Preparation, characterization and catalytic activity towards lean NOx reduction of over-exchanged Cu-ZSM-5 catalysts

We report on the preparation, characterization (XRD, DRS, magnetic susceptibility, XPS-XAES) and the catalytic performance of over-exchanged Cu-ZSM-5 (Si/Al=80) catalysts for removing NO x , CO and HC from lean automobile exhausts. Copper loadings were in the range 200–650% of exchange level. In the temperature programmed tests (room temperature-600°C; space velocity 36,000 h −1 ) these catalysts showed similar conversions for the three pollutants, independent on the Cu 2+ exchange level. However the durability tests at 400°C (space velocity 36,000 h −1 ) show that the higher Cu 2+ loadings may increase the resistence of the catalysts under real lean NO x reduction.