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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: In this paper, a series of catalysts of iron-manganese oxide supported on mesoporous silica (MPS) with different Mn/Fe ratio were studied for low-temperature selective catalytic reduction (SCR) of NO with ammonia in the presence of excess oxygen.
Abstract: A series of catalysts of iron–manganese oxide supported on mesoporous silica (MPS) with different Mn/Fe ratio were studied for low-temperature selective catalytic reduction (SCR) of NO with ammonia in the presence of excess oxygen. Effects of amounts of iron–manganese oxide and calcination temperatures on NO conversion were also investigated. It was found that the Mn–Fe/MPS with Mn/Fe = 1 at the calcination temperature of 673 K showed the highest activity. The results showed that this catalyst yielded 99.1% NO conversion at 433 K at a space velocity of 20,000 h −1 . H 2 O has no adverse impact on the activity when the SCR reaction temperature is above 413 K. In addition, the SCR activity was suppressed gradually in the presence of SO 2 and H 2 O, while such effect was reversible after heating treatment.

158 citations

Journal ArticleDOI
TL;DR: In this paper, solid-state ion exchange (SSIE) and one-pot synthesis were used to synthesize Cu/SAPO-34 catalysts, which were characterized with surface area/pore volume measurements.
Abstract: Cu/SAPO-34 catalysts are synthesized using two methods: solid-state ion exchange (SSIE) and one-pot synthesis. SSIE is conducted by calcining SAPO-34/CuO mixtures at elevated temperatures. For the one-pot synthesis method, Cu-containing chemicals (CuO and CuSO4) are added during gel preparation. A high-temperature calcination step is also needed for this latter method. Catalysts are characterized with surface area/pore volume measurements, temperature programmed reduction (TPR), electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR) spectroscopies, and scanning electron microscopy (SEM). Catalytic properties are examined using standard ammonia selective catalytic reduction (NH3-SCR) and ammonia oxidation reactions. For Cu/SAPO-34 samples prepared by SSIE, Cu presents both as isolated Cu2+ ions and unreacted CuO. The former are highly active and selective in NH3-SCR, while the latter catalyzes a side reaction; notably, the non-selective oxidation of NH3 above 350 °C. Using the one-pot method followed by a high-temperature aging treatment, it is possible to form Cu/SAPO-34 samples with predominately isolated Cu2+ ions at low Cu loadings. However at much higher Cu loadings, isolated Cu2+ ions that bind weakly with the CHA framework and CuO clusters also form. These Cu moieties are very active in catalyzing non-selective NH3 oxidation above 350 °C. At very low reaction temperature temperatures (

157 citations

Journal ArticleDOI
TL;DR: In this article, the selective catalytic reduction of nitrogen oxides has been studied in the presence of O2 over Fe/MFI catalysts with Fe/Al∼1, prepared by sublimation of FeCl3 vapor onto HMFI.

157 citations

Journal ArticleDOI
TL;DR: In this paper, non-noble metal copper (Cu) nanoparticles (NPs) with controlled size and surface coverage are decorated on silicon nanowire arrays (SiNWAs) by a simple galvanic displacement reaction.
Abstract: Non-noble metal copper (Cu) nanoparticles (NPs) with controlled size and surface coverage are decorated on silicon nanowire arrays (SiNWAs) by a simple galvanic displacement reaction. Using the combined efforts of all these approaches, SiNWAs-supported Cu NPs (SiNWAs–Cu) exhibit excellent and stable activity for the catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by sodium borohydride (NaBH4) in an aqueous solution, which can be recycled for five successive cycles of the reaction with a conversion efficiency of more than 95%. This novel catalyst also shows excellent catalytic performance for the degradation of other organic dyes, such as methylene blue (MB) and rhodamine B (RhB). Additionally, we demonstrate that the catalytic activity of SiNWAs–Cu is comparable to other SiNWAs-supported noble metal NPs (i.e., Ag and Au). Furthermore, SiNWAs as powerful substrates can be reused for decorating with Cu NPs after dilute HNO3 treatment. SiNWAs–Cu is particularly attractive as a catalyst, although Cu is orders of magnitude cheaper than any noble metals, its catalytic performance is comparable to other noble metals. So SiNWAs–Cu is thus expected to have the potential as a highly efficient, cost-effective and eco-friendly reusable catalyst to replace noble metals for certain catalytic applications.

157 citations

Journal ArticleDOI
TL;DR: In this paper, the optimal proportions of Pt-Cu and Pd-Cu in bimetallic catalysts on activated carbon, obtained by wetness impregnation, have been found.
Abstract: The increasing pollution of natural sources of drinking water encourages the development of new emerging technologies and processes for water remediation. This work deals with the study of catalytic reduction of contaminated waters containing nitrates (60 ppm) in a continuous reactor working at room temperature and atmospheric pressure and using hydrogen as reducing agent. Optimal proportions of Pt-Cu and Pd-Cu in bimetallic catalysts on activated carbon, obtained by wetness impregnation, have been found. Besides, novel catalysts obtained from copper nanoparticles doped with Pd or Pt and supported on activated carbon, have also been studied. For all catalysts the Pt-Cu pair seems to be more selective in the transformation of the nitrates ions to nitrogen compared to Pd-Cu pair. Furthermore, considering the noble metal amount, the bimetallic nanosphere catalysts are more active (between 20 and 50) than the impregnated ones. The catalysts have been characterized by hydrogen chemisorption, BET, X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analysis. During the reaction, a considerable amount of the noble metal in its oxidised form has been detected. Based on this result an additional step to the generally accepted reaction mechanism of the nitrate reduction has been proposed.

157 citations


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