DFT Study On Effect Of Surface Wettability On Catalytic Efficiency In Hydrogen Oxidation Catalytic Reaction

Heterogeneous catalytic reaction is a type of reaction widely used in chemical engineering.The catalytic reaction efficiency is often regulated by surface modification of the catalytic substrate.Adjusting surface wettability is a common method of surface modification.It is very important to adjust the catalytic reaction efficiency by regulating the wettability of the catalytic substrate surface.Surface wetting essentially reflects the strength of the interaction between the surface and the reactants or product molecules,which in turn affects the adsorption and diffusion of the reactants and product molecules near the catalytically active center,and ultimately affects the rate of the reaction.There are many experimental studies in this area,but the microscopic mechanism of surface wetting on the reaction efficiency has not been well elaborated.In this paper,the multiscale density functional theory is used to study the catalytic oxidation of hydrogen.The effect of surface wetting on the reaction efficiency is studied at the molecular level.(1)The effect of surface wettability on the efficiency of hydrogen-oxygen catalytic reaction under oxygen-rich conditions was studied.The concentration of hydrogen in the vicinity of the catalytic substrate is a controlling factor under oxygen-rich conditions.The reaction substrate model was constructed with graphite as the structure,and the adsorption of hydrogen and water in the graphite slit was calculated by classical density functional theory.The interaction strength between graphite surface and hydrogen or water molecules under the condition of grafting different numbers of hydroxyl groups on the graphite surface was investigated.The microscopic correspondence between surface wetting and molecular interaction strength was given.Based on this correspondence,the concentration distribution of hydrogen and water molecules near the substrate under different surface wetting conditions was studied.Studies have shown that the stronger the hydrophilicity of the surface,the smaller the adsorption amount of hydrogen on the surface is,which is not conducive to the hydrogen-oxygen catalytic reaction;In addition,the hydrogen adsorption capacity also increases when the bulk density of water increases.(2)The effect of surface wettability on the catalytic oxidation efficiency of hydrogen at different pore sizes was investigated.The effects of surface wettability on the adsorption of hydrogen,oxygen and water molecules at different pore sizes were investigated by changing the interaction between the graphite surface and the reactants or product molecules.And the influence mechanism of surface wetting on the reaction efficiency was studied microscopically.The results show that the bulk density of water has little effect on the adsorption of reactants,but surface wetting changes have a significant effect on the adsorption of hydrogen and oxygen at the same bulk water density.As the surface hydrophilicity increases,the amount of oxygen adsorption increases,and the amount of hydrogen adsorption first rises and then decreases.The size of the inflection point is related to the slit width and surface wetting strength.The theoretical research is in good agreement with the relevant experimental results,which verifies the reliability of the theoretical model.The study gives the microscopic mechanism of the effect of surface wetting on the catalytic oxidation of hydrogen in the slit.It can provide ideas for the regulation of gas adsorption and surface catalytic reaction efficiency.