Abstract: The present invention relates to a dual bed catalytic system for the reduction of nitrogen oxides comprising silver-deposited alumina (Ag/Al2O3) and zeolite (ZSM-5). The present dual bed catalytic system provides significantly improved NOx reducing efficiency as compared to the system using Ag/Al2O3 or ZSM-5.

Abstract: A method of performing quantitative analysis of nitrogen oxides occluded in heterogeneous catalysts, comprising the following steps, each performed in parallel for multiple samples: adsorption of nitrogen oxides by multiple samples using a batch adsorption apparatus, extraction of nitrogen oxides from the occluded samples using a solvent, reduction of nitrogen oxides to nitrite ions contained in the extract using hydrazine, and detection and quantification of nitrogen oxides by colorization using a modified Griess reagent. The method of the invention requires less time and expense as compared to the conventional method, wherein the process of serial adsorption, purge, desorption, and quantification is performed repeatedly to quantify the amount of nitrogen oxides adsorbed onto multiple samples. This method enables the efficient and reliable evaluation of nitrogen oxide adsorbing catalysts, which are commonly employed in automobiles for post-treatment of exhaust gases.