کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1411683 1501875 2008 8 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Interactions of amino acids with H-ZSM-5 zeolite: An embedded ONIOM study
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آلی
پیش نمایش صفحه اول مقاله
Interactions of amino acids with H-ZSM-5 zeolite: An embedded ONIOM study
چکیده انگلیسی

The adsorption of glycine and l-alanine on the H-ZSM-5 zeolite has been studied at an embedded ONIOM (MP2/6-31G(d,p):UFF) level of theory. The most stable adsorption structure involves ion-pair interactions between the protonated amino acid and the anionic zeolite framework. The adsorption energy is computed to be −31.3 and −34.8 kcal/mol for glycine and l-alanine, respectively. Two hydrogen bonded complexes are identified: one is the cyclic double hydrogen bonded complex via the interactions of the carboxyl group and the zeolite acid site having adsorption energies of −25.4 and −30.0 kcal/mol for glycine and l-alanine, respectively. The second is the hydrogen bonded complex via the interactions of the hydroxyl group and the zeolite acid site having weak interaction energies, −20.7 and −23.9 kcal/mol for glycine and l-alanine, respectively. The zwitterion form is not found in the acidic H-ZSM-5 due to the acid–base reaction, but the glycine zwitterion is found to be stably adsorbed on the Na-ZSM-5 with the adsorption energy of −24.8 kcal/mol. In addition to the interactions with the Brønsted acid site of the zeolite, the interactions with the nearby oxygen framework and van der Waals interactions with the zeolite walls are also found to be important for stabilizing the adsorbed amino acids and zwitterion, suggesting the role of the zeolite framework as a “solid solvent molecule”.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Molecular Structure - Volume 889, Issues 1–3, 29 October 2008, Pages 81–88
نویسندگان
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