Oxidative Adsorption of Nitrogen Monoxide on Zeolite

Abstract

Removal of nitrogen oxide (NO_x) from stationary sources was studied by adsorption of NO formed by the catalytic oxidation of nitrogen monoxide (NO). The adsorption measurements were carried out by using flow reactors (U-shaped glass tube, ID: 10 mm, and glass tube, ID: 21 mm) under atmospheric pressure and at 19-65°C. The adsorption of NO₂(about 500 ppm level) on some commercially available adsorbents was measured by a continuous method. For practical use, some zeolities adsorbed a sufficient amount of NO₂, that is, 1.41-5.78 g NO₂/100 g solid (Table 2). The zeolite of mordenite system was acid-stable. The oxidation of NO adsorbed on zeolite surface was retarded by H₂o, CO, , and NO₂. The effective oxidation of NO occurred when the concentration of H₂o in effulent gas was less than ca. O.04%. The oxidation of NO was not affected by the presence of SO₂ (200 ppm level), and was simultaneously removed. Desorption of NO from zeolite surface was carried out at 200-500°C. It has been shown that NO_x was adsorbed in the form of NO, NO₂, and (NO)_x(NO₂) as a result of the interaction between NO and NO₂.