High Resistance to Na Poisoning of the V2O5-Ce(SO4)2/TiO2 Catalyst for the NO SCR Reaction

Yanrong Chen,Mingxuan Wang,Li Zhang,Dingling Tang,Jingyu Ran,Xuesen Du

doi:10.4209/aaqr.2017.11.0521

Abstract

Poisoning by Na is one of the major issues for the commercial SCR catalyst. In this study, Ce(SO4)2 was added to the catalyst system of V2O5/TiO2 to enhance its resistance to Na poisoning. The results show that the addition of Ce(SO4)2 increases the NOx conversion of the V2O5/TiO2 catalyst at medium temperatures of 330°C–450°C. After being doped with sodium with a molar ratio of Na/V = 1/1, the V2O5-Ce(SO4)2/TiO2 catalyst still shows excellent DeNOx efficiency, about 40% higher than the commercial V2O5-WO3/TiO2 catalyst. The fresh and Na-poisoned catalysts were characterized using XRD, SEM, NH3-TPD and H2-TPR. The results show that the Ce(SO4)2 addition remarkably strengthens the surface acidity and redox ability of the V2O5/TiO2 catalyst. Furthermore, the TPD results show that the V2O5-Ce(SO4)2/TiO2 catalyst can maintain its surface acidity after being doped with Na, while the acidity of the V2O5-WO3/TiO2 catalyst dramatically decreases. The redox ability of the catalyst can also be retained more effectively when Ce(SO4)2 is added to the catalyst system.

Highlights

Nitrogen oxides (NOx) are the main pollutants in air pollution, causing great harm to human health
The catalyst is the core of the entire selective catalytic reduction DeNOx technology
The DeNOx efficiency of all the V2O5-Ce(SO4)2/TiO2 catalysts is higher than V2O5/TiO2 and Ce(SO4)2/TiO2 catalysts in the whole temperature range but slightly lower than that of commercial V2O5-WO3/TiO2 catalyst at a low temperature of 150°C to 330°C

Summary

INTRODUCTION

Nitrogen oxides (NOx) are the main pollutants in air pollution, causing great harm to human health. The catalyst is the core of the entire selective catalytic reduction DeNOx technology. The deposition of alkali metals in fly ash such as K and Na can lead to catalyst poisoning and reduce the activity (Kamata et al, 1999; Tang et al, 2010; Du et al, 2017, 2018; Wang et al, 2018b). Knowing how to adjust the formulation based on the existing catalysts to achieve better resistance to alkali poisoning is important. The new catalysts were prepared by using Ce(SO4) instead of WO3 in the catalyst to investigate the activity performance and catalytic mechanism of the new V2O5-Ce(SO4)2/TiO2 catalyst before and after alkali poisoning. NH3-TPD adsorption-desorption and H2-TPR characterization were carried out, and we obtained a novel catalyst with high resistance to alkali poisoning

METHODS AND MATERIALS

RESULTS AND DISCUSSION

CONCLUSIONS