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SILICON-SUBSTITUTED ALUMINOPHOSPHATE MOLECULAR-SIEVES - STUDIES ON SAPO-5, SAPO-11, SAPO-34 AND SAPO-44

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Title SILICON-SUBSTITUTED ALUMINOPHOSPHATE MOLECULAR-SIEVES - STUDIES ON SAPO-5, SAPO-11, SAPO-34 AND SAPO-44
 
Creator ASHTEKAR, S
SATYANARAYANA, CVV
CHAKRABARTY, DK
 
Subject crystalline inorganic solids
si
alpo4-11
nmr
al
silicon-substituted aluminophosphates
mas-nmr
temperature-programmed desorption of ammonia
 
Description Silicon-substituted aluminophosphates with different framework structures SAPO-5, -11, -34 and -44 have been synthesized by the hydrothermal method using organic templates. The extent of silicon substitution in these materials has been investigated by chemical analysis, measurement of acidity through temperature-programmed desorption of ammonia and silicon MAS-NMR spectroscopy. It has been found that for SAPO-5, and SAPO-11 a small amount of silicon substitution takes place at the phosphorus sites and most of the silicon atoms are present either as silica-rich regions in the structure or as amorphous silica. The amount of silicon in them is quite low. For SAPO-34 and -44, on the other hand, the major part of the silicon randomly substitutes the phosphorus atoms and the rest of it forms small silica patches in the structure. The last two structures cannot be prepared in pure form unless the concentration of the silica source in the synthesis gel is quite high.
 
Publisher INDIAN ACADEMY SCIENCES
 
Date 2011-08-02T07:22:40Z
2011-12-26T12:53:45Z
2011-12-27T05:40:45Z
2011-08-02T07:22:40Z
2011-12-26T12:53:45Z
2011-12-27T05:40:45Z
1994
 
Type Article
 
Identifier PROCEEDINGS OF THE INDIAN ACADEMY OF SCIENCES-CHEMICAL SCIENCES, 106(3), 621-628
0253-4134
http://dspace.library.iitb.ac.in/xmlui/handle/10054/8707
http://hdl.handle.net/10054/8707
 
Language en