An aerosol reactor for generation of ceramic particles was built and tested. This reactor can be operated up to 600 ℃ and used for generation of aerosol particles by decomposing a variety of organometallic precursors.
This reactor was used to investigate the effects of inert carrier gases on the formation of aerosol particles from the motivation that we may use the results in controlling aerosol size. Titanium tetraisopropoxide (TTIP) was chosen as a precuror and nitrogen, argon and helium as carrier gases. TTIP is decomposed into water, propylene and titanium oxide. The decomposition rates were calculated from the measurement of propylene using gas chromatograph with flame ionization detector.
At 400℃ of reactor temperature, conversions in argon, nitrogen and helium were 52%, 12% and 5% respectively. This trend in conversion was same between 250℃ and 500℃. The proposed reaction model predicted well the decomposition rate in helium, but deviates substantially in argon and nitrogen. This behavior can be explained by the mixing effect in the aerosol reactor and demonstrates the difficulty in designing aerosol reactors.
Particle size and size distribution analysis were performed with transmission electron microscope (TEM) and particle size analyzer called Autosizerllc. Particles made in argon were the largest and then in nitrogen and helium were the next at the same reactor conditions. Particles made in helium had the most narrow size distribution and in nitrogen the size distribution was the widest.
In conclusion, the faster the conversion is in three different inert carrier gases, the larger the particle size is. Only in helium, the proposed reaction model holds and in argon and nitrogen abnormal behavior occurs.