Insights into the Zn Promoter for Improvement of Ni/SiO2 Catalysts Prepared by the Ammonia Evaporation Method toward CO2 Methanation

As a pure combustible gas with a high calorific value, methane has long been favored, and that is why the CO 2 methanation reaction is attracting more and more attention. However, it is still challenging for this reaction due to the chemical inertness of CO 2 molecules, poor reaction efficiency at low temperatures, catalyst sintering at high temperatures, and carbon monoxide toxicity. Herein, the ammonia evaporation method was utilized to synthesize a series of Zn-modified Ni/SiO 2 catalysts with high surface area and high dispersity of active metals. The 80Ni-Zn/SiO 2 catalyst with an appropriate Ni/Zn molar ratio of 80:1 exhibited a high-performance breakthrough with a CO 2 conversion greater than 80% at 300 °C, good stability for 40 h at 310 °C, and a gas hourly space velocity of 18,000 mL·g –1 ·h –1 . These catalysts were further characterized by using a series of methods like in situ diffuse reflectance infrared Fourier transform spectroscopy to investigate the structural properties and potential reaction pathways. The effect of the Zn promoter on the Ni/SiO 2 catalyst for CO 2 methanation has been well investigated, namely, improving Ni dispersion and enhancing the H 2 adsorption. The findings demonstrate the broad availability, affordability, and remarkable high-performance practicability of the raw ingredients for the production of Ni-based catalysts for commercial applications.