AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Kinetics of Sub 3 nm Titanium Dioxide Particle Formation in an Aerosol Reactor during the Thermal Decomposition of Titanium Isopropoxide (TTIP)
YANG WANG, Pai Liu, Tandeep Chadha, Jiaxi Fang, Pratim Biswas, Washington University in St Louis
Abstract Number: 241 Working Group: Nanoparticles and Materials Synthesis
Abstract Measurements of particle size distributions using differential mobility analyzers (DMAs) can be utilized to study particle formation mechanisms. However, knowledge on the initial stages of particle formation has been missing because of the Brownian broadening effect in conventional DMAs, which limits the ability to measure sub 3 nm particles. Some studies have recently demonstrated the capability of a high resolution Half Mini DMA to measure sub 3 nm particles in a flame aerosol reactor. In this study, the Half Mini DMA was applied to investigate the particle formation mechanisms in a furnace aerosol reactor during the synthesis of titanium dioxide particles via thermal decomposition of titanium isopropoxide (TTIP).
Four different characteristic time scales: precursor reaction time, precursor residence time, particle coagulation time, and particle sintering time, were compared to examine particle inception and growth in the furnace aerosol reactor. At low synthesis temperatures (373 K ~ 673 K), a peak of TTIP precursor cluster with an approximate size of 1.8 nm was detected, along with scattered particles of smaller sizes, possibly generated from the fragmentation of TTIP molecules in the radioactive neutralizer. As synthesis temperatures increased to 723 K, the TTIP peak shape altered, due to the onset of the thermal decomposition reaction. In addition, a broader titanium dioxide particle size distribution following the TTIP peak appeared at higher synthesis temperatures, while the peak diameter further increased with temperature. Aerosol growth models will be used to simulate particle formation in the sub 3 nm range and compared with the experimental results.