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Selective catalytic reduction

About: Selective catalytic reduction is a research topic. Over the lifetime, 10502 publications have been published within this topic receiving 226291 citations.


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TL;DR: An iron vanadate (FeVO4) catalyst supported on TiO2 with high dispersion has been developed and applied in the selective catalytic reduction (SCR) of NOx with NH3, showing high activity, N-2 selectivity, and H2O/SO2 durability in medium temperature range as discussed by the authors.

145 citations

Journal ArticleDOI
TL;DR: In this paper, the performance of SCR and SCR catalysts was investigated individually and as a combined system for the removal of NOx by ammonia using synthetic gas mixtures matching the composition of diesel exhaust.
Abstract: The performances of oxidation and SCR catalysts were investigated individually and as a combined system for the removal of NOx by ammonia. Experiments were carried out with synthetic gas mixtures matching the composition of diesel exhaust. Introducing an oxidation catalyst upstream of the SCR catalyst enhances the removal of NOx at low temperatures. The beneficial effects of combining the two catalysts are the oxidation of unburned hydrocarbons that inhibit the SCR reaction and the conversion of NO to NO2 on the oxidation catalyst. NO2 fractions up to 50% of total NOx enhance the NOx conversion at temperatures below 300 °C. However, excess NO2 should be avoided because the reaction of NO2 with ammonia is slow, resulting in a decreased NOx conversion. Above 350 °C, the NOx conversion essentially does not depend on the ratio NO2/NOx or on the presence of hydrocarbons in the feed. A simple mathematical prediction of the NOx conversion for the combined system is also possible. The parameters used in this calc...

145 citations

Journal ArticleDOI
Zhaoyang Fan1, Jian-Wen Shi1, Chen Gao1, Ge Gao1, Baorui Wang1, Chunming Niu1 
TL;DR: In situ DRIFT suggested that the NH3-SCR of NO over MnOx-FeOx nanoneedles follows both Eley-Rideal and Langmuir-Hinshelwood mechanisms.
Abstract: In this work, a novel porous nanoneedlelike MnOx–FeOx catalyst (MnOx–FeOx nanoneedles) was developed for the first time by rationally heat-treating metal–organic frameworks including MnFe precursor synthesized by hydrothermal method. A counterpart catalyst (MnOx–FeOx nanoparticles) without porous nanoneedle structure was also prepared by a similar procedure for comparison. The two catalysts were systematically characterized by scanning and transmission electron microscopy, X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy, hydrogen temperature-programmed reduction, ammonia temperature-programmed desorption, and in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFT), and their catalytic activities were evaluated by selective catalytic reduction (SCR) of NOx by NH3. The results showed that the rationally designed MnOx–FeOx nanoneedles presented outstanding low-temperature NH3-SCR activity (100% NOx conversion in a wide temperature window from 120 to...

145 citations

Journal ArticleDOI
TL;DR: In this article, a second cation was exchanged into the zeolite to improve the performance of the La-promoted catalysts for reducing NOx to N2 in dry and wet gas flows.
Abstract: Fe/ZSM-5 catalysts with an Fe/Al ratio 1:0, were prepared by sublimation of FeCl3 into H/ZSM-5 They display high activity and durability for the selective catalytic reduction of NOx to N2, both in dry and wet gas flows These catalysts have now been modified by exchanging a second cation into the zeolite Mere neutralization of zeolite protons by Na+ lowers the selectivity for NOx reduction to N2, but the cations Ce3 + and La3 + act as true catalyst promoters With isobutane as the reductant in a simulated vehicular emission gas, almost 90% of NOx is reduced to N2 at 350°C over the La-promoted catalyst The presence of 10% H2O in the feed does not impair the catalyst performance at high temperature; in the temperature region below 350°C it even increases the N2 yield The beneficial effect of La is due to its lowering of the catalyst activity for the undesired combustion of the hydrocarbon No signs of zeolite destruction are evident after 100 h TOS in a wet gas flow at 350°C Carbonaceous deposits causing a slight deactivation are easily removed in an O2/He flow at 500°C; this in situ regeneration fully restores the original activity

145 citations

Journal ArticleDOI
Sheng He1, Jinsong Zhou1, Yanqun Zhu1, Zhongyang Luo1, Mingjiang Ni1, Kefa Cen1 
TL;DR: In this article, the process of the reaction among elemental mercury and reactive flue gas components across the selective catalytic reduction (SCR) catalyst was studied in a laboratory-scale reactor.
Abstract: The process of the reaction among elemental mercury (Hg0) and reactive flue gas components across the selective catalytic reduction (SCR) catalyst was studied in a laboratory-scale reactor. Prepared vanadia-based SCR catalysts were characterized and analyzed to understand the potential reaction pathways. Mercury oxidation was observed when pro-exposure of the SCR catalyst to HCl, followed by passing through Hg0/N2 in the absence of gas-phase HCl. At testing conditions, Hg0 was found to desorb from the catalyst surface by adding HCl to the gas steam, which implies that HCl adsorption onto the SCR catalyst is strong relative to the mercury. Surface analysis verified the absorption of HCl onto the SCR catalysts, and the potential reaction pathways were proposed. Indeed, the monomeric vanadyl sites on the catalyst surface were found to be responsible for the adsorption of both Hg0 and HCl, which means they are active for mercury oxidation. Furthermore, the detailed Langmuir−Hinshelwood mechanism was proposed ...

144 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023311
2022632
2021546
2020583
2019604
2018595