Synthesis of Inorganic Nanoparticles in Supercritical Fluids. a Simple Model to Predict Particle Size

One of the most promising developments of supercritical fluid technologies concerns today the field of inorganic, hybrid and organic materials processing. Two well known ways are generally associated to materials processing in supercritical fluids: the first way with processes based on a physical transformation (RESS, SAS, PGSS ... processes) and the second one with processes based on a chemical transformation (thermolysis, red-ox, solvolysis ... reactions). The process of materials synthesis in supercritical fluids, developed at ICMCB, is based on a chemical reaction which induces the nucleation and growth of inorganic nanoparticles. A wide range of nanostructured materials can also be produced (metals, semiconductors, oxides and nitrides); the knowledge of the influence of operating parameters allows to tune finely the characteristics of final particles (size, morphology, composition and structure). However, the development of materials processing in supercritical fluids is closely linked to the proposition of numerical tools. Regarding fine particles synthesis, we have developed a simple model of particle growth in supercritical fluids. This proceeding describes an attractive simulation tool based on a simple model to predict the evolution of particle size and particle size distribution depending on the operating parameters. The modeling of the growth of nanoparticles is based on a population balance equation taking into account the phenomena that occur in the reactor: the collision and the coalescence of particles. The developed numerical program has been validated in the case of the nucleation and growth of metal nanoparticles in a supercritical CO2/ethanol mixture.