• Title/Summary/Keyword: Nitrogen Oxides

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The Long-term Variations of Ozone and Nitrogen Oxides in Suwon City during 1991 ~2012 (수원시 대기 중 오존과 질소산화물의 장기변동 특성 (1991 ~ 2012))

  • An, Hyunjin;Han, Jihyun;Lee, Meehye;Kang, Eunha
    • Journal of Korean Society for Atmospheric Environment
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    • v.31 no.4
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    • pp.378-384
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    • 2015
  • The long-term variations of ozone and nitrogen oxides in Suwon city, the capital of Gyeong-gi province, were examined from 1991 to 2012. In this period, the annual average $O_3$ concentration increased from 13.8 ppbv to 22.7 ppbv and that of $99^{th}$ percentile increased from 58.0 ppbv to 80.0 ppbv. The monthly average and $99^{th}$ percentile of $O_3$ concentrations were the highest in June. The increase in $O_3$ concentration was the greatest in early summer (May and June) before monsoon season began. While the concentrations of NO and NOx have gradually decreased since 2000, $NO_2$ remained unchanged. As a result, $NO_2/NO_x$ ratio increased from 0.5 to 0.73 in 2012. The monthly $NO_2/NO_x$ ratio was the highest in early summer, when monthly average $O_3$ concentration was the highest. It suggests that the enhanced $NO_2/NO_x$ ratio is intimately coupled with increase in $O_3$ for the last two decades in Suwon.

A study on the application of DOE for optimization of blending oil with non-esterified biodiesel fuel at partial engine load (부분부하에서 비에스테르화 바이오디젤 5% 혼합유의 성능최적화를 위한 실험계획법 적용에 관한 연구)

  • Kim, Hee-Jung;Koh, Dae-Kwon;Yang, Ju-Ho;Koh, Sung-Wi;Kim, Yeong-Sik;Jeong, Tae-Young;Jung, Suk-Ho
    • Journal of Power System Engineering
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    • v.20 no.2
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    • pp.51-57
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    • 2016
  • Non-esterified biodiesel fuel is cheaper than esterified that because of a simple manufacturing process that only consists of filtering. Applicability of this on diesel engine with electronic control system was accomplished, then optimization adopting a fractional factorial design and response surface methodology was carried out at 25% and 50% of engine load in this study. Pressure of common rail and injection timing mainly effected on responses as specific fuel oil consumption and nitrogen oxides regardless of engine load. Estimations were 310.3 g/kWh of specific fuel oil consumption and 237 ppm of nitrogen oxides at 25% load, and 233.2 g/kWh of specific fuel oil consumption and 730 ppm of nitrogen oxides at 50% load. Tests to verify these estimations were accomplished and as the results, specific fuel oil consumption was 300.4 g/kWh and NOx was 277 ppm at 25% load and 236.8 g/kWh and 573 ppm at 50% load.

A Study on Catalysts for Simultaneous Removal of 1,2-Dichlorobenzene and NOx (1,2-Dichlorobenzene 및 질소산화물 동시제거를 위한 촉매연구)

  • Park, Kwang Hee;Hong, Sung Chang
    • Applied Chemistry for Engineering
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    • v.20 no.5
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    • pp.522-526
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    • 2009
  • The catalytic oxidation of 1,2-dichloribenzene (1,2-DCB) and simultaneous catalytic reduction of nitrogen oxides over the single catalyst has been investigated over various metals (Ru, Mn, Co and Fe) supported on $Al_2O_3$ and $CeO_{2}$. The activity of the different catalysts for catalytic oxidation of 1,2-dichloribenzene depended on the used metal, Ru/Co/$Al_2O_3$, Mn-Fe/CeO2 and Cr/$Al_2O_3$ (commercial catalysts) being the most actives ones. In the catalytic oxidation of chlorobenzene (CB), Ru/Co/$Al_2O_3$ is better than Pt-Pd/$Al_2O_3$, which is the well-known catalyst good for VOC oxidation. Furthermore, it has a good durability on the deactivation by $Cl_2$ and sulfur. For nitrogen oxides (NOx) removal, NOx conversion was 70% at $260^{\circ}C$.

Effect of Intermittent Plasma Discharge on the Hydrocarbon Selective Catalytic Reduction of Nitrogen Oxides (간헐적 플라즈마 방전이 질소산화물의 탄화수소 선택적 촉매환원에 미치는 영향)

  • Kyeong-Hwan Yoon;Y. S. Mok
    • Applied Chemistry for Engineering
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    • v.34 no.5
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    • pp.507-514
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    • 2023
  • The selective catalytic reduction (SCR) of nitrogen oxides (NOx) was investigated in a catalyst (Ag/γ-Al2O3) packed dielectric barrier discharge plasma reactor. The intermittent generation of plasma in the catalyst bed partially oxidized the hydrocarbon reductant for NOx removal to several aldehydes. Compared to using the catalyst alone, higher NOx conversion was observed with the intermittent generation of plasma due to the formation of highly reductive aldehydes. Under the same operating conditions (temperature: 250 ℃; C/N: 8), the NOx reduction efficiencies were 47.5%, 92%, and 96% for n-heptane, propionaldehyde, and butyraldehyde, respectively, demonstrating the high NOx reduction capability of aldehydes. To determine the optimal condition for intermittent plasma generation, the high voltage on/off cycle was adjusted from 0.5 to 3 min. The NOx reduction performance was compared between continuous and intermittent plasma generation on the same energy density basis. The highest NOx reduction efficiency was achieved at 2-min high voltage on/off intervals. The reason that the intermittent plasma discharge exhibited higher NOx reduction efficiency even at the same energy density, compared to the continuous plasma generation case, is that the intermediate products, such as aldehydes generated from hydrocarbon, were more efficiently utilized for the reduction of nitrogen oxides.

Combined effect of nitrogen- and oxygen functional groups on electrochemical performance of surface treated multi-walled carbon nanotubes (표면처리된 탄소나노튜브의 질소 및 산소관능기 도입에 따른 전기화학적 특성)

  • Kim, Ji-Il;Park, Soo-Jin
    • 한국신재생에너지학회:학술대회논문집
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    • 2011.05a
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    • pp.214.1-214.1
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    • 2011
  • In this work, the electrochemical properties of the surface treated multi-walled carbon nanotubes (MWNTs) are investigated for supercapacitors. Nitrogen- and oxygen functional groups containing MWNTs are prepared by nitrogen precursors and acidic treatment, respectively. The surface properties of the MWNTs are confirmed by X-ray photoelectron spectroscopy (XPS) and Zeta-potential measurements. The electrochemical properties of the MWNTs are investigated by cyclic voltammetry, impedance spectra, and charge-discharge cycling performance in 1 M $H_2SO_4$ at room temperature. As a result, these functionalized MWNTs lead to an increase in the specific capacitance as compared with the pristine MWNTs. It proposes that the pyridinic and pyridinic-N-oxides nitrogen species influence on the specific capacitance due to their positive charges, and thus an improved electron transfer at high current loads, since they are the most important functional groups affecting capacitive behaviors.

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An Experimental Study on the Reduction of Nitric Oxides from the Diesel Engine Exhaust Gas with Metal Supported Oxides Catalysts (디젤엔진 배기가스중 질소산화물 저감을 위한 금속 산화물 촉매를 이용한 실험적 연구)

  • Chae, Jae-Ou;Hwang, Jae-Won;Jung, Jee-Yong;Han, Jung-Hee;Hwang, Hwa-Ja;Kim, Seok;Eduard, Mikholap
    • Transactions of the Korean Society of Automotive Engineers
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    • v.9 no.3
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    • pp.68-75
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    • 2001
  • In this paper, a number of supported metal oxides and perovskite type catalysts were investigated for the NOx reduction from the diesel engine exhaust gas. All catalysts were made into pellets type with diameter of 3-4 mm alumina(Al$_2$O$_3$) as a supporter. These samples were tested by real diesel exhaust gas which contains CO, hydrocarbons and soot in the temperature range of 150~55$0^{\circ}C$ with the $3300h^{-1}$ space velocity (SV). Among the results, several promising catalysts showed NOx conversion above 50% in the temperature range of 150-35$0^{\circ}C$. From these results supported metal oxides catalysts and perovskite type could be recommended for the practical application to the automobile exhaust treatments.

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Reduction of Nitrogen Oxides from Fuel Nitrogen in New Fuelling System

  • 전영남;채재우
    • Bulletin of the Korean Chemical Society
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    • v.17 no.10
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    • pp.885-892
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    • 1996
  • The effects of NOx reduction by advanced fuel staging in a small scale combustor (6.6 kWT) have been investigated using propane gas flames laden with ammonia as fuel-nitrogen. The variables which had the greatest influence on NOx reduction were temperature, reducing stoichiometry (relate to main combustion zone stoichiometry, air fraction and reburning fuel fraction) and residence time of reducing zone. NOx reduction was best at the reburning zone temperature of above 1,000 ℃ and reburning zone stoichiometry was 0.85. In terms of residence time of the reburning zone, NOx reduction was effective when burnout air was injected at the point where the reburning zone had been already established. In the advanced fuel staging NOx reduction was relatively large at the burning of higher Fuel-N concentration in the fuel. Under optimum reburning conditions, fuel nitrogen content had a relatively minor impact on reburning efficiency.

Removal Characteristics of Nitrogen Oxides (NOx) in Low Concentration using Peat-Mixed Media (피트(peat) 혼합담체를 이용한 저농도 질소산화물(NOx) 제거특성)

  • Kang, Young-Heoun;Kim, Deok-Woo;Kang, Seon-Hong;Kwon, Pil-Joo;Kim, Dal-Woo;Hwang, Pil-Gi;Shim, Sang-Bo
    • Journal of Korean Society for Atmospheric Environment
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    • v.26 no.3
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    • pp.330-338
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    • 2010
  • In this study, removal characteristics of nitrogen oxides $(NO_x)$ from road transport by using peat as the packing media for biodegradation have been investigated in the long term. Physicochemical and biological treatment of peatmixed media eliminates any requirement to use chemical substances and also facilitates the biodegradable actions of microorganism. Safe biodegradation of pollutants, no need to apply additional microbes owing to their active growth, and no generation of secondary pollutants were found in this experiment. It was concluded that average removal efficiencies of nitric oxide (NO) and nitrogen dioxide $(NO_2)$ were 80% and 97% respectively with respect to the linear velocity 35~40 mm/s and 0.3 ppm ozone concentration in the long period operation. Inflow concentration of nitric oxide over 0.05 ppm was suitable when pretreated with ozone. Non-ozone stage was performed with linear velocity 20~100 mm/s and then the average removal efficiency of nitric oxide and nitrogen dioxide were 38% and 94% respectively. Other results showed that the apparent static pressure was raised with increases in applied water content and aerial velocity in mixed media during fan operation.

Application of Diffusion Modeling to Nitrogen Oxides using INPUFF Model in Complex Terrain (INPUFF MODEL을 이용한 복잡지형의 질소산화물 확산 모델링)

  • 박영한;이종범
    • Proceedings of the Korea Air Pollution Research Association Conference
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    • 1999.10a
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    • pp.154-155
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    • 1999
  • 동해 지역은 험준한 태백산맥을 경계로 동해안 연안에 위치하고 있으며 공업항만의 발달로 지방 산업의 발전이 가속화되고 있다. 특히 다량의 연료를 사용하는 대기배출시설인 시멘트공장 3개소와 화력발전소 1개소가 밀집되어 대기질 악화가 우려되고 있으며, 주요 배출물질로는 먼지, 질소산화물, 일산화탄소 등이 있다.(중략)

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