کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
60524 | 47535 | 2016 | 9 صفحه PDF | دانلود رایگان |
• Adsorption of linear pentenes in H-ZSM-5 at 323 K yields an almost equally stable π-complex and covalently bound alkoxide.
• The transformation from the π-complex to the chemisorbed complex is activated by a free energy in the range of 33–42 kJ/mol.
• The stability has been unravelled by contemporary static and dynamic first principle methods.
• Theoretical calculations can predict the stability of elusive and reactive intermediates in zeolite catalysis.
Adsorption of linear pentenes in H-ZSM-5 at 323 K is investigated using contemporary static and molecular dynamics methods. A physisorbed complex corresponding to free pentene, a π-complex and a chemisorbed species may occur. The chemisorbed species can be either a covalently bonded alkoxide or an ion pair, the so-called carbenium ion. Without finite temperature effects, the π-complex is systematically slightly more bound than the chemisorbed alkoxide complex, whereas molecular dynamics calculations at 323 K yield an almost equal stability of both species. The carbenium ion was not observed during simulations at 323 K. The transformation from the π-complex to the chemisorbed complex is activated by a free energy in the range of 33–42 kJ/mol. Our observations yield unprecedented insights into the stability of elusive intermediates in zeolite catalysis, for which experimental data are very hard to measure.
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Journal: Journal of Catalysis - Volume 340, August 2016, Pages 227–235