Effect Of Alkaline Promoter On The Structure Of Copper-Based Catalysts And The Activity Of CO₂ Hydrogenation To Methanol

Catalytic hydrogenation of carbon dioxide to methanol is a potential direction for carbon dioxide conversion and utilization.The physical and chemical properties and catalytic activity of the copper-based catalyst were studied.1.Study on Cu-ZnO-Al2O3(CZA)catalyst modified by Ga2O3 catalyst:the addition of Ga2O3 will affect the grain size of CZA catalyst,the specific surface of catalyst,copper dispersion,copper specific surface area and other physical parameters.When Al2O3/Ga2O3=2:1,larger specific surface area and pore capacity increase the contact area between catalyst and reactant.At the same time,when Al2O3/Ga2O3=2:1,the addition of Ga2O3 improves the surface alkali strength of the catalyst and makes the catalyst have better CO2 adsorption performance.The evaluation results of catalyst activity showed that when Al2O3/Ga2O3=2:1,the catalyst activity was the best,the CO2 conversion rate was 23.0%,and the methanol selectivity was 51.9%,which was improved compared with CZA catalyst.2.Study on Cu-ZnO-ZrO2(CZZ)composite catalyst with nitrogen doped graphene:copper based catalyst modified by nitrogen doped graphene with large specific surface area and alkaline surface was selected to improve physical and chemical properties and catalytic activity of the catalyst.The results showed that the addition of nitrogen-doped graphene reduced the crystallinity and increased the specific surface area and pore volume of the catalyst The dispersion degree of catalyst particles,copper dispersion and Cu specific surface area of catalyst were improved when the catalyst particles were distributed in the folded sheet structure with nitrogen doped graphene.The addition of nitrogen-doped graphene increased the catalytic activity of the catalyst.When the mass content of nitrogen-doped graphene was 7.5%,the catalyst had the best comprehensive performance,the carbon dioxide conversion rate was 9.0%,and the methanol selectivity was 71.8%.3.Effects of magnesium-aluminum-hydrotalcite and go on copper-based catalysts:the active component of copper was introduced into basic magnesium-aluminum-hydrotalcite and the effect of go on catalysts was investigated.The addition of go reduced the crystallinity and increased the specific surface area and pore volume of the copper based catalyst The addition of go makes the lamellar structure of mg-al hydrotalcite more orderly and complete.The results of catalyst evaluation showed that the addition of go was beneficial to improve methanol selectivity of catalyst.Cu-MgO-Al2O3(CMA)catalysts with lamellar channels were prepared by roasting go in an oxygen atmosphere.Compared with CMA catalysts with lamellar channels,the methanol selectivity of CMA catalysts with lamellar channels was further improved.