COMPUTER-AIDED-DESIGN OF ACTIVE CATALYSTS FOR THE REMOVAL OF NITRIC-OXIDE

We report here our computational studies on metal-exchanged ZSM-5 cata lysts using molecular dynamics and computer graphics techniques. The s tructure and the dynamic behavior of copper, gallium and cerium cation s in cation-exchanged ZSM-5 framework were studied. Various oxidation states of these metals were simulated and their relevance in the catal ytic removal of nitric oxide is discussed. The high Si/Al ratio in ZSM -5 explains the existence of an equilibrium between the different oxid ation states of exchanged copper cation, which favors NO reduction. Th e higher mobility of the oxygen atom attached to gallium and cerium, a nd the low coordination of these cations are also reasons for their ca talytic activity.