Effect of Catalyst Crystallinity on V-Based Selective Catalytic Reduction with Ammonia.

Min Lee,Bora Ye,Duck Lee,Taehyo Kim,Myeung-Jin Lee,Sun-I Kim,Jung Lee,Hong-Dae Kim

doi:10.3390/nano11061452

Abstract

In this study, we synthesized V2O5-WO3/TiO2 catalysts with different crystallinities via one-sided and isotropic heating methods. We then investigated the effects of the catalysts’ crystallinity on their acidity, surface species, and catalytic performance through various analysis techniques and a fixed-bed reactor experiment. The isotropic heating method produced crystalline V2O5 and WO3, increasing the availability of both Brønsted and Lewis acid sites, while the one-sided method produced amorphous V2O5 and WO3. The crystalline structure of the two species significantly enhanced NO2 formation, causing more rapid selective catalytic reduction (SCR) reactions and greater catalyst reducibility for NOX decomposition. This improved NOX removal efficiency and N2 selectivity for a wider temperature range of 200 °C–450 °C. Additionally, the synthesized, crystalline catalysts exhibited good resistance to SO2, which is common in industrial flue gases. Through the results reported herein, this study may contribute to future studies on SCR catalysts and other catalyst systems.

Highlights

We explored the effect of crystallinity of V2 O5 -WO3 /TiO2 on the nitrogen oxides (NOX)
We found that the NOX removal efficiency of the amorphous V2O5-WO3/TiO2 catalyst was negatively
We found that the NOX removal efficiency of the amorphous V2 O5 -WO3 /TiO2 catalyst was negatively impacted at temperatures below 300 ◦ C; it exceeded 94% at 300–400 ◦ C

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Air pollution has recently become a critical, global issue [1]. Environmental regulations have been tightened to reduce the emissions of chemical impurities (such as NOX , SOx , CO, volatile organic compounds (VOCs), and particulate matter (PM)). Among the numerous air pollutants, nitrogen oxides (NOX : NO, NO2 , and N2 O) are extremely dangerous as they can disperse over long distances and form secondary PM2.5 by reacting with water vapor, which causes acid rain and smog, contributes to global warming [4,5], and can deeply penetrate human lungs, causing adverse health effects such as increased cardiovascular and respiratory morbidity [6]

Methods

Results

Conclusion