Topic
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: In this paper, the authors used a noble metal-free ultrathin MnO2-x nanosheet array fabricated by in situ etching of a La layer from LaMnO3 under loose contact conditions in a NO-containing atmosphere.
Abstract: Diesel soot combustion suffers from ignition temperatures (T10) as high as > 450 °C in the absence of catalysts, which are unavailable in diesel exhaust during normal driving cycles (normally 200–400 °C). A catalytic diesel particulate filter (CDPF) could decrease T10 greatly, but it is often inadequate due to the poor contact associated with the solid (catalyst)-solid (soot) interactions. Herein, a highly significant T10, as low as ˜200 °C, was achieved on noble metal-free ultrathin MnO2-x nanosheet array fabricated by in situ etching of a La layer from LaMnO3 under loose contact conditions in a NO-containing atmosphere. A number of advantages were found with such a system including the improved reducibility. Then, the nanosheet array ensures high dispersion of soot on the catalyst. Finally, high NO-to-NO2 oxidation activity further facilitates contact between catalyst and soot via NO2, a stronger oxidant than O2.
72 citations
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TL;DR: Cerium-modified Cu-SSZ-13 catalysts were synthesized by an in situ hydrothermal method, and Ce was incorporated through ion exchange as mentioned in this paper, which showed better NOx removal efficiency and aging resistance.
Abstract: Cerium-modified Cu-SSZ-13 catalysts were synthesized by an in situ hydrothermal method, and Ce was incorporated through ion exchange. The catalytic performance and N2 selectivity over prepared catalysts were evaluated in the selective catalytic reduction (SCR) of NOx by NH3. The physicochemical properties of the samples were characterized using XRD, SEM, H2-TPR, XPS, NMR, XAS, and N2 adsorption. The results indicated that Cu-SSZ-13 modified by Ce showed better NOx removal efficiency and aging resistance. The optimized condition was ion exchanged for 2 h in a cerous nitrate solution. The introduction of Ce effectively restrained the conversion of an active Cu component (Cu2+ → Cu+) during the hydrothermal aging. Ce3+ species strongly associated with molecular sieve carriers and only slight skeleton dealumination was observed on the sample exchanged for 2 h, thus resulting in the further stabilization of catalyst active centers, which consequently maintained the catalytic activity and antiaging ability.
72 citations
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TL;DR: In this paper, an ultrasonic-modified MnO(x)/TiO(2) catalyst was prepared and compared with two different kinds of MnO/TiO (2) catalysts in the process of low-temperature selective catalytic reduction of NO with NH(3), and the physicochemical properties of the catalysts were studied by using various characterization techniques, such as Brunauer-Emmett-Teller (BET) surface measurement, X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), and in situ Fou
72 citations
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TL;DR: In this article, a novel Ni-Ce-Ti mixed oxide catalyst was developed for the selective catalytic reduction of NOx by NH3, which showed high NH3-SCR activity, excellent N2 selectivity with broad operation temperature window.
72 citations
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06 Oct 1994TL;DR: In this paper, the Selective Catalytic Reduction (SCR) method was used to reduce nitrogen oxide emissions in the exhaust of an internal combustion engine (ICE) by injecting ammonia into a catalyzer through which the exhaust gas flows, this ammonia reacting with nitrogen monoxide or nitrogen dioxide to form nitrogen and water.
Abstract: The method reduces the nitrogen oxide concentration in the exhaust of an internal combustion engine. A noticeable reduction in the NOx emission of a diesel motor can be achieved by applying the Selective Catalytic Reduction (SCR) method. In this method, ammonia is injected into a catalyzer through which the exhaust gas flows, this ammonia reacting with nitrogen monoxide or, respectively, nitrogen dioxide to form nitrogen and water. Since the exhaust gas should contain neither nitrogen monoxide nor excess ammonia, suitable methods are required for regulating the metering of NH3. For controlling the amount of urea added to the exhaust gas as a reduction agent, the NO and NH3 concentration is measured using a detector located in the exhaust systems following the SCR catalyzer. The detector contains a vanadate layer manufactured on the basis of a specific sputtering method as a sensitive element. The electrical resistance thereof is highest when the conversion of nitrogen monoxide to form nitrogen and water occurs stoichiometrically.
72 citations