Detection of the ammonia loading of a Cu Chabazite SCR catalyst by a radio frequency-based method

Zeolites are in use as catalyst materials in the selective catalytic reduction of NOx with NH3 as reducing agent. An initial NH3-adsorption on the catalyst is essential for the reaction with NO and NO2 to occur. Due to the adsorbed NH3, the proton conductivity of the zeolite increases markedly. This change of the electrical properties of the catalyst material can be monitored in a contactless way and in operando using a radio frequency-based method to determine the ammonia loading on the catalyst. In this work, the ammonia storage is examined on a copper exchanged Chabazite Cu-SSZ-13, a typical SCR catalyst as it is in use for serial applications, at different temperatures and various feed ratios.