| ZSM-5催化丙烯芳构化反应构效关系及反应特性 | |
| Structure-Activity Relationship and Reaction Characteristics of Propene Aromatization Catalyzed by ZSM-5 | |
| 摘要: 甲醇两步制芳烃反应中低碳烯烃芳构化反应稳定性优异，为分析其内在机制，制备了不同硅铝比（nSiO2/nAl2O3）及Zn负载量的ZSM-5催化剂，以丙烯芳构化为模型反应，分析ZSM-5表面酸性对低碳烯烃芳构化反应性能的影响规律，并探究反应微观特性。发现当硅铝比由150降至75时，增加的酸密度促进了烯烃氢转移芳构化过程，使芳烃选择性由31.0%增至34.4%，但丙烯直接参与的氢转移过程也被强化，使丙烷产物选择性由28.2%增至36.0%。引入Zn助剂可将部分Brønsted酸转变为Zn-Lewis酸，强化烯烃脱氢芳构化过程，使芳烃选择性进一步显著增加到62.4%。丙烯芳构化过程中芳烃烷基化深度比甲醇芳构化过程低，提升总芳烃选择性的同时，也明显抑制了难溶性积碳的形成，使反应稳定性明显提升。由此得出，甲醇两步制芳烃过程中甲醇制低碳烯烃过程对甲醇的预先消耗，抑制了低碳烯烃芳构化反应芳烃产物的深度烷基化，是该反应表现出优异稳定性的重要原因。 | |
| 关键词: 低碳烯烃 芳构化 ZSM-5分子筛 催化性能 酸性质 | |
| 基金项目: 国家自然科学基金（No.21978191，21878207）、国家重点研发计划（No.2018YFB0604901）和山西省重点研发计划国际合作项目（No.201803D421011）资助 | |
| Abstract: Aromatization of light olefins in methanol to aromatics via a two-step route showed better catalytic stability. To analyze the intrinsic mechanism, a series of ZSM-5 catalysts with different SiO2/Al2O3 ratios and Zn modified were prepared. Then propene aromatization, as the model reaction, was performed to analyze the effects of acidity on aromatization of light olefins and explore the reaction mechanism. The results illustrated that the increased acid density was in favor of the hydrogen transfer process, resulting in an increase of aromatics selectivity from 31.0% to 34.4% with the SiO2/Al2O3 ratio decreased from 150 to 75. Meanwhile, an increase in acid density will cause more propene to directly participate in the hydrogen transfer reaction to produce propane which was enhanced from 28.2% to 36.0%. Further introducing Zn could transform some Brønsted acid sites into Zn-Lewis acid sites, the aromatics selectivity was further significantly increased to 62.4% with the enhancement of the alkenes dehydrogenation aromatization process. Compared with direct methanol aromatization, propene aromatization had a less deep alkylation process, which not only increased the aromatics selectivity, but also inhibited the formation of insoluble coke, and improved the catalytic stability. These results suggested that the pre-conversion of methanol in methanol to light olefins was an important reason for the high catalytic stability of two-step methanol conversions, which inhibited the deep alkylation of aromatics in the subsequent aromatization process. | |
| Keywords: light olefins aromatization ZSM-5 zeolites catalytic performance acidic properties | |
| 投稿时间：2022-03-07 修订日期：2022-04-01 | |
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| 任坤,张亮亮,李忠,付廷俊.ZSM-5催化丙烯芳构化反应构效关系及反应特性[J].无机化学学报,2022,38(6):1090-1102. | |
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