• 한국수소및신에너지학회논문집
• /
• 제27권3호
• /
• pp.270-275
• /
• 2016

A simple solid state incorporation method was employed in order to incorporate Pd nanocatalyst into a Nafion film for polymer electrolyte membrane fuel cell (PEMFC) via the reduction of palladium (II) bis (acetylacetonate), $Pd(acac)_2$. It was sublimed, penetrated into Nafion film and then reduced to Pd nanoparticles simultaneously in a glass reactor of N2 atmosphere at $180^{\circ}C$ for 1, 3 and 5 min. This reaction was took place without any reducing agent and any solvent. The morphology of the Pd nanoparticles was observed by transmission electron microscopy (TEM), and Pd distribution was analyzed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). And 23% modification of tensile strength of Pd/Nafion composite film was measured by universal testing machine and I-V curve was estimated by using a unit cell with $5{\times}5cm^2$ active area.

• 공업화학
• /
• 제16권5호
• /
• pp.641-647
• /
• 2005

메탄의 부분산화반응은 수소 제조의 중요한 반응 중의 하나이다. 무전해 도금방법에 의해 제조된 팔라듐-은 막을 막반응기(membrane reactor)로서 메탄의 부분산화반응에 적용하여 반응온도, $O_2/CH_4$ 몰비, $CH_4$ 공급속도, $N_2$ 운반 가스 흐름속도 등의 변화에 따라 실험을 수행하였다. 막반응기의 메탄 전환율은 알루미나에 담지된 니켈 촉매를 사용하는 반응조건하에서 $350{\sim}730^{\circ}C$의 반응온도에 따라 증가하는 경향을 보였으며, 특히 $730^{\circ}C$와 $O_2/CH_4$ 몰비 0.5에서 메탄 전환율과 CO 선택도가 가장 높았다. 막반응기의 메탄 전환율은 전통적인 관형반응기와 비교한 결과 반응조건에 따라 10~40% 정도 높았다.

• 공업화학
• /
• 제18권1호
• /
• pp.94-97
• /
• 2007

대기압 조건에서 고정층 상압 유통식 반응기를 사용하여 Pd(5)/SPK 촉매상에서 산소의 몰 비 변화에 따른 메탄의 열분해 반응으로부터 탄소 나노튜브 및 탄소 나노선을 제조하였으며, SEM과 TEM을 이용하여 분석하였다. $CH_4/O_2$의 몰 비가 1인 경우, 촉매층 지지대 표면상에 탄소가 거의 침적되지 않았으나, $CH_4/O_2$의 몰 비가 2인 경우에는 촉매층 지지대 표면상에 반응기를 봉쇄할 정도로 다량의 탄소가 침적되었다. 침적된 탄소를 SEM과 TEM을 통하여 분석한 결과 많은 수의 단일 벽 탄소 나노튜브와 탄소 나노선들이 만들어졌음을 확인할 수 있었다. 촉매 표면상에 침적된 탄소 나노튜브의 생성 메카니즘은 첨단성장방식이었고, 촉매 지지대 표면상에 만들어진 탄소 나노튜브 및 나노선들의 생성은 일정한 탄소 성장속도 벡터와 탄소 나노선의 링구조의 핵형성이 중요한 역할을 하였다. SPK 촉매 담체는 열 안정성이 우수하였으며, $N_2$ 흡착등온선은 중기공 세공이 잘 발달된 IV형이었다.

• Bulletin of the Korean Chemical Society
• /
• 제33권2호
• /
• pp.387-392
• /
• 2012

A series of Pd-based catalysts were prepared and examined for the amination of 2,6-dimethylphenol in a fixedbed reactor. The best results were obtained for Pd/$Al_2O_3$-BaO with a conversion of 99.89% and a selectivity of 91.16%. These catalysts were characterized using BET, XRD, XPS, TEM and $NH_3$-TPD. Doped BaO not only improved the dispersion of the Pd particles but also decreased the acidity of the catalyst, which remarkably enhanced the selectivity and stability of the catalyst. The generality of Pd/$Al_2O_3$-BaO for this kind of reaction was demonstrated by catalytic aminations of o- and p-alkyl phenols.

• 공업화학
• /
• 제10권8호
• /
• pp.1210-1215
• /
• 1999

Pd/C촉매가 부유되어 있는 3상 슬러리 반응기에서 원료 p-nitroaniline(PNA)를 수소 첨가시켜 고순도의 p-phenylenediamine(PPD)를 합성하는 최적 반응조건을 구하였다. 수소첨가 반응시 활성점에서 수소부족을 줄이고 불순물의 생성을 감소시킬 수 있도록, 기체-액체, 액체-촉매사이의 물질전달 저항을 최소화하고 표면반응속도가 율속할 수 있게 반응조건을 설정하였다. 이 반응조건은 온도 $60^{\circ}C$, 압력 60~70 psig, 촉매농도 1~2 g-cat/L일 때가 최적이었으며, 반응속도는 PNA 농도에 0차, 수소 반응압력에 1차를 각각 보여주었으며, 총괄반응속도식은 $R_A=6.44{\times}10^6{\cdot}H{\cdot}P{\cdot}m{\cdot}$exp(-4659/T)로 나타났다.

• 한국대기환경학회지
• /
• 제20권5호
• /
• pp.663-670
• /
• 2004

The catalytic oxidation of benzene, toluene and xylene over a spent industrial catalyst (Pd-based) was investigated in a fixed bed flow reactor system. According to the priming condition, the properties of a spent Pd-based catalyst were characterized by XRD(X-ray diffraction). BET(Brunauer-Emmett-Teller) and ICP(Inductively coupled plasma). When air was used as a primer, optimum priming temperature was found to be 200$^{\circ}C$, and the catalytic activity decreased as the priming temperature increased. When a spent Pd-based catalyst primed with air at 200$^{\circ}C$ was re-treated with hydrogen at 200$^{\circ}C$, 300$^{\circ}C$ or 400$^{\circ}C$, respectively, the catalytic activity increased and thermal effect were negligible. $HNO_3$ aqueous solution priming resulted in slight decrease of the catalytic activity, with little effects on $HNO_3$ concentrations. The activity of a spent Pd-based catalyst with respect to VOC molecule was observed to follow sequence: xylene> toluene> benzene. Benzene. toluene and xylene could be removed to almost 100% by a spent Pd-based catalyst primed with hydrogen.

• 대한금속재료학회지
• /
• 제46권5호
• /
• pp.296-303
• /
• 2008

Hydrogen permeation through dense palladium-based membranes has attracted the attention of many scientists largely due to their unmatched potential as hydrogen-selective membranes for membrane reactor applications. Although it is well known that the permeation mechanism of hydrogen through Pd involves various processes such as dissociative adsorption, transitions to and from the bulk Pd, diffusion within Pd, and recombinative desorption, it is still unclear which process mainly limits hydrogen permeation at a given temperature and hydrogen partial pressure. In this study, we report an all-electron density-functional theory study of hydrogen permeation through Pd membrane (using VASP code). Especially, we focus on the variation of the energy barrier of the penetration process from the surface to the bulk with hydrogen coverage, which means the large reduction of the fracture stress in the brittle crack propagation considering Griffith's criterion. It is also found that the penetration energy barrier from the surface to the bulk largely decreases so that it almost vanishes at the coverage 1.25, which means that the penetration process cannot be the rate determining process.

• 한국대기환경학회지
• /
• 제14권1호
• /
• pp.63-72
• /
• 1998

Simultaneous CO and $C_3H_6$ oxidation was carried out over noble metal supported monolith catalysts in a flow thorugh type reactor at the temperature ranging from room temperature to $500^\circ$C. Pt and Pd were selected as major active species, 10wt% of Ce was impregnated as an additive and alumina and silica were used as supports. The reactant gases were simulated and the reaction products were analyzed by on-line G.C.. EDX, SEM, TGA, XRD and optical microscope were used to analyze the characteristics of the prepared catalysts. Under the given conditions in this study, the catalysts supported on alumina showed better activity for CO oxidation, while Pd catalysts showed better activity for $C_3H_6$ oxidation. The improvement of conversion due to increase in thermal stability possibily by Ce addition was observed only for Pt catalysts.

• Nuclear Engineering and Technology
• /
• 제51권3호
• /
• pp.647-653
• /
• 2019

A comprehensive study of photon interaction features has been made for some alloys containing Pd and Ag content to evaluate its possible use as alternative gamma radiations shielding material. The mass attenuation coefficient (${\mu}/{\rho}$) of the present alloys was measured at various photon energies between 81 keV - 1333 keV utilizing HPGe detector. The measured ${\mu}/{\rho}$ values were compared to those of theoretical and computational (MCNPX code) results. The results exhibited that the ${\mu}/{\rho}$ values of the studied alloys are in same line with results of WinXCOM software and MCNPX code results at all energies. Moreover, Pd75/Ag25 alloy sample has the maximum radiation protection efficiency (about 53% at 81 keV) and lowest half value layer, which shows that Pd75/Ag25 has superior gamma radiation shielding performance among the compared other alloys.

• 한국산학기술학회논문지
• /
• 제17권1호
• /
• pp.21-27
• /
• 2016

온실가스로 인한 지구 온난화는 전 세계적인 주요 문제로 인식되고 있으며, 많은 나라들은 $CO_2$ 배출 감축을 위한 많은 노력을 하고 있다. 연소 후, 연소 전, 순산소 연소의 다양한 $CO_2$ 포집 기술들이 개발되고 있으며, 그 중 본 연구에서는 연소 전 $CO_2$ 포집 기술로서 수성가스전환반응기와 기체분리막의 융합 시스템을 고찰하였다. CO 전환율을 높이기 위해 고온 수성가스반응과 저온 수성가스반응이 결합된 2단 WGS 반응기를 사용하였고, 비다공성 Pd/Cu 분리막을 이용하여 수소를 선택적으로 분리하여 $CO_2$를 농축하였다. 연소 전 $CO_2$ 포집에서의 활용을 고려하여 65% CO, 30 % $H_2$, 5% $CO_2$의 기체 혼합물에 대한 하이브리드 시스템의 성능을 CO 전환율과 수소 분리의 측면에서 평가하였다. 공급기체유량 1000ml/min에서 수성가스 전환반응의 운전조건으로 온도는 $200-400^{\circ}C$, 압력은 0-20bar, S/C 비는 2.5-5의 영역에서 성능을 평가하였다. 2단 수성가스전환반응기에서 CO의 전환율은 최고 99.5%이었으며, Pd/Cu 분리막을 통하여 $CO_2$를 83%로 농축시켰다.