Control of particle size and phase formation of TiO₂nanoparticles synthesized in RF induction plasma

Abstract

TiO2 nanoparticles have been synthesized in this work via Ar/O2 RF thermal plasma oxidation of atomized liquid precursors containing titanium tetrabutoxide and diethanolamine. Quench gases (Ar or He), either injected from the shoulder of the reactor (transverse injection) or injected counter to the plasma plume from the bottom of the reactor (counter-flow injection), are used to affect the quench rate and therefore the particle size and phase constituent of the resultant powders. The experimental results show that counter-flow injection is more effective in reducing the particle size, while He is more effective than Ar. As a result, well-dispersed TiO2 nanopowders with controllable phase structure (up to ∼90% of anatase) and average particle size (down to 20 nm) are obtained. The experimental results are well supported by numerical analysis on the effects of the quench gas on flow pattern and temperature field of the thermal plasma as well as trajectory and temperature history of the particles.

Decahedral-shaped anatase titania photocatalyst particles: Synthesis in a newly developed coaxial-flow gas-phase reactor

“…1373 K) and homogeneity of reaction mixture flow with the optimal range of LSR (0.08-0.1) and corresponding t res (0.8-1.0 s) determine the reaction yield and quality of products (F/T ratio). To improve the control of DAPs crystallization process additional cooling system for quenching of the final product is being considered [42].…”

A method for large-scale synthesis of Al-doped TiO2nanopowder using pulse-modulated induction thermal plasmas with time-controlled feedstock feeding

“…Among them, the inductively coupled thermal plasma (ICTP) method is a useful technique to synthesize nanoparticles of various kinds [11]- [18]. It provides one-step direct processing including rapid evaporation of injected raw materials, and enables rapid cooling of evaporated materials.…”

“…Several studies have examined the synthesis of TiO 2 nanoparticles using a steady-state type of inductively coupled thermal plasma (ICTP). They have mainly investigated control of its particle size and phase constituent [13,14,18]. However, some issues persist: the difficulty in controlling the synthesized particle size, and also the lower production rate from the instability of ICTP sustainability during heavy-load feeding of feedstock.…”

Highly dispersed behavior of thermal plasma-synthesized TiO2 nanoparticles in water

“…The experimental apparatus used in the synthesis of the TiO 2 nanoparticles, which has been described elsewhere, 11) consisted of a water-cooled RF induction plasma torch (Model PL-50, TEKNA Plasma Systems Inc., Sherbrooke, QC, Canada), a 2-MHz RF power supply system (Nihon Koshuha Co. Ltd., Yokohama, Japan), a water-cooled stainless steel reactor, and a stainless steel porous filter connecting the reactor and a vacuum pump. Nano-sized TiO 2 powders were synthesized via Ar/O 2 induction thermal plasma pyrolysis of a liquid precursor containing titanium tetrabutoxide [TTBO, the titanium source] (Wako Pure Chemical Industries Ltd., Tokyo, Japan) and diethanolamine [a chelate preventing the hydrolysis of TTBO] (Wako Pure Chemical Industries Ltd., Tokyo, Japan).…”