Theoretical Study Of CO₂ Hydrogenation To Methanol On Cu₃Zn Alloys

In response to the"carbon neutral"strategy,Cu/ZnO heterogeneous catalytic hydrogenation of carbon dioxide to methanol,an important industrial reaction,has become a hot topic in the field of catalytic research,and further research is urgently needed.Based on the previous work,this paper introduces an optimized surface excess free energy GGA functional and numerical analysis method based on the change of super cell thickness.It is planned to combine the Slab plate model,DFT theory and surface micro-reaction kinetics,and choose the more open Cu₃Zn（114）,Cu₃Zn（214）with obvious inflection step surface is used as the catalyst surface alloy model,and the traditional close-packed Cu（111）is used as the control group to carry out theoretical research on the hydrogenation of CO₂ on Cu₃Znalloy to produce methanol.First,we conduct research and discussion on the quick decision steps,calculate the thermodynamic properties of the 24 main elementary reactions of methanol on Cu₃Zn（114）,Cu₃Zn（214）and Cu（111）planes,and specifically examine the reactions of the key elementary steps.Co-adsorption model,transition state model,adsorption enthalpy change and corresponding system entropy value.Comparing with Cu（111）surface,it is found that Znatoms on the alloy surface do promote the reaction of important elements.The most affected is HCOOH^*+H^*→H₂COOH^*+^*,and the reaction rate constant is increased by two orders of magnitude.Among them,the Cu₃Zn（114）surface has a significant promoting effect on the quick decision step,and the catalytic performance is better.Then,on the optimized relaxation substrate,the optimized surface residual free energy GGA-PW91 algorithm is introduced.Qualitatively calculate the catalytic activity and experimental stability of different surfaces.The adsorption of all reactant phases（50 in total）involved in the main reaction channel HCOO pathway was investigated,the reaction kinetic parameters and thermodynamic energy values were calculated,and the performance of each adsorbate and all elementary reactions on different surfaces was systematically discussed.It is found by comparison that the adsorption site and the adsorption enthalpy in the middle of each reaction have not changed significantly due to the change of the substrate,but the entropy of the system is greatly affected.Finally,the paper conducts numerical analysis and fitting of the important surface micro-reaction kinetic parameters in the heterogeneous catalytic system:the pre-exponent factor and the reaction rate constant,aiming to construct related models,which can remove experimental condition constraints and save parallel calculation costs.,Or can be derived to extend to the calculation of special materials（such as energetic materials,etc）.The simulation calculations based on the micro-reaction kinetics based on the first principles show that CO₂ hydrogenation actually synthesizes methanol mainly through the HCOO mechanism,with HCOOH^*+H^*→H₂COOH^*+^*as the rapid reaction step.And the reaction rate constant shows that the Cu₃Znalloy does have a significant promotion effect on methanol synthesis compared to the surface of the pure copper substrate.