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.

Highlights

  • Serious environmental pollution has brought with it a significant threat to human survival and the ecological system, wherein the discharge of atmospheric pollutants, which mainly include nitric oxide (NOX ), has become the main phenomenon responsible for acid deposition, photochemical smog, and respiratory disease in mankind

  • The significant increase of NO oxidation efficiency in the presence of catalyst could be attributed to the activated species produced from catalytic decomposition of

  • The catalytic mechanism of a H2 O2 molecule over TiO2 is analogous to the Fenton-type mechanism, and the reaction pathways can be described by the following equations [13,15]: H2 O2 + Ti4+ → Ti3+ + H+ + HO2

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Summary

Introduction

Serious environmental pollution has brought with it a significant threat to human survival and the ecological system, wherein the discharge of atmospheric pollutants, which mainly include nitric oxide (NOX ), has become the main phenomenon responsible for acid deposition, photochemical smog, and respiratory disease in mankind. Conventional strategies for NOX control are mainly categorized into three groups: pre-combustion, combustion modification, and post-combustion technologies [1]. Since pre-combustion and combustion modification could not meet the strict new emissions regulations, they are often adopted as an adjunctive way to control NOX. The post-combustion technologies, which mainly include the selective catalytic reduction method (SCR), the selective non-catalytic reduction method (SNCR), electron-beam, and absorption, are the primary methods for NOX elimination. As the most common way to control NOX , SCR is capable of achieving a high level of NOX removal efficiency: up to.

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