Enhanced Catalytic Performance of Hierarchical MnOx/ZSM-5 Catalyst for the Low-Temperature NH3-SCR

A ZSM-5 zeolite with a hierarchical pore structure was synthesized by the desilication-recrystallization method using tetraethyl ammonium hydroxide (TEAOH) and cetyltrimethylammonium bromide (CTAB) as the desilication and structure-directing agents, respectively. The MnOx/ZSM-5 catalyst was synthesi...

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Bibliographic Details
Published in:Catalysts 2020-03, Vol.10 (3), p.311
Main Authors: Shao, Jing, Cheng, Shuyuan, Li, Zhaoxu, Huang, Bichun
Format: Article
Language:English
Subjects:
Ammonia
Ammonium hydroxide
Catalysts
Catalytic converters
Cetyltrimethylammonium bromide
Chemical reactions
Chemical synthesis
Ethanol
hierarchical pore structure
Low temperature
Mass transfer
Metal oxides
mnox/zsm-5
Nanoparticles
nh3-scr
Pore size
Porosity
Recrystallization
Selective catalytic reduction
Selectivity
so2 resistance
Structural hierarchy
X ray photoelectron spectroscopy
Zeolites
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Summary:A ZSM-5 zeolite with a hierarchical pore structure was synthesized by the desilication-recrystallization method using tetraethyl ammonium hydroxide (TEAOH) and cetyltrimethylammonium bromide (CTAB) as the desilication and structure-directing agents, respectively. The MnOx/ZSM-5 catalyst was synthesized by the ethanol dispersion method and applied for the low-temperature selective catalytic reduction of NOx with NH3. The results showed that NOx conversion of the hierarchical MnOx/ZSM-5 catalyst could reach 100% at about 120 °C and could be maintained in the temperature range of 120–240 °C with N2 selectivity over 90%. Furthermore, the hierarchical MnOx/ZSM-5catalyst presented better SO2 resistance performance than the traditional catalyst in the presence of 100 ppm SO2 at 120 °C. XRD, SEM, TEM, XPS, BET, NH3-TPD, and TG were applied to characterize the structural properties of the MnOx/ZSM-5 catalysts. These results showed that the MnOx/ZSM-5 catalyst had micropores (0.78 nm) and mesopores (3.2 nm) leading to a larger specific surface area, which improved the mass transfer of reactants and products while reducing the formation of sulfates. The better catalytic performance over hierarchical MnOx/ZSM-5 catalyst could be attributed to the higher concentration of Mn4+ and chemisorbed oxygen species and higher surface acidity. The improved SO2 resistance was related to the catalyst’s hierarchical pore structure.
ISSN:2073-4344
2073-4344
DOI:10.3390/catal10030311