Optimizing Low-Temperature CO 2 methanation with Aluminum-Doped Ni/ CeO 2 Catalysts: Insights into reaction pathway adjustments and strong Metal-Support interactions

Revealing the logical relationship between the structure, reaction mechanism and performance of the catalyst is a key step in the design of low -temperature CO 2 methanation catalyst. The elemental Al was introduced into Ni/ CeO 2 using a co -precipitation method to form a composite support CeO 2 -Al 2 O 3 loaded nickel -based catalyst. It was found that the incorporation of Al significantly improved the catalytic performance of low -temperature CO 2 methanation. Notably, at a molar ratio of Al/Ce equal to 0.1, the catalyst exhibited optimal CO 2 conversion of 88.83% and CH 4 selectivity of 99.96% at 240 degree celsius. The addition of appropriate amounts of Al not only increases the specific surface area of the catalyst but also maintains a moderate strong interaction between metal Nisupport, thereby promoting the formation of active metal Ni species. Furthermore, the presence of Al leads to an increase in oxygen vacancy concentration, which facilitates the generation of numerous hydroxyl groups. Consequently, this alters the distribution of basic sites on the catalyst surface, resulting in a shift from the CO* pathway to a dual pathway involving both CO* and formate pathways. Remarkably, these divergent reaction pathways correspond to distinct active sites, thereby maximizing the utilization of each region within the catalyst. The diversity of reaction pathways and active sites represents pivotal factors for enhancing the catalytic performance of low -temperature CO 2 methanation catalysts.