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Catalytic activity and characterization of V2O5/γ-Al2O3 for ammoxidation of m-xylene system
설용건,Yukwon Jeon,Sung wook Row,Altansukh Dorjgotov,Sang Duek Lee,Kyeongseok Oh 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.8
An ammoxidation of m-xylene was evaluated in a fixed-bed reactor using V2O5 on various oxides. Catalysts were prepared by wet impregnation method. At first, the loading of V2O5 was varied from 5 wt% to 20 wt% on γ-Al2O3support to estimate the most effective amount of V2O5. Second, the effect of catalyst supports was examined at 10 wt%loading of V2O5. V2O5/TiO2 and V2O5/SiO2 catalysts were employed to compare the ammoxidation reaction with V2O5/γ-Al2O3. Most catalytic activity was observed when γ-Al2O3 was used as a support. Careful characterization was followed by physicochemical techniques, such as BET measurement, X-ray diffraction (XRD), Raman spectroscopy and temperature-programmed reduction (TPR). The results provided the clue that monolayer V2O5 was favorably dispersed on the surface of γ-Al2O3 up to 10 wt%, which led to the highest yield of isophthalonitrile (IPN).
Physical degradation of MEA in PEM fuel cell by on/off operation under nitrogen atmosphere
설용건,Dongho Seo,Sangsun Park,Yukwon Jeon,Sung-Won Choi 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.1
The durability of PEMFCs is one of the most important issues for application in automotive vehicles with a repeated start-up and shut-down system. The understanding of degradation phenomena such as causes, mechanisms and influence of working condition is essential to improving the performance and lifetime of PEMFC. We conducted on/off cyclic operation in a single cell configuration with ultra purity nitrogen gas to investigate the physical degradation of membrane electrode assembly (MEA). After on/off cycle operation for 100,000 cycles under different humid condition,the characteristics of the MEAs were examined by in situ and ex situ analyses techniques. The physical degradation of MEA by on/off cycling led to a change in the membrane-electrode interfacial structure, which is mainly attributed to the loss of cell performance.
설용건,조영일,한학수,채재근,강문식 한국화학공학회 1996 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.34 No.6
환원제 침투법으로 Solid Polymer Electrolyte(이하 SPE)에 백금을 담지시켜서 SPE전극촉매(이하 전극촉매)를 제조하고 백금의 담지량 및 형태학적 특성, 전기화학적 특성, 그리고 물 전해조에서의 조전압 특성을 조사하였다. 그 결과, 환원제 농도를 증가시키면, 백금 담지량이 증가하다 감소하였는데. 환원제 농도 1.0㏖/L일 때 담지량이 가장 많아서 3.56 ㎎/㎠이었고 이때, 가장 두꺼운 촉매층이 형성되었다. 제조한 전극촉매의 전류-전압도에서 수소 흡착 피크로부터 계산한 전기량과 거칠기 인자는 환원제 농도 1.0 ㏖/L에서 284.92 mC, 1356.75로 가장 컸지만, 활성 비표면적은 다소 작아졌다. 한편, 전극촉매의 전류 밀도에 따른 조전압 변화를 실험한 결과, 백금 담지량이 많을수록 조전압이 감소하는 현상을 보였는데, 담지량이 3.56 ㎎/㎠, 전류 밀도 1A/㎠, 전해조 온도 25℃일 때, 조전압은 3.0 V이었다. 또한, 온도가 올라갈수록 조전압은 낮아지며 담지량이 3.56 ㎎/㎠, 전류 밀도 1A/㎠ 하에서 50℃, 80℃일 때, 각각 2.9 V. 2.7 V를 나타내었다. 이 때, 환원제 농도는 1.0 ㏖/L이었다. SPE electrocatalysts were made by reducing agent penetrating method. Pt loading, morphological, and electrochemical characteristics and cell voltage properties were investigated. The amount of Pt loading increased upto the reducing agent concentration of 1.0 ㏖/L and then decreased. At that concentration, the amount of Pt loading was the most, 3.56㎎/㎠ and Pt layer was the thickest. The largest electricity and roughness factor from cyclic voltammogram were 284.92 mC and 1356.75 respectively at the reducing agent concentration 1.0 ㏖/L. But surface area per unit weight of Pt was somewhat lower. As the amount of Pt loading increased, cell voltage became lower. At the amount of Pt loading 3.56㎎/㎠, current density 1 A/㎠, and temperature 25℃ it was the lowest, 3.0 V. As temperature increased, cell voltage became lower. Cell voltages at 50℃, 80℃ were 2.9 V, 2.7 V respectively under the condition of 3.56 ㎎/㎠, 1 A/㎠, It was at the reducing agent concentration 1.0 ㏖/L.