Investigation on the redox/acidic features of bimetallic MOF-derived CeMOx catalysts for low-temperature NH3-SCR of NOx

Low-temperature selective catalytic reduction with NH3 (LT-SCR) is a promising approach for NOx remediation. This work utilized bimetallic metal-organic frameworks (MOFs) to prepare CeMOx (M=Ti, Cu) catalysts allowing the homogeneous distribution of promoters to investigate LT-SCR explicitly. The st...

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Bibliographic Details
Published in:Applied catalysis. A, General General, 2022-08, Vol.643, p.118796, Article 118796
Main Authors: Zhou, Qimin, He, Kailin, Wang, Xiaoxiang, Lim, Khak Ho, Liu, Pingwei, Wang, Wenjun, Wang, Qingyue
Format: Article
Language:English
Subjects:
Ammonia
Bimetallic oxides
Bimetals
Catalysts
Cerium oxides
Chemical reduction
Conversion
Low temperature
Low-temperature NH3-SCR of NOx
Metal-organic frameworks
Redox property
Selective catalytic reduction
Selectivity
SO2 resistance
Substitution reactions
Surface acidity
Titanium
X ray photoelectron spectroscopy
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Summary:Low-temperature selective catalytic reduction with NH3 (LT-SCR) is a promising approach for NOx remediation. This work utilized bimetallic metal-organic frameworks (MOFs) to prepare CeMOx (M=Ti, Cu) catalysts allowing the homogeneous distribution of promoters to investigate LT-SCR explicitly. The strong interfacial interaction between nanoscale-mixed components was characterized on CeTiOx by HRTEM, micro-Raman, and XPS, resulting in high acidity and good redox properties with abundant Ce3+ and Ti4+. It obtained over 80% conversion from 180 °C to 300 °C with 100% N2 selectivity, and maintained stable performance in SO2/H2O at a high GHSV of 150,000 h−1. In situ DRIFTS reveals that NH3 adsorption was promoted on CeTiOx, which accelerated reaction between NOx and adsorbed NH3 via Eley-Rideal mechanism. Meanwhile, the aliovalent substitution of ceria by Cu2+ was observed on CeCuOx, forming oxygen vacancies. Its high redox properties enhanced NOx conversion by Langmuir-Hinshelwood mechanism, but triggered NH3 peroxidation, leading to poor N2 selectivity. [Display omitted] •Bimetallic MOF-derived catalysts exhibited a homogenous nanoscale distribution.•Bimetallic oxides were used to study effect of redox/acidic properties on NH3-SCR.•Strong acidity of CeTiOx improved N2 selectivity and broadened working temperature window.•High redox properties of CeCuOx enhanced LT activity but led to NH3 peroxidation.•An insight into the catalyst design is provided for low-temperature NH3-SCR.
ISSN:0926-860X
1873-3875
DOI:10.1016/j.apcata.2022.118796