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Published on: November 27, 2015
Descriptor-Led Nonmetal Doping of MnO2 Enables Selective NH3-SCR With Suppressed N2O Formation
Kai Xie1, Ying Wang1, Fenghui Li1
1State Key Laboratory of Engines, Tianjin University, Tianjin, China.
Small (Weinheim an Der Bergstrasse, Germany)
|July 27, 2026
Summary
Nonmetal substitution in manganese dioxide (MnO2) catalysts suppresses harmful nitrous oxide (N2O) formation and enhances ammonia-selective catalytic reduction (NH3-SCR) for nitrogen oxides (NOx) abatement.
Area of Science:
- Materials Science
- Catalysis
- Environmental Chemistry
Background:
- Low-temperature ammonia-selective catalytic reduction (NH3-SCR) is crucial for controlling nitrogen oxides (NOx) emissions.
- A significant challenge is the co-production of nitrous oxide (N2O), a potent greenhouse gas, during NH3-SCR over MnO2 catalysts.
- Optimizing catalyst performance requires addressing the trade-off between activity and selectivity, particularly concerning N2O byproduct formation.
Purpose of the Study:
- To investigate the effect of oxygen-site nonmetal substitution in β-MnO2 catalysts for low-temperature NH3-SCR.
- To simultaneously suppress N2O formation and enhance the SCR reaction rate.
- To establish a computational workflow for predicting and designing effective catalyst modifications.
Main Methods:
- Employed a computational workflow combining structural compatibility, orbital hybridization, and stability screening to identify viable nonmetal dopants.
- Utilized density functional theory (DFT) calculations to estimate reaction kinetics and energy barriers for N2O and N2 formation.
- Analyzed electronic structure using Bader charge, COHP/ICOHP, and ELF to elucidate reaction mechanisms.
Main Results:
- Oxygen-site substitution with Fluorine (F) and Sulfur (S) in β-MnO2 effectively suppressed N2O formation and accelerated NH3-SCR.
- F and S doping raised the N2O-forming barrier and lowered the N2-forming barrier, improving kinetic N2 selectivity.
- At 200°C, F- and S-doped catalysts showed significantly increased turnover frequencies (TOF) and enhanced kinetic N2 selectivity compared to undoped MnO2.
Conclusions:
- Nonmetal substitution at oxygen sites in β-MnO2 offers a promising strategy to mitigate N2O byproduct formation in NH3-SCR.
- The Mn(d)-nonmetal(p) band center alignment serves as a mechanistic descriptor for predicting catalyst performance.
- These findings provide a theoretical framework for designing advanced oxide catalysts with improved activity and selectivity for NOx abatement.
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