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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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Journal ArticleDOI
TL;DR: In this paper, the activity of Birnessite and cryptomelane for catalysed combustion of soot under NOx/O2 gas mixtures has been studied and compared with that of some other commercially available pure manganese oxides, namely MnO, MnO 2, MnO 3, Mn2O3, Mn3O4, and natural MnO2.
Abstract: Birnessite and cryptomelane samples have been prepared and characterised by N2 adsorption at −196 °C, XRD, XRF, XPS and H2-TPR. The activity of birnessite and cryptomelane for catalysed combustion of soot under NOx/O2 gas mixtures has been studied and compared with that of some other commercially available pure manganese oxides, namely MnO, MnO2, Mn2O3, Mn3O4, and natural MnO2. Birnessite and cryptomelane are more active for soot combustion than all the commercial oxides tested. Among the manganese oxides studied, birnessite shows the highest catalytic activity, lowering the soot combustion temperature by 150 °C regarding the uncatalysed reaction, and cryptomelane lowers this temperature by 120 °C. The NOx removal profiles suggest that birnessite chemisorbs NOx and forms potassium nitrate, which melts and reacts with soot. On the contrary, the main soot combustion pathway for cryptomelane and for the commercial manganese oxide tested is based on the catalytic oxidation of NO to NO2. Birnessite and cryptomelane only yield CO2 as carbon-containing soot combustion product.

137 citations

Journal ArticleDOI
TL;DR: In this article, the authors studied the kinetics and mechanism of the selective reduction of nitric oxides (NOx) by hydrogen by using a trimetallic Pt-Mo-Co/a-Al2O3 catalyst under oxidising conditions.
Abstract: The kinetics and the mechanism of the selective reduction of nitric oxides (NOx) by hydrogen is studied on a trimetallic Pt–Mo–Co/a-Al2O3 catalyst under oxidising conditions. This system is interesting in view of an exhaust gas control of power plants or lean-burn cars. It can be shown that the NO dissociation is the crucial step, dominating the overall reaction behaviour and that it depends on temperature and on the partial pressure of H2. With increasing temperatures the reaction reveals an autocatalytic behaviour resulting in bistability and hysteresis. At higher temperatures, where no bistability is found, the NO/H2 as well as the competing O2/H2 reaction occur only above a certain critical partial pressure of H2. The kinetics of the NO/H2/O2 reaction are established using a modified Langmuir–Hinshelwood model (T=142°C–160°C, yO2>4%) which takes into account the critical H2 partial pressure. The model describes the experimental data within ±15%. The determined activation energies are: 63 kJ/mol for the NOx consumption, 77 and 45 kJ/mol for the N2 and N2O formation, respectively, and 130 kJ/mol for the O2/H2 reaction. Adsorption enthalpies are determined to -59 kJ/mol for the adsorption of H2, -77 kJ/mol for the adsorption of NO and -97 kJ/mol for the adsorption of O2. An interesting feature of the reaction is the enhancement of the NO/H2 reaction by oxygen for low partial pressures of O2. This appears to be the first study where a promoting effect of oxygen for the NO/H2 reaction is found on a platinum supported catalyst.

137 citations

Journal ArticleDOI
TL;DR: In this paper, the effect of the addition of Ba was explored with the aim of promoting the interaction of the solid with NO2, thus combining the NOx catalytic trap concept with the soot combustion for filter regeneration.

137 citations

Journal ArticleDOI
TL;DR: The experimental results show that the reaction of OH radicals, NO3 radicals and/or ozone with the first generation products of toLUene oxidation are sources of organic aerosol during the atmospheric oxidation of toluene.
Abstract: Organic aerosol formation during the atmospheric oxidation of toluene was investigated using smog chamber systems. Toluene oxidation was initiated by the UV irradiation of either toluene/air/NOx or toluene/air/CH3ONO/NO mixtures. Aerosol formation was monitored using scanning mobility particle sizers and toluene loss was monitored by in-situ FTIR spectroscopy or GC-FID techniques. The experimental results show that the reaction of OH radicals, NO3 radicals and/or ozone with the first generation products of toluene oxidation are sources of organic aerosol during the atmospheric oxidation of toluene. The aerosol results fall into two groups, aerosol formed in the absence and presence of ozone. An analytical expression for aerosol formation is developed and values are obtained for the yield of the aerosol species. In the absence of ozone the aerosol yield, defined as aerosol formed per unit toluene consumed once a threshold for aerosol formation has been exceeded, is 0.075 ± 0.004. In the presence of ozone t...

137 citations

Journal ArticleDOI
01 Mar 2016-Fuel
TL;DR: In this paper, the effect of WCOME blending ratio on viscosity and sooting propensity of the biodiesel-diesel fuel mixture was investigated, and the engine performance was expressed in terms of the in-cylinder pressure data as well as the engine mechanical and environmental aspects measured at engine rated speed (1500 rpm) and different engine loads.

137 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