Structural transitions in zeolite P An insitu FTIR study

Abstract

In situ FTIR spectroscopy is applied to characterise structural transitions occurring in zeolites NaP and NaA upon hydration–dehydration in conjunction with adsorption measurements. Little spectral variation is observed in the region of structural vibrations of zeolite NaA. By contrast, NaP shows prominent reversible changes in the region of asymmetric stretching T–O vibrations, 900–1150 cm^-1, including both ‘internal’ and ‘external’ linkages, although the former are usually considered as structure insensitive. Based on regression analysis of our IR data and on XRD results reported previously, phase composition of NaP is determined and four stages in the hydration of P zeolite are outlined.