Insight into the mechanisms of activity promotion and SO2 resistance over Fe-doped Ce-W oxide catalyst for NOx reduction

Hui Zhang; Zhihua Lian; Chunxi Lin; Ying Zhu; Wenpo Shan; Hong He

doi:10.1016/j.jcis.2023.08.129

Insight into the mechanisms of activity promotion and SO₂ resistance over Fe-doped Ce-W oxide catalyst for NO_x reduction

J Colloid Interface Sci. 2023 Dec 15;652(Pt A):923-935. doi: 10.1016/j.jcis.2023.08.129. Epub 2023 Aug 22.

Authors

Hui Zhang¹, Zhihua Lian², Chunxi Lin¹, Ying Zhu¹, Wenpo Shan³, Hong He⁴

Affiliations

¹ Center for Excellence in Regional Atmospheric Environment and Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; University of Chinese Academy of Sciences, Beijing 100049, China.
² Center for Excellence in Regional Atmospheric Environment and Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China. Electronic address: zhlian@iue.ac.cn.
³ Center for Excellence in Regional Atmospheric Environment and Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; Zhejiang Key Laboratory of Urban Environmental Processes and Pollution Control, Ningbo Urban Environment Observation and Research Station, Institute of Urban Environment, Chinese Academy of Sciences, Ningbo 315800, China.
⁴ Center for Excellence in Regional Atmospheric Environment and Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; University of Chinese Academy of Sciences, Beijing 100049, China; State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. Electronic address: honghe@rcees.ac.cn.

PMID: 37634365
DOI: 10.1016/j.jcis.2023.08.129

Abstract

Ceria-based catalysts for the selective catalytic reduction of NO_x with NH₃ (NH₃-SCR) are always subject to deactivation by sulfur poisoning. In this study, Fe-doped Ce-W mixed oxides, which were synthesized by the co-precipitation method, improved the SCR activity and SO₂ durability at low temperatures of undoped Ce-W oxides. The improved low-temperature activity was mainly due to the enhancement of redox properties at low temperatures and more active oxygen species, together with the adsorption and activation of more abundant NO_x species, facilitating the "fast SCR" reaction. In the presence of SO₂, doping with Fe species effectively prevented sulfate deposition on the CeW catalyst, due to the interaction between Fe, Ce, and W species inducing electron transfer among different metal sites and altering the electron distribution. The competitive adsorption behavior between NO and SO₂ was changed by Fe doping, in which the adsorption and oxidation of SO₂ were restrained. Besides, the elevated NO oxidation accelerated the decomposition of ammonium bisulfate, causing the SCR reaction to not be greatly suppressed. Hence, Fe-doped Ce-W oxides catalysts showed excellent sulfur resistance. This study provides an in-depth understanding of efficient Ce-based catalysts for SO₂-tolerance strategies.

Keywords: Ce-based catalysts; Fe; Low-temperature; Selective catalytic reduction; Sulfur resistance.