FTIR spectroscopy is used for the investigation of hydrogen bonding of the Bronsted hydroxyls in H-ZSM-5 zeolite with a number of weak bases (Ar, H2,02, N2, CH4, C2H6, CsHs, CO, C2H4). The following correlation for the increase in intensity of the hydroxyl band, due to its shift resulting from perturbation, is observed: M I A 0 = 0.018Auo~. Applying this correlation to the HF-LF pair in the infrared spectra of H-Y, H-EMT, and H-EM0 zeolites, it is shown that the distribution of Bronsted hydroxyls between super and @cages is approximately 1: 1 whereas in SAPO-37 samples this ratio is close to 3: 1. This is in agreement with results for the deconvolution of the hydroxyl region of the lH MAS N M R spectra. The estimated values of the extinction coefficients for the HF and LF band in H-Y zeolite (Si/Al = 2.7) are 3.2 and 8.5 cmpmol-l, respectively.

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Proton affinities of Brsnsted hydroxy groups in H-forms of zeolites and SAPOs are determined by an FTIR study of the low-temperature adsorption of carbon monoxide. This method reveals the range of heterogeneity of Brsnsted hydroxy groups associated with unmodified zeolites where only one band interacting with carbon monoxide is evident in the infrared spectrum. Three types of acid hydroxy groups associated with different IR bands are detected in a modified zeolite (US-Y), (i) strongly acidic [3599 cm-', proton affinity (€,J = 1112 kJ mol-'1, (ii) medium acidic (3627 cm-', E,, = 1142 kJ mol-') and (iii) weakly acidic (ca. 3740 and 3675 cm-', ED, = 1192 f 29 kJ mol-I).