Zeolite binding energy

The XPS spectra of the freshly sulfided Co-Mo/NaY catalysts were measured on an XPS-7000 photoelectron spectrometer (Rigaku, A1 anode 1486.6 eV). The sample mounted on a holder was transferred from a glove bag into a pretreatment chamber attached to the spectrometer as possible as carefully not to be contacted with air. The binding energies (BE) were referenced to the Si2p band at 103.0 eV for the NaY zeolite, which had teen determined by the Cls reference level at 285.0 eV due to adventitious carbon. 

Zeolite Type Band Gap Energy (ev) W(4d5/2) Binding Energy (eV) W(4f7/2) Binding Energy (eV)... 

The variations of acidic properties in the surface layers and in the bulk solid catalysts after calcination, reduction, or coking were examined by pyridine Nls XPS [4,7] and by the pyridine infrared adsorption techniques, respectively. This provides a means to compare the changes in the characteristic BrBnsted and Lewis acidity functions after those treatment conditions. First of all, TPD of ammonia revealed that both coked and regenerated samples exhibited much decreased acidity as compared with either calcined or reduced samples before the reaction of n-heptane conversion in either N2 or H2 stream [7]. The adsorption of pyridine may cause further perturbation to the Pt4+ or Pt 2+ species in the zeolite as indicated by the increase in binding energies of Pt3d5/2 electrons, as shown in Table 3 and Figure 4,... 

Binding energy (B.E, eV) of zeolite constituent elements in PtHY catalysts as measured by XPS after pyridine adsorption... 

Si/Al and Na/Zn atomic ratios, atomic %Zn and Zn (LMN), Na (KLL) binding energies for ZnNaX exchanged zeolite... 

For Pd/NaX, it was found with ESR and XPS that reduction of Pd at low temperature results in Pd and small charged clusters Pd " (y > j ) (278,279). Likewise, monopositive Pd" was observed with XPS in zeolite Y after mild reduction (780). As shown in Fig. 18, the binding energy of Pd 3ds/2 in Pd/NaHY is significantly shifted to higher values with respect to the Pd reference. This shift is, in part, due to the small particle size. However, neutralization of Pd/NaHY at low temperature will leave the particle... 

Some authors have used the emission of adventitious carbon at a fixed value of 285.0 eV. (Some others prefer 284.4, 284.5 or 284.6 eV without real justification). This practice is not recommended because of the complexity associated with the possible differential charging of carbon impurities. Moreover it is not unusual to observe multicomponent Cjs peaks in zeolite spectra [11] and the span in binding energy expands over 8 eV in the literature. 

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