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NOx

About: NOx is a research topic. Over the lifetime, 26367 publications have been published within this topic receiving 496555 citations.


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Patent
28 Sep 1979
TL;DR: In this article, a process for catalytic combustion of carbon monoxide and hydrocarbons and the catalytic reduction of the oxides of nitrogen contained in a gas stream is described.
Abstract: A process for the catalytic combustion of carbon monoxide and hydrocarbons and the catalytic reduction of the oxides of nitrogen contained in a gas stream. The process involves intimately contacting the gaseous stream with a catalyst bed comprising copper metal or copper ion and a high silica zeolite.

141 citations

Journal ArticleDOI
TL;DR: In this paper, the exhaust gas from a common-rail direct injection diesel engine was investigated both upstream and downstream warm-up catalytic converters (WCC) and three different types of ultra-low sulfur fuels (ethanol-diesel blend, ethanol-diesels blend with cetane improver and pure diesel) were tested in this study.

141 citations

Journal ArticleDOI
TL;DR: In this paper, the authors report NOx removal via reduction processes using two types of combined system of pulse corona discharge and catalysts: the single-stage plasma-driven catalyst (PDC) system, and the two-stage selective catalytic reduction (PE-SCR) system.
Abstract: In this paper, we will report NOx removal via reduction processes using two types of combined system of pulse corona discharge and catalysts: the single-stage plasma-driven catalyst (PDC) system, and the two-stage plasma-enhanced selective catalytic reduction (PE-SCR) system. Several catalysts, such as γ-alumina catalysts, mechanically mixed catalysts of γ-alumina with BaTiO3 or TiO2, and Co-ZSM-5 were tested. In the PDC system, which is directly activated by the discharge plasma, it was found that the use of additives was necessary to achieve NOx removal by reduction. Removal rates of NO and NOx were linearly increased as the molar ratio of additive to NOx increased. The dependence of NO and NOx removal on the gas hourly space velocity (GHSV) at a fixed specific input energy (SIE) indicates that plasma-induced surface reaction on the catalyst plays an important role in the PDC system. It was found that the optimal GHSV of the PDC system with the γ-alumina catalyst was smaller than 6000 h-1. Mechanical mixing of γ-alumina with BaTiO3 or TiO2 did not enhance NO and NOx removal and γ-alumina alone was found to be the most suitable catalyst. The dielectric constant of the catalyst only influenced the plasma intensity, not the NOx removal. In the PE-SCR system, plasma-treated NOx (mostly NO2) was reduced effectively with NH3 over the Co-ZSM-5 catalyst at a relatively low temperature of 150 °C. Under optimal conditions the energy cost and energy yield were 25 eV/molecule and 21 g-N (kWh)-1, respectively.

140 citations

Journal ArticleDOI
TL;DR: This review provides a chemical perspective on the production, combustion, and environmental aspects of automotive fuels and suggests the best prospects for achieving the highest efficiency and lowest emissions lie with optimizing the entire fuel-engine-after-treatment system.
Abstract: Commercial transportation fuels are complex mixtures containing hundreds or thousands of chemical components, whose composition has evolved considerably during the past 100 years. In conjunction with concurrent engine advancements, automotive fuel composition has been fine-tuned to balance efficiency and power demands while minimizing emissions. Pollutant emissions from internal combustion engines (ICE), which arise from non-ideal combustion, have been dramatically reduced in the past four decades. Emissions depend both on the engine operating parameters (e.g. engine temperature, speed, load, A/F ratio, and spark timing) and the fuel. These emissions result from complex processes involving interactions between the fuel and engine parameters. Vehicle emissions are comprised of volatile organic compounds (VOCs), CO, nitrogen oxides (NOx), and particulate matter (PM). VOCs and NOx form photochemical smog in urban atmospheres, and CO and PM may have adverse health impacts. Engine hardware and operating conditions, after-treatment catalysts, and fuel composition all affect the amount and composition of emissions leaving the vehicle tailpipe. While engine and after-treatment effects are generally larger than fuel effects, engine and after-treatment hardware can require specific fuel properties. Consequently, the best prospects for achieving the highest efficiency and lowest emissions lie with optimizing the entire fuel–engine–after-treatment system. This review provides a chemical perspective on the production, combustion, and environmental aspects of automotive fuels. We hope this review will be of interest to workers in the fields of chemical kinetics, fluid dynamics of reacting flows, atmospheric chemistry, automotive catalysts, fuel science, and governmental regulations.

140 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20241
20231,699
20223,249
20211,405
20201,353
20191,367