N2O5 Formation Mechanism during the Ozone-Based Low-Temperature Oxidation deNOx Process

With advantage of the solubility improving from NO into a higher valence state of nitrogen oxides, especially N 2 O 5, the ozone-based low-temperature oxidation deNO x process was investigated, especially the N 2 O 5 formation mechanism. The temperature ranging from 60 to 150 °C and O 3 /NO ratios and residence time changing were investigated by a well-designed experiment. N 2 O 5 was detected by Fourier transform infrared spectroscopy (FTIR). A 24-step mechanism was also proposed, specially for describing the formation of N 2 O 5 . Results demonstrated that the formation of N 2 O 5 was greatly influenced by the temperature and residence time. N 2 O 5 could be formed at relatively low temperatures, such as 60–80 °C, within 3–5 s when O 3 /NO > 1.0. There was no N 2 O 5 detected when the temperature was higher than 130 °C as a result of the decomposition of NO 3 . The proposed mechanism could give a good prediction of the experimental results with kinetic simulation. To speed up the N 2 O 5 formation process and reduce the O 3 dosage and O 3 slip, a type of MnO x -based catalyst was developed. Results showed that the MnO x -loaded spherical alumina catalyst had obviously a positive effect on the formation of N 2 O 5, with more than 90% NO converted into N 2 O 5 at 80 °C within 0.24 s and O 3 /NO = 1.5, with less than 15 ppm of O 3 leftover.