In situ FT-IR Study of Photocatalytic NO and CH4 Reaction on Photocatalysts

NOx is a well-known air pollutant. We propose to remediate NOx by
photo catalytic reduction at low temperature (<100℃). In situ FTIR was
used to observe reaction intermediates and to explore possible
mechanisms. The thermal-hydrolysis method was used to prepare TiO2
and 1wt% Pt-TiO2 photocatalysts. UV light was used as light source. The
reactants, CH4 and NO, are adsorbed on the photocatalyst (TiO2 or 1wt%
Pt-TiO2), the reaction was performed at three temperatures (25, 50 and
100℃). Under light irradiation, most of the CH4 is converted to formic
acid and CO2. When NO is adsorbed on the photocatalyst, it becomes
NO2, bidentate nitrites and monodentate nitrate. After light irradiation,
bidentate nitrite disappears, while bidentate nitrate, monodentate nitrate
and isocyanate are generated. Literatures suggest that NCO is the main
intermediate in the selective catalytic reduction (SCR) process. In
addition, NH2 was also observed in this experiment. Finally it is
concluded that NO can be reduced to N2 by low temperature SCR under
light irradiation.