کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
75515 | 49117 | 2008 | 11 صفحه PDF | دانلود رایگان |
The crystal structure of the fully dehydrated Co, Na–X zeolite (Na16Co38Al92Si100O384) is investigated and compared to that of three partially hydrated zeolites. In the fully dehydrated crystal, cobalt ions almost entirely occupy Site I, and partially Site II while the residual sodium cations partly occupy Site II and Site III. The dehydration induces a migration of Co2+ cations from Site I′ to Site I and severely affects the structure, the structural strain being released by changes of framework valence angles or, to a less extent, by distortions of TO4 tetrahedra. Comparison with dehydrated M–X zeolite structures (M = Ba, Na, Ca, Tl, Li) confirms the relation between the size of the charge compensating cation and the stresses on the skeleton that are mainly explained by cation–oxygen electrostatic interactions.
Journal: Microporous and Mesoporous Materials - Volume 114, Issues 1–3, 1 September 2008, Pages 155–165