X-ray powder diffraction and EXAFS studies on SnAPO-5 and Cu:SnAPO-5

被引:8
作者
Flavell, WR
Nicholson, DG
Nilsen, MH [1 ]
Ståhl, K
机构
[1] Norwegian Univ Sci & Technol, Dept Chem, N-7491 Trondheim, Norway
[2] Univ Manchester, Dept Phys, Manchester M60 1QD, Lancs, England
[3] Tech Univ Denmark, Dept Chem, DK-2800 Lyngby, Denmark
关键词
D O I
10.1039/b005321j
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
SnAPO-5 was synthesised and calcined at 800 degreesC. Copper was introduced into the calcined material by the incipient wetness method. The as-synthesised, calcined and copper-incorporated SnAPO-5 have been studied using X-ray powder diffraction and EXAFS. Rietveld refinements show that the overall microporous AlPO4-5 framework is unaffected by the incorporation of tin or copper. EXAFS shows that tin substitutes for aluminium and/or phosphorus, with an oxygen multiplicity between five and six. X-Ray powder diffraction confirms that tin substitutes into the framework on positions that are close to the tetrahedral faces. Based on crystal chemical considerations it is suggested that tin is five-coordinate in a trigonal bipyramid with its second axial corner protruding into the extra-framework area. For the copper-incorporated material, Cu : SnAPO-5, EXAFS shows that the copper environment is tetragonally distorted octahedral. Powder diffraction confirms an extra-framework disordered square-planar copper-coordination connected to two framework oxygens by longer axial bonds. EXAFS results of calcined Cu : SnAPO-5 show that copper is sited near the tin sites in the framework.
引用
收藏
页码:620 / 627
页数:8
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