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Journal ArticleDOI

Promoting effect of Ti addition on three-dimensionally ordered macroporous Mn-Ce catalysts for NH3-SCR reaction: Enhanced N2 selectivity and remarkable water resistance

15 Dec 2021-Applied Surface Science (North-Holland)-Vol. 569, pp 151047
TL;DR: In this article, a series of 3D-Mn3CeyTiz catalysts with threedimensional ordered macroporous (3DOM) structure were synthesized by a soft template method.
About: This article is published in Applied Surface Science.The article was published on 2021-12-15. It has received 27 citations till now. The article focuses on the topics: Catalysis & Selectivity.
Citations
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Journal ArticleDOI
01 Jul 2022-Fuel
TL;DR: In this paper , the authors investigated low-temperature NH3-SCR performance of several Mn and/or Ce oxides on blast furnace slag-derived (BFS-derived) zeolite X catalysts and found that Mn-Ce/X catalyst had the highest NO conversion of nearly 98% at 250 °C and excellent N2 selectivity of nearly 100% during 75-175 °C.

37 citations

Journal ArticleDOI
01 Jan 2023-Fuel
TL;DR: In this paper , the effects of catalyst parameters on denitrification efficiency are summarized, including Si/Al ratio, Cu or Fe loading, specific surface area, coordination structure and calcination temperature.

24 citations

Journal ArticleDOI
TL;DR: In this article , a new bimetallic biochar (Cr-Fe/BC) was synthesized via pyrolysis by using chrome shaving and ferric sulfate as the raw materials.

14 citations

Journal ArticleDOI
TL;DR: In this article , different precursors were adopted to adjust the isolated Cu2+ ions and CuO species in the Cu-SSZ-13 catalysts, which showed an unexpected increase of the high-temperature activity after hydrothermal treatment.

9 citations

References
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Journal ArticleDOI
TL;DR: This review summarizes the latest SCR reaction mechanisms and emerging poison-resistant mechanisms in the beginning and subsequently gives a comprehensive overview of newly developed SCR catalysts, including metal oxide catalysts ranging from VOx, MnOx, CeO2, and Fe2O3 to CuO based catalysts.
Abstract: Selective catalytic reduction with NH3 (NH3-SCR) is the most efficient technology to reduce the emission of nitrogen oxides (NOx) from coal-fired industries, diesel engines, etc. Although V2O5-WO3(MoO3)/TiO2 and CHA structured zeolite catalysts have been utilized in commercial applications, the increasing requirements for broad working temperature window, strong SO2/alkali/heavy metal-resistance, and high hydrothermal stability have stimulated the development of new-type NH3-SCR catalysts. This review summarizes the latest SCR reaction mechanisms and emerging poison-resistant mechanisms in the beginning and subsequently gives a comprehensive overview of newly developed SCR catalysts, including metal oxide catalysts ranging from VOx, MnOx, CeO2, and Fe2O3 to CuO based catalysts; acidic compound catalysts containing vanadate, phosphate and sulfate catalysts; ion exchanged zeolite catalysts such as Fe, Cu, Mn, etc. exchanged zeolite catalysts; monolith catalysts including extruded, washcoated, and metal-mesh/foam-based monolith catalysts. The challenges and opportunities for each type of catalysts are proposed while the effective strategies are summarized for enhancing the acidity/redox circle and poison-resistance through modification, creating novel nanostructures, exposing specific crystalline planes, constructing protective/sacrificial sites, etc. Some suggestions are given about future research directions that efforts should be made in. Hopefully, this review can bridge the gap between newly developed catalysts and practical requirements to realize their commercial applications in the near future.

800 citations

Journal ArticleDOI
TL;DR: Diffuse reflectance infrared Fourier transform spectroscopy studies showed that the synergetic effect between Mn and Ce contributes to the formation of reactive intermediate species, thus promoting the NH3-SCR to proceed.
Abstract: Mn-Ce-Ti mixed-oxide catalyst prepared by the hydrothermal method was investigated for the selective catalytic reduction (SCR) of NOx with NH3 in the presence of oxygen. It was found that the environmentally benign Mn-Ce-Ti catalyst exhibited excellent NH3-SCR activity and strong resistance against H2O and SO2 with a broad operation temperature window, which is very competitive for the practical application in controlling the NOx emission from diesel engines. On the basis of the catalyst characterization, the dual redox cycles (Mn4+ + Ce3+ Mn3+ + Ce4+, Mn4+ + Ti3+ Mn3+ + Ti4+) and the amorphous structure play key roles for the high catalytic deNO(x) performance. Diffuse reflectance infrared Fourier transform spectroscopy studies showed that the synergetic effect between Mn and Ce contributes to the formation of reactive intermediate species, thus promoting the NH3-SCR to proceed.

362 citations

Journal ArticleDOI
TL;DR: In this paper, the impact of nitrogen oxides on the environment and human health including the low-temperature selective catalytic reduction of NOx by ammonia (NH3-SCR) over manganese-based materials is discussed.
Abstract: An overview is given of the impact of nitrogen oxides on the environment and human health including the low-temperature selective catalytic reduction of NOx by ammonia (NH3-SCR) over manganese-based materials. The review gives a comprehensive overview of NH3-SCR chemistry including the impacts of NOx, stringent regulations, limitations on NOx emissions and aspects of the reaction mechanism over Mn-based catalysts using isotopic labeled and in situ FT-IR studies. The review attempts to correlate catalyst activity and stability with the acidity, manganese oxidation state, surface texture, and structural morphology. Prospectively, low-temperature SCR of NOx over Mn-based catalysts opens up novel views to mitigate NOx and help us design the next generation industrial catalysts.

360 citations

Journal ArticleDOI
TL;DR: It was found that the in situ prepared catalyst exhibited the highest activity and the most extensive operating-temperature window, compared to the catalysts prepared by impregnation or mechanically mixed methods.
Abstract: The MnOx and CeOx were in situ supported on carbon nanotubes (CNTs) by a poly(sodium 4-styrenesulfonate) assisted reflux route for the low-temperature selective catalytic reduction (SCR) of NO with NH3. X-Ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), X-ray photoelectron spectroscopy (XPS), H2 temperature-programmed reduction (H2-TPR) and NH3 temperature-programmed desorption (NH3-TPD) have been used to elucidate the structure and surface properties of the obtained catalysts. It was found that the in situ prepared catalyst exhibited the highest activity and the most extensive operating-temperature window, compared to the catalysts prepared by impregnation or mechanically mixed methods. The XRD and TEM results indicated that the manganese oxide and cerium oxide species had a good dispersion on the CNT surface. The XPS results demonstrated that the higher atomic concentration of Mn existed on the surface of CNTs and the more chemisorbed oxygen species exist. The H2-TPR results suggested that there was a strong interaction between the manganese oxide and cerium oxide on the surface of CNTs. The NH3-TPD results demonstrated that the catalysts presented a larger acid amount and stronger acid strength. In addition, the obtained catalysts exhibited much higher SO2-tolerance and improved the water-resistance as compared to that prepared by impregnation or mechanically mixed methods.

285 citations

Journal ArticleDOI
TL;DR: In this article, the authors summarized the recent advances in the application of ceria-based catalysts for low-temperature selective catalytic reduction of NO with NH3 (NH3-SCR) operated at low temperatures.

269 citations