Rapid and Continuous Hydrothermal Crystallization of Metal Oxide Particles in Supercritical Water

TLDR

Metal salt solutions were hydrolyzed in supercritical water to produce fine metal oxide particles, whose size, morphology, and crystal structure were subsequently characterized. The process yielded fine metal oxide particles in under 2 minutes, with sizes ranging from 20 to 600 nm and a relatively narrow distribution across different metal systems.

Abstract

Hydrolysis of 10 metal salt aqueous solutions of 6 metal oxides was conducted in supercritical water. Continuous and rapid production of metal oxide fine particles was achieved by mixing a metal salt aqueous solution with preheated water fed from another line. The reaction time required was less than 2 min. Particle size, morphology, and crystal structure of the obtained metal (hydrous) oxides were examined. Particle size (20 to 600 nm) was different among the systems but the size range was relatively narrow in all the cases.