日本ゼオライト学会　刊行物 Publication of Japan Zeolite Association

IR spectroscopy is known to be very informative method for the studies of zeolites, and identification of Bronsted and Lewis acid sites is widely conducted by using probe molecules. In this article, different use of probe molecule-IR method is firstly introduced, which determines the locations of the acidic OH groups and silanols on zeolites. Secondary, the transformation of the IR band of acidic OH groups due to various types of interaction is explained by using some different adsorbed molecules. Using this knowledge, the observation of olefin adsorption at low temperature range revealed that different structures of adsorption exist for the same molecules. The diffusion process of butene molecules was clearly found for ferrierite zeolite also at low temperature range. As a result, the dynamic behaviors of molecules adsorbed on zeolites were described, and they varied depending on the pore sizes of zeolites. A method for quantification is introduced, and the importance of it is emphasized by quantitative analysis of the acidic OH groups observed during reactions of olefins on zeolites. The determination of dimerization of a reaction of butene at room temperature and the elucidation of the structure of produced dimer molecules are shown as examples. Finally, the effectiveness of the newly developed two-dimensional infrared (2D-COS) method for the studies of reactions on zeolites is demonstrated.