• Journal of the Korean Institute of Gas
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• v.28 no.2
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• pp.7-16
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• 2024

This study presents investigation on the technical characteristics and field cases of the salt cavern storage method for large-scale hydrogen storage. The salt cavern storage method enables effective hydrogen storage compared to other methods due to the low porosity and permeability of the rock salt that constitutes the cavern, which is not likely to leak and requires a small amount of cushion gas for operation. In addition, there is no chemical reaction between rock salt and hydrogen, and multiple injection/withdrawl cycles can be performed making it effective for peak shaving and short-term storage. The salt cavern is formed in three stages: leaching, debrining, and filling, and leakage tests are conducted to ensure stable operation. Field applications are currently performing to meet industrial demand in the surrounding area of four sites in the UK and Texas, USA, and salt cavern operation is being prepared for energy storage in European countries such as Germany and France. The investigated results in this study can be utilized as a basic guideline for the design of future hydrogen storage projects.

• Elastomers and Composites
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• v.40 no.2
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• pp.136-142
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• 2005

Liquid crystalline poly(allylsulfone) networks having $SO_2$ in a main chain and mesogens in a side chain were synthesized and their gas permeability and permselectivity were determined. The monomer II having two allyl groups on the each end group was able to form polymer networks by polymerization reaction, while the monomer I having only one allyl group was not. Molecular motion of the poly(allylsulfone) networks were retarded with increasing the cross-linking density, and the segmental motion of networks was developed enough to show isotropic phase transition. Gas permeabilities of poly(II-5 $01/I-OCH_3$ 99) were 2.58 baller for $O_2$ and 18.4 barrer for $H_2$. It means that hydrogen gas are 7 times more permeable than oxygen. Its permselectivities were high as 23.9 for ${\alpha}(H_2/N_2)$. The permselectivity was increased with increasing the cross-linking density. For example, ${\alpha}(H_2/N_2)$ was 36.8 in poly(II-5 $10/I-OCH_3$ 90), which was shown to be the highest value among these poly(allylsulfone) networks.

• Analytical Science and Technology
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• v.12 no.2
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• pp.125-129
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• 1999

Portable-type two electrode system for the determination of highly concentrated hydrogen peroxide (10-75%) has been studied. The electrode body was made with teflon rod (length=10 cm, diameter=1.5 cm) to withstand the highly corrosive power of hydrogen peroxide. Glass carbon rod (diameter=3 mm) was used as the working electrode and a carbon cylinder (i.d.=5 mm; o.d.=9 mm) was used as counter electrode. The applied voltage for the determination of $H_2O_2$ was 0.8 V. Diluting the highly concentrated samples taken from the industrial batch to 10% or less, it was possible to make quantitative determinations, while eliminating the interference from the stabilizer contained in the sample and preventing the surface of the electrode from oxidative corrosion. Employing hydrogen peroxide permeable membrane (teflon membrane${\leq}100{\mu}m$) for the electrode system, it was possible to measure the content of $H_2O_2$ in highly concentrated samples directly, quantitatively and reproducibly with no extra dilution step. However, it was necessary to change the internal electrolyte frequently to maintain the analytical performance of the electrode.

• Membrane Journal
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• v.17 no.2
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• pp.81-92
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• 2007

Membrane-based separation processes are receiving increasing attention in the scientific community and industry since they provide a desirable alternative to processes that are not easy to achieve by conventional separation technologies. In particular, gas separation using polymeric membranes have annually grown so fast owing to advantages such as easy installation, no moving parts, small footprint and low energy process. The key element is definitely a polymer membrane exhibiting high permeability and high selectivity to compete with other gas separation technologies. Current polymer membranes used for commercial gas separation are a family of hydrocarbon polymers for hydrogen separation, air separation and carbon dioxide separation from natural gas sweetening. Relatively, gas or vapor separation properties of fluoropolymers are not known so much as compared with those of hydrocarbon polymers. Accordingly, in this study, membranes prepared from amorphous perfluoropolymers are of particular interest because of the unique properties of these polymers. The advantages offered by these amorphous perfluoropolymers for use in gas and vapor separation will be discussed. In addition, membrane properties and separation performance will be compared with other membranes available on the market.

• Journal of Hydrogen and New Energy
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• v.22 no.2
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• pp.161-167
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• 2011

Proton conductors have attracted considerable attention for solid oxide fuel cell (SOFC), hydrogen pump, gas sensor, and membrane separators. Doped $SrCeO_3$ exhibits appreciable proton conductivity in hydrogen-containing atmosphere at high temperature. However commercial realization has been hampered due to the reactivity of $SrCeO_3$ with $CO_2$. The chemical stability and proton conductivity are dependent on dopant type. The purpose of this work is to investigate chemical stability of $SrCe_{0.95}Gd_{0.05}O_{3-\alpha}-Ce_{0.9}Gd_{0.1}O_{2-\beta}$ composites in $CO_2$ and $H_2$ gases. Thermogravimetric analysis (TGA) was performed in gaseous $CO_2$ and electrical conductivity of the composites were also measured between 500 and $900^{\circ}C$ in air and $H_2$ atmosphere. $SrCe_{0.95}Gd_{0.05}O_{3-\alpha}-Ce_{0.9}Gd_{0.1}O_{2-\beta}$ composite membranes showed good chemical stability of in $CO_2$ atmosphere and high conductivity at hydrogen condition. The hydrogen permeation of $SrCe_{0.95}Gd_{0.05}O_{3-\alpha}-Ce_{0.9}Gd_{0.1}O_{2-\beta}$ composite membranes was investigated as a function of volumetric content of $SrCe_{0.95}Gd_{0.05}O_{3-\alpha}$. The $SrCe_{0.95}Gd_{0.05}O_{3-\alpha}-Ce_{0.9}Gd_{0.1}O_{2-\beta}$(6:4) membrane with a thickness of 1.0 mm showed the highest hydrogen permeability with the flux reaching of 0.12 $ml/min{\cdot}cm^2$ at $800^{\circ}C$ in 100%$H_2/N_2$ as feed gas.

• Journal of the Korean Vacuum Society
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• v.19 no.4
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• pp.275-280
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• 2010

The influence of $O_2$-plasma treatment on $H_2$ post-treated BZO (ZnO:B) thin film using MOCVD (Metal-Organic Chemical Vapor Deposition) are investigated. An $O_2$-plasma treatment of the $H_2$ post-treated BZO thin films resulted in XRD peak of (100), (101) and (110). Also, electrical properties resulted in an increase in sheet resistance and work function. The weighted optical transmittance and haze at 300~1,100 nm of BZO thin films with $O_2$-plasma treatment on the $H_2$ post-treatment show approximately 86% and 15%, respectively.

• Membrane Journal
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• v.32 no.6
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• pp.486-495
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• 2022

This study presents the improved recovery efficiency of rare metal ions through the modified separation membrane wettability and hydrogen ion permeation in the anion exchange membrane (AEM) under the recovery process of combined electrodialysis and solvent extraction. Specifically, the wettability of the separator was enhanced by hydrophilic modification on one separator surface through polydopamine (PDA) and lipophilic modification on the other surface through SiO₂ or graphene oxide (GO). In addition, the modified surface of AEM with polyethyleneimine (PEI), PDA, poly(vinylidene fluoride) (PVDF), etc. reduces the water uptake and modify the pore structure for proton ions generation. The suppressed transport resulted in the reduced hydrogen ion permeation. In the characterization, the surface morphology, chemical properties and composition of membrane or AEM were analyzed with Scanning Electron Microscopy (SEM) and Fourier Transform-Infrared Spectroscopy (FT-IR). Based on the analyses, improved extraction and stripping and hydrogen ion transport inhibition were demonstrated for the copper ion recovery system.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.42.1-42.1
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• 2011

박막형 디스플레이구서에 있어서 투명전극은 필수적이다. 투명전극은 정보를 표시하기 위해 빛을 외부로 방출시키거나 태양광 등을 소자 내부로 입사시켜야 한다. 또한 전극을 형성하는 박막은 높은 광투과율과 ${\sim}10-4{\Omega}cm$ 정도의 낮은 전기비저항을 가져야 한다. 가장 널리 사용되는 투명전극으로 ITO (Indium Tin Oxide)는 인듐의 독성, 저온증착의 어려움, 스퍼터링시 음이온 충격에 의한 막 손상으로 저항의 증가 및 액정디스플레이의 투명전극으로 사용될 경우 $400^{\circ}C$정도의 높은 온도와 수소플라즈마 분위기에서 장시간 노출시 열화로 인한 광학적 특성변화가 문제로 지적된다. 이러한 문제 해결의 대안으로 ZnO 산화물 반도체가 있는데 ITO 박막에 비해 비저항이 높기 때문에 도핑을 이용한 비저항을 ${\sim}10-4{\Omega}cm$ 정도로 낮추어야 한다. 투명전도막으로는 ITO, FTO 등과 더블어 체적 저항율은 다소 높으나 환원성 분위기에 대한 내성, 가시광 영역에서의 높은 광투과율과 저렴한 가격 등의 장점 등으로 AZO 박막이 주목 받고 있다. ZnO는 ITO 나 FTO에 비해서 700 kJ/mol의 큰 분해에너지를 가지므로 코팅 때 발생하는 전도도 및 투과율이 나빠지는 현상이 발생하지 않는 특징이 있으며, 위의 두 재료에 비해 밴드갭도 가장 낮아서 자외선 투과율이 낮다. 그러나 내습성이 약하기 때문에 이를 보완하기 위하여 내습성향상과 전도성 향상을 위해서 3족 원소인 B, In, Al, Ga 등을 도핑한 ZnO 투명전도막의 연구가 진행되고 있다. 이러한 원소들 중에서 Al로 도핑했을 때 가장 낮은 비저항을 얻을 수 있다고 알려져 있다. 본 연구에서는 SiOC 박막위에 AZO 박막을 제조하기 위하여 RF 마그네트론 스퍼터링법을 이용하여 박막을 성장시켰으며, 박막의 전기적 및 광학적 특성을 조사하였다. AZO 박막은 rf power가 5~200 W인 RF 마그네트론 스퍼터 방법에 의해서 제작되었다. SiOC 박막은 산소와 DMDMOS 전구체의 유량비를 다르게 하여 플라즈마 발생 화학적 기상 증착방법으로 증착되었다. 증착된 SiOC박막은 UV visible spectroscopy에 의해서 분석하였다. 투명전극의 비저항은 rf 전력이 작을 수록 낮았으며, SiOC 절연막 위에 AZO를 증착시킨 후 반사률은 반대로 바뀌는 것을 확인하였다.

• Journal of the Korean Chemical Society
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• v.34 no.4
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• pp.377-383
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• 1990

Three kinds of hydrogel membranes were prepared by the copolymerization of 2-hydroxyethylmethacrylate (HEMA) with acrylamide, N, N-dimethylamide and methylmethacrylate in the presence of solvent and crosslinker respectively. The equilibrium water content, relative permeability and partition coefficient of the membranes for alcohol solutes were measured. It has been found that the permeation of organic solute occurs through the water-filled regions in the hydrogel membrane, and that the gpermeability coefficient of organic solute depends on the molecular size. But the permeability of organic solute was controlled by the interaction of solute-membrane at the low water content. By the partition data, it has been shown that the partition of solute is only controlled by hydrophobic interaction between solute and membrane. The diffusion coefficient data were interpreted on the basis of water-solute interaction. It has been found that the diffusion of organic solute is determined by the free volume of water in the membrane, and that hardly depends on polarity-polarizability and hydrogen bonding ability between water and solute.

• Membrane Journal
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• v.18 no.3
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• pp.226-233
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• 2008

PTMSP/PMMH dendrimer composite membranes were made by dispersing $0{\sim}20$ wt% (based on polymer content) PMMH dendrimer nanoparticles in the PTMSP casting solution. The effect of PMMH dendrimer on gas permeability characteristics of the composite membranes was investigated. The permeabilities of $H_2,\;N_2,\;CO_2$, and $CH_4$ decreased as the PMMH dendrimer content within PTMSP increased. The permeabilities of different gases except hydrogen in PTMSP/PMMH dendrimer membranes follow the order: $N_2\;<\;CH_4\;<\;CO_2$ which are consistent with the order of critical temperature ($N_2\;<\;CH_4\;<\;CO_2$). The selectivities of gases for $N_2$ increased as the PMMH dendrimer content within PTMSP increased. The $CO_2/N_2$ selectivity increased from 5.6 up to 16.9.