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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Periodic Quantum Chemical Studies on Anhydrous and Hydrated Acid Clinoptilolite
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Periodic Quantum Chemical Studies on Anhydrous and Hydrated Acid Clinoptilolite

机译：无水和水合酸斜发沸石的周期性量子化学研究

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摘要

Periodic quantum chemistry methods as implemented in the CRYSTAL09 code were considered to study acid clinoptilolite (HEU framework type), both anhydrous and hydrated. The most probable location of acid sites and water molecules together with other structural details has been the object of particular attention. Calculations were performed at hybrid and pristine DFT levels of theory with a VDZP quality basis set in order to compare performances. It arises that PBE0 provides the best agreement with experimental data as concerns structural features and the most stable Al distribution in the framework. The role of the water molecule distribution in the stability of the systems, the most probable structure that they induce in the material, and their eventual influence on further chemical modification processes, such as dealumination, are discussed in detail. Results show that, apart from the usually considered interactions of water molecules with the zeolite framework, that is, a H-bond with Bro?nsted acid sites and coordination with framework Al as Lewis ones, it is necessary to consider cooperation of other weaker effects so as to fully understand the hydration effect in this kind of materials.
机译：考虑使用CRYSTAL09代码中的周期性量子化学方法来研究无水和水合酸性斜发沸石（HEU骨架类型）。酸位和水分子最可能的位置以及其他结构细节一直是特别关注的对象。为了比较性能，在具有VDZP质量基础的混合DFT和原始DFT理论水平上进行了计算。由此看来，PBE0在结构方面和框架中最稳定的Al分布方面提供了与实验数据的最佳一致性。详细讨论了水分子分布在系统稳定性中的作用，它们在材料中诱导的最可能的结构以及它们最终对进一步的化学修饰过程（如脱铝）的影响。结果表明，除了通常认为的水分子与沸石骨架的相互作用（即具有布朗斯台德酸位点的氢键和与骨架铝（如路易斯）的配位）外，还必须考虑其他弱效应的协同作用以便充分了解这类材料的水合效果。

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