四乙基氢氧化铵后晶化处理对ZSM-5分子筛结构及其甲醇制丙烯催化性能的影响

采用四乙基氢氧化铵（TEAOH）溶液对以四丙基氢氧化铵（TPAOH）为模板剂合成的高硅ZSM 5分子筛进行“后晶化”处理，制得晶内扩孔的多级孔ZSM 5分子筛。采用X 射线衍射仪（XRD）、N2物理吸附、透射电子显微镜（TEM）、氨气程序升温脱附仪（NH3 TPD）等对母体及改性后的ZSM 5分子筛进行物化性能表征，并采用固定床微反应装置考察其在甲醇制丙烯（MTP）反应中的催化性能。结果表明，TEAOH后晶化处理使高硅ZSM 5分子筛形成晶内介孔，在相对结晶度保留较高的同时，介孔孔容增加超过50%，成为具有微、介孔结构的多级孔分子筛。在反应温度480℃、反应压力01 MPa、甲醇/水质量比1/1、甲醇质量空速45 h-1的条件下，多级孔ZSM 5分子筛的丙烯碳基收率比母体ZSM 5分子筛略有提高，寿命由改性前的25 h增加至100 h。

Enhancing the Catalytic Performance of ZSM-5 Zeolite in Methanol to Propene Reaction via Recrystallization in the Presence ofTetraethylammonium Hydroxide

Highly siliceous ZSM 5 zeolite synthesized with tetrapropylammonium hydroxide (TPAOH) as structure directing agent was post treated by tetraethylammonium hydroxide (TEAOH), to obtain intracrystalline mesopores. Both ZSM 5 and hierarchical ZSM 5 zeolites were characterized by X ray diffraction (XRD), N2 adsorption, transmission electron microscope (TEM) and NH3 temperature programmed desorption (NH3 TPD). Methanol to propylene reaction over ZSM 5 and hierarchical ZSM 5 zeolites was carried out in a fixed bed microreactor. It is shown that TEAOH treatment of high siliceous ZSM 5 generates the intracrystalline mesopore by more than 50% with high 〖JP2〗relative crystallinity because of the participation of tetraethylammonium ion (TEA+). Under the following operating conditions: T=480℃, p=01 MPa, m(Methanol)/m(H2O)=〖JP〗1/1 and methanol mass hourly space velocity MHSV=45 h-1, the yield of propylene for hierarchical ZSM 5 zeolite is much higher than that of ZSM 5. Moreover, it exhibits long catalytic lifespan from 25 hours to 100 hours.