FTIR MICROSCOPY WITH POLARIZED IR RADIATION FOR THE ANALYSIS OF SAPO-5 AND P-XYLENE-LOADED SAPO-5

Citation
F. Schuth et al., FTIR MICROSCOPY WITH POLARIZED IR RADIATION FOR THE ANALYSIS OF SAPO-5 AND P-XYLENE-LOADED SAPO-5, Journal of the American Chemical Society, 116(3), 1994, pp. 1090-1095
Citations number
25
Categorie Soggetti
Chemistry
ISSN journal
00027863
Volume
116
Issue
3
Year of publication
1994
Pages
1090 - 1095
Database
ISI
SICI code
0002-7863(1994)116:3<1090:FMWPIR>2.0.ZU;2-F
Abstract
Using an optimized procedure, large SAPO-5 single crystals (up to 250 X 75 mu m) with a very high optical quality could be synthesized. NMR spectroscopy proved the perfect incorporation of silicon on phosphorus sites. IR microscopy with polarized IR radiation revealed that both t ypes of OH groups, with absorption bands at 3627 and 3519 cm(-1), ate oriented almost perpendicularly to the crystal c-axis, thus protruding into the 12-membered and the 6-membered ring channels, respectively. Adsorbed p-xylene reacts with both types of OH groups, giving rise to one broad band for the OH vibration at 3233 cm(-1), which indicates a- shift of the proton from the 6-membered ring to the 12-membered ring. From the dichroic ratios of the bands due to the p-xylene, it can be i nferred that the long axis of the p-xylene molecule is oriented parall el to the channel axis of the molecular sieve.