The Research Into Catalyst Modification Of CuO/ZnO/Al₂O₃ For Methanol Hydrogenation Synthesis From Carbon Dioxide

A large amount of carbon dioxide emission from fossil fuel combustion led to global greenhouse effect and environmental pollution.Research of carbon dioxide emission reduction and utilization is of focus and urgent issues in the world.Methanol is considered as an important fundamental organic chemical raw material and a new-type environmental protection clean fuels.Carbon dioxide hydrogenation to methanol is an efficient way for carbon dioxide practical utilizaiton,and also a new pathway for strategic adjustment of energy structure.Mathanol synthesis from carbon dioxide is great significant for solving increasing environmental pollution and energy questions.This research prepared CuO/ZnO/A1₂O₃ catalyst by the method of co-precipitation.The factors,such as catalyst components,preparation conditions,and additives,were considered for studying the activities and selection of catalysts.Analysis methods were H2-TPR、XRD、BET、SEM,which were used to characterize catalyst structure and their chemical properties.Experimental results indicated that the best calcination temperature of catalyst was 350℃.The ratio of Cu to Zn influenced greatly on the activity of catalyst.The catalytic activity of Cu O/Zn O/Al₂O₃ had the highest value with Cu/Zn/Al ratio of 6:3:1 at calcination temperature of 350 ℃.Generally,additives would influence markedly on catalyst structures and properties of mathanol hydrogenation synthesis from carbon dioxide.So additives of Mg O,Ba O and La₂O₃ were considered.It had been shown that additives enlarged the specific surface area and pore capacity of catalyst.And also catalyst pore size and its distribution were improved.The dispersion of Cu O and Zn O became better which led to better synergistic effect.Further,Cu O was easy to be reduced contributing to enhance the conversion rate of CO2 and the selectivity of methanol.The order of activity of the three additives from high to low was Ba O,La₂O₃ and Mg O.Especially,the conversion rate of CO2 increased by9.65% and the yield of methanol increased by 2.88% could be obtained on theconditions of reaction pressure of 2.6MPa,space velocity 3600h-1,hydrogen to carbon molar ratio of 3,reaction temperature of 260℃ with addtive of Ba O.Catalyst evalution was carried out in a fixed-bed plug flow reactor.Technological factors were considered.The result showed temperature,weight hourly space velocity,pressure,the ratio of hydrogen and carbon influenced greatly on the synthesis process.The optimal experimental conditions in this research were at reaction temperature of 260℃,weight hourly space velocity of 3600h-1,and H₂/CO₂ of 3.