The Preparation And Performance Of Pd-Zn-Zr Catalysts For Methanol Synthesis From CO₂ Hydrogenation

Carbon dioxide leads to global warming,so how to reduce CO2 emissions or transform and utilize it has become a recent research hotspot.Copper-based catalysts have been used in industrial production to catalyze the hydrogenation of carbon dioxide to methanol.However,traditional copper-based catalysts have disadvantages such as easy sintering,low stability and low selectivity of methanol.Therefore,there is an urgent market demand to develop catalysts with high activity,high stability and high selectivity of methanol.ZnO-ZrO2 oxide has high stability and selectivity,but the high reaction pressure requires high equipment quality and needs to be reacted at a higher temperature,which cannot be directly applied in practice.In this paper,we design a noble metal-doped Pd-Zn-Zr catalyst to help solve this problem.In this thesis,Pd-Zn-Zr catalysts with different Pd contents and methods are prepared for the hydrogenation of carbon dioxide to methanol.Various characterization methods such as BET,XRD,TEM,H2-TPR,XPS,Raman and TPD were used to comprehensively analyze the catalyst.This article first discusses the preparation of Pd-Zn-Zr catalysts with different Pd content by the co-precipitation method.All catalysts were tested for catalytic performance,and the experimental results showed that the 1%Pd-10%Zn-Zr catalyst has a higher carbon dioxide conversion rate and higher methanol selectivity and yield.This may be due to the tetragonal crystal form formed by the 1%Pd-10%Zn-Zr catalyst and the higher oxygen vacancy concentration and reduction degree on the surface are beneficial to methanol synthesis.In order to further study the methanol synthesis performance of the Pd-Zn-Zr catalyst,we will then explore the performance comparison of Pd-Zn-Zr catalysts with different preparation methods.Pd-Zn-Zr catalysts were prepared by urea method,coprecipitation method and reverse microemulsion method.Comparing the catalytic performance results of all the catalysts,we found that the catalyst prepared by the urea method(Pd-Zn-Zr-Urea)has better methanol synthesis performance and higher methanol selectivity and methanol yield.Benefiting from the high content of zirconium species exposed on the catalyst surface,the catalyst has a strong adsorption capacity for carbon dioxide and hydrogen.