{"title":"解密正庚烷在 H-ZSM-5 沸石上脱氢环化的反应机理网络","authors":"Guangyuan He , Donghai Mei","doi":"10.1016/j.jcat.2024.115623","DOIUrl":null,"url":null,"abstract":"<div><p>The dehydrocyclization of naphtha is a process of great significance in the petrochemical industry, as it enables the production of valuable aromatics. While experimental studies have demonstrated the catalytic activity of H-ZSM-5 zeolite in converting alkanes to aromatics, there is a notable absence of theoretical investigations into the reaction mechanisms involved in the dehydrocyclization of naphtha. Herein, the conversion of n-heptane to toluene over H-ZSM-5 zeolite was examined using first-principles density functional theory (DFT) calculations. The dehydrocyclization process of n-heptane involves several key steps, including dehydrogenation, isomerization, and cyclization. Specifically, the dehydrogenation of n-heptane produces 1-heptene, 2-heptene, and 3-heptene, which then undergo various dehydrocyclization pathways leading to the formation of toluene: (i) C1-C5 ring closure of 1-heptene; (ii) C1-C6 ring closure of 1-heptene; (iii) C2-C6 ring closure of 2-heptene; (iv) dehydrogenation of 3-heptene to heptadiene, with C1-C5 ring closure; and (v) dehydrogenation of 3-heptene to heptatriene, with C1-C6 ring closure, followed by sequential ring expansion and/or dehydrogenation to toluene. The DFT results indicate that the dehydrogenation steps are energetically demanding, with the conversion of n-heptane to toluene via 1-heptene identified as the most favorable cyclization route. This theoretical investigation provides valuable insights into the fundamental mechanisms underlying the dehydrocyclization of naphtha for the production of aromatics, with potential implications for the development of more efficient catalytic processes in the petrochemical industry.</p></div>","PeriodicalId":346,"journal":{"name":"Journal of Catalysis","volume":null,"pages":null},"PeriodicalIF":6.5000,"publicationDate":"2024-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Deciphering reaction mechanism network of n-heptane dehydrocyclization over H-ZSM-5 zeolite\",\"authors\":\"Guangyuan He , Donghai Mei\",\"doi\":\"10.1016/j.jcat.2024.115623\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>The dehydrocyclization of naphtha is a process of great significance in the petrochemical industry, as it enables the production of valuable aromatics. While experimental studies have demonstrated the catalytic activity of H-ZSM-5 zeolite in converting alkanes to aromatics, there is a notable absence of theoretical investigations into the reaction mechanisms involved in the dehydrocyclization of naphtha. Herein, the conversion of n-heptane to toluene over H-ZSM-5 zeolite was examined using first-principles density functional theory (DFT) calculations. The dehydrocyclization process of n-heptane involves several key steps, including dehydrogenation, isomerization, and cyclization. Specifically, the dehydrogenation of n-heptane produces 1-heptene, 2-heptene, and 3-heptene, which then undergo various dehydrocyclization pathways leading to the formation of toluene: (i) C1-C5 ring closure of 1-heptene; (ii) C1-C6 ring closure of 1-heptene; (iii) C2-C6 ring closure of 2-heptene; (iv) dehydrogenation of 3-heptene to heptadiene, with C1-C5 ring closure; and (v) dehydrogenation of 3-heptene to heptatriene, with C1-C6 ring closure, followed by sequential ring expansion and/or dehydrogenation to toluene. The DFT results indicate that the dehydrogenation steps are energetically demanding, with the conversion of n-heptane to toluene via 1-heptene identified as the most favorable cyclization route. This theoretical investigation provides valuable insights into the fundamental mechanisms underlying the dehydrocyclization of naphtha for the production of aromatics, with potential implications for the development of more efficient catalytic processes in the petrochemical industry.</p></div>\",\"PeriodicalId\":346,\"journal\":{\"name\":\"Journal of Catalysis\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":6.5000,\"publicationDate\":\"2024-06-26\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of Catalysis\",\"FirstCategoryId\":\"92\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0021951724003361\",\"RegionNum\":1,\"RegionCategory\":\"化学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"CHEMISTRY, PHYSICAL\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Catalysis","FirstCategoryId":"92","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0021951724003361","RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
Deciphering reaction mechanism network of n-heptane dehydrocyclization over H-ZSM-5 zeolite
The dehydrocyclization of naphtha is a process of great significance in the petrochemical industry, as it enables the production of valuable aromatics. While experimental studies have demonstrated the catalytic activity of H-ZSM-5 zeolite in converting alkanes to aromatics, there is a notable absence of theoretical investigations into the reaction mechanisms involved in the dehydrocyclization of naphtha. Herein, the conversion of n-heptane to toluene over H-ZSM-5 zeolite was examined using first-principles density functional theory (DFT) calculations. The dehydrocyclization process of n-heptane involves several key steps, including dehydrogenation, isomerization, and cyclization. Specifically, the dehydrogenation of n-heptane produces 1-heptene, 2-heptene, and 3-heptene, which then undergo various dehydrocyclization pathways leading to the formation of toluene: (i) C1-C5 ring closure of 1-heptene; (ii) C1-C6 ring closure of 1-heptene; (iii) C2-C6 ring closure of 2-heptene; (iv) dehydrogenation of 3-heptene to heptadiene, with C1-C5 ring closure; and (v) dehydrogenation of 3-heptene to heptatriene, with C1-C6 ring closure, followed by sequential ring expansion and/or dehydrogenation to toluene. The DFT results indicate that the dehydrogenation steps are energetically demanding, with the conversion of n-heptane to toluene via 1-heptene identified as the most favorable cyclization route. This theoretical investigation provides valuable insights into the fundamental mechanisms underlying the dehydrocyclization of naphtha for the production of aromatics, with potential implications for the development of more efficient catalytic processes in the petrochemical industry.
期刊介绍:
The Journal of Catalysis publishes scholarly articles on both heterogeneous and homogeneous catalysis, covering a wide range of chemical transformations. These include various types of catalysis, such as those mediated by photons, plasmons, and electrons. The focus of the studies is to understand the relationship between catalytic function and the underlying chemical properties of surfaces and metal complexes.
The articles in the journal offer innovative concepts and explore the synthesis and kinetics of inorganic solids and homogeneous complexes. Furthermore, they discuss spectroscopic techniques for characterizing catalysts, investigate the interaction of probes and reacting species with catalysts, and employ theoretical methods.
The research presented in the journal should have direct relevance to the field of catalytic processes, addressing either fundamental aspects or applications of catalysis.