Removal of NOX using hydrogen peroxide vapor over Fe/TiO2 catalysts and an absorption technique

Abstract

In this study, we proposed an innovative oxidation–absorption method for low-temperature denitrification (160–240◦C), in which NO is initially catalytically oxidized by hydrogen peroxide (H2O2) vapor over titania-based catalysts, and the oxidation products are then absorbed by NaOH solution. The effects of flue gas temperature, molar H2O2/NO ratio, gas hourly space velocity (GHSV), and Fe substitution amounts of Fe/TiO2 catalysts on the denitrification efficiency were investigated by a well-designed experiment. The results indicated that the Fe/TiO2 catalyst exhibited a combination of remarkable activity and deep oxidation ability (NO converted into harmless NO3−). In order to comprehend the functional mechanism of the Fe dopant’s local environment in TiO2 support, the promotional effect of the calcination temperature of Fe/TiO2 on the denitration performance was also studied. A tentative synergetic mechanism could be interpreted from two aspects: (1) Fe3+ as a substitute of Ti4+, leading to the formation of enriched oxygen vacancies at the surface, could significantly improve the adsorption efficiency of •OH; (2) the isolated surface Fe ion holds a strong adsorption affinity for NO, such that the adsorbed NO could be easily oxidized by the pre-formed •OH. This process offers a promising alternative for current denitrification technology.