pass CO conversion of nearly 100% and a methane selectivity exceeding 82% in the CO methanation reaction, and it exhibited a single pass CO₂ conversion surpassing 91% and a remarkable 100% methane selectivity in the CO₂ methanation process. Furthermore, the catalyst showcased excellent stability throughout both reactions, further highlighting its potential for practical applications. This study offers a promising approach for the synthesis of efficient nickel catalysts with high nickel contents of highly dispersed active sites.