燃料化学学报（中英文）2025，Vol.53Issue(4)：493-503,11.DOI:10.3724/2097-213X.2024.JFCT.0023
不同载体对CO2加氢制烯烃Fe基催化剂反应性能的影响
Effects of different supports on catalytic performance of iron-based catalysts in CO2 hydrogenation to olefins
摘要
Abstract
The combustion of carbon-based fossil fuels(coal,oil and natural gas)for power generation is accompanied by large emissions of anthropogenic CO2 into the atmosphere,leading to global climate change and ocean acidification.Direct conversion of CO2 and H2 via reverse water-gas shift(RWGS)and subsequent Fischer-Tropsch synthesis(FTS)is well-known as a sustainable alternative for the synthesis of olefins,replacing conventional petrochemical process of naphtha stream-cracking or separation.The structure and properties of the inert support have significant effects on the activity,selectivity and stability of the catalyst,but there are few reports about the effects of different supports on the active phase formation and olefins selectivity of Fe-based catalysts in CO2 hydrogenation.Therefore,the study of the influence of different support on the CO2 hydrogenation performance of Fe-based catalysts has important guiding significance for the design and synthesis of efficient catalysts.Herein,the Fe-based catalysts with different supports(Q-30,Q-10,Al2O3 and TiO2)were prepared by impregnation method,and the effects of supports on the catalytic activity and olefins selectivity in CO2 hydrogenation were studied.The catalyst samples were characterized by N2 adsorption-desorption,XRD,HAADF-STEM,TEM,XPS,H2-TPR,CO2-TPD and NH3-TPD.The N2 adsorption-desorption isotherms of Q-10,Q-30,Al2O3 and TiO2 support were all classified as type IV by IUPAC.At the same time,there are hysteresis loops in the absorption and desorption curves of these samples,indicating the existence of mesoporous structures.Combined with the reaction data,it can be seen that the specific surface area and pore structure of the support are not regularly correlated with the catalyst activity and olefin selectivity.No XRD diffraction peak attributed to Fe phase was observed in all fresh catalysts.Combined with the results of XPS and STEM-EDX of the fresh catalysts,it can be inferred that this is due to the low content of iron oxide and good dispersion.In the TEM images of the catalysts after the reaction,a large number of lattice fringes belonging to the(501)crystal face of Fe5C2 phase were observed in both FeNa/Al2O3 and FeNa/TiO2 catalysts,while no Fe5C2 phase was found in FeNa/Q-30 and FeNa/Q-10 catalysts.XRD peaks of Fe5C2 species appeared on both FeNa/Al2O3 and FeNa/TiO2 catalysts after reaction at 2θ=40°-50°,indicating that the Fe2O3 species was partially carbonized to Fe5C2 after reaction.However,FeNa/Q-30 and FeNa/Q-10 catalysts did not have significant iron carbide diffraction peaks.This may indicate that the iron oxide in FeNa/Al2O3 and FeNa/TiO2 catalysts are more likely to be reduced and carbonized to produce Fe5C2.The catalytic results show that the Fe-based catalyst with Al2O3 as support has the highest activity,highest olefins selectivity,and good stability.The single-pass CO2 conversion is 28.2%,the selectivity of all olefins reach 68.1%,and the selectivity of long chain olefins is 45.1%.The reduction and carburization of iron species were promoted in the high dispersed FeNa/Al2O3 catalyst,due to the moderate metal-support interaction.Meanwhile,it exhibits strongest CO2 adsorption ability and more surface acid sites,which can enhance CO2 activation and C-C coupling process.The chain growth factor(α)was as high as 0.74.The CO2 conversion of FeNa/TiO2 catalyst was 24.2%,but showed higher CO by-product selectivity and lower C2+olefin selectivity than FeNa/Al2O3.In contrast,the activity of Fe-based catalysts with SiO2(Q-30,Q-10)support are very low(～10%),and the products are mainly CO and methane from RWGS and CO2 methanation reaction,probably due to the low reduction and carburization ability,low CO2 adsorption ability and less acid sites of catalysts.关键词
CO2加氢/Fe基催化剂/载体/烯烃/酸性位Key words
CO2 hydrogenation/iron-based catalysts/supports/olefins/acid sites分类
化学化工引用本文复制引用
潘新安,张鹏,何若南,韩志华,韦慧,徐晓颖,秦绍东,刘意..不同载体对CO2加氢制烯烃Fe基催化剂反应性能的影响[J].燃料化学学报（中英文）,2025,53(4):493-503,11.基金项目
The project was supported by National Natural Science Foundation of China(22078006).国家自然科学基金(22078006)资助 （22078006）
