• Transactions of the Korean hydrogen and new energy society
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• v.17 no.4
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• pp.440-447
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• 2006

Solid polymer electrolyte(SPE) membrane with electrodes embedded on both faces offer unique possibilities for the electrochemical cells like water electrolyzer with fuel cell. The Nafion 117 membrane was used as the SPE, and $Pt(NH_3)_4Cl_2$ and $NaBH_4$ as the electrocatalysts and reducing agent, respectively. The 'impregnation-reduction(I-R) method' has been investigated as a tool for the preparation of electrocatalysts for water electrolyzer by varying the concentration of reducing agent and reduction time at fixed concentration of platinum salt, 5 mmol/L. Pt-SPE electrocatalysts prepared by non-equilibrium I-R method showed the lowest cell voltage of 2.17 V at reduction time, 90 min and with concentration of reducing agent 0.8 mol/L and the cell voltage with those by equilibrium I-R method was 2.42 V at reduction time, 60 min and with concentration of reducing agent 0.8 mol/L. The cell voltage were obtained at a current density $1\;A/cm^2$ and $80^{\circ}C$. In water electrolysis, hydrogen production efficiency by Pt-SPE electrocatalyst is 68.2% in case of non-equilibrium I-R method and 61.2% at equilibrium I-R method.

• 한국전기화학회:학술대회논문집
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• 2002.07a
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• pp.237-240
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• 2002

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.220-223
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• 2007

이 논문은 DMFC와 태양전지의 하이브리드형 연료전지에 적합한 $TiO_{2}$구조에 대한 연구로서, DMFC에 사용되는 귀금속 Pt의 사용량을 줄이기 위해 Pt를 $TiO_{2}$광촉매 지지체에 함침 시켜 UV가 조사될 때 Pt의 활성을 극대화시키기 위한 연구이다. $TiO_{2}$는 Rutile결정 구조를 이루었으며, 반응 시간에 따라 나노막대 모양을 형성하였다. $NaBH_{4}$ 환원법을 통해 Pt를 함침 시켜 전극을 제조하였다. 이 전극들은 UV가 입사되지 않을 때보다 UV가 입사될 때 메탄올 산화성능이 주목할 만큼 향상되었다. 특히 긴 막대모양의 $TiO_{2}$에 백금이 잘 분산된 촉매의 메탄올 산화반응 성능이 크게 향상되었다. 이러한 $Pt/TiO_{2}$의 주목할 만한 성능 향상은 UV가 조사될 때 빛에 의해 생성된 $TiO_{2}$의 hole들에 의해 메탄올 산화반응이 향상된 것으로 사료된다.

• Korean Chemical Engineering Research
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• v.55 no.5
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• pp.679-684
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• 2017

The influence of catalytic activity on Fe loading methods over Fe/BEA zeolite catalyst in the simultaneous reduction of $N_2O/NO$ has been studied. The Fe/BEA zeolite catalysts were prepared by ion exchange and impregnation. Catalytic tests were carried out in the selective catalytic reduction using ammonia as a reductant to identify the activity of prepared catalysts. The results show that the ion exchanged catalyst exhibited higher NO and $N_2O$ conversions than the impregnated catalysts did. To investigate the difference in catalytic activity, we performed various analyses such as XRD, $H_2-TPR$, $O_2-TPD$ and XPS. It is considered that the increase in the activity of the ion exchange catalyst is due to improved reducibility and increased oxygen desorption rate. In addition, the ion exchange catalyst was found through the XPS analysis that $Fe^{2+}$, which is related to the catalytic activity, is formed about 1.6 times more than the impregnated catalyst.

• Applied Chemistry for Engineering
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• v.5 no.2
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• pp.285-294
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• 1994

Some supported gold catalysts were prepared by impregnation and coprecipitation methods. Effect of gold addition and active sloe formation were studied by investigating particle sizes of gold, amounts of oxygen adsorbed, adsorption properties of CO and NO, and reduction and oxidation properties, etc.. The gold particles of the catalyst by impregnation were irregular and very large as 30~100 nm, but those by coprecipitation were uniform and ultra-fine as about 4 nm. On $Au/Al_2O_3$ catalyst, the addition of gold to inactive $Al_2O_3$ caused the decomposition of $N_2O$, and CO was not irreversibly adsorbed while $O_2$ was atomically and irreversibly adsorbed. The adsorption sites of oxygen were attributed to the active sites which were restricted to the circumference of hemispherical gold particle-support interface rather than all atoms on the surface of gold particle. Also, CO was reversibly and irreversibly adsorbed on $Al_2O_3$ at low temperature, and the addition of gold weakened both reversible and irreversible adsorptions. The affinity for CO on $Au/Co_3O_4$ catalyst decreased conspicuously compared to $Co_3O_4$. The effect of gold addition did not appear in reduction step but did remarkably in reoxidation step; the added gold promoted the reoxidation of the reduced cobalt atoms.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.3
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• pp.249-256
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• 2006

Catalytic combustion of toluene was investigated on the Cu-Mn oxide catalysts prepared by the impregnation(Imp) and the deposition-precipitation(DP) methods. The mixing of copper and manganese has been found to enhance the activity of catalysts. It is then found that catalytic efficiency of the Cu-Mn oxide catalyst prepared by the DP method on combustion of toluene is much higher than that of the Cu-Mn oxide catalyst prepared by Imp method with the same chemical composition. The catalyst prepared by the deposition-precipitation method observed no change of toluene conversion at time on stream during 10 days and at the addition of water vapor. On the basis of catalyst characterization data, it has been suggested that the catalysts prepared by the DP method showed uniform distribution and smaller particle size on the surface of catalyst and then enhanced reduction capability of catalysts. Therefore, we think that the DP method leads on progressive capacity of catalyst and promotes stability of catalyst. It was also presumed that catalytic conversion of toluene on the Cu-Mn oxide catalyst depends on redox reaction and $Cu_{1.5}Mn_{1.5}O_4$ spinel phase acts as the major active sites of catalyst.

• Membrane Journal
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• v.17 no.4
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• pp.381-386
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• 2007

Hollow fibers were made using the nickel slurry containing nickel particles and polymers by phase inversion method. And then, metallic filters were fabricated by sintering method at $1,150^{\circ}C$ under reduction condition. Metallic microfiltration membranes were prepared by coating nickel particles on the metallic filter. The properties of the metallic hollow fiber filters and microfiltration membranes such as pore size and strength were investigated. The metallic membrane showed good resistance against acid, base and chlorine. It was observed that the membrane exhibited good recovery rate by back washing.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05b
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• pp.396-400
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• 1997

중수형 발전소에서 삼중수소 제거나 중수분리와 관련된 수소동위원소 교환반응에 이용되는 백금담지 고분자촉매제조시 환원과정 이전의 열처리 조건이 백금분산도에 미치는 영향을 관찰하였다. 고분자 담체(SDBC)에 함침법을 이용하여 백금을 담지시켰으며, 8$0^{\circ}C$의 공기중에서 그리고 15$0^{\circ}C$의 산소흐름하에서 열처리하여 제조한 Pt/SDBC촉매의 열적 안정성을 TGA와 BET 실험결과로부터 확인할 수 있었다. 백금담지량이 커지면 백금분산도가 감소하였으며, 가능한 한 고온의 산소로 열처리하면 고분자촉매의 백금분산도가 향상됨을 수소흡착 실험을 통하여 입증하였다.

• Clean Technology
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• v.19 no.3
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• pp.287-294
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• 2013

The $NH_3$-selective catalytic reduction (SCR) reaction of NO with excess of oxygen were systematically investigated over Cu-zeolite and Fe-zeolite catalysts. Cu-zeolite and Fe-zeolite catatysts to adapt the SCR technology for mobile diesel engines were prepared by liquid ion exchange and incipient wetness impregnation of $NH_4$-BEA and $NH_4$-ZSM-5 zeolites. The catalysts were characterized by BET, XRD, FE-TEM (field emission transmission electron microscopy) and SEM/EDS. The SCR examinations performed under stationary conditions showed that the Cu-exchanged BEA catalyst revealed pronounced performance at low temperatures of $200{\sim}250^{\circ}C$. With respect to the Fe-zeolite catalyst, the Cu-zeolite catalyst showed a higher activity in the SCR reaction at low temperatures below $250^{\circ}C$. BEA zeolite based catalyst exhibited good activity in comparison with ZSM-5 zeolite based catalyst at low temperatures below $250^{\circ}C$.

• Journal of the Korean Institute of Gas
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• v.14 no.2
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• pp.7-14
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• 2010

Synthesis gas was produced by the partial oxidation of methane. For the preparation of catalysts, Ni, known to be active in this reaction and cheap, was used as the active component and $CeO_2$, having high oxygen storage capability and high redox ability, was used as the support. The catalysts were prepared by the impregnation and urea methods. The catalyst prepared by the urea method showed about 11 times higher surface area and finer particle size than that prepared by the impregnation method. The catalysts prepared by the urea method showed higher methane conversion and synthesis gas selectivity than that prepared by the impregnation method. In this reaction, carbon deposition is a problem to be solved, so La was added to the catalyst system to reduce the carbon deposition. TGA analysis results showed that there was 2% carbon deposition with La-added catalysts and 16% with La-free catalysts. It was found that the addition of La decreases the amount of carbon deposition and prevents catalyst deactivation.