S. Ashtekar et al., SMALL-PORE ALUMINUM PHOSPHATE MOLECULAR-SIEVES WITH CHABAZITE STRUCTURE - INCORPORATION OF MAGNESIUM IN STRUCTURES -34 AND -44, Journal of the Chemical Society. Faraday transactions, 92(13), 1996, pp. 2481-2486
Citations number
15
Categorie Soggetti
Chemistry Physical","Physics, Atomic, Molecular & Chemical
MgAPO and MgSAPO with -34 and -44 framework structures have been synth
esized with various amounts of magnesium. Magic-angle spinning (MAS) N
MR results showed the presence of three phosphorus environments: P(4Al
, 0Mg), P(3Al, 1Mg) and P(2Al, 2Mg) in MgAPO-44 and MgSAPO-44. In MgAP
O-34, some of the NMR peaks are split, possibly owing to the presence
of non-equivalent T sites. It was indicated from Si-29 MAS NMR results
that in MgSAPOs, the magnesium content of the samples affects the sil
icon environment: with increased magnesium content, more silica-rich r
egions were formed. Structural acidity, determined from temperature-pr
ogrammed desorption of ammonia, supported the results on the formation
of silica-rich regions in the structure.