XAFS (both XANES and FT-EXAFS) measurements revealed that the Pb2+/ZSM-5 catalyst prepared from precursor H-ZSM-5 by a conventional ion-exchange method includes a highly dispersed 3-fold coordinated Pb2+ ion species within the zeolite framework. UV-irradiation of Pb2+/ZSM-5 led to effective decomposition of NO and N2O producing N2. The photocatalytic decomposition of NO is found to be slightly preferable than that of N2O. The isolated Pb2+ ions play a significant role in the decomposition of pollutant NOx. Ab initio and DFT quantum chemical studies at the HF/Lanl2dz and B3PW91/Lanl2dz levels further shed light on local structures of the Pb2+ active site of lead-containing zeolites, as well as on their interactions with pollutant NO and N2O molecules. In agreement with experiments, 3-fold coordination was found to be the most favorable state for the Pb2+ site within the zeolite framework.
ASJC Scopus subject areas
- 化学 (全般)