Studies On Synthesis,Characteristics And Catalysis Performance Of The Metal-doped Copper-Manganese Catalysts For Water-Gas Shift Reaction

In this thesis, the metal-doped Copper-Manganese catalysts are prepared byco-precipitation. The as-prepared catalyst samples were characterized by XRD, lowtemperature N2adsorption/desoption, TG/DTA, TPR/TPD/s-TPR, the amount of ammoniaabsorption and tested for water gas shift (WGS) reaction. The research emphasis is focusedon the impact of the metal-doped (Zr, Ce, La, Fe, Zn, Al, Co) on the texture，thermal-stability and catalytic performance of Copper-Manganese catalysts prepared by themolar ratio of [Cu2+]/[Mn2+],1/2and1/1separately. Simultaneously the different contentof Zr are investigated.The results showed that the texture and catalytic performance of Copper-Manganesecatalysts were closely related to the metal species, in which doping Zr, Fe, Al samplescould enhance and improve the catalytic properties of copper and manganese catalyst from200℃to300℃. The metal-doped copper-manganese catalysts were mainly composed ofCu1.5Mn1.5O4phase and a small amount of Mn2O3when the molar ratio of [Cu2+]/[Mn2+] is1/2. The metal-doped didn`t change the crystal structure of copper-manganese system,but it decreased catalyst grain size and increased the specific surface area of the catalyst.Main crystalline phase were MnCO3, while Cu1.5Mn1.5O4were decomposed into Cu andMn3O4after shift reaction in all samples. Zr-doped catalyst effectively improved theactivity and stability of the copper-manganese system water gas shift reaction because itmade the distribution of copper and manganese component uniform, significantlyimproving reduction performance, increasing its surface area.The metal-doped catalysts were the single crystalline spinel structure of Cu1.5Mn1.5O4solid solution when the molar ratio of [Cu2+]/[Mn2+] is1/1. The main crystalline phase ofeach sample were MnCO3. Meanwhile Cu1.5Mn1.5O4were decomposed into Cu and CuOafter the shift reaction. The Cu crystal phase of doped metal (Zr, Fe, Al) in sample showeda highly decentralized state, effectively increasing the surface area of the sample andimproving the dispersion of the copper surface. They were most obvious for Zr-dopedsample especially. CO conversion of the catalyst reaches60.06%at200℃. The specificsurface area of Zn-doped sample significantly decreased. The activity were much lowerthan the non-doped samples due to the reduced dispersion of the copper surface, COconversion of the catalyst was only60.06%at200℃. The amount of Zr-doped had a greater impact on the structure and performance ofcopper-manganese catalysts. when the molar ratio of [Cu2+]/[Mn2+] was1/1, the singlecrystalline spinel structure of Cu1.5Mn1.5O4solid solution dominates in the different contentof Zr-doped samples, and the main crystal phase of each sample were MnCO3. While themain crystalline phase Cu1.5Mn1.5O4wee decomposed into CuO, Cu2O, and Cu after theshift reaction. The Cu showed a highly decentralized state in samples containing5%. Thesurface area of catalyst increased with the increase of Zr doping, but the dispersion ofcopper surface changed little. The grain size of the catalyst was minimum, the dispersionof the copper surface was maximum and the activity of catalyst was best.