Surface Texture of Microcrystalline Tunnel-Structured Manganese(IV) Oxides: Nitrogen Sorptiometry and Electron Microscopy Studies
| Autor: | A.A. Ali, F.A. Al-Sagheer, M.I. Zaki |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2002 |
| Předmět: | |
| Zdroj: | Adsorption Science & Technology, Vol 20 (2002) |
| Druh dokumentu: | article |
| ISSN: | 0263-6174 2048-4038 |
| DOI: | 10.1260/02636170260504314 |
| Popis: | Three different modifications of manganese(IV) oxide, viz. cryptomelane, nsutite and todorokite-like, were synthesized by hydrothermal methods. The bulk chemical composition, phase composition, crystalline structure and particle morphology of the resulting materials were determined by thermogravimetry, atomic absorption spectroscopy, X-ray diffractometry, infrared spectroscopy and scanning electron microscopy. The surface chemical composition, texture and structure were assessed using X-ray photoelectron microscopy, nitrogen sorptiometry and high-resolution electron microscopy. The results highlighted the hydrothermal conditions under which such tunnel-structured modifications of manganese(IV) oxide can be successfully synthesized. Moreover, they revealed that (i) the bulk was microcrystalline, (ii) the crystallites were either fibrils (cryptomelane and nsutite) or rod-like (todorokite) with low-index exposed facets, (iii) the surface chemical composition mostly reflected that of the bulk and (iv) the surface texture was linked with high specific areas, slit-shaped mesopores associated with particle interstices and micropores which allowed surface accessibility to the bulk tunnels of the test oxides. The application of such test oxides as shape-selective oxidation catalysts appears worthy of investigation. |
| Databáze: | Directory of Open Access Journals |
| Externí odkaz: |
|