Best-fit parameters optimized by EXAFS fits of the k3-weighted spectrum of activated copper-exchanged zeolites of different topologies employing two DFT-optimized geometries for dicopper mono-μ-oxo sites and copper clusters as the starting guess. The fit was performed in R-space in the range of 1.0–3.2 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(3.4)MOR(10) | Cu(4.0)MFI(12) | Cu(2.8)BEA(12) | Cu(2.7)FAU(15) |
|---|---|---|---|---|---|
| ΔE, eV | +2.9(7) | +2.3(6) | 0.3(9) | 0.1(9) | |
| N O | O | 3.7(2) | 3.9(2) | 3.7(2) | 3.5(3) |
| R(Cu–O), Å | 1.944(3) | 1.944(3) | 1.943(4) | 1.959(5) | |
| Debye–Waller factor, 10−3 Å2 | 6.3(3) | 6.0(3) | 5.5(4) | 6.1(6) | |
| N Al | Al or Si | 1.7(5) | 1.1(3) | 1.2(4) | 1.1(4) |
| R(Cu–Al, Si), Å | 2.70(1) | 2.67(1) | 2.70(2) | 2.77(8) | |
| Debye–Waller factor, 10−3 Å2 | 10.8(38) | 6.7(20) | 4.7(20) | 11.7(22) | |
| N Cu | Cu1 | 0.3(1) | 1.1(4) | 2.3(9) | 1.7(9) |
| R(Cu–Cu1), Å | 2.841(16) | 2.904(8) | 2.888(3) | 2.938(2) | |
| Debye–Waller factor, 10−3 Å2 | 5.0(21) | 9.4(27) | 10.0(33)a | 6.9(24)a | |
| N Cu | Cu2 | 2.6(9) | 1.8(9) | ||
| R(Cu–Cu2), Å | 3.05(1) | 3.08(1) | |||
| Debye–Waller factor, 10−3 Å2 | 10.0(33)a | 6.9(24)a | |||
| R-factor | 0.0029 | 0.0024 | 0.0054 | 0.0066 | |
| χ 2-parameter | 187 | 23 | 134 | 116 | |
a
Fixed to be equal in the fit. Both scatters are of the same nature (copper atoms); therefore, their Debye–Waller factors are assumed to be similar.