کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
9610105 | 47191 | 2005 | 6 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Co- and Ni-exchanged ferrierite: The contribution of synchrotron X-ray diffraction data to siting of TMIs
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
مهندسی شیمی
کاتالیزور
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چکیده انگلیسی
High-silica zeolites exchanged with transition metal ions (TMIs) are the subject of great interest for their unusual catalytic activity and selectivity. Structural information like coordination and accessibility of TMIs in zeolites are important factors for understanding their catalytic activity. Siting of TMIs in zeolites is typically obtained by spectroscopic (EXAFS, EPR, UV-vis and IR) and computational methods, as in the case of Co-ferrierite. However, some controversy exists in the literature concerning the model for incorporation of bare Co ions in ferrierite. We show here that the results of our synchrotron X-ray powder diffraction studies on Co- and Ni-exchanged ferrierite (Si/Al = 8.5) are in a good agreement with the model of Co siting based on an indirect spectroscopic approach and help to validate this model. By direct structural evidences, a possible explanation for the larger catalytic activity of Co sites in the main channels of ferrierite can be inferred. A combination of data from in situ XRD continuous monitoring of the Co ion migration during calcination and crystal-chemical considerations allows to device a strategy for the design of optimised co-cations containing Co-ferrierite catalysts.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Catalysis Today - Volume 110, Issues 3â4, 30 December 2005, Pages 345-350
Journal: Catalysis Today - Volume 110, Issues 3â4, 30 December 2005, Pages 345-350
نویسندگان
Maria Chiara Dalconi, Giuseppe Cruciani, Alberto Alberti, Paolo Ciambelli,