关键词:

纳米颗粒, 高温气相合成, TiO₂, 可控制备

Abstract:

Controlled synthesis of nano-sized titania (TiO2) powder was performed by an improved design of a flame reactor, where titanium tetrachloride (TiCl4) was oxidized in vapor phase at high temperature conditions.By isolating the methane (CH4) flames from the injection of TiCl4, the formation of TiO2 occurred at a certain distance from the TiCl4 inlet, which accordingly avoided the scaling phenomenon often encountered in such processes.The particle diameter and its distribution could be effectively influenced by the operating conditions.The results showed that a lower precursor concentration and a higher carrier-gas flow rate benefited the production of smaller particles of TiO2.The increase of the carrier-gas flow rate resulted in the transition from laminar flow to turbulent flow and the decrease of flame length,and consequently the formation of smalle particles.With increasing flow rate of CH4, the flame, i.e., the reaction zone, enlarged, causing larger particle size owing to the longer time for the formed TiO2 to stay in the flame.While, extra oxygen supply around the center nozzle of TiCl4 could effectively reduce the particle size of TiO2, which may be attributed to the better initial mixing of TiCl4 and oxygen.The nano-sized TiO2 particles ranging from 20 nm to 80 nm on average were obtained in most of the experiments.

Key words:

纳米颗粒, 高温气相合成, TiO₂, 可控制备