Excessively Copper Ion-exchanged ZSM-5 Zeolites as Highly Active Catalysts for Direct Decomposition of Nitrogen Monoxide

Repeated ion exchange of the ZSM-5 zeolite using aqueous copper(II) acetate solution was found to bring about excess loading of copper ions above 100% of exchange level. The catalytic activities of the resulting Cu-ZSM-5 zeolites for direct decomposition of nitrogen monoxide were very high and increased with increasing exchange level. The activity did not decrease even after 30 h of continuous service.