Adsorption of CO2 on Cu/SiO2 nano-catalyst: Experimental and theoretical study

Abstract

Copper-based silica is a promising catalyst for several reaction pathways for CO2 conversion to hydrocarbons. The activity of this catalyst in terms of conversion and product selectivity is affected by CO2 adsorption, surface reaction, and product desorption resistances on the surface of the catalyst. The effect of CO2 adsorption on the surface of Cu/SiO2 nano-catalyst was studied using the sol?gel method. The CO2 adsorption on the surface of SiO2 is investigated at different Cu loading, and the surface morphology is analyzed. The results showed a well-dispersed Cu in an amorphous silica structure with a surface area of 407.70 m2/g and pore volume of 0.000891 cm3/g. SEM analysis indicated non-uniform cluster shapes with large parallel slits and plate-like aggregates on the surface. Adsorption isotherms for different Cu loading provided a nonlinear CO2 uptake with increasing Cu content. The experimental results are supported by theoretical predictions obtained from molecular dynamic simulations and showed a 4% confidence limit when the Cu:SiO2 ratio was 2:1. Both results suggest physisorption of the CO2 molecules, CO2- with oxygen atoms on the surface. This work provides insights into the CO2 uptake at different pressure values, which is critical for the reaction kinetics and CO2 conversion to hydrocarbons.