N2 and CO as probe molecules for determining the properties of acid sites on the surface of zeolites

Abstract

The applicability of molecular nitrogen as a probe for the Bronsted and Lewis acid sites of HNaY and HZSM-5 zeolites was studied by Fourier transform IR spectroscopy. The integrated absorption coefficients of bands due to N-N vibrations in complexes with Bronsted and Lewis acid sites were determined. The correlation between the integrated absorption coefficients and the positions of bands due to N-N vibrations in nitrogen interacting with the acid sites of test samples is discussed. We propose using the low-temperature adsorption of nitrogen for express determination of the concentrations of strong Lewis and Bronsted acid sites in zeolites.