协同高效的铁催化剂构建及其在CO_2加氢制高碳烃中的应用

采用物理掺杂法制备了生物质灰分作为助剂的融铁催化剂,通过X射线衍射、透射电镜、穆斯堡尔谱等方法对催化剂进行了表征,并在固定床反应器中对其CO_2加氢制高碳烃的催化性能进行了评价。结果表明,与不含生物质灰分助剂的催化剂相比,添加助剂的融铁催化剂粒径较小且尺寸分布较窄,Fe_3O_4、Fe_5C_2、Fe_3C和α-Fe四相协同共存,进而促使逆水气变换反应与C-C偶联的串联反应高效进行,在有效抑制甲烷生成的同时,可明显提升高碳烃选择性。高碳烃产物以C_(4-18)的烃类为主,在300℃、1. 0 MPa、4800 h~(-1)、H~2/CO_2=3. 0、助剂添加量为5%(质量分数)的条件下,其在烃类产物中选择性最高可达73. 9%。

Construction of synergistic and efficient iron-based catalysts for hydrogenation of CO2 to higher hydrocarbons

A series of fused iron (FI) catalysts promoted with biomass ash were prepared by physical mixing method and characterized by X-ray diffraction, transmission electron microscopy and Mossbauer spectroscopy. The catalytic performance of CO₂ hydrogenation to higher hydrocarbons was evaluated in a fixed bed reactor. The results show that compared with the catalyst without biomass ash (B-ash), the fused iron catalysts promoted with biomass ash have smaller particle size and narrower size distribution, and the four phases of Fe₃O₄, Fe₅C₂, Fe₃C as well as α-Fe coexist in synergy. Thus, the tandem reaction of reverse water gas shift (RWGS) and C-C coupling proceed efficiently, and the selectivity of higher hydrocarbons is significantly improved while methane formation is effectively suppressed. Among the products, C_4-18 hydrocarbons are dominant. The C_4-18 hydrocarbons' selectivity in all hydrocarbons reaches 73.9% at the conditions of 300℃, 1.0 MPa, 4800 h^-1, H₂/CO₂=3.0 as well as the additive amount of the promoter is 5% (mass ratio).