Ammonia Loading Detection of Zeolite SCR Catalysts using a Radio Frequency based Method

Abstract

<div class="section abstract"><div class="htmlview paragraph">Ammonia adsorption on the catalyst surface is a crucial step in the selective catalytic reduction of nitrogen oxides over zeolites with NH<sub>3</sub> as the reducing agent. In this study, two small pore zeolites with chabazite frameworks, H-SSZ-13 and Cu exchanged SSZ-13, are examined. Adsorption of NH<sub>3</sub> on the zeolite causes changing electrical properties of the material. They can be detected by a radio frequency based technique. We have found that with this method it is possible to determine the amount of adsorbed NH<sub>3</sub> on these catalysts, examining both the influences of temperature and NH<sub>3</sub>/NO feed gas ratio. At constant temperature, a fairly linear correlation between the resonance frequency and the amount of adsorbed ammonia was observed. Furthermore, this method also allows differentiation between some of the NH<sub>3</sub> adsorption sites.</div></div>