无溶剂法原位合成多级孔Fe@MFI催化剂对费托合成反应性能的影响

Effect of in-situ synthesis of hierarchical Fe@MFI catalyst via solvent-free method on the performance of Fischer-Tropsch synthesis

采用联合浸渍法-无溶剂法制备了一系列负载型和封装型催化剂,通过XRD、N_2吸附-脱附、NH_3-TPD、SEM和TEM等手段对催化剂进行物化性能表征,并考察了所制备催化剂对合成气直接转化成汽油烃类的反应性能的影响。表征结果显示,采用无溶剂法成功合成了具有MFI骨架结构的Fe@MFI催化剂,Fe粒子较好地封装在沸石内部;催化剂的孔结构和酸中心的协调作用是影响费托合成产物分布的主要因素。实验结果表明,具有多级孔结构的Fe@MFI催化剂展现出良好的汽油选择性,离子交换作用有效改善了H型Fe@HZSM-5催化剂的孔结构和表面酸性,使得汽油和异构烷烃的选择性得到了明显提升。

A series of encapsulated catalysts were prepared by a combination of impregnation and solvent-free method. The physicochemical properties of the catalysts were characterized by XRD,N2 adsorption-desorption,NH3-TPD,SEM and TEM techniques,and the reaction performance of as-prepared catalysts on direct synthesis of gasoline-hydrocarbons from syngas was measured as well.These results showed that Fe@MFI catalyst with MFI skeleton structure was successfully synthesized by solvent-free strategy and the iron particles were well encapsulated inside the zeolite cage. The coordination between the pore structure and the acid center of the catalyst was the main factor affecting the distribution of products of Fischer-Tropsch synthesis reaction. The results showed that Fe@MFI catalyst with hierarchical pore structure exhibited good gasoline selectivity. Moreover,for H-type Fe@HZSM-5 catalyst,the selectivity to gasoline and isoparaf?n was signi?cantly improved,due to the fact that the ion exchange effectively improved the pore structure and the surface acidity.