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首页> 外文期刊>Reaction kinetics,mechanisms and catalysis >The comparison of mesoporous HZSM-5 zeolite catalysts prepared by different mesoporous templates and their catalytic performance in the methanol to aromatics reaction
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The comparison of mesoporous HZSM-5 zeolite catalysts prepared by different mesoporous templates and their catalytic performance in the methanol to aromatics reaction

机译：不同介孔模板制备的介孔HZSM-5分子筛催化剂的比较及其在甲醇制芳烃反应中的催化性能

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摘要

Three kinds of mesoporous HZSM-5 were synthesized successfully by using a hydrothermal methodology with different mesoporous templates, namely, hexadecyl trimethyl ammonium bromide (CTAB), dimethyl distearylammonium chloride (DDAC) and carbon nanotube (CNT). The differences in crystallinity, textural property and acidity among these micro-mesoporous composite molecular sieves were characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy techniques, transmission electron microscopy, nitrogen adsorption and NH3 temperature programmed desorption. The catalytic performances of these mesoporous HZSM-5 zeolites were evaluated by methanol to aromatics (MTA) reaction, and the conventional microporous HZSM-5 was also tested in this reaction for comparison. The results show that mesoporous HZSM-5 zeolite synthesized with CNT mesoporous templates exhibited the highest BTX yields and lowest rate of carbon deposition in MTA reaction among all catalysts. This improved catalytic performance is mainly attributed to not only the well-preserved strong acid sites, which would provide enough active sites for methanol aromatization, but also the generated intra-crystalline mesopores, which would facilitate the access of reactant to the active sites and improve the mass transfer of products. However, mesoporous HZSM-5 synthesized with CTAB and DDAC mesoporous templates did not present improved catalytic performances due to their disconnected micro-mesopores and inadequate strong acidic sites.
机译：采用水热方法成功地合成了三种介孔模板HZSM-5，分别为十六烷基三甲基溴化铵（CTAB），二甲基二硬脂基氯化铵（DDAC）和碳纳米管（CNT）。通过粉末X射线衍射，傅立叶变换红外光谱技术，透射电子显微镜，氮吸附和NH3程序升温脱附，表征了这些微中孔复合分子筛在结晶度，质构性质和酸度上的差异。这些中孔HZSM-5沸石的催化性能通过甲醇制芳烃（MTA）反应进行了评估，并且在该反应中还测试了常规的微孔HZSM-5进行比较。结果表明，在所有催化剂中，以CNT介孔模板合成的介孔HZSM-5沸石在MTA反应中表现出最高的BTX产率和最低的碳沉积速率。改善的催化性能主要归因于不仅保存完好的强酸位点（可以为甲醇芳构化提供足够的活性位点），还归因于生成的晶体内中孔，这将有助于反应物进入活性位点并改善产品的大规模转移。然而，CTAB和DDAC介孔模板合成的介孔HZSM-5由于其不连续的微介孔和不足的强酸性位而没有表现出改善的催化性能。

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