Study On Cu Fe Slurry Catalyst Performance For Higher Alcohol Synthesis At Low Temperature

China’s energy structure is characterized by"rich coal,poor oil,and less gas".To achieve the"dual carbon"goal,fully developing and utilizing syngas to produce higher alcohols not only reduces the primary utilization of coal and improves economic value,but also alleviates limitations brought by petrochemical resources and protecting the ecological environment.In previous work,combining the advantage of the complete liquid-phase method with stronger carbon chain growth ability of the Cu Fe catalyst,our research group prepared Cu Fe-based slurry catalysts for synthesis of higher alcohols from syngas in slurry reactor.So prepared catalysts showed high total alcohols selectivity and higher alcohols proportion at low temperature（220℃）with low CO conversion.On the basis of the previous research,the effects of Ti and Zn promoter addition ratio,catalyst preparation method,and pre-carbonization time on the structure and performance of Cu Fe catalyst were investigated in this thesis.The Cu Fe-based catalysts were characterized by XRD,H₂-TPR,BET,CO-TPD-MS,and NH₃-TPD-MS.The main contents of combining the characterization results with the activity evaluation data of the catalysts for CO hydrogenation at 220℃and 3 MPa are shown as follows:（1）An appropriate content of Ti promoter helped to reduce the size of Cu⁰ grains,enhance the stability of Cu⁰ grains,increase the content of Cu⁺and Fe C_x in the catalyst,strengthen the synergistic effect between Cu Fe.Moreover,the addition of Ti promoter significantly inhibited the water-gas shift reaction and decreased CO₂ selectivity.Thus,the selectivity of total alcohols and higher alcohols was increased.Among them,CF-Ti_0.6 catalyst with Cu:Fe:Ti=2:1:0.6showed the best catalytic performance,with the total alcohols selectivity of 45.09%and the higher alcohols mass fraction in total alcohols of 54.85%.（2）Zn promoter helped to form more Fe C_x and enhance the carbon chain growth ability of the catalyst.Thus,the selectivity of higher alcohols was improved.Moreover,the addition of Zn promoter made the reducible copper species easily to be reduced.However,the catalyst existed serious carbon deposition and the stability of the catalyst decreased.Among them,CF-Zn_0.5 catalyst with Cu:Fe:Zn=2:1:0.5 showed the best initial activity.The total alcohols selectivity was 48.55%,and the higher alcohols mass fraction in total alcohols reached 57.60%.（3）Compared with physical mixing method,Cu Fe Ti slurry catalyst prepared by sol-gel method and coprecipitation method strengthened the interaction between Ti promoter and Cu Fe,obvously increased the specific surface area and improved the dispersion of Cu Fe active components,which further enhanced the selectivity of total alcohols.Moreover the Cu Fe₂O₄,which is easy to decompose and reduce during the reaction,could promote bimetal synergy,which was beneficial to the production of higher alcohols.The Cu Fe Ti slurry catalyst prepared by sol-gel method promoted the copper species to be easily reduced,and showed a satisfactory synergistic action between Cu Fe.SG-CF-Ti_0.6 catalyst showed optimal catalytic performance,the total alcohols selectivity was 63.58%,and the higher alcohols mass fraction in total alcohol accounted for 36.69%.（4）The Cu Fe Ti slurry catalyst pre-carbonized by syngas shortened the catalyst induction period and improved the stability,but the CO conversion rate was not obvously improved.Among them,the SG-CFTi_0.6-8 catalyst pre-carbonized for 8 hours possessed the best catalytic performance in the reaction process,the total alcohols selectivity reached 68.67%,the higher alcohols mass fraction in total alcohol was 40.32%.