Photodegradation of Ammonia by TiO<sub>2</sub> Nanoparticles Produced by Flame CVD Process

Abstract

Photodegradation of ammonia by mixed-phase TiO2 nanoparticles, synthesized by the oxidation of TiCl4 in turbulent propane/air flame chemical vapor deposition (CVD) process, has been investigated experimentally by using a tubular photoreactor with thin TiO2 films coated on the reactor wall by sedimentation. Effects of ammonia initial concentration from 2-40mg/m3, relative humidity from 30-75%, rutile mass fraction from 20-50% of TiO2 nanoparticles on degradation degree are examined under the conditions of 38g/cm2 catalyst loading, 24mW/cm2 UV irradiation of 254nm, and 5.7sec residence time in the reactor. Results show that photocatalytic activity is higher when rutile mass fraction is from 0.2 to 0.4, corresponding higher PL intensity, and 60% conversion is achieved at initial ammonia concentration of around 5mg/m3 and 70% relative humidity. Based on experimental results, separation of photoinduced electron (e-) and hole (h+) pairs by rutile phase is discussed.