Preparation And Research Of Copper-based Catalyst For Methanol Synthesis Via CO₂Hydrogenation

The methanol is an important feedstock for the organic chemical industry and a potentialalternative to fossil fuels. Therefore, efficiently synthesis of methanol possesses broadapplication foreground. The effective use of carbon dioxide has attracted tremendous attentionin recent years due to the growing global warm. Synthesis of methanol through CO₂hydrogenation is one effective way of rational use of carbon resources.In the present study, the CuO/ZnO/Al₂O₃catalyst was prepared by different methods（gel-network-coprecipitation method, oxalate gel-coprecipitation method and conventionalcoprecipitation method） and was applied to methanol synthesis from CO₂hydrogenation. Thecatalysts were characterized by X-ray diffraction, temperature-programmed reduction andtransmission electron microscopy. The analysis results indicated that the CuO/ZnO/Al₂O₃catalyst prepared by the gel-network-coprecipitation method （calcination temperature of350℃, pressure of2.0MPa, GHSV=2400mL/（g·h）） exist in much smaller particle size and lowerreduction temperature. Compared with the above two methods, gel-network-coprecipitationmethod could improve the selectivity and space-time yield.Then, the influence of molar ratio Cu/Zn and calcination temperature to the activity ofthe catalyst were optimized, the influence of agar concentration on catalyst particle size wasalso investigated. The catalysts of CuO/ZnO/Al₂O₃were characterized by X-ray diffraction,N2adsorption-desorption, temperature-programmed reduction transmission electronmicroscopy and thermogravimetry. The analysis results indicated that the difference inparticle size of CuO was probably due to the different the molar ratio of Cu/Zn, calcinationtemperature and agar concentration, which might lead to the different of catalytic performance.On the basis of the XRD and H2-TPR results, both catalysts showed smaller particle size ofCuO was benefit to improve catalytic activity and stability of the catalyst. The highest activitywas achieved over the Cu/Zn molar ratio of1.5, catalyst calcined at450℃and agarconcentration of2wt%, the selectivity and yield of methanol were43.46%and2.78%,respectively.the catalytic performance can be further optimized by introducing five promotors of Er、Ce、La、Co、Fe into CuO/ZnO/Al₂O₃catalyst in order to enhance catalytic activity.Experiments results have shown that the CuO/ZnO/Al₂O₃catalytic performance was improved by introducing Er、Ce, the catalytic performance of added Er were better than thatof Ce. The effects of various parameters such as the molar amount of Er, calcinationtemperature, agar concentration, space velocity, pressure and the filling style of quartz sandand catalyst on the catalytic performance for CO₂hydrogenation were investigated.The analysis results indicated that the2-C_4.5Z₃A₁-6Er-450, when the reaction parameterswere: reaction temperature of230℃, pressure of2.0MPa, GHSV=2400mL/（g·h）,V（H2）/V（CO₂）=3:1, under the condition that the quartz sand and catalyst filled by mixing themtogether. The selectivity and yield of methanol were57.79%and3.01mmol/（g·h）,respectively.