THE PROMOTIONAL EFFECT OF POTASSIUM ON IRON-BASED SILICA SUPPORTED CATALYST FOR CO2 HYDROGENATION

Abstract

Climate change is one of the biggest global challenges. As a result of human activity, large amounts of greenhouse gases are released into the atmosphere, contributing to global warming. Carbon dioxide (CO2) is a major greenhouse gas, therefore, hydrogenation of CO2 to value-added chemicals and liquid fuels is of great importance for a sustainable future. It is well known that iron-based catalysts can demonstrate good activity in the hydrogenation of CO2. However, catalysts need to be improved to promote the formation of liquid hydrocarbons. In this study, a series of silica supported iron catalysts promoted with potassium were prepared by impregnation method. The samples were characterized by X-ray fluorescence spectroscopy, X-ray diffraction, and N2 adsorption-desorption analysis. Catalytic performance of K-0, K-2, and K-5 was investigated for CO2 hydrogenation in a fixed bed reactor operated at 300 degrees Celsius and 20 bar. The reaction products were analysed by gas chromatography and FT-IR spectroscopy. The results showed that promotion with potassium reduces the selectivity of methane and reduces the amount of gas phase hydrocarbons. At the same time promotion with potassium contributed to the formation of alcohols in the liquid phase products. The highest methanol yield was obtained using the K-2 catalyst, while the K-5 catalyst promoted the formation of both methanol and ethanol in the liquid phase.