The Separate Removal of Trace ~(14)CO_2 and Moist NO_x from Off-gases by Adsorption on H-type Mordenite

摘要

Three kinds of mordenite were examined for the adsorptive separation and removal of trace amounts of ~(14)CO_2 and moist NO_x contained in the off-gases of reprocessing plants for spent nuclear fuels. It was found that protonation of mordenite eliminated any possible removal of CO_2 by specific adsorption but induced the dissociative adsorption of NO_2 with the formation of nitric acid-like adsorbed species and NO oxidation. FT-IR spectroscopic results confirmed that the Bronsted acid sites existing on H-type mordenites exhibit no interaction with CO_2 molecules but can catalyze the dissociative adsorption of NO_2. Such properties, together with the lower adsorption temperature and the thermal stability of the adsorbent, suggest a promising process involving H-type mordenites whereby NO_x can be selectively captured and returned to the dissolving solution while trace amounts of ~(14)CO_2-containing carbon oxides pass through the system allowing their subsequent complete removal by entrapment in a solid matrix.