DEACTIVATION OF COPPER-ION EXCHANGED MORDENITE CATALYSTS BY SO2 FOR NO REDUCTION WITH NH3 - ROLE OF COPPER

Abstract

The sulfur poisoning behavior of CuHM catalysts are influenced by the copper content on catalyst surface, which is mainly due to the oxidizing properties of cupric ions. The surface areas of deactivated HM and CuHM31 catalysts are well correlated with sulfur content, while that of deactivated CuHM58 with higher cupric ion content greatly decreased, regardless of sulfur content and reaction temperatures. It may be due to the blockage of pore by the copper-NH3 complex as well as by the deactivating agent, mainly (NH4)(2)SO4 andlor NH4HSO4 from the results of thermal analysis such as TGA, DTA and TPD. The formation of these ammonium salts depends on the reaction temperature and the SO3 concentration produced by SO2 oxidation on cupric ions of catalyst surface.