Fine structures of the copper oxide clusters involved in catalytic reduction of NO were studied by X-ray absorption spectroscopy. The Extended X-ray absorption fine structural (EXAFS) spectra indicate that about 2.89 nearest oxygen atoms bond to the Cu central atoms with a Cu-O bond distance of 1.96 Å for the oxidized Cu-ZSM-5 catalyst. Reduction of the catalyst in hydrogen at 573 K led to the formation of mainly Cu-Cu (2.54 Å) species with the coordination number (CN) of 2.91. The Cu4O2 clusters in the channels of ZSM-5 observed by EXAFS were formed in the NO reduction process via incorporation of oxygen into the metallic copper matrix with desorption of N2. Due to the restricted channel structure of ZSM-5, the Cu4O2 clusters were reduced promptly by CH4.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry