Formation of Non-Agglomerated Titania Nanoparticles in a Flame Reactor

• Published in: JOURNAL OF CHEMICAL ENGINEERING OF JAPAN Vol. 44; no. 1; pp. 7 - 13
• Main Authors: Okada, Yoshiki, Kawamura, Hidehisa, Ozaki, Hirofumi
• Format: Journal Article
• Language: Japanese; English
• Published: The Society of Chemical Engineers, Japan 01.01.2011
• Subjects: Aerosols; Cooling; Flame Aerosol Reactor; Laval Nozzle; Non-Agglomeration; Nozzles; Quenching; Quenching (cooling); Rapid Cooling; Reactors; Titania Nanoparticles; Titanium dioxide
• ISSN: 0021-9592; 1881-1299; 1881-1299
• DOI: 10.1252/jcej.10we195

The formation of non-agglomerated titania particles by oxidation of titanium-tetra-isopropoxide (TTIP) has been studied in a methane/oxygen coflow diffusion-flame reactor. A change in the proportion of virtually non-agglomerated particles in TEM images was observed using a rapid cooling of the entire flame aerosol with a blow of cold Ar quenching gas and supercooling in a Laval nozzle placed above the flame. The proportion of non-agglomerates was 25% for TiO2 particles produced without any cooling steps. When the quenching gas of 25 L/min Ar cooled at −70°C blew on the tip of the flame, the proportion of non-agglomerates was 70%. When the flame aerosol was supercooled in the Laval nozzle after blowing −70°C Ar quenching gas, a decrease in the aerosol temperature was induced from approximately 1500 to 300°C in 0.9 ms and, as a result, the proportion of non-agglomerates was as large as 90%. It was found that the rapid cooling in the region of the flame tip is quite effective for preventing agglomeration.