摘要
采用有机胺模板剂合成的ＨＺＳＭ－５沸石，在催化甲醇制汽油反应或负载ＭｏＣｌ５过程中都发生了Ａｌ组分由外表面向内孔道的表面迁移，而无胺“直接法”合成的样品，外表面上的非骨架铝并不发生向内孔道的迁移。不同的表面迁移影响着Ｍｏ／ＺＳＭ－５在甲醇制汽油（ＭＴＧ）反应中的催化性质。
Different catalytic behaviors of MoCl_5 loaded on two samples of HZSM_5 zeolite,HZSM_5(34.5) synthesized using TPA template and HZSM_5(22) without organic template,were revealed in MTG reaction and interpreted in the terms of different surface state on catalysts.Both Mo and Al atoms/species on the external surface of Mo/ZSM_5(345)were found to migrate into channels during the reaction.Migration of Mo made both strength and amount of L acid sites increased in the channels,while migration of Al caused the density of B acid sites increased,and increased the strength of B acid sites through the syneristic electronic effect of B and L acid sites.Consequently the acid distribution of the catalyst was changed obviously resulting in that the propotion of aromatic products was almost doubled in the MTG reaction over Mo/ZSM_5(34.5).On the surface of Mo/ZSM5(22),however,only migration of Mo occurred toward the channels,while the Al atoms of external surface reinserted into intercrystalline defects and only changed their coordination state instead of migration.So the acid strength of Mo/ZSM5(22) was not enhanced.Oppositely the migrating Mo species blocked the channels and decreased both the yield of aromatic products and the activity of catalyst in MTG reaction.
出处
《石油学报（石油加工）》
EI
CAS
CSCD
北大核心
1998年第1期46-51,共6页
Acta Petrolei Sinica(Petroleum Processing Section)
