Best-fit parameters optimized by EXAFS fits of the k3-weighted spectrum of activated copper-exchanged mordenite with different Si/Al ratios. DFT-optimized geometry for dicopper mono-μ-oxo sites located in the 8-membered ring of MOR was used as the starting guess. The fit was performed in R-space in the range of 1.0–3.0 Å, employing the k-range of 3.0–16.0 Å−1 for the FT, resulting in a number of independent points Nind > 16.
| Parameter | Scatter | Cu(4.3)MOR(6) | Cu(3.4)MOR(10) | Cu(1.2)MOR(46) |
|---|---|---|---|---|
| ΔE, eV | +1.7(6) | +2.9(7) | −2.8(13) | |
| N O | O | 3.9(2) | 3.7(2) | 3.9(4) |
| R(Cu–O), Å | 1.938(3) | 1.944(3) | 1.917(7) | |
| Debye–Waller factor, 10−3 Å2 | 6.8(4) | 6.3(3) | 9.2(9) | |
| N Al | Al or Si | 1.8(7) | 1.7(5) | 0.5(3) |
| R(Cu–Al, Si), Å | 2.69(2) | 2.70(1) | 2.64(2) | |
| Debye–Waller factor, 10−3 Å2 | 11.3(60) | 10.8(38) | 4.1(37) | |
| N Cu | Cu | 0.3(4) | 0.25(7) | 0.3(3) |
| R(Cu–Cu), Å | 2.86(3) | 2.84(2) | 2.87(2) | |
| Debye–Waller factor, 10−3 Å2 | 7.1(68) | 5.0(21) | 5.0(49) | |
| R-factor | 0.0022 | 0.0029 | 0.0072 | |
| χ 2-parameter | 111 | 187 | 207 | |