Plasma-Catalytic Removal of NOx in Mobile and Stationary Sources

Khacef, Ahmed; Costa, Patrick Da

doi:10.1007/978-3-030-05189-1_5

Cited by 3 publications

(8 citation statements)

References 105 publications

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“…Nevertheless, at operating temperatures ≥225 °C, the NO x removal efficiency in the presence of plasma was lower than that for the catalyst alone, which is attributed to the decreased C1/NO x ratio (number of moles of carbon in the hydrocarbon reducing agent per number of moles of nitrogen in NO x ) owing to the partial oxidation of n -heptane to CO 2 in the plasma stage as discussed above. This result is in good agreement with that in previous reports that the performance of the hydrocarbon SCR process largely depends on the C1/NO x ratio. , The reaction mechanism of the hydrocarbon SCR for NO x has been reported in the literature. ,, …”

Section: Resultssupporting

confidence: 93%

“…50,51 The reaction mechanism of the hydrocarbon SCR for NO x has been reported in the literature. 9,11,53 To explain the partial oxidation of n-heptane in the honeycomb discharge at ambient temperature, the optical emission spectra of the honeycomb discharge at the surrounding power electrode were recorded. The plasma discharge was performed at 100 ppm NO, 86 ppm n-heptane, 2.4% water vapor, and a SEI of 25 J/L.…”

Section: Methodsmentioning

confidence: 99%

“…Hydrocarbon selective catalytic reduction (HC-SCR) has been successfully used for NO x removal within a narrow temperature window (250–350 °C). − The use of non-thermal plasma in conjunction with a catalyst has been proposed to expand the temperature window with the view of lowering the temperature. − This comes from a plasma state consisting of energetic electrons, excited species, radicals, and ions. Indeed, energetic electrons produced by dielectric barrier discharge (DBD) plasma have energies in the range of 1–10 eV .…”

Section: Introductionmentioning

confidence: 99%

“…DBD plasma is commonly used in research to investigate the removal of NO x . ,,− However, from the viewpoint of practical application with high throughput, the main disadvantage of the DBD plasma is the size of the discharge gap (a few millimeters), which is a significant limitation of this technique. The narrow discharge gap and the use of dielectric barrier have been shown to be responsible for the pressure drop and low mechanical resistance in a variety of reactors .…”

Section: Introductionmentioning

confidence: 99%

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High-Throughput NO_x Removal by Two-Stage Plasma Honeycomb Monolith Catalyst

Nguyen

Matyakubov

Saud

et al. 2021

Environ. Sci. Technol.

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A two-stage plasma catalyst system for highthroughput NO x removal was investigated. Herein, the plasma stage involved the large-volume plasma discharge of humidified gas and was carried out in a sandwich-type honeycomb monolith reactor consisting of a commercial honeycomb catalyst (50 mm high; 93 mm in diameter) located between two parallel perforated disks that formed the electrodes. The results demonstrated that, in the plasma stage, the reduction of NO x did not occur at room temperature; instead, NO was only oxidized to NO 2 and n-heptane to oxygenated hydrocarbons. The oxidation of NO and n-heptane in the honeycomb plasma discharge state was largely affected by the humidity of the feed gas. Furthermore, the oxidation of NO to NO 2 occurs preferably to that of n-heptane with a tendency of the NO oxidation to decrease with increasing feed gas humidity. The reason is that the generation of O 3 decreases as the amount of water vapor in the feed gas increases. Compared to the catalyst alone, the two-stage plasma catalyst system increased NO x removal by 29% at a temperature of 200 °C and an energy density of 25 J/L.

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Section: Resultssupporting

confidence: 93%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

High-Throughput NO_x Removal by Two-Stage Plasma Honeycomb Monolith Catalyst

Nguyen

Matyakubov

Saud

et al. 2021

Environ. Sci. Technol.

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“…4 However, the use of diesel fuel gives rise to the emission of NO x , which is a concern because it is harmful to human health as well as to the environment. 5 Furthermore, the standard requirements for diesel emission are becoming increasingly stringent in the emission regulations and are represented by a significant decrease in the amount of chemical pollution resulting from diesel exhaust gases. 6 Consequently, the manufacturers of diesel engines are under pressure to lower the emissions of pollutants caused by diesel to comply with standard requirements.…”

Section: Introductionmentioning

confidence: 99%

Enhancing the Selective Catalytic Reduction of NO_x at Low Temperature by Pretreatment of Hydrocarbons in a Gliding Arc Plasma

Matyakubov

Nguyen

Saud

et al. 2022

Ind. Eng. Chem. Res.

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The removal of NO x over a Ag/γ-Al 2 O 3 catalyst coupled with gliding arc plasma at low temperatures is demonstrated. Specifically, n-heptane (the reducing agent) was pretreated by exposure to gliding arc plasma (the outlet gas temperature of 73.4 °C) before injecting into the simulated diesel exhaust gas and passing it through the catalyst zone. As a result of the plasma treatment, the feed gas consisted of oxygenated hydrocarbons (OHCs), which serve as reducing agents, instead of only n-heptane without plasma treatment. Consequently, the NO x removal efficiency increased substantially by approximately 10% at temperatures of [165−225 °C] owing to the presence of the OHCs. The dependence of the NO x removal efficiency on typical reducing agents was examined; these results agreed with our hypothesis that aldehyde derivatives were more effective than the parent compound (n-heptane) for NO x removal at low temperatures. However, enhancement of the NO x removal efficiency after plasma pretreatment was not observed at high plasma discharge power. This is because NO x is formed from the air and a significant amount of n-heptane is completely oxidized to CO 2 when the gliding arc plasma is operated at high power. Besides, the plasma treatment of n-heptane did not improve the NO x removal under high operating temperature conditions at which the catalyst itself exhibits high catalytic activity. This led us to surmise that boosting the effectiveness of the OHCs generated during plasma pretreatment would require the ratio of the exhaust gas flow rate to the reducing agent flow rate to be high, which is challenging to realize in laboratory-scale experiments. This method would lower the energy consumption of the plasma stage.

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