Remarkable enhancement in durability of Pd/H-ZSM-5 zeolite catalysts for CH4-SCR

Effect of second components on the catalytic performance of Pd/H-ZSM-5 zeol ite (Pd: 0.4 wt.%) was evaluated by a durability test of NO reduction with CH4 at a relatively high temperature of 500 degrees C in the presence of wa ter vapor for a prolonged period. The Pd/H-ZSM-5 showed high stable activit y for this reaction without H2O in the reactant feed, while immediate and i rreversible deactivation was observed in the presence of H2O, resulting in no activity after 7 h. The second components such as Co, Rh, Ag, Ce, and Fe introduced individually to the Pd/H-ZSM-5 enhanced the durability, and in particular the addition of 3.3 wt.% Co led to a stable NO conversion for mo re than 40 h in the presence of H2O. (C) 2000 Published by Elsevier Science B.V.