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Cu and Co exchanged ZSM-5 zeolites: activity towards no reduction and hydrocarbon oxidation

“…This signal is associated to the extra-framework octahedrally co-ordinated aluminium, whose phase was not observed by SEM, indicating that it is well dispersed on the external surface or in the micropores of the ZSM-5 crystals. In addition to the lower |Na|[Si 12 Al]-MFI and |Na|[Si 25 Al]-MFI crystal size above commented, the presence of extra-framework aluminium might also explain the lower crystallinity observed by XRD.…”

“…Similar trends were observed by Sullivan and Cunningham 16 , who attributed such phenomena to an enhanced interaction between the cationic copper species and the zeolite structure. In the TPR-H 2 profiles of samples with higher Cu content, |Cu 0.49 |[Si 12 Al]-MFI and |Cu 0.30 |[Si 12 Al]-MFI, can be observed a small shoulder at around 350 ºC (indicated in Figure 4 with an arrow), which might be attributed to the reduction of finely dispersed CuO particles to elemental Cu 0 17,18 . As can be seen from Table 4, the sum of H 2 /Me ratio corresponding to peak 1 (A1) with the H 2 /Me ratio (Figures 2a and 2b).…”

“…From Figure 1 it can also be observed for sample |Na|[Si 45 Al]-MFI, the presence of a low intensity peak at 26.64 º(2Θ). This peak corresponds to the reflections related to the α-quartz (101) atomic plane 12 .…”

“…The precursor |Na|[Si y Al]-MFI zeolites (where y = 12, 25, and 45 represent the Si/Al ratio in the solid and MFI the ZSM-5 structure) 11,12 were synthesised as described elsewhere 13 . The synthesis was achieved using n-butylamine (C 4 H 9 NH 2 98%, Riedelde-Häen) as organic template and sodium trisilicate (Na 2 Si 3 O 7 ×H 2 O 99%, Aldrich) and aluminium sulphate hydrate (Al 2 SO 4 ×14-18H 2 O 99%, Reagen) as silica and aluminium sources, respectively.…”

“…The XRD patterns of the synthesised |Na|[Si y Al]-MFI zeolites ( Figure 1) reveal the presence of the MFI structure that is typical for ZSM-5 zeolites 12 . From Figure 1 it can also be observed for sample |Na|[Si 45 Al]-MFI, the presence of a low intensity peak at 26.64 º(2Θ).…”