DFT and IR studies on copper sites in CuZSM-5: structure ― redox conditions ― denox activity relationship

摘要

In this work we have studied by quantum chemical (DFT) modelling electronic and geometrical properties of copper centres in β position in ZSM-5. The results were compared with our earlier data concerning α sites. It was evidenced that the properties of both Cu~(2+) and Cu~+ in α sites differ from those in β sites. This is the most pronounced for Cu~+ the positive charge of which is to the largest extent neutralised by framework oxygens when located in α sites. Consequently Cu~+ in α site has the highest energy of HOMO orbital, it is therefore the best electron donor to π~* antibonding orbital of NO and activates the most the adsorbed molecule.