Lytvyn N. Mechanochemistry of complex oxide compositions on the base of molybdenum and vanadium compounds

The dissertation is connected with the study of the peculiarities of mechanochemical treatment of complex oxide compositions on the base of molybdenum and vanadium and their initial compounds. The influence of the mechanochemical activation conditions of initial compounds: V2O5, MoO3, (NH4)2Mo2O7, NH4VO3 and their mixtures on the physical-chemical properties of obtained samples was established. The formation of the sidwillite phase (МоО3(Н2О)2) and hydrate of vanadium oxide V2O5·0,1H2O at the treatment of corresponding oxides in water was shown. The mechanochemical activation of МоО3 in air leads to fast transformation of orthorhombic МоО3 to its monoclinic modification but in the case of V2O5 the chaotic destruction of the oxide crystals was observed. The partial reduction of the both oxides was established by different methods. The treatment in ethanol allows to anisotropic deformation of V2O5 crystals with an increase of (010) plane relative content and in the case of MoO3 the delay of orthorhombic phase transformation the monoclinic connected with the heat dissipation from local warming-up points by solvent was observed. Specific activation of ethanol at its oxidation (structural sensitivity of reaction) on mechanochemical activated MoO3 was shown. As result of this effect in the presence of monoclinic MoO3 ethanol oxidation proceeds with high selectivity to acetaldehyde, in contrary the high selectivity to ethylene was obtained in the presence of sidwillite phase. Firstly it was established that mechanochemical treatment of (NH4)2Mo2O7 in water led to formation of (NH4)6Mo7O24·4H2O and partial reduced molybdenum oxide ?-Мо4О11 (Magnelli phase). The treatment of (NH4)2Mo2O7 in air and ethanol accompanied by an increase of defect number in (NH4)2Mo2O7 structure and МоО3 formation beginning. The treatment of NH4VO3 in air and in ethanol leads to an increase of the defect number in its structure also but the formation vanadium oxide was observed after treatment in water. Firstly the formation of MoV2O8 phase after mechanochemical treatment of V2O5/МоО3 mixture in air was shown. Treatment in ethanol leads to anisotropic deformation of V2O5 and its deposition on МоО3 surface. The chaotic destruction of the crystals of both oxides was observed after treatment in water. It was established that maximum catalytic activity in n-butane and benzene partial oxidation possessed the samples which contained the MoV2O8 phase. In the case of the other samples their catalytic activity increases with V2O5 crystals size decrease and their selectivity depends from (010) vanadyl plane exposition. Firstly was shown that mechanochemical treatment of the mixtures of oxide with the one of sales (V2O5/(NH4)2Mo2O7 or MoO3/NH4VO3 composition) leads to partial reduction of molybdenum with molybdenum suboxides formation. Simultaneously, the formation of ammonium hexavanadate proceeds as result of ammonium metavanadate decomposition or reaction between ammonia and vanadium oxide hydrate.