کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
9617771 | 49168 | 2005 | 6 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Nature of cadmium cationic sites in cadmium-modified ZSM-5 zeolite according to the DRIFT studies of molecular hydrogen adsorption
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
مهندسی شیمی
کاتالیزور
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
The samples of CdZSM-5 prepared by ion-exchange, incipient wetness impregnation, and the interaction of HZSM-5 with cadmium vapor were studied by DRIFT spectroscopy using molecular hydrogen as a probe adsorbed at 77Â K. Three different cadmium cationic species were detected. Dicadmium Cd22+ ions most weakly perturb adsorbed hydrogen molecules. They are characterized by a band at 4102Â cmâ1. Two other kinds of isolated Cd2+ sites are characterized by bands at 3982 and 3940Â cmâ1. The former band was ascribed to isolated Cd2+ cations which compensated the negative charges of neighboring aluminum-oxygen tetrahedra. The latter band corresponds to isolated Cd2+ cations which compensate the negative charges of distantly separated aluminum-oxygen tetrahedra. The calcination of samples containing Cd22+ species in oxygen converts these species into cadmium oxocations [Cd2Ox]2+. Hydrogen molecules dissociate at room temperature on the isolated Cd2+ cations which most strongly perturb adsorbed hydrogen molecules at 77Â K.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Microporous and Mesoporous Materials - Volume 80, Issues 1â3, 2 May 2005, Pages 321-326
Journal: Microporous and Mesoporous Materials - Volume 80, Issues 1â3, 2 May 2005, Pages 321-326
نویسندگان
A.I. Serykh,