Study On Effect Of Zr, Sr Additive On DME Catalyst Properties

With the increasing of the greenhouse effect and decreasing of oil resources, search for sustainable clean fuel, has become the important task of today in energy field. Carbon dioxide is the nature of carbon resources. DME (Dimethyl Ether) is an important fuel and ideal substitute for the compression engine diesel. Therefore, DME synthesis by the hydrogenation of carbon dioxide has important significance.The reaction of DME synthesis from CO2hydrogenation includes hydrogenation of carbon dioxide, methanol synthesis, methanol dehydration to DME and the reversed water-gas shift reaction. Hybrid catalysts were prepared by the mechanical mixing of adding additives (ZrO2or SrO) to the copper-based catalyst (as a methanol synthesis catalyst) and HZSM-5(as dehydration catalyst), and characterized by using the technologies of SEM, BET, XRD, IR and activity-evalution in a laboratory fixed-bed reactor. The impact of the solution concentration, aging temperature, aging time and additive content of the catalyst were systemically investigated. The effects of reaction conditions including temperature, pressure and space velocity on the reactivity over the optimized catalyst were also tested.Through the experimental results, the feasible reaction conditions were suggested.Experimental results show that good catalytic activity and dimethyl ether selectivity had been obtained on the hybrid catalyst under the conditions of H2/CO2=3,518K, with the pressure of5MPa. With the hybrid catalyst of adding the additive of ZrO2, the conversion of CO2is19.81%, the overall yield of methanol and dimethyl ether is17.78%.When the mass fraction of nitrate is10%, the aging temperature is403K and aging time is10h during preparation process of the hybrid catalyst comprising ZrO2additive, the particle size of the catalyst is minimum (about150nm) and the specific surface area is160.46m2/g. Catalyst life is up to120h. Dimethyl ether was synthesized by feeding CO2and H2into a reactor under the pressure of5MPa, with space velocity of3000ml/h at538K, and the H2/CO2mole ratio of3. The conversion of CO2is19.81%, the overall yield of methanol and dimethyl ether is17.78%. When the mass fraction of nitrate is10%～15%, the aging temperature is403K, aging time is10h. SrO content is of about6%, the particle size of the catalyst with additive of SrO is minimum (about150nm) and the specific surface area is153.21m2/g. Catalyst life is up to150h. Dimethyl ether was synthesized by feeding CO2and H2into a reactor under the pressure of5MPa at538K, with space velocity of3000ml/h and the H2/CO2mole ratio of3. The conversion of CO2is30.30%, the overall yield of methanol and dimethyl ether is27.80%.