Chemical Vapor Synthesis of Zinc Oxide Nanoparticles: Experimental and Preliminary Modeling Studies

The chemical vapor synthesis of ZnO tetrapods from zinc metal has been studied using a combination of\udexperiments and fluid dynamics modeling. On one hand, an experimental study allowed production of ultrapure\udZnO particles whose mean lengths (250-450 nm) and diameters (14-27 nm) depended on the reactor\udconfiguration (i.e., parallel flow/crossflow), but not on the position of air injection. On the other hand, the\udyield of the reaction depended both on the reactor configuration and on the position of air injection. We then\uddeveloped an original kinetic model implemented in the computation fluid dynamics code FLUENT. Within\udthe limits of certain assumptions, the model successfully predicts the experimental yield of the reaction for\udall the conditions tested. This good agreement shows that the kinetics of nucleation/growth of ZnO nanoparticles\udare probably very rapid compared to the reaction of oxidation of Zn vapor. The combination of the experimental\udand simulated results led to a better understanding of the heat- and mass-transfer phenomena involved. Finally,\udseveral processing parameters, such as argon and air flow rates, position of air injection, and reactor diameter,\udwere varied in the simulations to find optimized reaction conditions for maximum yield and production rate.\udFor the crossflow configuration, a yield of 71% and a production rate 7 times higher than the nominal value\udhave been obtained