Synthesis of Hierarchical ZSM-5 Zeolite and Performance of Its Mo-Based Catalyst for Methane Dehydroaromatization
Synthesis of Hierarchical ZSM-5 Zeolite and Performance of Its Mo-Based Catalyst for Methane Dehydroaromatization
复制标题
多级孔ZSM-5沸石的合成及其钼基甲烷脱氢芳构化催化剂的性能
DOI：
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发表时间：
2009
影响因子：
16.5
通讯作者：
Wang, JQ
中科院分区：
文献类型：
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作者：
Yang, JH;Lu, JM;Yu, SX;Chu, NB;Li, G;Wang, JQ
以多壁碳纳米管为第二模板剂，首先用浓盐酸回流纯化碳纳米管24 h，直到碳纳米管中的杂质在盐酸中消失，再用盐酸回流纯化碳纳米管24 h，合成了一种分级结构的类球形ZSM-5沸石然后，将设置的纳米管加入到ZSM-5的合成溶液中，所述ZSM-5的合成溶液通过混合H2O、原硅酸四乙酯、Al（C3 H8 O）3、和四丙基氢氧化铵（TPAOH）的混合物，然后在不同温度下进行结晶，所得产物用X射线衍射、傅立叶变换红外光谱、透射电子显微镜、结果表明，合成的ZSM-5分子筛粒径均匀，在300-400 nm之间，其为类球形聚集体，具有由许多20-40 nm的ZSM-5纳米管构成的分级结构。将分级ZSM-5沸石改性形成Mo/HZSM-5催化剂，考察了改性Mo/HZSM-5催化剂对甲烷脱氢芳构化反应的催化性能，结果表明，改性Mo/HZSM-5催化剂的甲烷转化率高达19%，使用寿命较长，甲烷转化率保持在10结果表明，分级结构有利于催化剂性能的提高，这是由于微孔和中孔的共同存在.
A hierarchical spherical-like ZSM-5 zeolite was synthesized using multiwall carbon nanotubes as secondary template.First, the nanotubes were purified by reflux with concentrated hydrochloric acid for 24 h.This purification step was repeated until the hydrochloric acid was no longer colored by impurities from the nanotubes(typically 3-4 times).Then the disposed nanotubes were added into the synthesis solution of ZSM-5, which was obtained by mixing H2O, tetraethylorthosilicate, Al(C3H8O)3, and tetrapropylammonium hydroxide(TPAOH).Afterward, this mixture was subjected to crystallization at varying temperatures.The obtained products were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, and nitrogen adsorption analysis.The results indicated that ZSM-5 zeolite with uniform size of 300-400 nm was synthesized, and it was spherical-like aggregates and has hierarchical structure constructed by many ZSM-5 nanotubes of 20-40 nm.The hierarchical ZSM-5 zeolite was modified to form a Mo/HZSM-5 catalyst, and its catalytic performance for methane dehydroaromatization was investigated.The modified Mo/HZSM-5 catalyst exhibited CH4 conver-sion as high as 19% and better life time.The CH4 conversion was kept at 10% even when the reaction time was 24 h.It is suggested that hierarchical structure was favorable for the enhancement of catalyst performance, which is due to the presence of both micropores and mesopores.