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

Characterization of active sites and potential fields on solid surfaces or in pores of porous materials provides useful information toward the application for catalysis or adsorption.

Compared with acidic sites, characterization methods for basic sites have not been well established yet. In situ infrared spectroscopy using probe molecules is a useful technique for this purpose. Methane is a strong candidate as a probe molecule for basic sites, although it is also sensitive to the electric fields that exist, for example, around the extra-framework cations of zeolites. A competitive adsorption with carbon monoxide partly solves this problem, because this technique makes it possible to identify the methane molecules adsorbed on the sites that have strong electric fields. In this article, some requirements for a probe molecule and the way to interpret spectra are reviewed. Then, the results of an application of this technique to titanosilicate ETS-10 (Na- and Cs-exchanged forms) are briefly introduced.