• Title/Summary/Keyword: NO/sub x/ Reduction

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Performance Evaluation of Nitrogen Oxide Removal by Air Purification Blocks with Titanium Dioxide (이산화티타늄을 이용한 대기정화 블록의 질소산화물 제거 성능 평가)

  • Oh, Ri-On;Kim, Hwang-Hee;Park, Sung-Ki;Cha, Sang-Sun;Park, Chan-Gi
    • Journal of The Korean Society of Agricultural Engineers
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    • v.62 no.5
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    • pp.39-46
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    • 2020
  • This study evaluated the nitrogen oxide (NOx) removal efficiency by air purification concrete blocks with titanium dioxide (TiO2). The concrete in the mixtures had a 30% water:cement ratio, to which TiO2 was added at 0%, 5%, and 10% of cement weight. The compressive strength reduction rate and removal efficiency of NOx were investigated. The result of the compressive strength test in the study indicated that addition rate of TiO2 did not lead to signifcant effect. In terms of the average removal efficiency of NOx, mix No. 1 using a TiO2 mixing ratio of 0% had a removal efficiency of 0.57% on average; thus, the removal effect w as not significant. For the other samples prepared by mixing, the average removal efficiencies for mix No. 2 (5% TiO2) were 58.86% and 62.05% for normal and washing surface treatments, respectively, and those of sample No. 3 (10% TiO2) were 59.94% and 67.61%. mixs No. 4 (5%) and No. 5 (10%), in which TiO2 diluted with distilled water was sprayed onto the block surface, had an average NOx removal efficiency of 61.72% and 68.48%, respectively. In terms of NOx removal efficiency, Mixs No. 3 and No. 5 with 10% TiO2 were better than Mixs No. 2 and No. 4 with 5% TiO2. In addition, analyzing the NOx removal efficiency results from the fixing method, it was capable to apply mixing (washing) and the diluted spray methods. Therefore, it was found that the diluted spray method applied in this study can be employed in any manufacture of air purification concrete blocks.

Catalytic Reduction of ortho- and meta-Nitroaniline by Nickel Oxide Nanoparticles

  • Jeon, Sugyeong;Ko, Jeong Won;Ko, Weon Bae
    • Elastomers and Composites
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    • v.55 no.3
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    • pp.191-198
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    • 2020
  • Nickel oxide (NiO) nanoparticles were synthesized by a reaction of nickel nitrate hexahydrate (Ni(NO3)2·6H2O) and sodium hydroxide (NaOH). The synthesized NiO nanoparticles were examined with X-ray diffraction, scanning electron microscopy, Raman spectroscopy, and ultraviolet-visible (UV-vis) spectroscopy. The NiO nanoparticles were used as the catalyst for the reduction of o- and m-nitroaniline to phenylenediamine. The reduction rate of m-nitroaniline was faster than that of o-nitroaniline. The reduction rate for both o- and m-nitroaniline increased as the reaction temperature increased. The rate of reduction for nitroaniline followed a pseudo first-order reaction rate law.

PM2.5 Simulations for the Seoul Metropolitan Area: ( I ) Contributions of Precursor Emissions in the 2013 CAPSS Emissions Inventory (수도권 초미세먼지 농도모사: ( I ) 2013 CAPSS 배출량 목록의 전구물질별 기여도 추정)

  • Kim, Soontae;Bae, Changhan;Kim, Byeong-Uk;Kim, Hyun Cheol
    • Journal of Korean Society for Atmospheric Environment
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    • v.33 no.2
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    • pp.139-158
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    • 2017
  • CMAQ (Community Multiscale Air Quality Model) simulations were carried out to estimate the potential range of contributions on surface $PM_{2.5}$ concentrations over the Seoul Metropolitan Area (SMA) with the gaseous precursors and Primary Particulate Matters(PPM) available from a recent national emissions inventory. In detail, on top of a base simulation utilizing the 2013 Clean Air Policy Supporting System (CAPSS) emission inventory, a set of Brute Force Method (BFM) simulations after reducing anthropogenic $NO_x$, $SO_2$, $NH_3$, VOCs, and PPM emissions released from area, mobile, and point sources in SMA by 50% were performed in turn. Modeling results show that zero-out contributions(ZOC) of $NH_3$ and PPM emissions from SMA are as high as $4{\sim}5{\mu}g/m^3$ over the region during the modeling period. On the contrary, ZOC of local $NO_x$ and $SO_2$ emissions to SMA $PM_{2.5}$ are less than $1{\mu}g/m^3$. Moreover, model analyses indicate that a wintertime $NO_x$ reduction at least up to 50% increases SMA $PM_{2.5}$ concentrations, probably due to increased HNO3 formation and conversion to aerosols under more abundant ozone and radical conditions after the $NO_x$ reduction. However, a nation-wide $NO_x$ reduction decreased SMA $PM_{2.5}$ concentrations even during winter, which implies that nation-wide reductions would be more effective to curtail SMA $PM_{2.5}$ concentrations than localized efforts.

Preliminary Research to Support Air Quality Management Policies for Basic Local Governments in Gyeonggi-do (경기도 기초지자체 대기환경 관리정책 지원을 위한 선행 연구)

  • Chanil Jeon;Jingoo Kang;Minyoung Oh;Jaehyeong Choi;Jonghyun Shin;Chanwon Hwang
    • Journal of Environmental Health Sciences
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    • v.49 no.5
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    • pp.275-288
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    • 2023
  • Background: When basic local governments want to improve their air quality management policies, they need fundamental evidence, such as the effectiveness of current policies or scenario results. Objectives: The purpose of this study is to lay the groundwork for a process to calculate air pollutant reduction from basic local government air quality policies and provide numerical estimates of PM2.5 concentrations following improved policies. Methods: We calculated the amount of air pollutant reduction that can be expected in the research region based on the Gyeonggi-do Air Environment Management Implementation Plan issued in 2021 and guidelines from the Korean Ministry of Environment. The PM2.5 concentration variations were numerically simulated using the CMAQ (photochemical air quality model). Results: The research regions selected were Suwon, Ansan, Yongin, Pyeongtaek, and Hwaseong in consideration of population, air pollutant emissions, and geographical requirements. The expected reduction ratios in 2024 compared to 2018 are CO (3.0%), NOx (7.9%), VOCs (0.7%), SOx (0.1%), PM10 (2.4%), PM2.5 (6.1%), NH3 (0.05%). The reduced PM2.5 concentration ratio was highest in July and lowest in April. The expected concentration reduction of yearly mean PM2.5 in the research region is 0.12 ㎍/m3 (0.6%). Conclusions: Gyeonggi-do is now able to quickly provide air pollutant emission reduction calculations by respective policy scenario and PM2.5 simulation results, including for secondary aerosol particles. In order to provide more generalized results to basic local governments, it is necessary to conduct additional research by expanding the analysis tools and periods.

A Study on Removal of NOx in Diesel Engine using Reductive Catalyst (환원촉매를 이용한 디젤엔진 배기가스 중 NOx 저감에 관한 연구)

  • Huang, H.Z.;Hwang, J.W.;Jung, J.Y.;Han, J.H.;Demidiouk, V.I.;Chae, J.O.
    • Journal of Korean Society of Environmental Engineers
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    • v.22 no.12
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    • pp.2255-2261
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    • 2000
  • To eliminate $NO_x$ in diesel emission. selective catalyst reduction (SCR) was used in real diesel engine. Among the SCR methods, metal oxide and perovskite catalysts were introduced in this paper. The removal efficiencies with various major, promoter catalysts on ${\gamma}-Al_2O_3$ at different reaction temperature were investigated, and $LaCuMnO_x$ catalyst which has high removal efficiency at the temperature of real diesel exhaust gas was selected. $NO_x$ reduction was carried out over these catalysts in the flow-through type reactor using by-pass ($SV=3,300h^{-1}$). Under the given condition to this study, perovskite catalysts showed considerably high removal efficiency and $LaCuMnO_x$ was the best one among these catalysts in the temperature range of $150{\sim}450^{\circ}C$.

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NO2 gas sensing based on graphene synthesized via chemical reduction process of exfoliated graphene oxide

  • Khai, Tran Van;Prachuporn, Maneeratanasarn;Shim, Kwang-Bo
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.22 no.2
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    • pp.84-91
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    • 2012
  • Single and few-layer graphene nanosheets (GNs) have successfully synthesized by a modified Hummer's method followed by chemical reduction of exfoliated graphene oxide (GO) in the presence of hydrazine monohydrate. GO and GNs were characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), X-ray diffractions (XRD), Raman spectroscopy, Transmission electron microscopy (TEM), Atomic force microscopy (AFM), Optical microscopy (OM) and by electrical conductivity measurements. The result showed that electrical conductivity of GNs was significantly improved, from $4.2{\times}10^{-4}$ S/m for GO to 12 S/m for GNs, possibly due to the removal of oxygen-containing functional group during chemical reduction. In addition, the $NO_2$ gas sensing characteristics of GNs are also discussed.

Development of NO2/NOx Ratio Estimation Model for Urea-SCR System Application on Non-road Diesel Engine (비도로용 디젤엔진의 Urea SCR system 적용을 위한 NO2/NOx ratio 예측모델 개발에 관한 연구)

  • Kang, Seokho;Kim, Hoonmyung;Kang, Jeongho;Park, Eunyong;Kwon, Ohyun;Kim, Daeyeol
    • Journal of ILASS-Korea
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    • v.25 no.4
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    • pp.178-187
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    • 2020
  • The current emission regulations, US Tier-4 and EU Stage-V, are only able to satisfy the regulations when all currently mass-produced emission reduction technologies such as EGR, DOC, DPF, and SCR are applied. Therefore, in this study, for the application of the Urea-SCR system to non-road diesel engines, the database was established by measuring the NO, NO2 concentration and calculating the NO2/NOx ratio based on the catalyst temperature and exhaust mass flow rate. Also, based on the measured NO2/NOx ratio data, a mathematical model was proposed to predict the NO2/NOx ratio at SCR catalyst, and the suitability of the model was verified through steady-state and transient mode. As a result of comparing the NO2/NOx ratio measured at the DOC outlet under the steady-state condition to two model values separately, the R2 was 0.9811 for the 3D map model and 0.9303 for the mathematical model. And in the case of the NO2/NOx ratio measured at the DPF outlet, the R2 was 0.9797 for the 3D map model and 0.935 for the mathematical model. It was confirmed that the R2 with the model value of the 3D Map of the mathematical model in the transient mode is 0.957, which shows high reliability.

A Study of the characteristics of NOx measurement and analysis methods of the SCR system for ships (선박용 SCR 시스템 NOx 측정 및 분석 방식의 특성 연구)

  • Kim, Sung-Yoon;Lee, Young-Ho;Kim, Min;Park, Sam-Sik
    • Journal of Advanced Marine Engineering and Technology
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    • v.39 no.4
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    • pp.387-392
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    • 2015
  • A method for measuring and analyzing the $NO_x$ in ships is described in $NO_x$ Technical Code 2008. The analysis device, as required by the Code, has been to use a Chemi-luminescence detection method or Heated Chemi-luminescence detection. on the other hand, selective catalytic reduction using $NH_3$ as a reducing agent has an interference effect on the analyzer, and causes measurement error. In this study, the Chemi-luminescence detection method was examined according to how it affects the concentration of $O_2$, CO, $SO_2$, $NH_3$. Fourier transform infrared spectrometry analysis equipment and measurement methods were compared. In order to confirm the effect of the physical interference of the measuring device, it was confirmed by decomposing a measuring device. Consequently, white precipitate and moisture were generated inside the chemiluminescence detection system and I found that affecting interference. The influence of interference highlights the need to consider the minimized $NO_x$ measurement method.

Selective Catalytic Reduction (SCR) Technology Trend for the Removal of Nitrogen Oxide from Ship Flue Gas (선박 배가스 내 질소산화물 제거를 위한 선택적촉매환원법(SCR) 기술동향)

  • Won, Jong Min;Hong, Sung Chang
    • Prospectives of Industrial Chemistry
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    • v.22 no.5
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    • pp.25-40
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    • 2019
  • 전 세계적으로 환경문제를 해결하기 위한 방안으로 환경규제를 강화시키며 특히 다양한 대기오염 물질 중 최근 큰 이슈인 초미세먼지 저감을 위해 전구물질로 알려진 질소산화물을 제어하기 위한 다양한 기술개발이 가속화되고 있다. 특히, 다양한 처리기술 중에 기술적·경제적인 이점을 갖춘 선택적 촉매환원법(selective catalytic reduction, SCR) 기술을 통하여 질소산화물 제거를 위해 암모니아를 환원제로 반응에 참여시켜 인체에 무해한 H2O, N2로 전환하는 기술이 대표적이다. 최근 전 세계적으로 다양한 산업군에서 질소산화물이 배출되고 있으며, 점오염원뿐만이 아니라 비점오염원(mobile sources)에 대한 규제가 강화되고 있다. 디젤엔진이 장착된 선박 배가스 처리장치 내 SCR 기술이 주목을 받고 있으며, NH3-SCR에 사용되는 촉매는 주로 VOx/TiO2, VOx/W/TiO2 촉매가 대표적이다. 한편 선박 디젤엔진에 사용되는 연료에 따라 연소배가스 특성이 다르다. 이러한 연료가 연소됨에 따라 SO2, SO3가 발생되고 환원제인 NH3와 결합하여 황산암모늄염((NH4)2SO4), ABS (ammonium bisulfate, NH4HSO4)과 같은 염을 형성시켜 탈질촉매의 비활성화 문제가 발생된다. 이러한 비활성화 물질이 침적된 탈질촉매를 재활성화 시키기 위하여 열 산화를 통해 재생시키고 있다. 이처럼 선박용 SCR 촉매는 강화되는 배출규제 및 엔진기술의 발달로 저감되는 운전 온도에 대비하여 저온 활성 재생이 가능한 고활성, 고내구성 촉매기술 개발이 필요하다.

Comparison on Exhaust Gas of Heavy Duty Diesel Trucks; THC and CO Emission Affected by NOx Control Devices (EGR, SCR) (대형 경유트럭의 NOx 저감장치에 따른 배출가스 특성비교)

  • Mun, SunHee;Yoo, Heung-Min;Son, JiHwan;Yun, Changwan;Park, Gyu Tae;Kim, JeongSoo;Lee, Jongtae
    • Journal of ILASS-Korea
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    • v.20 no.3
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    • pp.149-155
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    • 2015
  • With increasing of GDP, the registration number of passenger cars has exceeded 20 million last year in Korea. Especially, the registration number of the diesel engine vehicles has been increasing. However, the WHO(World Health Organization) IARC (International Agency for Research on Cancer) has reported that diesel engine exhaust gas is an one of HAPs, which has carcinogenic for human, and they have designated it to Group 1. To solve this problem, exhaust gas from diesel engines has to be controlled. Thus, it has been controlling by European regulatory standard in Korea. On the other hand, in order to meet the enhanced emission regulations, all manufacturing company applied $NO_x$ control device to vehicles such as EGR (Exhaust Gas Recirculation), SCR (Selective Catalytic Reduction) and so on. However, these devices (EGR, SCR) were operated by difference reaction mechanism respectively, and the composition of exhaust gas would be differenced from that of them. In this study, it was conducted to evaluate variety characteristics on changing of exhaust gas composition by each $NO_x$ control device, and the heavy duty diesel trucks were chosen as experimental vehicles. From the result, it revealed that vehicles (with EGR) were discharged higher THC as 52.5% than that of others (with SCR). However, it did not followed that trend, in the case of CO; it was discharged as 57.2% lower than that of others (with SCR). In the future, these data would be used to apply to efficient $NO_x$ control device for meeting to EURO 6.