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Formation of hierarchical porous structure at mechanochemical treatment of powder vanadium-containing oxide composition |
Krystyna Wieczorek-Ciurowa 1, Svitlana Khalameida 2, Volodymyr Sydorchuk 2, Jadwiga Skubiszewska-Ziemba 3, Valeriy Zazhigalov 2, Roman Leboda 3 |
1. Cracow University of Technology (CUT), Warszawska 24, Kraków 31-155, Poland |
Abstract |
Mechanochemical treatment (MChT) is effective and modern method for synthesis and modification of nanodispersed materials (adsorbents, catalysts e.a.). Increase of specific surface area (SSA) of treated samples takes place during MChT on air as a rule. In our opinion porous structure can be formed at MChT of nonporous matters in liquid mediums, first of all in water. This aspect is not examined in literature at all. High-energy MChT (700 rpm) in water and ethanol was used for milling of coarsely dispersed crystal powders of V-containing oxides. Intensive mechanical influence, higher temperature and pressure promote increased solubility of solid on the one hand and creation of contacts between crystals on the other hand. It results in formation of hard framework of porous material during next drying of treated dispersion. For investigated oxide compositions samples with hierarchically organized porous structure were prepared: primary large crystals form macroporous part and mesopores are created by means of precipitation of dissolved substance in places of contacts of crystals. Porosity of obtained at MChT samples was studied with the help of nitrogen adsorption, mercury porometry, SEM, AFM. Experimental data are following: system V-Mo-O – SSA=2-20 m2/g, pore volume V=0,10-0,60 ml/g, predominating diameter of mesopores – 50 and 100 nm, macropores – 500-600 nm; system V-Mo-Zr-O – SSA=12-40 m2/g, V=0,32-0,53 ml/g; system V-P-O modified by oxides Mo and Zr at MChT – SSA=7-38 m2/g, V=0,30-053 ml/g. Oxide compositions prepared by means of MChT in liquid phase with biporous structure are perspective as catalysts. |
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Presentation: Oral at E-MRS Fall Meeting 2007, Symposium A, by Krystyna Wieczorek-CiurowaSee On-line Journal of E-MRS Fall Meeting 2007 Submitted: 2007-05-13 14:17 Revised: 2009-06-07 00:44 |