FeVO4-supported Mn–Ce oxides for the low-temperature selective catalytic reduction of NOx by NH3
18 Oct 2021-Catalysis Science & Technology (The Royal Society of Chemistry)-Vol. 11, Iss: 20, pp 6770-6781
TL;DR: In this paper, the additive effect between manganese (Mn) and cerium (Ce) oxides for selective catalytic reduction (SCR) of nitrogen oxides (NOx) with NH3 for the first time was investigated.
About: This article is published in Catalysis Science & Technology.The article was published on 2021-10-18. It has received 16 citations till now. The article focuses on the topics: Selective catalytic reduction & Catalysis.
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TL;DR: In this paper , the Gd-Mn-Ti composite oxides are anchored on waste coal fly ash (CFA) as catalyst for the reduction of NOx by the NH3-SCR technology.
9 citations
TL;DR: In this article , a number of Ce-La-Fe/γ-Al2O3 catalysts were prepared by impregnation and microwave hydrothermal heating based on the ratio of Ce, La, and Fe in natural bastnäsite to examine the synergistic relationship between Ce and La and its effects on ammonia selective catalytic reduction (NH3-SCR).
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References
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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
TL;DR: In this article, a series of Mn-Ni/TiO 2 catalysts were prepared by adopting incipient wetness technique and investigated for low-temperature SCR of NO with NH 3 in the presence of excess oxygen.
458 citations
TL;DR: In this paper, the effect of Sm on the physicochemical properties of the Sm-MnOx catalyst were investigated by XRD, low-temperature N2 adsorption, XPS, and FE-SEM techniques.
Abstract: Sm-Mn mixed oxide catalysts prepared by the coprecipitation method were developed, and their catalytic activities were tested for the selective catalytic reduction (SCR) of NO with ammonia at low temperature. The results showed that the amount of Sm markedly influenced the activity of the MnOx catalyst for SCR, that the activity of the Sm-Mn mixed oxide catalyst exhibited a volcano-type tendency with an increase in the Sm content, and that the appropriate mole ratio of Sm to Mn in the catalyst was 0.1. In addition, the presence of Sm in the MnOx catalyst can obviously enhance both water and sulfur dioxide resistances. The effect of Sm on the physiochemical properties of the Sm-MnOx catalyst were investigated by XRD, low-temperature N2 adsorption, XPS, and FE-SEM techniques. The results showed that the presence of Sm in the Sm-MnOx catalyst can restrain the crystallization of MnOx and increase its surface area and the relative content of both Mn4+ and surface oxygen (OS) on the surface of the Sm-MnOx catal...
417 citations
TL;DR: In this paper, the Eley-Rideal mechanism and the Langmuir-Hinshelwood mechanism were compared for low temperature selective catalytic reduction (SCR) of NO with NH3.
Abstract: (Fe3−xMnx)1−δO4 was synthesized using a co-precipitation method and then developed as a catalyst for the low temperature selective catalytic reduction (SCR) of NO with NH3. The SCR activity of (Fe3−xMnx)1−δO4 was clearly enhanced with the increase of Mn content. The results of in situ DRIFTS study demonstrated that both the Eley–Rideal mechanism (i.e. reaction of activated ammonia with gaseous NO) and the Langmuir–Hinshelwood mechanism (i.e. reaction of adsorbed ammonia species with adsorbed NOx species) might happen during the SCR reaction over (Fe3−xMnx)1−δO4. According to the kinetic analysis, the respective contribution of the Langmuir–Hinshelwood mechanism and the Eley–Rideal mechanism on the SCR reaction was studied. Only the adsorption of NO + O2 on (Fe2.8Mn0.2)1−δO4 was promoted, so the Langmuir–Hinshelwood mechanism predominated over NO conversion on (Fe2.8Mn0.2)1−δO4 especially at lower temperatures. Both the adsorption of NO + O2 and the adsorption of NH3 on (Fe2.5Mn0.5)1−δO4 were obviously promoted, so NO conversion on (Fe2.5Mn0.5)1−δO4 mainly followed the Eley–Rideal mechanism especially at higher temperatures. Both the nitrate route and the over-oxidization of adsorbed ammonia species contributed to the formation of N2O on (Fe2.8Mn0.2)1−δO4 above 140 °C. However, the formation of N2O on (Fe2.5Mn0.5)1−δO4 mainly resulted from the over-oxidization of adsorbed ammonia species. Although the activity of (Fe2.5Mn0.5)1−δO4 was suppressed in the presence of H2O and SO2, the deactivated catalyst can be regenerated after the water washing.
414 citations
TL;DR: In this paper, a series of Mn-Ce/TiO2-X (X = Hk, N1, N2 and N3) were prepared by adopting incipient wetness technique and investigated for the low-temperature selective catalytic reduction (SCR) of NOx with NH3 at industrial relevant conditions.
392 citations