• 한국컴퓨터정보학회논문지
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• 제22권1호
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• pp.63-69
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• 2017

In this paper, we propose a method to optimize the geometry and installation position of the mixer in the selective catalytic reduction (SCR) system by computational fluid dynamic(CFD). Using the commercial CFD software of CFD-ACE+, the flow dynamics of the flue gas was numerically analyzed for improving the injection uniformity of the reduction agent. Numerical analysis of the mixed gas heat flow into the upstream side of the primary SCR catalyst layer was performed when the denitrification facility was operated. The characteristics such as the flow rate, temperature, pressure loss and ammonia concentration of the mixed gas consisting of the flue gas and the ammonia reducing gas were examined at the upstream of the catalyst layer of SCR. The temperature difference on the surface of the catalyst layer is very small compared to the flow rate of the exhaust gas, and the temperature difference caused by the reducing gas hardly occurs because the flow rate of the reducing gas is very small. When the mixed gas is introduced into the SCR reactor, there is a slight tendency toward one wall. When the gas passes through the catalyst layer having a large pressure loss, the flow angle of the exhaust gas changes because the direction of the exhaust gas changes toward a smaller flow. Based on the uniformity of the flow rate of the mixed gas calculated at the SCR, it is judged that the position of the test port reflected in the design is proper.

• 한국융합학회논문지
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• 제10권4호
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• pp.131-138
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• 2019

디젤엔진은 열효율이 높고 연비가 좋으며 CO, HC 및 $CO_2$의 배출량이 낮은 등 가솔린 엔진보다 상당한 장점이 있다. 그러나 디젤엔진은 배기가스 중에 $O_2$ 농도가 높기 때문에 NOx 저감이 어렵고, 삼원촉매를 적용하기 어렵다. Urea-SCR과 LNT는 디젤엔진에서 NOx를 연속적으로 저감하는데 활용 가능한 두 기술이다. 디자인 엔진에 Urea-SCR 시스템을 구현함으로써 2.5l 이상 엔진에서 Euro-6의 강화된 NOx 기준을 충족시킬 수 있게 되었다. 본 연구에서는 엔진 회전속도, 부하, 촉매 방식 및 $NH_3$/NOx 비율에 따른 NOx 저감 특성을 연구하여 NOx 저감을 극대화하는 조건을 제시하고자 한다. 또한 Euro-6 이상의 규제에 대응할 수 있도록 Urea-SCR에 대한 정밀한 실험 데이터를 제공하고자 한다.

• 대한안전경영과학회지
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• 제24권2호
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• pp.1-9
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• 2022

In korea, 500MW standard coal fired power plants were designed and operated for the initial base load, so facility stability was prioritized from facility problem to treatment, but now we needed to research for minimizing greehouse gas emissions at the operation of coal fired power plants. research on various facilities and technologies was actively conducted to reduce environment pollutants was drastically reduced, but research and attempts on coping measures in the event of a reduction facility problem were in sufficient. this study considered investigated ways to minimized pollutants by quickly responding to logic development and application of the load runback concept in case of serious problems with environmental pollutant reduction facilities such as NOx reduction selective catalytic reduction facilities, SOx reduction wet flue gas desulpherisation facilities, and TSP(Total Suspended Particles) collection low temperature electric precipitator.

• Bulletin of the Korean Chemical Society
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• 제30권3호
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• pp.695-699
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• 2009

A short and efficient synthesis of (2S,3S)-safingol from commercially available D-ribo-(2S,3S,4R)-phytosphingosine is described. The highlights of the synthesis are a stereoselective one-pot transformation of a diol into an epoxide under phase transfer catalytic conditions and a regioselective epoxide-opening reduction with a hydride reagent.

• 공업화학
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• 제19권1호
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• pp.17-26
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• 2008

기후변화협약에 이은 교토의정서가 발효되면서 온실가스 저감은 세계적인 당면 문제가 되어 있는 가운데 청정개발체제(CDM) 및 공동이행(JI) 등을 통한 배출권 확보가 국가적인 경쟁이 되고 있다. 이산화탄소($CO_2$) 및 메탄가스($CH_4$)와 더불어 대표적인 온실가스의 하나인 $N_2O$는 온난화효과가 $CO_2$에 비해 310배에 이르며 120년의 분해기간이 소요될 만큼 대기 중에서 매우 안정하여 성층권에서 오존층을 파괴하는 물질로 알려져 있다. 또한 $N_2O$는 분해하기가 쉽지 않아 고온 열분해 시키는 방법 외에 $400^{\circ}C$ 이상에서 촉매에 의해 선택적으로 분해시키는 방법이 알려져 있으나 대개 NOx가 같이 존재하여 $N_2O$ 분해를 방해하는 역할을 한다. 본 보문은 국내외의 $N_2O$ 발생원에 대한 내역과 더불어 각종 온실가스 저감사업에 의한 배출권 거래현황과 탄소시장의 성장 및 $N_2O$ 저감사업의 위치, $N_2O$ 촉매 분해에 관한 기술개발의 현황과 방향, 그리고 CDM 사업으로서의 전망 등을 분석 집약하였다.

• 전기화학회지
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• 제12권1호
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• pp.75-80
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• 2009

The effect of polyoxometalate monolayers on the electrodeposition of Au nanoparticles (AuNPs) on glassy carbon (GC) surfaces was examined by electrochemical and scanning electron microscope techniques. The presence of $SiMo_{12}O^{4-}_{40}$-layers resulted in average particle sizes of ca. 60 nm, which is larger than AuNPs deposited on bare GC surfaces. AuNPs electrodeposited on $SiMo_{12}O^{4-}_{40}$-modified GC surfaces for 20 s exhibited the best electrocatalytic activity for oxygen reduction. This system exhibited similar or slightly better efficiency for oxygen reduction than a bare Au electrode. Rotating disk electrode experiments were also performed and revealed that the catalytic reduction of oxygen on AuNPs deposited on $SiMo_{12}O^{4-}_{40}$-modified GC electrodes is a two-electron process.

• Bulletin of the Korean Chemical Society
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• 제21권4호
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• pp.405-411
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• 2000

Electrochemical and spectroelectrochemical studies of cobalt-Schiff (Co-SB) base complexes, Co(salen) [N-N'-bis(salicylaldehyde)-ethylenediimino cobalt(II)] and Co(salophen) [N-N'-bis(salicylaldehyde)-1,2-pheny-lenediimino cobalt(II)], have been c arried out to test them as oxygen reduction catalysts. Both compounds were found to form an adduct with oxygen and exhibit catalytic activities for oxygen reduction. Comparison of spec-tra obtained from electrooxidized complexes with those from Co-SB complexes equilibrated with oxygen in-dicates that the latter are consistent with the postulated complex formed with oxygen occupying the coaxial ligand position, namely, Co(III)-SB·O2 - .The catalysis of oxygen reduction is thus achieved by reducing Co(III) in the oxygen-Co-SB adduct, releasing the oxygen reduction product, e.g., O2 - ., from the Co(II)-SB complex.

• 한국결정성장학회지
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• 제24권5호
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• pp.213-218
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• 2014

Anatase $TiO_2$에 각기 다른 텅스텐(W) 함유원료와 제조방법을 적용하여 $WO_3$ 촉매가 첨가된 SCR(selective catalytic reduction)용 분말을 합성하였으며, W 촉매 첨가가 합성분말의 상합성 및 SCR 촉매능에 미치는 영향에 대해 연구하였다. 촉매의 지지체인 $TiO_2$는 침전법으로 anatase 상으로 합성되었으며, anatase에서 고온상인 rutile로의 상전이 온도는 $1200^{\circ}C$였으나, $WO_3$를 10 wt% 첨가할 경우 이 상전이 온도는 $900^{\circ}C$로 낮아졌다. 건식으로 $WO_3$ 분말을 직접 첨가하여 $WO_3(10wt%)/TiO_2$를 제조한 경우 $350^{\circ}C$에서 $NO_X$ 제거 촉매능이 최고점에 이르나 온도증가에 따라 그 효율이 상당히 감소하였다. 암모늄-메타-텅스테이트를 습식으로 첨가하여 제조한 경우, 보다 고온인 $450^{\circ}C$에서 촉매능이 최고점에 이르렀으며 온도에 따른 효율감소 폭도 적었다. 이와 같은 경향은 $WO_3$와 $V_2O_5$를 동시 첨가하여 제조한 $V_2O_5(5wt%)-WO_3(10wt%)/TiO_2$ 촉매에서도 나타났다. 즉, 암모늄-메타-텅스테이트를 습식으로 첨가한 경우, $WO_3$를 직접 첨가한 경우에 비해 넓은 온도범위($300^{\circ}C{\sim}500^{\circ}C$)에 걸쳐 90 %에 이상의 우수한 $NO_X$ 변환효율을 보였다.

• 대한환경공학회지
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• 제27권6호
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• pp.651-656
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• 2005

톨루엔은 섬유산업 공정에서 발생하는 주요한 유해성 대기 오염원으로 간주된다. 본 연구에서는 ${\gamma}-Al_2O_3$를 지지체로 한 전이 금속 산화물 촉매(Cu, Mn, V, Cr, Co, Ni, Ce, Sn, Fe, Sr, Cs, Mo, La, W, Zn)를 제조하여 톨루엔 완전 산화 반응을 조사하였다. XRD, FE-SEM, BET와 TPR 기법을 사용하여 금속 촉매의 특성을 조사하였다. 촉매 가운데 Cu/${\gamma}-Al_2O_3$ 촉매가 가장 우수한 활성을 보여주었다. BET결과 촉매 활성의 증가는 비표면적과는 관련이 적은 것으로 나타났으며, X선 회절 분석에서 대부분의 촉매들이 무정형으로 존재함이 관찰되었다. FE-SEM을 관찰한 결과, 전이금속 산화물 촉매 중 구리산화물 촉매가 지지체 표면에 고르게 분산되어 있음을 확인할 수 있었다. 톨루엔 산화반응에 따른 촉매활성 효과는 ${\gamma}-Al_2O_3$ 지지체 위에 전이금속 산화물 촉매가 고르게 분산된 점과 촉매 표면의 우수한 환원 특성에 기인하는 것으로 설명할 수 있었다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2018년도 춘계학술대회 논문집
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• pp.62-62
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• 2018

Pt is still considered as one of the most active electrocatalysts for ORR in alkaline fuel cells. However, the high cost and scarcity of Pt hamper the widespread commercialization of fuel cells. As a strong candidate for the replacement of Pt catalyst, silver (Ag) has been extensively studied due to its high activity, abundance, and low cost. Ag is more stable than Pt in the pH range of 8~14 as the equilibrium potential of Ag/Ag+ being ${\approx}200mV$ higher than that of Pt/PtO. However, Ag is the overall catalytic activity of Ag for oxygen reduction reaction(ORR) is still not comparable to Pt catalyst since the surface Ag atoms are approximately 10 times less active than Pt atoms. Therefore, further enhancement in the ORR activity of Ag catalysts is necessary to be competitive with current cutting-edge Pt-based catalysts. We demonstrate the architectural design of Ag catalysts, synthesized using plasma discharge in liquid phase, for enhanced ORR kinetics in alkaline media. An attractive feature of this work is that the plasma status controlled via electric-field could form the Ag nanowires or dendrites without any chemical agents. The plasma reactor was made of a Teflon vessel with an inner diameter of 80 mm and a height of 80 mm, where a pair of tungsten(W) electrodes with a diameter of 2 mm was placed horizontally. The stock solutions were made by dissolving the 5-mM AgNO3 in DI water. For the synthesis of Agnanowires, the electricfield of 3.6kVcm-1 in a 200-ml AgNO3 aqueous solution was applied across the electrodes using a bipolar pulsed power supply(Kurita, Seisakusyo Co. Ltd). The repetition rate and pulse width were fixed at 30kHz and 2.0 us, respectively. The plasma discharge was carried out for a fixed reaction time of 60 min. In case of Ag nanodendrites, the electric field of 32kVcm-1 in a 200-ml AgNO3 aqueous solution was applied and other conditions were identical to the plasma discharge in water in terms of electrode configuration, repetition rate and discharge time. Using SEM and STEM, morphology of Ag nanowires and dendrites were investigated. With 3.6 kV/cm, Ag nanowire was obtained, while Ag dendrite was constructed with 32 kV/cm. The average diameter and legth of Ag nanowireses were 50 nm and 3.5 um, and thoes values of Ag dendrites were 40 nm and 3.0 um. As a results of XPS analysis, the surface defects in the Ag nanowires facilitated O2 incorporation into the surface region via the interaction between the oxygen and the electron cloud of the adjacent Ag atoms. The catalytic activity of Ag for oxygen reduction reaction(ORR) showed that the catalytic ORR activity of Ag nanowires are much better than Ag nanodendrites, and electron transfer number of Ag nanowires is similar to that of Pt (${\approx}4$).