Promotion Effect of TiO2 on Ni/SiO2 Catalysts Prepared by Hydrothermal Method for CO2 Methanation

Abstract

Herein, the effects of TiO2 addition and different preparation methods on catalyst structure and CO2 methanation activity of Ni/SiO2 catalysts are investigated. Compared with wetness impregnation and sol–gel method, hydrothermal method is demonstrated to be a more efficient means for preparing Ni/SiO2 catalysts with more suitable pore structure, more active sites on the catalyst surface, and better catalytic performance. Ni/SiO2 catalysts with different TiO2 concentrations are synthesized by hydrothermal method for comparison with those without TiO2 introduced. The results show that TiO2‐promoted Ni/SiO2‐HS‐xTi exhibits higher activity and CH4 selectivity. Among this group, the Ni/SiO2‐HS‐2Ti catalyst performs the best, achieving 53.2% CO2 conversion at 350 ºC, 0.1 MPa, and WHSV of 45 000 mL g−1 h−1. The conclusions of the characterization analysis indicate that TiO2 effectively promotes the Ni dispersion on the SiO2 surface while reducing Ni particle size. In addition, TiO2 increases the amount of weak basic sites on the SiO2 surface and the electron cloud density around the active metal Ni, which facilitates the CO2 adsorption and activation.