Modeling of NOx adsorption–desorption–reduction cycles on a ruthenium loaded Na–Y zeolite

Adsorption of NO from a gas stream containing oxygen and water and desorption and reduction using a rich gas mixture were investigated in the temperature range 230–315 °C on Na–Y zeolite loaded with 3 wt.% ruthenium. The NOx storage capacity was found little dependent on temperature and water content of the gas. The adsorption–desorption–reduction process was modeled using a one-dimensional fixed-bed model and assuming co-adsorption of NO and NO2 molecules on Na–Y zeolite, ruthenium catalyzed NO into NO2 oxidation by molecular oxygen during adsorption and ruthenium catalyzed NOx reduction by hydrogen during desorption. Kinetic constants were estimated through data fitting. An acceptable agreement between experimental and calculated values was obtained. NOx adsorption and desorption kinetics on Na–Y zeolite with and without ruthenium were substantially different revealing that ruthenium besides catalyzing NOx oxidation and reduction had a drastic influence on the NOx adsorption sites of Na–Y zeolite.