Preparation Of CuO-ZnO-ZrO₂ Catalyst Via Microwave Assisted Methods And Its Catalytic Performance For CO₂ Hydrogenation To Methanol

In recent years, the increasing CO2 emission leads to an aggravation of global warming.Even though these issues have been discussed and some measures have been made. CO2 recycling is still the focus of government and scientific researchers. Now catalysts are usually applied in CO2 utilization for synthesis of methanol, dimethyl ether (DME) and olefins, which shows the significance in the research of catalyst materials. Owning to the uniform heating,rapid, efficient and energy-saving process, microwave assisted method can make up for deficiency among these preparation methods, which can be widely applied in catalyst preparation.A series of CuO-ZnO-ZrO2 catalysts were prepared by microwave assisted methods. Under microwave heating, the way of heating, different solvents, different hydrothermal temperatures and different preparation methods were investigated for the CO2 hydrogenation reaction. The results show as following:(1) The influence of aging methods on CuO-ZnO-ZrO2 catalystsCuO-ZnO-ZrO2 catalysts were prepared by microwave assisted co-precipitation. Compared with conventional co-precipitation, the catalyst structure, component and catalytic performance prepared by microwave assisted method were discussed. With the introduction of microwave in aging process, the CO2 conversion and methanol yield increased much.Furthermore, microwave can influence the catalyst porous structure and particle morphology and shorten aging time to 20 min.(2) The solvent effect on CuO-ZnO-ZrO2 catalystsUnder the above mentioned aging conditions. the influences of different solvents(n-propanol, methanol, water) on the CuO-ZnO-ZrO2 catalysts' properties were investigated.The results showed the catalytic activity increased gradually with the increase of solvent polarity. The solvent with higher polarity could promote the adsorption to microwave, which led to fast reaction rate and more active component.(3) The hydrothermal temperature on CuO-ZnO-ZrO2 catalystsA series of CuO-ZnO-ZrO2 catalysts were successfully synthesized through a microwave assisted hydrothermal method to synthesize methanol via CO2 hydrogenation. The effects of hydrothermal reaction temperature (80?, 100?, 120?, and 150?) on the microstructure and physic-chemical properties were also investigated and discussed. With increasing reaction temperature (in a proper range), the catalyst represents higher activity and methanol yield,which exhibited the better catalytic performance and exhibited smaller particles with higher surface area and superior dispersion.(4) Different preparation methods under microwave heating on CuO-ZnO-ZrO2 catalysts CuO-ZnO-ZrO2 catalysts were prepared by different preparation methods with microwave assisted heating. The effects of preparation methods on the microstructure and physic-chemical properties were also investigated and discussed. Catalyst prepared by oxalate co-precipitation exhibited the highest catalytic performance, which showed larger copper metal area (Scu) and Cu active sites. However, catalyst prepared by microwave hydrothermal method led to higher methanol selectivity, owning to the higher CO2 adsorption. Oxalate co-precipitation is an efficient method for the preparation of catalyst and leads to a higher methanol yield.