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International Journal of Photoenergy
Volume 2007, Article ID 32524, 6 pages
Research Article

Gas-Phase and Aqueous Photocatalytic Oxidation of Methylamine: The Reaction Pathways

1Department of Chemical Engineering, Lappeenranta University of Technology, P.O. Box 20, Lappeenranta 53851, Finland
2Department of Chemical Engineering, University of Barcelona, c/Martí i Franquès 1-11, Barcelona 08028, Spain

Received 19 April 2007; Accepted 26 June 2007

Academic Editor: Panagiotis Lianos

Copyright © 2007 Anna Kachina et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Photocatalytic oxidation (PCO) of methylamine (MA) on titanium dioxide in aqueous and gaseous phases was studied. A simple batch glass reactor for aqueous PCO and an annular continuous flow reactor for the gas-phase PCO were used. Maximum aqueous PCO efficiency was achieved in alkaline media. Two mechanisms of aqueous PCO—decomposition to formate and ammonia, and oxidation of organic nitrogen directly to nitrite—lead ultimately to CO2, water, ammonia, and nitrate: formate and nitrite were observed as intermediates. A part of the ammonia formed in the reaction was oxidized to nitrite and nitrate. Volatile PCO products of MA included ammonia, nitrogen dioxide (NO2), nitrous oxide (N2O), carbon dioxide, and water. Thermal catalytic oxidation (TCO) resulted in the formation of ammonia, hydrogen cyanide, carbon monoxide, carbon dioxide, and water. The gas-phase PCO kinetics is described by the monomolecular Langmuir-Hinshelwood model. No deactivation of TiO2 catalyst was observed.