Abstract: Potassium promoted iron-zinc catalysts prepared by co-precipitation method (C-Fe-Zn/K), solvothermal method (S-Fe-Zn/K) and hydrothermal method (H-Fe-Zn/K) could selectively convert CO₂ to light olefins, respectively. The physicochemical properties of the obtained catalysts were determined by SEM, N₂ physisorption, XRD, H₂-TPR, CO₂-TPD and XPS measurements. The results demonstrated that preparation methods had great influences on the morphology, phase structures, reduction and adsorption behavior, and hence the catalytic performance of the catalysts. The samples prepared by hydrothermal and co-precipitation method generated small uniform particles and led to lower specific surface area. In contrast, microspheres with larger specific surface area were formed by self-assembly of nanosheets using solvothermal method. ZnFe₂O₄ was the only detectable phase in the fresh C-2Fe-1Zn/K, S-3Fe-1Zn/K and S-2Fe-1Zn/K samples. ZnFe₂O₄ and ZnO co-existed with increasing Zn content in S-1Fe-1Zn/K sample, while ZnO and Fe₂O₃ could be observed over H-2Fe-1Zn/K sample. All the used samples contained Fe3O4, ZnO and Fe₅C₂. The peak intensity of ZnO was strong in the AR-H-2Fe-1Zn/K sample while it was the lowest in the AR-C-2Fe-1Zn/K sample after reaction. The formation of ZnFe₂O₄ increased the interaction between iron and zinc for C-2Fe-1Zn/K and S-Fe-Zn/K samples, causing easier reduction of Fe₂O₃ to Fe3O4. The surface basicity of the sample prepared by co-precipitation method was much more than that of the other two methods. During CO₂ hydrogenation, all the catalysts showed good activity and olefin selectivity. The CO selectivity was increased with increasing Zn content over S-Fe-Zn/K samples. H-2Fe-1Zn/K catalyst preferred to the production of C₅⁺ hydrocarbons. CO₂ conversion of 54.76% and C₂⁼-C₄⁼ contents of 57.38% were obtained on C-2Fe-1Zn/K sample, respectively.

Key words: CO₂ hydrogenation, Light olefins, Preparation methods, Iron-zinc catalyst

摘要： Potassium promoted iron-zinc catalysts prepared by co-precipitation method (C-Fe-Zn/K), solvothermal method (S-Fe-Zn/K) and hydrothermal method (H-Fe-Zn/K) could selectively convert CO₂ to light olefins, respectively. The physicochemical properties of the obtained catalysts were determined by SEM, N₂ physisorption, XRD, H₂-TPR, CO₂-TPD and XPS measurements. The results demonstrated that preparation methods had great influences on the morphology, phase structures, reduction and adsorption behavior, and hence the catalytic performance of the catalysts. The samples prepared by hydrothermal and co-precipitation method generated small uniform particles and led to lower specific surface area. In contrast, microspheres with larger specific surface area were formed by self-assembly of nanosheets using solvothermal method. ZnFe₂O₄ was the only detectable phase in the fresh C-2Fe-1Zn/K, S-3Fe-1Zn/K and S-2Fe-1Zn/K samples. ZnFe₂O₄ and ZnO co-existed with increasing Zn content in S-1Fe-1Zn/K sample, while ZnO and Fe₂O₃ could be observed over H-2Fe-1Zn/K sample. All the used samples contained Fe3O4, ZnO and Fe₅C₂. The peak intensity of ZnO was strong in the AR-H-2Fe-1Zn/K sample while it was the lowest in the AR-C-2Fe-1Zn/K sample after reaction. The formation of ZnFe₂O₄ increased the interaction between iron and zinc for C-2Fe-1Zn/K and S-Fe-Zn/K samples, causing easier reduction of Fe₂O₃ to Fe3O4. The surface basicity of the sample prepared by co-precipitation method was much more than that of the other two methods. During CO₂ hydrogenation, all the catalysts showed good activity and olefin selectivity. The CO selectivity was increased with increasing Zn content over S-Fe-Zn/K samples. H-2Fe-1Zn/K catalyst preferred to the production of C₅⁺ hydrocarbons. CO₂ conversion of 54.76% and C₂⁼-C₄⁼ contents of 57.38% were obtained on C-2Fe-1Zn/K sample, respectively.

关键词: CO₂ hydrogenation, Light olefins, Preparation methods, Iron-zinc catalyst