In situ investigation of solid state lon exchange in zeolites using Fourier transform infrared spectroscopy

Abstract

The solid-state ion-exchange reaction in H-ZSM-5 zeolite was investigated in situ up to a temperature of 550 °C by diffuse reflectance Fourier transform infrared spectroscopy. At 550 °C, the exchange rate of the framework OH groups inside the zeolite channels is faster than that of the terminal OH groups at the crystallite surface. The positions of the OH stretching bands are not shifted during the exchange process. The relationship between the OH groups and a constant acid strength during the exchange of Zn²⁺ ions is discussed.