Effect Of Ce Modification And Pretreatment On Cu-based Catalyst Of CO₂ Hydrogenation To Methanol

CO2 hydrogenation to methanol can decrease the demand of fossil fuels effectively.It is great significance for sustainable energy economy.At present,the copper-based catalyst is the main research catalyst system because of its advantage of cheap,but the copper-based catalysts generally have the problems such as low activity,easy agglomeration and deactivation.In this reasearch,copper-based catalysts was modified with Ce and reduced with glucose for the state of Cu.The catalytic performance,characterization,stability and structure-activity relationship of catalysts were studied.The main research and results are summarized as follows:1.Cu-ZnO-Al2O3-CeO2(CZA-Ce)catalysts were prepared by coprecipitation method.The effect of CeO2 on the catalytic hydrogenation CO2 to methanol of CZA catalysts was studied.The results showed that,after adding an appropriate amount of CeO2 to CZA catalysts,the Cu particle size and reduction temperature were decreased,Cu dispersion and specific surface area were increased,and the number of medium base sites of CZA catalysts surface was also increased.At the reaction condition of P=3.0 MPa,T=250?,H2/CO2=3/1,W/F=10 g·h/mol,the activity of CZA-Ce0.1 catalyst was the best The conversion rate and the selectivity of CH3OH were 20.8%and 55.8%,respectively.The space-time yield(STY)of CH3OH was 58.0 g-kg-1·h-1,which was increased by 10.5%compared with CZA catalyst.2.CZC catalysts were prepared by coprecipitation method.The influence of Cu/Ce mass ratio in CZC catalysts on the catalytic hydrogenation of CO2 to methanol was investigated.The results showed that proper Cu/Ce mass ratio of the catalysts has superior parameters,such as higher specific surface area and dispersion of Cu particles,stronger synergistic interaction of Cu-ZnO,and improve the adsorption capacity of the reaction raw marerial.At the reaction conditions of P=3.0 MPa,T=250?,H2/CO2=3/1,W/F=10 g·h/mol,the CH3OH selectivity increased from 45.0%to 51.0%,and the space-time yield(STY)of methanol increased from 45.3 g-kg-1·h-1 to 57.8 g·kg-1·h-1 compared with Cu-ZnO(CZ)catalyst.3.CuZnO-Al2O3(CZA)catalyst was also prepared by coprecipitation method,and then mixed with C6H12O6 for reduced by pretreatment Effect of C6H12O6 different dose on the experiment of catalyst was investigated.The results show that,after the appropriate amount of C6H12O6 for reducing CuO-ZnO-Al2O3 catalyst,the specific surface area of CZA catalyst is reduced,but the adsorption capacity of CO2 is improved,and the catalysts can form some Cu+species compared with the atmospheric reduction of H2/N2 syngas.the CH3OH selectivity of the catalyst increased by 6.3%,the CO2 conversion decreased by 1.9%,and the optimal CH3OH space-time yield(STY)was 49.0 g·kg-1·h-1 at the reaction of P=3.0 MPa,T=200?,H2/CO2=3/1,W/F=10 g·h/mol.