X-Ray Photoelectron Spectra of Various ZSM-5 Zeolites and Related Substances
| Autor: | Yoshisada Ogino, Yoshitaka Abe, Tatsuya Yamazaki, Isao Watanuki |
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| Rok vydání: | 1989 |
| Předmět: | |
| Zdroj: | NIPPON KAGAKU KAISHI. :186-195 |
| ISSN: | 2185-0925 0369-4577 |
| DOI: | 10.1246/nikkashi.1989.186 |
| Popis: | XP spectra of eighteen samples (Table 1) were obtained using an MgKa X-ray source (hν=1253.6eV). The main results are as follow.The ratio aluminum to silicon on the surface (Al/Si)s was a little larger than that in the bulk (Al/Si)b for all samples except HZSM-5 (Fig.1). The (Al/Si)s, value for the HZSM -5zeolite was exceptionally smaller than the bulk value, indicating that part of Al had dissolved out during the ion-exchange process. The surface ratios cation to silicon (cation/Si)s were larger than the bulk ratio value (cation/Si)b (Fig.2), but the differences between (cation/Si)s and (carion/Si)b for the group of KZSM-5, RbZSM-5, CsZSM-5 were found to be small as well as for the group of CaZSM-5, SrZSM-5, BaZSM-5. In addition the (cation/Si), ratio for the former group was about twice as large as that for the latter group. Theser results are interpreted in terms of two cationic sites required for ion exchange of a bivalent cation.Binding energies of Si(2p)., 0(1s), and 0(2s) decreased with the increase in the (Al/Si)s, ratio of the sample (Figs.3 and 4), representing an increase in the concentration of Al- 0 bond in the surface phase. The existence of surface Al-0 bond was also revealed by subtrac ting the valence band spectrum of silicalite from that of zeolite (Fig.8).The half height width of the C(1s) XPS peak could be correlated with those of Si(2p), Al(2p), and 0(1s) (Fig.6), suggesting that the surface carbon species had interacted with the cation site Al-OH+-Si over the zeolite surface. |
| Databáze: | OpenAIRE |
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