硅烷化和有机弱碱改性Mo/HZSM-5对甲烷无氧芳构化催化性能的影响

Effects of silylation and organic weak alkali modified Mo/HZSM-5 on catalytic performance in non-oxidative aromatization of methane reaction

催化剂的形态及晶粒的组装对其催化性能有重要影响,采用硅烷化处理对Mo基催化剂表面酸性进行毒化制备了核壳型(Mo基催化剂@Silicalite-1)复合材料;采用四丙基氢氧化铵或正丁胺有机弱碱对Mo/HZSM-5进行刻蚀,然后经过脱硅再结晶分别制备了表面富硅型中空结构Mo/HZSM-5微球和表面富硅、核内含有多级孔道的Mo/HZSM-5微球。采用XRD、TEM、N_2等温吸脱附和NH_3-TPD对催化剂结构进行表征,并考察了三种不同后处理方法对Mo基催化剂在甲烷无氧芳构化反应中催化性能的影响。硅烷化和有机碱处理均能够调变Mo/HZSM-5催化剂的表面酸性,而经有机碱处理以后,催化剂结晶度、介孔比表面积和孔容均具有不同程度的增加,三种不同后处理方法均能改善Mo/HZSM-5催化剂的反应稳定性,对产物的分布也产生了显著影响。

The morphology of catalysts and the assembly of catalysts particles have important influence on the catalytic performance. The core-shell composite materials with Mo/HZSM-5 as the core and silicalite-1 zeolite as shell were prepared by silylation. The hollow structure of Mo/HZSM-5 catalyst microspheres with rich silicon surface and hierarchical pore structure was prepared by the weak organic alkali etching method. The structure of Mo/HZSM-5 were characterized by XRD, TEM, N2-adsorption-desorption and NH3-TPD. The surface acidity of Mo/HZSM-5 catalysts was modulated by silylation or the weak organic alkali etching method. The crystallinity, mesoporous specific surface and pore volume of Mo/HZSM-5 catalyst increased by the weak organic alkali etching method. The catalytic performance of Mo/HZSM-5 catalysts via different post-treatment was investigated, the results show that the catalyst stability could be improved and the distribution of the product has a significant influence in non-oxidative aromatization of methane reaction.