Direct synthesis of bulk VPO catalysts by barothermal, solid-state and mechano- chemical reaction

Svitlana Khalameida 1Volodymyr Sydorchuk 1Valeriy Zazhigalov 1Krystyna Wieczorek-Ciurowa 2Katarzhyna Gamrat 3

1. Institute of Sorption and Problems of Endoecology NAS of Ukraine, 13 Gen Naumova Str., Kyiv 03164, Ukraine
2. Wieczorek-Ciurowa Krystyna (kwc), Warszawska 24, Kraków 31-155, Poland
3. Cracow University of Technology, Department of Chemistry and Technology of Polymers, ul. Warszawska 24, Kraków 31-155, Poland


Vanadium-phosphorus oxide (VPO) catalysts are used in many processes of hydrocarbons oxidation, ammonium-containing VPO for ammoxidation of substituted toluenes. For preparation of more effective VPO catalysts it was investigated alternative approaches. Barothermal synthesis permits to diminish of synthesis duration to 7-10h. Organic compounds are applied in role of reducing agent and solvent. VHP was prepared with following parameters: specific surface area S=5-20 m2/g, relation of intensities of (001) and (220) crystalline planes 1-10, general acidity according to pyridine adsorption C=0,1- 0,33 mmol/g. First solid-state interaction of V2O5, VO2, NH4VO3 and (NH4)2HPO4 was investigated in autoclave without solvent. Ammonium-containing VPO phases NH4VP2O7, (NH4)2(VO)3P2O7 are formed at 200-250C. VHP is crystallized at 300C already for 2 h with size of particles D=21-23 nm. Under higher temperature either structure disorder or formation of intecalated compounds and vanadyl pyrophosphate occurs. The same systems were undergone mechanochemical activation (MChA) in planetary mill with agate grinding (700 rpm) in various mediums. At MChA conditions analogous to barothermal and solid-state reactions can be realized. However phases that are formed under MChA possess some peculiarities namely unusual thermal transformations, higher solubility in water. New VPO phases first of all ammonium-containing appear. MChA of mixture V2O5-(NH4)2HPO4 in water and in air at addition of citric acid obviously leads to creation distorted structure of VHP. Obtained by means of MChA samples have S=2-25 m2/g, D=20-40 nm and C=0.3-3,0mmol/g. All suggested methods allows to prepare catalytic active VPO phases with nanosized crystallites (nanodots).

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Presentation: Poster at E-MRS Fall Meeting 2006, Symposium B, by Svitlana Khalameida
See On-line Journal of E-MRS Fall Meeting 2006

Submitted: 2006-05-15 10:39
Revised:   2009-06-07 00:44
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