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Abstract: 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 3wt.% ruthenium. The NO x 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 NO x reduction by hydrogen during desorption. Kinetic constants were estimated through data fitting. An acceptable agreement between experimental and calculated values was obtained. NO x adsorption and desorption kinetics on Na–Y zeolite with and without ruthenium were substantially different revealing that ruthenium besides catalyzing NO x oxidation and reduction had a drastic influence on the NO x adsorption sites of Na–Y zeolite. [Copyright &y& Elsevier]

Platinum metal was dispersed on microporous, mesoporous, and nonporous support materials including the zeolites Na-Y, Ba-Y, Ferrierite, ZSM-22, ETS-10, and AIPO-11, alumina, and titania. The oxidation of carbon black loosely mixed with catalyst powder was monitored gravimetrically in a gas stream containing nitric oxide, oxygen, and water. The carbon oxidation activity of the catalysts was found to be uniquely related to the Pt dispersion and little influenced by support type. The optimum dispersion is around 3-4% corresponding to relatively large Pt particle sizes of 20-40 nm. The carbon oxidation activity reflects the NO oxidation activity of the platinum catalyst, which reaches an optimum in the 20-40 nm Pt particle size range. The lowest carbon oxidation temperatures were achieved with platinum loaded ZSM-22 and AIPO-11 zeolite crystallites bearing platinum of optimum dispersion on their external surfaces.