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首页> 外文期刊>Applied Catalysis, A. General: An International Journal Devoted to Catalytic Science and Its Applications >Theoretical study on the cracking reaction catalyzed by a solid acid with zeolitic structure: The catalytic cracking of 1-hexene on the surface of H-ZSM-5
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Theoretical study on the cracking reaction catalyzed by a solid acid with zeolitic structure: The catalytic cracking of 1-hexene on the surface of H-ZSM-5

机译：具有沸石结构的固体酸催化裂化反应的理论研究：H-ZSM-5表面1-己烯的催化裂化

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摘要

The cracking mechanism of 1-hexene over H-ZSM-5 zeolite has been studied by using the ONIOM(B3LYP/6-31G(d,p):UFF) method with an 88T cluster model and the B3LYP/6-31G(d,p) method with a 5T cluster model. The computation results show that the cracking process follows a two-step mechanism involving a carbenium ion intermediate. When the 88T cluster model is used, a stable carbe-nium ion can be found. When the 5T cluster model is used, no stable carbenium ion is obtained, however, the intrinsic reaction coordinate prompts that there exists a carbenium ion intermediate during the reaction process. The theoretical researches indicate that the H-ZSM-5 zeolite environment plays a significant role in stabilizing the hexyl carbenium ion. The adsorbed carbenium ion on the surface of zeolite is an active high energetic species, and the cleavage of the C—C bond on β position occurs easily. The extended zeolite framework has a large effect on the energetics of the adsorbed complexes. The apparent energy barrier of the cracking reaction with 88T cluster model is 104.73 kJ/mol and that with 5T cluster model is 149.50 kJ/mol.
机译：利用ONIOM（B3LYP / 6-31G（d，p）：UFF）方法和88T团簇模型以及B3LYP / 6-31G（d）研究了H-ZSM-5分子筛上1-己烯的裂解机理，p）使用5T群集模型的方法。计算结果表明，裂解过程遵循涉及碳正离子中间体的两步机理。当使用88T团簇模型时，可以找到稳定的碳正离子。当使用5T簇模型时，无法获得稳定的碳正离子，但是，固有反应坐标提示在反应过程中存在碳正离子中间体。理论研究表明，H-ZSM-5沸石环境在稳定己基碳鎓离子方面起着重要作用。沸石表面吸附的碳正离子是高活性的高活性物种，容易发生β位置的CC键的断裂。扩展的沸石骨架对吸附的配合物的能量有很大的影响。 88T团簇模型的裂解反应的表观能垒为104.73 kJ / mol，5T团簇模型的裂解反应的表观能垒为149.50 kJ / mol。

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