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 surface changes during the NTP-activated HC-SCR deNOx reaction over a silver-based catalyst at ambient temperature using simulated diesel fuels (toluene and n-octane).
Abstract: The current paper reports on a newly developed DRIFTS-MS system for the investigation of non-thermal plasma (NTP) assisted heterogeneously catalyzed reactions. Specifically, this methodology has been utilized to investigate the surface changes during the NTP-activated hydrocarbon selective catalytic reduction (HC-SCR) deNOx reaction over a silver-based catalyst at ambient temperature using simulated diesel fuels (toluene and n-octane). The experimental setup and the methods used to investigate the plasma activation operating with helium as the carrier gas in order to examine low-temperature reactions are described. The technique has identified the importance, even at low temperatures, of isocyanate species in the HC-SCR deNOx reaction as well as the critical role of water in the formation of N2.
67 citations
02 Oct 2015
TL;DR: In this article, the most relevant catalytic NOx abatement systems for Diesel engine vehicles are summarized in a short review, with focus on the main catalytic aspects and materials.
Abstract: The catalytic reduction of nitrogen oxides (NOx) under lean-burn conditions represents an important target in catalysis research. The most relevant catalytic NOx abatement systems for Diesel engine vehicles are summarized in this short review, with focus on the main catalytic aspects and materials. Five aftertreatment technologies for Diesel NOx are reviewed: (i) direct catalytic decomposition; (ii) catalytic reduction; (iii) NOx traps; (iv) plasma-assisted abatement; and (v) NOx reduction combined with soot combustion. The different factors that can affect catalytic activity are addressed for each approach (e.g. promoting or poisoning elements, operating conditions, etc.). In the field of catalytic strategies, the simultaneous removal of soot and NOx using multifunctional catalysts, is at present one of the most interesting challenges for the automotive industry.
67 citations
Patent•
05 Nov 2003TL;DR: In this paper, an emissions control system is used with a compression ignition engine capable of producing an exhaust gas stream to be treated by a reduction agent which is mixed with the exhaust gasses to convert the exhaust gases stream prior to being directed into an SCR catalyst capable of reducing NOx in the exhaust gas streams.
Abstract: An emissions control system is used with a compression ignition engine capable of producing an exhaust gas stream to be treated by a reduction agent which is mixed with the exhaust gas stream to convert the exhaust gas stream prior to being directed into an SCR catalyst capable of reducing NOx in the exhaust gas stream. An exhaust gas recirculation valve is associated with the compression ignition engine for directing the exhaust gas stream back into the compression ignition engine. An electronic control unit and sensors determine whether the temperature of the exhaust gas stream is at a predetermined temperature, and if so control operation of the valve to allow a portion of the exhaust gas stream to be directed into the SCR catalyst. A bypass valve may also be provided to prevent the exhaust gas stream from entering into the SCR catalyst.
67 citations
TL;DR: The reasons for the gap of catalytic performance between fresh and As-Ca poisoned catalyst were proposed as follows: surface area decrease; crystalline WO3 particles generation; and oxygen defect sites irreversible loss.
Abstract: An extraordinary deactivation offset effect of calcium and arsenic on CeO2–WO3 catalyst had been found for selective catalytic reduction of NO with NH3 (NH3–SCR). It was discovered that the maximum NOx conversion of As–Ca poisoned catalyst reached up to 89% at 350 °C with the gaseous hourly space velocity of 120 000 mL·(g·h)−1. The offset effect mechanisms were explored with respect to the changes of catalyst structure, surface acidity, redox property and reaction route by XRD, XPS, H2-TPR, O2-TPD, NH3-TPD and in situ Raman, in situ TG, and DRIFTS. The results manifested that Lewis acid sites and reducibility originating from CeO2 were obviously recovered, because the strong interaction between cerium and arsenic was weakened when Ca and As coexisted. Meanwhile, the CaWO4 phase generated on Ca poisoned catalyst almost disappeared after As doping together, which made for Bronsted acid sites reformation on catalyst surface. Furthermore, surface Ce4+ proportion and oxygen defect sites amount were also restor...
67 citations
TL;DR: In this paper, the NH3-selective catalytic reduction (SCR) catalysts were deactivated due to NH4HSO4 deposition at low temperatures due to the NH4 HSO4 degradation.
Abstract: The deactivation of NH3-selective catalytic reduction (SCR) catalysts due to NH4HSO4 deposition at low temperatures (
67 citations