Electron microscopy studies of vanadium phosphorus oxide catalysts derived from VOPO4�2H2O

Autor: Sujata Sajip, Jean-Claude Volta, Christopher J. Kiely, Graham J. Hutchings, Maria T. Sananes, Ian J. Ellison
Rok vydání: 1995
Předmět:
Zdroj: Catalysis Letters. 33:357-368
ISSN: 1572-879X
1011-372X
DOI: 10.1007/bf00814238
Popis: An electron microscopy study of vanadium phosphorus oxide (VPO) catalysts is reported. The catalyst precursor VOHPO4·0.5H2O was prepared from VOPO4·2H2O using isobutanol as the reducing agent. The catalyst was then fully activated by heating for ca. 75 h under reaction conditions (385‡C, GHSV 1000 h−1, 1.5% butane in air). Scanning electron microscopy studies demonstrated that a topotactic transformation occurs between the precursor and the final catalyst. Transmission electron microscopy experiments revealed that there were three distinctive morphologies present in the final catalyst; namely (i) rosette shaped clusters composed of (VO)2P2O7 crystallites, (ii) crystalline platelets of αII-VOPO4 and (iii) disordered platelets exhibiting surface patches of (VO)2P2O7. This latter morphology corresponds to the disordered remnants of hemihydrate particles which have only partially transformed to (VO)2P2O7. The (VO)2P2O7 platelets were found to be the majority phase making up more than 95% of the volume fraction.
Databáze: OpenAIRE
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