The Synthesis Of MgTeMoO₆Microcrystal In Super/subcritical Water System

Supercritical fluids technology is a green technology emerging in the past several decades. Not only has it been found wide application in the extraction and material processing, but also it has attracted widely attention and study in the aspect of materials synthesis. At present, the investigation and application are mostly focused on supercritical carbon dioxide technology and supercritical water technology. Due to its unique physical and chemical properties, supercritical water technology has caused a lot of concerns. Supercritical water technology shows its broad prospect of application in biomass conversion, environmental protection, organic synthesis, recycling waste polymer and so on. Especially in the area of materials synthesis, powder material with high purity, good crystallinity, monodisperse and uniform morphology can be obtained in the supercritical water system instead of traditional hydrothermal synthesis technology.In this thesis, multicomponent oxide material MgTeMoOe with micro-scale was prepared in the super/subcritical water system. While its properties are characterized in detail.Firstly, MgTeMoO6micro-bulk material with high purity, uniform morphology, good crystallinity and monodisperse distribution has been synthesized in supercritical water system by using high-temperature and high-pressure reaction kettle. The MgTeMoO6powder materials were characterized in detail by XRD, SEM, solid-state fluorescence and thermal analysis methods. Moreover, the reaction parameters influencing the phase structure and morphology of the final products, such as reaction temperature, reaction time, cooling way and addition of reactants, were investigated in detail. The formation mechanism of MgTeMoO6in supercritical water system is explored and analyzed. At the same time, preliminary experiment of propylene selective oxidation has been carried out to research the catalytic effect of MgTeMoO6 preparing by different synthesis methods.Through this work, the synthesis process of multicomponent oxide material in supercritical water system is investigated in detail. The basic rules of reaction conditions influencing the phase and morphology of final products have been grasped. The experiment provides a quick, effective and environmental friendly synthetic method to prepared ultrafine particles of multicomponent oxide material. It not only accumulates experience in the synthesis of multicomponent oxide, but also extended the applications fields of supercritical water technology in materials synthesis.