The role of dual-cation sites in zeolites has received a renaissance in chemistry and industry directed toward fixation and activation of various gases; such sites may be expected to be more efficient than a single-cation site. We aimed to clarify the real active centers in the copper-ion-exchanged MFI-type zeolite (CuMFI) for ethane (C 2H 6). A peculiar feature was found in the appearance of the characteristic IR bands at 2644 and 2582 cm -1 when C 2H 6 was adsorbed on Cu + formed in CuMFI. The existence of dual species composed of two Cu + ions bridging C 2H 6 was clearly indicated by extended X-ray absorption fine structure (EXAFS) data. Density functional theory calculations gave clear evidence that the two IR bands are distinctly due to C 2H 6 adsorbed on the dual-Cu + site and not on a single site; this agrees with the EXAFS data. These data lead us to conclude that the dual-Cu + site in the CuMFI sample is indispensable for efficient activation of C 2H 6 through the simultaneous interaction of C 2H 6 with two Cu + ions.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films