• Title/Summary/Keyword: hydrogen separation

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The Effect of Cu Reflow on the Pd-Cu Alloy Membrane Formation for Hydrogen Separation (수소분리용 Pd-Cu 합금 분리막의 Cu Reflow 영향)

  • Mun, Jin-Uk;Kim, Dong-Won
    • Journal of the Korean institute of surface engineering
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    • v.39 no.6
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    • pp.255-262
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    • 2006
  • Pd-Cu alloy membrane for hydrogen separation was fabricated by sputtering and Cu reflow process. At first, the Pd and Cu was continuously deposited by sputtering method on oxidized Si support, the Cu reflow process was followed. Microstructure of the surface and permeability of the membrane was investigated depending on various reflow temperature, time, Pd/cu composition and supports. With respect to our result, Pd-Cu thin film (90 wt.% Pd/10 wt.% Cu) deposited by sputtering process with thickness of $2{\mu}m$ was heat-treated for Cu reflow The voids of the membrane surface were completely filled and the dense crystal surface was formed by Cu reflow behavior at $700^{\circ}C$ for 1 hour. Cu reflow process, which is adopted for our work, could be applied to fabrication of dense Pd-alloy membrane for hydrogen separation regardless of supports. Ceramic or metal support could be easily used for the membrane fabricated by reflow process. The Cu reflow process must result in void-free surface and dense crystalline of Pd-alloy membrane, which is responsible for improved selectivity oi the membrane.

Hydrogen Isotope Separation by using Zeolitic lmidazolate Frameworks (ZIF-11) (ZIF-11을 이용한 수소 동위원소 분리)

  • Lee, Seulji;Oh, Hyunchul
    • Korean Journal of Materials Research
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    • v.30 no.12
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    • pp.655-659
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    • 2020
  • Hydrogen isotopes (i.e. deuterium and tritium) are supplied to the tokamak in the International Thermonuclear Experimental Reactor (ITER) fuel cycle. One important part of the ITER fuel cycle is the recycling of unused fuel back to the tokamak, as almost 99 % of fuel is unburned during fusion reaction. For this, cryogenic distillation has been used in the isotope separation system (ISS) of ITER, but this technique tends to be energy-intensive and to have low selectivity (typically below 1.5 at 24 K). Recently, efficient isotope separation by porous materials has been reported in the so-called quantum sieving process. Hence, in this study, hydrogen isotope adsorption behavior is studied using chemically stable ZIF-11. At low temperature (40 K ~ 70 K), the adsorption increases and the sorption hysteresis becomes stronger as the temperature increases to 70K. Molar ratio of deuterium to hydrogen based on the isotherms shows the highest (max. 14) ratio at 50 K, confirming the possibility of use as a potential isotope separation material.

Theoretical Study for Hydrogen Production from an Integrated Gasification Combined Cycle System

  • Lee, Sang-Sup
    • Environmental Engineering Research
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    • v.16 no.1
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    • pp.35-39
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    • 2011
  • An integrated gasification combined cycle (IGCC) system has been attracting attention due to its increased energy conversion efficiency and ability to treat various carbonaceous materials. IGCC is also expected to play an important role in the future supply of hydrogen energy. The use of a palladium-based membrane to separate the hydrogen from the synthesis gas stream has been intensively studied due to its exceptional hydrogen-separating capability. However, theoretical research on hydrogen separation is still an unfamiliar area in Korea. First-principle density functional theory was applied in this study to investigate the dissociative adsorption of hydrogen onto a palladium surface. The stability of hydrogen on the surface was theoretically evaluated with various adsorption configurations, partial pressures and temperatures. Further theoretical and experimental studies were also suggested to find a more hydrogen-selective material.

Comparison of Pervaporation and Vapor Permeation Separation Processes for MTBE-methanol System

  • Kim, Youn-Kook;Lee, Keun-Bok;Rhim, Ji-Won
    • Korean Membrane Journal
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    • v.2 no.1
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    • pp.36-47
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    • 2000
  • This paper deals with the separation of MTBE-methanol mixtures using crosslinked Poly(vinyl alcohol)(PVA) membranes with sulfur-succinic acid(SSA) as a crosslinking agent by pervaporation and vapor permeation technique. The operating temperatures, methanol concentration in feed mixtures, and SSA concentrations in PVA membranes were varied to investigate the separation performance of PVA/SSA membranes and the optimum separation characteristics by pervaporation and vapor permeation. And also, for PVA/SSA membranes, the swelling measurements were carried out to study the transport phenomena. The swelling measurements were carried out for pure MTBE and methanol, and MTBE/methanol=90/10, 80/20 mixtures using PVA/SSA membranes with varying SSA compositions. There are two factors of the membrane network and the hydrogen bonding. In pervaporation separation was also carried out for MTBE/methanol=90/10, 80/20 mixtures at various temperatures. The sulfuric acid group in SSA took an important role in the membrane performance. The crosslinking effect might be over the hydrogen bonding effect due to the sulfuric acid group at 3 and 5% SSA membranes, and this two factors act vice versa on 7% SSA membrane. In this case, the 5% SSA membrane shows the highest separation factor of 2,095 with the flux of 12.79g/㎡$.$hr for MTBE/methanol=80/20 mixtures at 30$^{\circ}C$ which this mixtures show near the azeotopic composition. Compared to pervaporation, vapor permeation showed less flux and similar separation factor. In this case, the flux decreased significantly because of compact structure and the effect of hydrogen bonding. In vapor permeation, density or concentration of methanol in vaporous feed is lower than that of methanol in liquid feed, as a result, the hydrogen bonding portion between the solvent and the hydroxyl group in PVA is reduced in vapor permeation. In this case, the 7% SSA membranes shows the highest separation factor of 2,187 with the flux of 4.84g/㎡$.$hr for MTBE/methanol=80/20 mixtures at 30$^{\circ}C$.

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Comparison of Pervaporation and Vapor Permeation Separation Processes for MTBE-methanol System

  • 김연국;이근복;임지원
    • Membrane Journal
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    • v.2 no.1
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    • pp.36-36
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    • 1992
  • This paper deals with the separation of MTBE-methanol mixtures using crosslinked Poly(vinyl alcohol)(PVA) membranes with sulfur-succinic acid(SSA) as a crosslinking agent by pervaporation and vapor permeation technique. The operating temperatures, methanol concentration in feed mixtures, and SSA concentrations in PVA membranes were varied to investigate the separation performance of PVA/SSA membranes and the optimum separation characteristics by pervaporation and vapor permeation. And also, for PVA/SSA membranes, the swelling measurements were carried out to study the transport phenomena. The swelling measurements were carried out for pure MTBE and methanol, and MTBE/methanol=90/10, 80/20 mixtures using PVA/SSA membranes with varying SSA compositions. There are two factors of the membrane network and the hydrogen bonding. In pervaporation separation was also carried out for MTBE/methanol=90/10, 80/20 mixtures at various temperatures. The sulfuric acid group in SSA took an important role in the membrane performance. The crosslinking effect might be over the hydrogen bonding effect due to the sulfuric acid group at 3 and 5% SSA membranes, and this two factors act vice versa on 7% SSA membrane. In this case, the 5% SSA membrane shows the highest separation factor of 2,095 with the flux of 12.79g/㎡·hr for MTBE/methanol=80/20 mixtures at 30℃ which this mixtures show near the azeotopic composition. Compared to pervaporation, vapor permeation showed less flux and similar separation factor. In this case, the flux decreased significantly because of compact structure and the effect of hydrogen bonding. In vapor permeation, density or concentration of methanol in vaporous feed is lower than that of methanol in liquid feed, as a result, the hydrogen bonding portion between the solvent and the hydroxyl group in PVA is reduced in vapor permeation. In this case, the 7% SSA membranes shows the highest separation factor of 2,187 with the flux of 4.84g/㎡·hr for MTBE/methanol=80/20 mixtures at 30℃.

Effect of Surface Modification of the Porous Stainless Steel Support on Hydrogen Perm-selectivity of the Pd-Ag Alloy Hydrogen Separation Membranes (다공성 스테인리스 강 지지체의 표면개질에 따른 팔라듐-은 합금 수소 분리막의 수소 투과 선택도의 변화)

  • Kim, Nak-Cheon;Kim, Se-Hong;Lee, Jin-Beum;Kim, Hyun-Hee;Yang, Ji-Hye;Kim, Dong-Won
    • Journal of the Korean institute of surface engineering
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    • v.49 no.3
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    • pp.286-300
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    • 2016
  • Pd-Ag alloy membranes have attracted a great deal of attention for their use in hydrogen purification and separation due to their high theoretical permeability, infinite selectivity and chemical compatibility with hydro-carbon containing gas streams. For commercial application, Pd-based membranes for hydrogen purification and separation need not only a high perm-selectivity but also a stable long-term durability. However, it has been difficult to fabricate thin, dense Pd-Ag alloy membranes on a porous stainless steel metal support with surface pores free and a stable diffusion barrier for preventing metallic diffusion from the porous stainless steel support. In this study, thin Pd-Ag alloy membranes were prepared by advanced Pd/Ag/Pd/Ag/Pd multi-layer sputter deposition on the modified porous stainless steel support using rough polishing/$ZrO_2$ powder filling and micro-polishing surface treatment, and following Ag up-filling heat treatment. Because the modified Pd-Ag alloy membranes using rough polishing/$ZrO_2$ powder filling method demonstrate high hydrogen permeability as well as diffusion barrier efficiency, it leads to the performance improvement in hydrogen perm-selectivity. Our membranes, therefore, are expected to be applicable to industrial fields for hydrogen purification and separation owing to enhanced functionality, durability and metal support/Pd alloy film integration.

Hydrogen Separation from Multi-Component Mixture Gases by Pressure Swing Adsorption Process (PSA 공정을 이용한 다성분 혼합가스의 수소 분리)

  • Yang, Se-Il;Ahn, Eui-Sub;Jang, Seong-Cheol;Choi, Do-Young;Choi, Dae-Ki
    • 한국신재생에너지학회:학술대회논문집
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    • 2006.11a
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    • pp.447-450
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    • 2006
  • Hydrogen separation from multi-component mixture gases by the four-bed PSA process was studied experimentally and theoretically using layered bed of activated carbon and zeolited 5A. Effects of the adsorption time, the linear velocity on the process performance were investigated. The adsorption time and linear velocity affected the purity and recovery of the product $H_2$ purity is increases according as the adsorption time and linear velocity decrease; however, $H_2$ recovery shows an opposite phenomena to the purity. PSA process simulation studied to find optimum operation condition. In the results, 50sec adsorption time, 3cm/s linear velocity might be optimal values to obtain more than 99.999% purity and 65% recovery hydrogen.

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Phase Separation Characteristics of Low Temperature Bunsen Reactions In Sulfur-Iodine Hydrogen Production Process (황-요오드 수소 제조 공정에서 저온 분젠 반응의 상 분리 특성)

  • Han, Sang-Jin;Lee, Kwang-Jin;Kim, Hyo-Sub;Kim, Young-Ho;Park, Chu-Sik;Bae, Ki-Kwang;Lee, Jong-Gyu
    • Journal of Hydrogen and New Energy
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    • v.22 no.4
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    • pp.424-431
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    • 2011
  • The Sulfur-Iodine(SI) thermochemical hydrogen production process consists of three sections, which are so called the Bunsen reaction section, the $H_2SO_4$ decomposition section and the HI decomposition section. In order to identify the phase separation characteristics in the reaction conditions with the high solubility of $SO_2$, we conducted the Bunsen reaction at the low temperatures, ranging from 283 to 298K, with the $I_2/H_2O$ molar ratios of 2.5/16.0 and 3.5/16.0. The molar ratios of HI/$H_2SO_4$ products obtained from low temperature Bunsen reactions were ca. 2, indicating that there were no side reactions. The amount of reacted $SO_2$ was increased with decreasing the temperature, while the amounts of unreacted $I_2$ and $H_2O$ were decreased. In the phase separation of the products, the amount of a $H_2SO_4$ impurity in $HI_x$ phase was increased with decreasing the temperature, though the temperature has little affected on HI and $I_2$ impurities in $H_2SO_4$ phase.

Fabrication and Hydrogen Permeation Properties of $V_{99.8}B_{0.2}$ Alloy Membrane for Hydrogen Separation (수소 분리를 위한 $V_{99.8}B_{0.2}$ 분리막의 제조와 수소투과특성)

  • Jung, Yeong-Min;Jeon, Sung-Il;Park, Jung-Hoon
    • Membrane Journal
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    • v.21 no.4
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    • pp.345-350
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    • 2011
  • No investigation has yet been accomplished to screen the boron-doped effects on vanadium based metal membranes. The synthesis, hydrogen permeation properties and chemical stability of a novel Pd-coated $V_{99.8}B_{0.2}$ alloy membrane are presented in this report. Hydrogen permeation experiments have been performed to investigate the hydrogen transport properties through the Pd-coated $V_{99.8}B_{0.2}$ alloy membrane in the absolute pressure range 1.0~3.0 bar under pure hydrogen, hydrogen-carbon dioxide gas mixture at $400^{\circ}C$. The maximum hydrogen permeation flux was $48.5mL/min/cm^2$ for a 0.5 mm thick membrane under pure hydrogen. This results offer new direction in the synthesis of novel non-Palladium-based metal membranes for hydrogen separation in water-gas shift reaction.

Study on Pressurized Diesel Reforming System for Polymer Electrolyte Membrane Fuel Cell in Underwater Environment (수중 환경에서 고분자 전해질 연료전지(PEMFC) 공급용 수소 생산을 위한 가압 디젤 개질시스템에 관한 연구)

  • Lee, Kwangho;Han, Gwangwoo;Bae, Joongmyeon
    • Journal of the Korea Institute of Military Science and Technology
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    • v.20 no.4
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    • pp.528-535
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    • 2017
  • Fuel cells have been spotlighted in the world for being highly efficient and environmentally friendly. A hydrogen which is the fuel of fuel cell can be obtained from a number of sources. Hydrogen source for operating the polymer electrolyte membrane fuel cell(PEMFC) in the current underwater environment, such as a submarine and unmanned underwater vehicles are currently from the metal hydride cylinder. However, metal hydride has many limitations for using hydrogen carrier, such as large volume, long charging time, limited storage capacity. To solve these problems, we suggest diesel reformer for hydrogen supply source. Diesel fuel has many advantages, such as high hydrogen storage density, easy to transport and also well-infra structure. However, conventional diesel reforming system for PEMFC requires a large volume and complex CO removal system for lowering the CO level to less than 10 ppm. In addition, because the preferential oxidation(PROX) reaction is the strong exothermic reaction, cooling load is required. By changing this PROX reactor to hydrogen separation membrane, the problem from PROX reactor can be solved. This is because hydrogen separation membranes are small and permeable to pure hydrogen. In this study, we conducted the pressurized diesel reforming and water-gas shift reaction experiment for the hydrogen separation membrane application. Then, the hydrogen permeation experiments were performed using a Pd alloy membrane for the reformate gas.