Material Synthesis in Supercritical Water —Specific Features of Reactions in Supercritical Water and Novel Processes for Organic and Inorganic Syntheses—

摘要

In this paper, we describe specificfeatures of reactions in supercritical water. Aroundthe critical point, phase behavior and reaction rateor kinetics varies significantly. In highertemperature region, contribution of noncatalyticreaction becomes significant even for hydrolysis,dehydration, or other heterolitic reactions. Complexcontribution of these factors and the change of theseeffects sometimes lead to the appearance ofextraordinary reactions. Previously reportedresearches on organic and inorganic synthesisreactions in supercritical water are summarized,referring to these key features, and controllabilityof reactions around the critical point is pointed outbased on these results. Especially for the hydrothermalsynthesis of metal oxide fine particles, the method ofwhich we have proposed and developed, detailedexplanation and discussion has been made. Key featuresof the method (control of phase, reactions andcrystallization) are summarized and then applicationsof this method to the continuous production of magneticmaterials (BaO_6 Fe_2O_3), Phosphor (YAG: Tb), andlithium ion battery materials (LiCoO_2) are explained,with discussing the possibility of creating new materials.