Catalyst deactivation in the gas phase destruction of nitrogen-containing organic compounds using TiO2/UV–VIS

Possible application of the TiO2/UV–VIS photocatalytic process in the destruction of nitrogen-containing malodorous compounds was evaluated. Pyridine (C5H5N), propylamine (C3H7NH2) and diethylamine (C4H10NH) were photodegraded in the presence and in the absence of oxygen. Degradation of nitrogen-containing organic compounds was confirmed by mass balance taking into consideration NH4+ and NO3− ions trapped at the TiO2 surface. Photocatalytic deactivation was observed in all cases. On-line mass spectrometry was used to identify byproducts in the gas phase formed during the degradation process. GC–MS analysis of the dichloromethane-extract of aqueous species leached from the surface of deactivated catalyst, as well as pre-concentration in a Tenax column were used to identify intermediates in the gas phase. These byproducts are considered to be the major ones responsible for deactivation of TiO2.