Remarkable enhancement in the N2 selectivity of NH3-SCR over the CeNb3Fe0.3/TiO2 catalyst in the presence of chlorobenzene.

Pengchao Zang,Guojie Zhang,Jianjun Chen,Xiaoqing Liu,Junhua Li,Yongfa Zhang,Jun Liu

doi:10.1007/s11356-021-17116-y

Abstract

The simultaneous removal of NOx and dioxins is the frontier of environmental catalysis, which is still in the initial stage and poses several challenges. In this study, a series of CeNb3Fex/TiO2 (x = 0, 0.3, 0.6, and 1.0) catalysts were prepared by the sol-gel method and examined for the synergistic removal of NOx and CB. The CeNb3Fe0.3/TiO2 catalyst exhibits an optimum catalytic performance, with an NOx conversion greater than 95% at 260-380°C. It also exhibits an optimal CB oxidation activity, in which CB promoted both the NOx conversion and N2 selectivity below 250°C. Moreover, the more favorable ratios of Ce4+ to Ce3+ and plentiful surface-adsorbed oxygen species are the reasons why CeNb3Fe0.3/TiO2 catalyst has better catalytic activity than other catalysts at the lower temperature. Simultaneously, owing to the modulation of Fe to the redox properties of Ce and Nb, the large number of oxygen vacancies and acid sites was generated, and the CeNb3Fe0.3/TiO2 catalyst is beneficial to NOx reduction and CB oxidation. Furthermore, the results of in situ DRIFTS study reveal the NH3-SCR reactions over CeNb3Fe0.3/TiO2 catalysts are mainly conformed to by the L-H mechanism (< 350°C) and E-R mechanism (> 350°C), respectively, and the multi-pollutant conversion mechanism in the synergistic reaction was systematically studied.

Highlights

With the acceleration in the industrialization in China, air pollution has attracted national attention (Chen et al 2014, Li et al 2015)
A series of CeNb3Fex/TiO2 (x = 0, 0.3, 0.6, and 1.0) catalysts were prepared by the sol-gel method and investigated for the synergistic removal of nitrogen oxides (NOx) and chlorobenzene
With the increase in the Fe content, the CB conversion rate gradually decrease further confirming that excess Fe can inhibit the CB catalytic oxidation of CeNb3Fex/TiO2 catalysts

Summary

Introduction

With the acceleration in the industrialization in China, air pollution has attracted national attention (Chen et al 2014, Li et al 2015). For CeNb3Fe0.3/TiO2, these catalysts exhibited highest catalytic activity, and the NOx conversion rate exceeded 90 % at 250–400°C. CB oxidation promoted N2 selectivity over the CeNb3Fe0.3/TiO2 catalyst at a low temperature (Fig. 2(b)).

Results

Conclusion