• 한국진공학회:학술대회논문집
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• 한국진공학회 2003년도 제25회 학술발표회 초록집
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• pp.38-39
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• 2003

• 한국재료학회지
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• 제32권11호
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• pp.496-507
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• 2022

For the selective catalytic reduction of NOx with ammonia (NH₃-SCR), a V₂O₅WO₃/TiO₂ (VW/nTi) catalyst was prepared using V₂O₅ and WO₃ on a nanodispersed TiO₂ (nTi) support by simple impregnation process. The nTi support was dispersed for 0~3 hrs under controlled bead-milling in ethanol. The average particle size (D₅₀) of nTi was reduced from 582 nm to 93 nm depending on the milling time. The NOx activity of these catalysts with maximum temperature shift was influenced by the dispersion of the TiO₂. For the V_0.5W₂/nTi-0h catalyst, prepared with 582 nm nTi-0h before milling, the decomposition temperature with over 94 % NOx conversion had a narrow temperature window, within the range of 365-391 ℃. Similarly, the V_0.5W₂/nTi-2h catalyst, prepared with 107 nm nTi-2h bead-milled for 2hrs, showed a broad temperature window in the range of 358~450 ℃. However, the V_0.5W₂/Ti catalyst (D₅₀ = 2.4 ㎛, aqueous, without milling) was observed at 325-385 ℃. Our results could pave the way for the production of effective NOx decomposition catalysts with a higher temperature range. This approach is also better at facilitating the dispersion on the support material. NH₃-TPD, H₂-TPR, FT-IR, and XPS were used to investigate the role of nTi in the DeNOx catalyst.

• 한국가스학회지
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• 제26권5호
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• pp.22-27
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• 2022

반도체 생산 설비 중 ALD는 열이나 플라즈마로 분해한 Gas를 Wafer에 증착시켜 원자층을 형성시키는 설비로 주로 인화성 물질인 NH₃와 SIH4이 사용된다. 이중 NH₃는 연소·폭발 범위가 상한(UFL) 33.6%, 하한(LEL) 15%로 폭발 범위가 비교적 좁지만 많은 양이 갑자기 한곳에 모이면 폭발할 수 있고, 피부에 닿거나 흡입하면 치명적이다. NH₃는 ALD Gas inlet의 배관과 전기·기계 기구를 통해 Chamber로 공급되는데 많은 누출 가능점이 존재하여 누출 시 화재·폭발 또는 중독 사고로 이어질 수 있어 NH₃ 누출 시나리오에 대한 내부 유동과 제어 속도를 이해하고 고환기가 가능한 배기장치를 설계하는 것이 필요하여 본 연구자는 NH₃의 누출시나리오를 CFD에 적용하여 내부유동과 제어 속도를 수치 분석하여 설계 시 반영할 수 있도록 하였다.

• 한국대기환경학회지
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• 제24권5호
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• pp.512-522
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• 2008

Ammonia is a major compound of odor in livestock house. To enhance the performance of ammonia oxidation (decomposition). the gas-liquid, two phase photocatalytic oxidation system was designed and prepared in this study. Commercial P-25 as $TiO_2$ catalyst was used for ammonia decomposition. V/P-25 catalyst prepared by sol gel method was also used for the removal of by-producted $NO_x$ in $NH_3$ oxidation reaction. When $TiO_2$ was used as a photocatalyst, the conversion to $N_2$ in ammonia decomposition reached above 90% until 200hr (The air flow rate of 4L/min with the ammonia concentration up to 25ppm.). However, considerable amounts of NO and $NO_2$ were formed as a result of $NH_3$ oxidation (as a by-product). Therefore, we added Vanadia impregnated $TiO_2$(P-25) catalyst for the removal of $NO_x$ at the end of reaction trail. The results of a pilot-scale operation were successful to achieve the simultaneous removal of $NH_3\;and\;NO_x$ about 81 and 87%, respectively.

• 한국자기공명학회논문지
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• 제23권2호
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• pp.40-45
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• 2019

The phase transition temperatures and thermodynamic properties of $(NH_4)_2MnCl_4{\cdot}2H_2O$ grown by the slow evaporation method were studied using differential scanning calorimetry and thermogravimetric analysis. A structural phase transition occurred at temperature $T_{C1}$ (=264 K), whereas the changes at $T_{C2}$ (=460 K) and $T_{C3}$ (=475 K) seemed to be chemical changes caused by thermal decomposition. In addition, the chemical shift and the spin-lattice relaxation time $T_{1{\rho}}$ were investigated using $^1H$ magic-angle spinning nuclear magnetic resonance (MAS NMR), in order to understand the role of $NH_4{^+}$ and $H_2O$. The rise in $T_{1{\rho}}$ with temperature was related to variations in the symmetry of the surrounding $H_2O$ and $NH_4{^+}$.

• 대한기계학회논문집B
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• 제39권2호
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• pp.177-182
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• 2015

디젤 엔진과 산업용 보일러에서의 질소산화물(NOX) 배출은 환경오염을 유발시키는 주요물질 중의 하나이다. 이러한 질소산화물 발생을 저감시키기 위한 방법으로 후처리 기술 중의 하나인 우레아 선택적 촉매 환원(Urea-SCR)기술이 널리 사용되고 있다. 본 연구에서는 선박용 디젤엔진의 배기가스 조건을 모사한 실험실 스케일의 실험장치를 통해 우레아 수용액의 열분해 특성에 대해 고찰하였다. 40 wt. %의 우레아 농도를 가진 우레아 수용액을 사용하였고, 모사가스의 온도와 유속변화, 우레아 수용액의 유량에 따른 총 전환율 뿐만 아니라 암모니아($NH_3$)와 이소시안산(HNCO)의 전환율 차이를 알아보았다. $210^{\circ}C$와 $250^{\circ}C$ 모사가스 온도에서 체류시간에 따라 암모니아의 전환율이 이소시안산의 전환율보다 높게 나타남을 확인하였다.

• 한국분말재료학회지
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• 제16권3호
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• pp.196-202
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• 2009

A visible-light photoactive $TiO_{2-x}N_x$ photocatalyst was synthesized successfully by means of cogrinding of anatase-$TiO_2(a-TiO_2)$ in $NH_3$ ambient, followed by heat-treatment at $200^{\circ}C$ in air environment. In general, it is well known that the grinding-operation induces phase transformation of a-$TiO_2$ to rutile $TiO_2$. This study investigates the influence of the amount of $NH_3$ gas on the phase transformation rate of a-$TiO_2$ and enhancement of visible-light photocatalytic activity, and also examines the relation between the photocatalytic activity and the period of grinding time. The phase transformation rate of a-$TiO_2$ to rutile is retarded with the amount of NH3 injected. And the visible-light photocatalytic activity of samples, was more closely related to the period of grinding time than $NH_3$ amount injected, which means that the doping amount of nitrogen into $TiO_2$ more effective to mechanical energy than $NH_3$ amount injected. XRD, XPS, FT-IR, UV-vis, Specific surface area (SSA), NOx decomposition techniques are employed to verify above results more clearly.

• 센서학회지
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• 제4권2호
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• pp.58-63
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• 1995

$SiH_{4}$와 $NH_{3}$의 RF 글로우방전 분해에 의한 PECVD법으로 a-SiNx:H박막을 제조하고 기판온도, RF 전력, 그리고 $NH_{3}/SiH_{4}$ 유량비 등의 변화에 따른 a-SiNx:H 박막의 유전상수와 광학적 밴드갭 등을 조사하였다. a-SiNx:H막의 유전상수와 광학적 밴드갭은 기판온도, RF 전력 및 $NH_{3}/SiH_{4}$ 유량비 등의 증착변수에 따라 크게 변화하였다. 기판온도가 증가할수록 a-SiNx:H막의 유전상수는 증가하였으며 광학적 밴드갭은 감소하였다. 기판온도, RF 전력, 가스압력, $NH_{3}/SiH_{4}$ 유량비 및 두께를 각각 $250^{\circ}C$, 20 W, 500 mTorr, 10 및 $1500\;{\AA}$로 하였을 때 a-SiNx:H막의 유전상수, 절연파괴전장 및 광학적 밴드갭은 각각 4.3, 1 MV/cm 및 2.9 eV로 나타났다.

• Journal of Biosystems Engineering
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• 제34권1호
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• pp.44-49
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• 2009

This study was conducted to investigate the pyrolysis characteristics of switchgrass using TGA-FTIR instrument. Switchgrass is a high yielding perennial grass that has been designated as a potential energy crop, because of its high energy value. Ground switchgrass were pyrolysed at different heating rates of 10, 20, 30, and $40^{\circ}C/min$ in a TGA-FTIR instrument. The thermal decomposition characteristics of switchgrass were analyzed, and the gases volatilized during the experiment were identified. The thermal decomposition of switchgrass started at approximately $220^{\circ}C$, followed by a major loss of weight, where the main volatilization occurred, and the thermal decomposition was essentially completed by $430^{\circ}C$. The pyrolysis process was found to compose of four stages; moisture evaporation, hemicellulose decomposition, cellulose decomposition, and lignin degradation. The peak temperatures for hemicellulose decomposition ($306^{\circ}C$ to $327^{\circ}C$) and cellulose decomposition ($351^{\circ}C$ to $369^{\circ}C$) were increased with greater heating rates. FTIR analysis showed that the following gases were released during the pyrolysis of switchgrass; $CO_2$, CO, $CH_4$, $NH_3$, COS, $C_{2}H_{4}$, and some acetic acid. The most gas species were released at low temperature from 310 to $380^{\circ}C$, which was corresponding well with the observation of thermal decomposition.

• 공업화학
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• 제21권3호
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• pp.323-327
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• 2010

La 이온이 도핑된 Ti-SBA-15 촉매를 수열합성법으로 제조하였고, 이들의 특성을 XRD, FT-IR, DRS, $NH_3$-TPD 및 PL 등을 이용하여 조사하였다. 또한, 이 촉매를 사용하여 메틸렌블루에 대한 광분해 반응성을 조사하였다. La 이온이 도핑되더라도 Ti-SBA-15 촉매는 메조동공체 구조를 유지하고 있으며, $500^{\circ}C$에서 6 h 동안 소성 한 것이 가장 결정성이 좋았다. La 이온의 치환량이 증가함에 따라 기공의 크기와 기공의 부피가 줄어들었으며 표면적은 오히려 증가하였다. 메틸렌블루의 광분해 반응에서 1%의 La 이온을 첨가 시킨 것이 가장 높은 광촉매 활성을 보여주었으며, 도핑량이 5% 이상이 되면 순수한 Ti-SBA-15 촉매보다 오히려 활성이 떨어진 것을 볼 수 있다.