Mechanism of photo-oxidation of NH3 over TiO2: Fourier transform infrared study of the intermediate species

作者：Yamazoe Seiji; Okumura Taro; Hitomi Yutaka; Shishido Tetsuya; Tanaka Tsunehiro^*

来源：Journal of Physical Chemistry C, 2007, 111(29): 11077-11085.

DOI：10.1021/jp0726790

Selective catalytic oxidation of NH3 to give N-2 under UV irradiation (photo-SCO) takes place at a low temperature over the TiO2 catalyst. An active site for the photo-SCO is a Lewis acid site on TiO2, and adsorption of NH3 to the Lewis acid site is the first step in the photo-SCO. The adsorbed NH3 on the Lewis acid site is activated under UV irradiation to generate NH2 radical and Ti-OH (Bronsted acid site). The formed NH2 radical reacts with an oxygen anion radical species formed under UV irradiation resulting in the formation of NO. The NO is changed to surface NO2-, nitro, and NO3- (monodentate and bidentate) species by a reaction with O-2. The generated monodentate and bidentate NO3- species, nitro species, and NO react with the NH2 radical to produce N-2 selectively via nitrosoamide species. Additionally, NH4+ generated under the photo-SCO also reacts with NOx (maybe NO3- species) and would produce N-2 under photoirradiation. A small amount of N2O is produced when Ti3+ reacts with NO instead of O-2.

• 出版日期2007-7-26