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고농도 NaBH4 수용액에서 비담지 촉매의 가수분해 반응 특성
이혜리 ( Hye Ri Lee ),나일채 ( Il Chai Na ),박권필 ( Kwon Pil Park ) 한국화학공학회 2016 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.54 No.5
Sodium borohydride, NaBH4, shows a number of advantages as hydrogen source for portable proton exchange membrane fuel cells (PEMFCs). Properties of NaBH4 hydrolysis reaction using unsupported Co-P-B Co-B, catalyst at high concentration NaBH4 solution were studied. In order to enhance the hydrogen generation yield at high concentration of NaBH4, the effect of catalyst type, NaBH4 concentration and recovery of condensing water on the hydrogen yield were measured. The yield of hydrogen evolution increased as the boron ratio increased in preparation process of Co-P-B catalyst. The hydrogen yield decreased as the concentration increased from 20 wt% to 25 wt% in NaBH4 solution during hydrolysis reaction using 1:5 Co-P-B catalyst. Maximum hydrogen yield of 96.4% obtained by recovery of condensing water and thinning of catalyst pack thickness in reactor using Co-P-B with Co-B catalyst and 25 wt% NaBH4solution.
고분자전해질연료전지에서 폴리이미드 강화 sPEEK막 MEA의 내구성
이혜리 ( Hye-ri Lee ),나일채 ( Il-chai Na ),오성준 ( Sung-jun Oh ),박권필 ( Kwon-pil Park ) 한국화학공학회 2017 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.55 No.3
Recently, there are many efforts focused on development of more economical non-fluorinated membranes for PEMFCs (Proton Exchange Membrane Fuel Cells). In this study, sulfonated poly (ether ether ketone) (sPEEK) membrane reinforced with poly imide was made to enhance of membrane durability. In order to test durability of single (un-reinforced) membrane and reinforced membrane MEA (Membrane and Electrode Assembly), degradation accelerated stress test was used. Before and after degradation, I-V polarization curve, hydrogen crossover current, electrochemical surface area, membrane resistance and charge transfer resistance were measured. As a result of experiments, hydrogen crossover current of reinforced MEA was lower than that of single MEA, therefor durability of reinforced MEA was higher than that of single MEA. There was not especially short phenomena in reinforced MEA after degradation accelerated stress test.
고분자 전해질 연료전지 구동 조건에 따른 MEA 열화 및 배출수 특성
황병찬 ( Byungchan Hwang ),이세훈 ( Sehoon Lee ),나일채 ( Il-chai Na ),박권필 ( Kwonpil Park ) 한국화학공학회 2017 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.55 No.4
Humidity control of proton exchange membrane fuel cell(PEMFC) is very important control condition during driving. In terms of water management, low humidification conditions are advantageous, and high humidification is advantageous in terms of drainage utilization and energy efficiency. In this study, the characteristics of outlet water in low humidification and high humidification process were studied in terms of utilization of discharged water. Since the impurities in the effluent are generated during the degradation of the membrane and the electrode assembly( MEA), degradation of the MEA under low humidification and high humidification conditions was also studied. The rate of radical generation was high at low humidification condition of the anode RH 0%, which showed that it was the main cause of the degradation of the polymer membrane. Analysis of effluent showed low concentration of fluoride ion concentration of about 20 ppb at high humidification (both electrodes RH 100%) and 0.6 V, which was enough to be used as the feed water for electrolysis. Very low concentration of platinum below 0.2 ppb was detected in the condensate discharged from the high humidification condition.
효소연료전지의 Cathode 제조조건이 OCV에 미치는 영향
이세훈 ( Se-hoon Lee ),김영숙 ( Young-sook Kim ),추천호 ( Cheun-ho Chu ),나일채 ( Il-chai Na ),이정훈 ( Jung-hoon Lee ),박권필 ( Kwon-pil Park ) 한국화학공학회 2016 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.54 No.2
Enzyme fuel cells were composed of enzyme cathode and PEMFC anode. Enzyme cathode was fabricated by compression of a mixture of graphite particle, laccase as a enzyme and ABTS as a redox mediator, and then coated with Nafion ionomer. Open circuit voltage (OCV) were measured with variation of cathode manufacture factors, to find optimum condition of enzyme cathode. Optimum pressure was 4.0 bar for enzyme cathode pressing process. Highest OCV was obtained at 95% graphite composition in enzyme cathodee. Optimum glucose concentration was 0.4 mol/l in cathode substrate solution.
고분자 전해질 연료전지에서 sPEEK 막을 이용한 전극과 막 합체(MEA)의 열화에 관한 연구
이혜리 ( Hye-ri Lee ),이세훈 ( Se-hoon Lee ),황병찬 ( Byung-chan Hwang ),나일채 ( Il-chai Na ),이정훈 ( Jung-hun Lee ),오성준 ( Sung-june Oh ),박권필 ( Kwon-pil Park ) 한국화학공학회 2016 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.54 No.3
Recently, there are many efforts focused on development of more economical non-fluorinated membranes for PEMFCs (Proton Exchange Membrane Fuel Cells). In this study, to test the durability of sPEEK MEA (Membrane and Electrode Assembly), ADT (Accelerated Degradation Test) of MEA degradation was done at the condition that membrane and electrode were degraded simultaneously. Before and after degradation, I-V polarization curve, hydrogen crossover, electrochemical surface area, membrane resistance and charge transfer resistance were measured. Although the permeability of hydrogen through sPEEK membrane was low, sPEEK membrane was weaker to radical evolved at low humidity and OCV condition than fluorinated membrane such as Nafion. Performance after MEA degradation for 144 hours and 271 hours were reduced by 15% and 65%, respectively. It was showed that the main cause of rapid decrease of performance after 144 hours was shorting due to Pt/C particles in the pinholes.
sPEEK 막으로 제조한 고분자전해질 연료전지(PEMFC) 막전극합체(MEA)의 특성
이혜리 ( Hye-ri Lee ),이세훈 ( Se-hoon Lee ),황병찬 ( Byung-chan Hwang ),나일채 ( Il-chai Na ),이정훈 ( Jung-hun Lee ),오성준 ( Sung-june Oh ),박권필 ( Kwon-pil Park ) 한국화학공학회 2016 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.54 No.2
Recently, there are many efforts focused on development of more economical non-fluorinated membranes for use in PEMFCs (Proton Exchange Membrane Fuel Cells). In this study, characteristics of sulfonated Poly(ether ether ketone) (sPEEK) were compared according to degrees of sulfonation (DS), relative humidity, cell temperatures at PEMFC operation condition. I-V polarization curve, hydrogen crossover, electrochemical surface area, membrane resistance and charge transfer resistance were measured. sPEEK membrane showed high performance at high DS, high temperature and high relative humidity, in particular, performance of sPEEK membrane decreased largely due to low ionic conductivity at low DS and low relative humidity.
비담지 촉매를 이용한 NaBH<sub>4</sub> 가수분해반응에서 부산물의 특성
이혜리 ( Hye-ri Lee ),박대한 ( Dae-han Park ),주원 ( Won Ju ),나일채 ( Il-chai Na ),박권필 ( Kwon-pil Park ) 한국화학공학회 2017 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.55 No.1
Sodium borohydride, NaBH4, shows a number of advantages as hydrogen source for UAV PEMFC (Unmaned Aerial Vehicle Proton Exchange Membrane Fuel Cells). In order to use for UAV, the weight and volume of byproduct should be small after NaBH4 hydrolysis reaction. Therefore, the weight and volume of byproduct were studied after NaBH<sub>4</sub> hydrolysis reaction using unsupported catalyst. The effect of catalyst type, concentra-tion of NaBH<sub>4</sub>, concentration of NaOH and thickness of catalyst pack on the weight and volume of byproduct were studied. Most of byproduct was NaB(OH)<sub>4</sub> and superficial volume of byproduct increased due to foam evolved from byproduct. The weight and volume of byproduct were not affected by concentration of NaOH used stabilizer. The weight of byproduct decreased as con-centration of NaBH<sub>4</sub> solution increased, but maximum volume of byproduct obtained at 23 wt% of NaBH<sub>4</sub>. Suitable defoaming agent reduced the volume of byproduct.
이세훈 ( Se-hoon Lee ),김영숙 ( Young-sook Kim ),추천호 ( Cheun-ho Chu ),나일채 ( Il-chai Na ),오용환 ( Yong-hwan Oh ),박권필 ( Kwon-pil Park ) 한국화학공학회 2017 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.55 No.1
Recovery of sulfuric acid is very important after biomass converted to sugar by acid hydrolysis. In this work, the separation of sulfuric acid from sulfuric acid/glucose solution was studied by electrodiaysis. Three chamber method, which requires both anion membrane and cation membrane, is the most commonly used in the electrodialysis process, but two chamber method using only an anion membrane was the focus of this study. Sulfuric acid was perfectly separated from a mixture of 10~30 wt% glucose and 1~3 M sulfuric acid by electrodialysis using two chamber method. The separation rate of sulfuric acid lineary increased with higher current density when the affect of diffusion and convection of the membrane was small. Without electric energy, 45% of sulfuric acid was separated by diffusion and convection only.
고분자전해질 연료전지 열화 분석방법에 의한 PEM 수전해 열화 평가
오소형 ( Sohyeong Oh ),양진원 ( Jinwon Yang ),추천호 ( Cheun-ho Chu ),나일채 ( Il-chai Na ),박권필 ( Kwonpil Park ) 한국화학공학회 2021 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.59 No.1
The PEM(Proton Exchange Membrane)water electrolysis uses the same PEM electrolyte membrane as the PEM fuel cell and proceeds by the same reaction but the opposite direction. The PEM fuel cell has many methods of degradation analysis since many studies have been conducted on the degradation and durability of the membrane and catalyst. We examined whether PEM fuel cell durability evaluation method can be applied to PEM electrolytic durability evaluation. During the PEM electrolytic degradation process, LSV(Linear sweep voltammetry), CV(Cyclic voltammetry), Impedance, SEM(Scanning Electron Microscope) and FT-IR(Fourier Transform Infrared spectroscopy) were analyzed and compared under the same conditions as the PEM fuel cell. As the PEM fuel cell, hydrogen passing through the membrane was oxidized at the Pt/C electrode, and the hydrogen permeation current density was measured to analyze the degree of degradation of the PEM membrane. Electrode degradation could be analyzed by measuring the electrode active area (ECSA) by CV under hydrogen/nitrogen flowing conditions. While supplying hydrogen and air to the Pt/C electrode and the IrO<sub>2</sub> electrode, the impedance of each electrode was measured to evaluate the durability of the electrode and membrane.