Preparation And Properties Of Cu - ZnO - ZrO 2 Catalysts For Hydrogenation

In various environmental problems facing humanity, global temperature rise caused by the greenhouse effect is one of the most serious problems, large amounts of CO2 emission is the main cause of the greenhouse effect, so the CO2 emissions is urgently needed.One of effective ways to reduce the emissions of carbon dioxide is transformed into value-added products, in which CO2 hydrogenation catalyzed by methanol is the research direction of the representative area.At present, the CO2 hydrogenation of methanol synthesis technology is not yet mature, high-performance catalyst research and development is one of the key links must break through.Three synthetic methods have been used to make a serious Cu-ZnO-ZrO2 catalysts, They are, respectively, precipitation method, citric acid sol-gel method and surfactant-templates method. The structures of the catalysts have been carefully characterized by TG-DSC, XRD, H2TPR, CO2TPD, BET techniques. And the activities of the catalysts for CO2 hydrogenation to methanol have been evaluated. The results showed that the catalyst prepared by citric acid sol-gel method active component high dispersion, small grains, in CO2 hydrogenation reaction synthesis methanol showed better reactivity, CO2 conversion rate was 22.9%,23.1% methanol selectivity.Based on the above research,do a system studied to prepared Cu-ZnO-ZrO2 catalyst used citric acid sol-gel method. the initial pH value, the amount of citric acid, gelation temperature of catalyst on the reaction conditions such as the structure-activity relationship.The study found that changing the initial pH value, form of existence in regulation of citric acid in the solution, thus changing the nature of dry gel.The initial pH of 6, citric acid and metal ion complexing reaction, preparation of catalysts with high specific surface and the copper surface dispersion, to improve catalyst in CO2 hydrogenation reaction activity of methanol synthesis reaction.Change the amount of citric acid, the regulation is the amount of citric acid root anion in the solution, will affect citric acid complexing degree between the metallic cations.Adopt the experimental conditions, the n/n gold mixed with = 1.5:1, the catalyst showed good reactivity.Gelation temperature affect the stability of the gel, decrease the gelation temperature is beneficial to improve the stability of the dry gel, but the temperature is too low to form gel long time exposed to air, absorb the moisture in the air, cause the hydrogen bond rupture in the gel, gel structure was destroyed.The results showed that the gelation temperature of 60℃, the gel structure is stable and to prevent grain grew up in the process of roasting and reunion between particles, the preparation of the catalyst has good reactivity.