CO2 methanation on Na‐promoted Ni/ZrO2 catalysts: Experimental characterization and kinetic studies

Abstract

AbstractCarbon dioxide (CO2) hydrogenation to methane (CH4) can not only reduce the greenhouse effect but also provide a recyclable source of hydrocarbon fuel. However, traditional Ni‐based catalysts have poor low‐temperature activity and the kinetic reaction mechanism for CO2 methanation is not well understood. This work investigates the effects of Na promoter on the catalytic performance, kinetics, and mechanism of Ni/ZrO2 catalysts for the CO2 methanation reaction. Herein, a series of Ni/ZrO2 catalysts with different Na content (0–5 wt%) are prepared by the hydrogel method and used for CO2 methanation. The experimental results show the CO2 reaction rate and Na content have a strong correlation. The addition of Na increases the basic sites and oxygen vacancies, which greatly improves the catalytic activity and selectivity to CH4. Of the studied catalysts, NiNa2.5/ZrO2 exhibits the highest catalytic performance, revealing that a CO2 reaction rate of ∼0.33 moL·gNi–1·h–1, a CH4 selectivity of ∼100% at 300°C, 0.1 MPa, a high GHSV of 30,000 mL·g–1·h–1 are achieved. Kinetic experiments were performed with samples of Ni/ZrO2 and NiNa2.5/ZrO2 at 300°C. These studies suggest that the higher performance of NiNa2.5/ZrO2 is attributed to its lower reaction activation energy. The structure–activity relationships observed herein could provide useful guidance in the design of highly active industrial catalysts.