TiO2 photocatalytic oxidation of nitric oxide:: transient behavior and reaction kinetics

Photocatalytic oxidation (PCO) of nitric oxide (NO) over TiO2 catalyst was studied at source levels (5-60 ppm). The PCO process involves a series of oxidation steps by the OH. radical: NO --> HNO2 --> NO2 --> HNO3. The product NO2 can be collected in an adsorbent bed and either recycled back to the combustion chamber or recovered as nitric acid. The ratio of NO2- to NO3- from spent catalyst liquor drops with irradiation time until a steady state is reached. The reactions are limited by thermodynamic equilibrium after similar to 12 s space time. The steady-state experimental data from space time and inlet concentration effects can be described with the Langmuir-Hinshelwood (L-H) kinetic model with R-2 = 0.9208. (C) 2003 Elsevier Science B.V. All rights reserved.