在不同的Si/Al比率和温度下,H-BEA热石的Al分布和结构稳定性:一项第一原则研究
Changdong Li1,2,3, Xiuqin Dong1,2,3, Haipeng Yu1,2,3
1Key Laboratory for Green Chemical Technology of Ministry of Education, R&D Center for Petrochemical Technology, Tianjin University, Tianjin 300072, China. yzhyu@tju.edu.cn.
Physical chemistry chemical physics : PCCP
|September 4, 2023
概括
合成温度和与的比率影响H-BEA热中的分布,影响催化活性. 脱光主要发生在T7和T9部位,而T1和T2部位更有抵抗力.
科学领域:
- 材料科学 材料科学 材料科学
- 催化剂是一种催化剂.
- 计算化学计算化学
背景情况:
- 由于其独特的特性,β-烯 (BEA) 在酸催化中至关重要.
- 了解H-BEA中的 (Al) 分布是优化热酸催化剂性能的关键.
- 在脱光过程中形成西拉诺,会影响石的稳定性和反应性.
研究的目的:
- 研究合成温度和Si/Al比对H-BEA中的Al分布的影响.
- 为了研究非发光的BEA热石中西拉诺的形成和结构.
- 阐明不同T位点在Al替代和脱光中的作用.
主要方法:
- 使用密度函数理论 (DFT) 的计算.
- 模拟集中在T1,T2,T7和T9晶体学位点上.
- 替代能量的分析和西兰醇的结.
主要成果:
- 合成温度显著改变了Al分布和T位的比例.
- T7和T9位点主导H-BEA结构,随着合成温度的提高而下降.
- 低Si/Al比率 (<8) 有利于Al-O-Si-O-Al物种的形成,特定的含Al的组稳定结构.
- 在非化BEA中的西拉诺,呈现出明显的西拉诺方向,并形成四个键.
- 与T1和T2网站相比,T7和T9网站更容易受到脱光.
结论:
- 在H-BEA中,Al分布和T位点占用可通过合成条件进行调整.
- 特定的Al配置稳定H-BEA,并促进Si(2Al,2Si) 物种的形成.
- 不发光的BEA热石对T1和T2位点的修改具有挑战,因为它们对非发光的抵抗性.
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