Mastering the Foreign Ionic Radius in CeO<sub>2</sub> Supports of Ni-Based Catalysts for Efficient CO<sub>2</sub> Methanation
Hao Lou, Jie Ren, Nuo Xu, Inam Ullah, Syed Musab Ahmed, Zeeshan Abbasi, Wenlong Wu, Zhandong Wang
Abstract
A Ni-based catalyst is a common non-noble-metal system for CO 2 methanation, and metal modification for the support is an effective method to further improve its activity. Doping metals with various ionic radii already exhibited different effects on the methanation performance, but the promotion mechanism remains indistinct. Herein, we report a universal doping strategy to fabricate Ni-based catalysts by tailoring foreign ions (Al 3+, Zr 4+, Y 3+, and Sm 4+ ) with different radii in CeO 2 . Among them, Ni/Ce 0.9 Al 0.1 O x exhibited the highest catalytic performance (72.4% of CO 2 conversion at 300 °C) compared with other catalysts at all temperatures and with the lowest kinetic temperature range. Furthermore, the change in the foreign ionic radius had a variety of effects on the structure of the catalysts, in which the specific surface area and oxygen vacancy concentration were the main factors. According to mechanical measurements, the doping of foreign ions reduced the temperature of the started methanation and inhibited CO formation, resulting in enhanced catalytic activity CO 2 conversion and increased CH 4 selectivity. The hydroxyl groups derived from the oxygen vacancy facilitated the transformation of CO 2 to CH 4 via the HCOO* path. This work contributes to developing a promising approach to controlling the performance of CO 2 methanation by regulating the foreign ionic radius.