کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
10243951 | 47193 | 2005 | 6 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
The activation of CO bond in acetone by Cu+ cations in zeolites: IR studies and quantum chemical DFT calculations
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
مهندسی شیمی
کاتالیزور
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چکیده انگلیسی
Our previous IR studies as well as quantum chemical DFT calculations evidenced that Cu+ ions in zeolites were able to activate CC double bond in alkenes by Ï back donation of d electrons of Cu+ to Ï* antibonding orbitals of alkenes. It resulted in a distinct weakening of CC bond. The present study was undertaken in order to answer the question if Cu+ ions in zeolites were also able to activate another than CC double bond. We studied therefore the interaction of acetone with Cu+ in zeolites CuZSM-5, CuMCM-41, CuX and CuY. IR studies showed a weakening of CO bond and a red shift of IR band by 39-51Â cmâ1. The experiments in which the small doses of acetone were adsorbed as well as desorption studies evidenced that Cu+ bonded acetone more strongly than other adsorption sites, such as hydroxyl groups. DFT modeling of the adsorption of the acetone molecule on copper site gave the information about the function of the zeolite as a host for transition metal cationic sites and as an electron reservoir. Calculated values of electron affinity and HOMO energy allowed to explain that, on the basis of the charge distribution analysis, electrons flowed from the acetone molecule to the copper site, so that the molecule was positive. It was evidenced by the analysis of the charge distribution. Therefore, the activation upon adsorption has been justified by the electronic structure of the molecule, its electron affinity as well as the ability of the site to Ï back donation. Moreover, the calculated value of the red shift of the IR band of the activated CO bond was similar as experimental one.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Catalysis Today - Volume 101, Issue 2, 30 March 2005, Pages 117-122
Journal: Catalysis Today - Volume 101, Issue 2, 30 March 2005, Pages 117-122
نویسندگان
J. Datka, P. Kozyra, E. Kukulska-ZajÄ
c, W. Kobyzewa,