Abstract
Kinetic study was carried out for photo-oxidation of NH3 (photo-SCO: 4NH3+3O2→2N2+6H2O) to elucidate the mechanisms of the photo-SCO over anatase and rutile TiO2. The reaction orders of the reactant gases reveal that the photo-SCO activity depends only on the concentration of O2 with either anatase or rutile TiO2. Steady-state kinetics suggests that the rate-determining step is the formation of nitrosoamide species from surface NO species and NH2 radical. The surface NO species may play an important role in the high activity of the photo-SCO. O3 anion radical, which is a strong oxidant, was detected only over anatase TiO2 and the concentration of surface NO species would be increased by O3 anion radical. This may be the reason why anatase TiO2 shows higher activity than rutile TiO2. The photo-SCO activity is enhanced as the reaction temperature increased. 100% NH3 conversion and 94% N2 selectivity were achieved at GHSV=50,000h−1 at 435K. This enhancement of the activity at higher reaction temperature is caused by (1) the increase in the surface NO species and (2) the improvement of reactivity between surface NO and NH2 radical. The SCO activity is moderately high even at low temperature: the Arrhenius activation energy is only 24.4kJmol−1.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
