Sulfur-doping promoting peroxone reaction over TiO2 for highly effective NO oxidation at low temperature: Experimental and DFT studies

The peroxone reaction between O 3 and H 2 O 2 over TiO 2 exhibits bright prospects for low-temperature flue gas denitration, which effectively overcomes the limitations of traditional peroxone reaction and remains advanced poison resistant ability. In this study, sulfur-doped TiO 2 was successfully adopted to improve the catalytic performance under low consumption of O 3 and H 2 O 2 , making this technology take a pivotal step towards practical application. Compared with TiO 2 /H 2 O 2 /O 3 system (68% NO conversion), the NO conversion could reach up to 85% in S-doped TiO 2 /H 2 O 2 /O 3 system under test condition (GHSV = 1.2 × 10 5 h −1 , H 2 O 2 /NO = 1.2, and O 3 /NO = 0.5). Characterizations and density functional theory calculations revealed that sulfur-doping modified the local structure of the catalyst, which enables a more effective combination between Ti 5c and hydroperoxyl, thus facilitating the reaction. Besides, the introduction of sulfur could increase the adsorption capacity of NO x and enhance the Lewis acidity of the catalyst, thus improving the NO conversion performance. The stability and applicability of the process were systematically tested from the following aspects: varied gas composition, H 2 O 2 consumption, pH value, and SO 2 /CO concentration. Results revealed that the S-doped TiO 2 /H 2 O 2 /O 3 system exhibited good stability and poison resistant ability, the potential for practical applications.