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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 article, the kinetics of the selective catalytic reduction (SCR) of NO by NH3 in the presence of O2 has been studied on a 5.5% Cu-faujasite (Cu-FAU) catalyst.
Abstract: The kinetics of the selective catalytic reduction (SCR) of NO by NH3 in the presence of O2 has been studied on a 5.5% Cu-faujasite (Cu-FAU) catalyst. Cu-FAU was composed of cationic and oxocationic Cu species. The SCR was studied in a gas phase-flowing reactor operating at atmospheric pressure. The reaction conditions explored were: 458
85 citations
TL;DR: In this article, the effect of Ce doping on the structure and the catalytic performance of the Cu/ZSM-5 catalyst was investigated in detail for the selective catalytic reduction (SCR) of NO with NH3.
Abstract: Cu/ZSM-5 and Ce doped Cu/ZSM-5 catalysts were prepared by the incipient-wetness-impregnation method, and the effect of Ce doping on the structure and the catalytic performance of the Cu/ZSM-5 catalyst was investigated in detail for the selective catalytic reduction (SCR) of NO with NH3. The results showed that the addition of Ce can markedly broaden the operation temperature window of the Cu/ZSM-5 catalyst for NH3-SCR and enhance its H2O and SO2 resistance. The presence of Ce promoted an enrichment of copper species (isolated Cu2+ ions and CuO nanoparticles) on the catalyst surface and the increase in the Lewis acid sites on the surface of the Cu/ZSM-5 catalyst, and strengthened the redox property of the Cu/ZSM-5 catalyst. As a result, Ce-doped Cu/ZSM-5 catalyst possessed the high adsorption ability of NH3 and nitrite/nitrate, which is propitious to the increase in the reactivity of the Ce-doped Cu/ZSM-5 catalyst. In situ DRIFTS results indicated that the NH3-SCR reaction on the Cu/ZSM-5 catalyst and Ce1–Cu4/ZSM-5 catalysts definitely followed Langmuir–Hinshelwood mechanisms, and bridged nitrates and bidentate nitrates were the active intermediate. However, Eley–Rideal mechanism can't be confirmed over the Cu/ZSM-5 and Ce1–Cu4/ZSM-5 catalysts.
85 citations
TL;DR: In this paper, the authors investigated the role of surface nitrates in selective catalytic reduction (SCR) of NOx using long paraffins as reducing agents and quantified their formation on the Ag/Al2O3 catalyst under typical reaction conditions of 500-1000 ppm NOx, 6% O2 and 12% H2O.
85 citations
TL;DR: In this paper, a single-step co-gelation technique was used for the selective catalytic reduction of NO with methane (CH4-SCR), which was shown to be highly active and stable for a wide range of Ag loading.
Abstract: Silver-alumina catalysts prepared by a single-step co-gelation technique are reported in this letter as highly active and stable for the selective catalytic reduction of NO with methane (CH4–SCR). This type catalyst is active over a wide-temperature range (450–650°C), and for a relatively wide range of Ag loading (1–7 wt.%). Excess O2 in the feed gas favors the SCR reaction. Catalysts capable of high conversions of NOx by CH4 in excess O2-containing gas streams would be an attractive alternative to high temperature NH3–SCR, which is commercially practised for NOx reduction in gas turbine exhausts at >500°C. The structural stability of Ag was studied in reduction-oxidation cycles from 25–600°C by UV–VIS diffuse reflectance spectroscopy. Totally reversible structures were observed. The catalyst is active both for CH4–SCR as well as for the complete oxidation of CH4. This bifunctionality appears to be related to the coexistence of highly dispersed silver clusters and silver nanoparticles in the alumina matrix. The catalyst activity/stability remained high under demanding reaction conditions; namely in 10%O2, 30 ppm SO2 and 10%H2O and high space velocities.
85 citations
Patent•
07 Jul 1994TL;DR: In this article, a process for the treatment of exhaust gas, which process uses a specially prepared catalyst composition, for the selective catalytic reduction of NOx contained in the exhaust gas.
Abstract: There is presented a process for the treatment of exhaust gas, which process uses a specially prepared catalyst composition, for the selective catalytic reduction of NOx contained in the exhaust gas An embodiment of the process of this invention comprises a catalytic stage to selectively catalytically reduce NOx over a catalyst composition comprising a molecular sieve that has been treated with a metal in a way effective to maximize metal dispersion The catalyst of this invention typically comprises a silica, titania, or zirconia binder, eg a binder including a high molecular weight, hydroxyl functional silicone resin The catalyst of this invention may be formed into a desired shape, eg, by extrusion, and finished in a humidified atmosphere after forming
85 citations