• 제목/요약/키워드: Hydrogen selectivity

검색결과 263건 처리시간 0.025초

우주탐사용 직접 수소화붕소나트륨/과산화수소 연료전지의 환원극 촉매 (Cathode Catalyst of Direct Borohydride/Hydrogen Peroxide Fuel Cell for Space Exploration)

  • 유수상;오택현
    • 한국수소및신에너지학회논문집
    • /
    • 제31권5호
    • /
    • pp.444-452
    • /
    • 2020
  • This study investigated the cathode catalyst of direct borohydride/hydrogen peroxide fuel cells for space exploration. Various catalysts such as Au, Ag, and Ni were supported on multiwalled carbon nanotubes (MWCNTs). Various techniques, such as transmission electron microscopy, Brunauer-Emmett-Teller method, scanning electron microscopy, and X-ray diffraction were conducted to investigate the characteristics of the catalysts. Fuel cell tests were performed to evaluate the performance of the catalysts. Ag/MWCNTs exhibited better catalytic activity than the Ni/MWCNTs and better catalytic selectivity of the Au/MWCNTs. Ag/MWCNTs presented good catalytic activity and selectivity even at an elevated operating temperature. The performance of Ag/MWCNTs was also stable for up to 60 minutes.

팔라듐 합금 수소 분리막의 전처리에 관한 연구 (A Study on the Surface Pre-treatment of Palladium Alloy Hydrogen Membrane)

  • 박동건;김형주;김효진;김동원
    • 한국표면공학회지
    • /
    • 제45권6호
    • /
    • pp.248-256
    • /
    • 2012
  • A Pd-based hydrogen membranes for hydrogen purification and separation need high hydrogen perm-selectivity. The surface roughness of the support is important to coat the pinholes free and thin-film membrane over it. Also, The pinholes drastically decreased the hydrogen perm-selectivity of the Pd-based composite membrane. In order to remove the pinholes, we introduced various surface pre-treatment such as alumina powder packing, nickel electro-plating and micro-polishing pre-treatment. Especially, the micro-polishing pretreatment was very effective in roughness leveling off the surface of the porous nickel support, and it almost completely plugged the pores. Fine Ni particles filled surface pinholes with could form open structure at the interface of Pd alloy coating and Ni support by their diffusion to the membrane and resintering. In this study, a $4{\mu}m$ surface pore-free Pd-Cu-Ni ternary alloy membrane on a porous nickel substrate was successfully prepared by micro-polishing, high temperature sputtering and Cu-reflow process. And $H_2$ permeation and $N_2$ leak tests showed that the Pd-Cu-Ni ternary alloy hydrogen membrane achieved both high permeability of $13.2ml{\cdot}cm^{-2}{\cdot}min^{-1}{\cdot}atm^{-1}$ permation flux and infinite selectivity.

Gas Permeation of Y2O3-SiC Composite Membrane

  • Song, Daheoi;Jung, Miewon
    • 한국세라믹학회지
    • /
    • 제52권4호
    • /
    • pp.234-236
    • /
    • 2015
  • $Y_2O_3$-SiC composite membrane was dip-coated using $Y_2O_3$ sol solution; this membrane was compared with a non- coated one. Each membrane was characterized by XRD, FE-SEM and BET techniques. Hydrogen and CO permeation were tested with self-manufactured Sievert's type equipment. $Y_2O_3$ coating was enhanced for the selectivity of the membrane ($H_2$ versus CO). The hydrogen permeation was measured at 1 bar with increasing temperatures. In case of the coated membrane, hydrogen permeation was found to be $1.24{\times}10^{-7}mol/m^2sPa$ with perm-selectivity of 4.26 at 323 K.

복합 TiN-Al2O3 합성과 수소투과도 특성 평가 (Composite TiN-Al2O3 Syntheses and Hydrogen Permeability Characteristics Evaluation)

  • 조경원;이영환;한정흠;유제선;홍태환
    • 한국수소및신에너지학회논문집
    • /
    • 제31권2호
    • /
    • pp.177-183
    • /
    • 2020
  • To utilize hydrogen energy, high-yield, high-purity hydrogen needs to be produced; therefore, hydrogen separation membrane studies are being conducted. The membrane reactor that fabricates hydrogen needs to have high hydrogen permeability, selective permeability, heatresistant and a stable mechanical membrane. Dense membranes of Pd and Pd alloys are usually used, but these have drawbacks associated with high cost and durability. Therefore, many researchers have studied replacing Pd and Pd alloys. Dense TiN membrane is highly selective and can separate high-purity hydrogen. The porous alumina has a high permeation rate but low selectivity; therefore, separating high-purity hydrogen is difficult. To overcome this drawback, the two materials are combined as composite reclamations to produce a separation membrane with a high penetration rate and high selectivity. Accordingly, TiN-alumina was manufactured using a high-energy ball mill. The TiN-alumina membrane was characterized by X-ray diffraction analysis, scanning electron microscopy, and energy dispersive spectroscopy. The hydrogen permeability of the TiN-alumina membrane was estimated by a Sievert-type hydrogen permeation membrane apparatus. Due to the change in the diffusion mechanism, the transmittance value was lower than that of the general TiN ceramic separator.

액상 슬러리 반응기에서 합성가스로부터 DME 직접 제조 (Direct Synthesis of Dimethyl Ether From Syngas in Slurry Phase Reactor)

  • 황갑진;김정민;이상호;박주식;김영호;김종원
    • 한국수소및신에너지학회논문집
    • /
    • 제15권2호
    • /
    • pp.119-128
    • /
    • 2004
  • DME(Dimethyl Ether) was directly produced from the synthesis gas using the slurry phase reactor. The catalyst for DME production prepared two types (A type; Cu:Zn:Al=57:33:10, B type; Cu:Zn:Al=40:45:15, molar ratio). It was evaluated for the effect of the reaction medium oil using the small size slurry phase reactor. DME production yield and the methanol selectivity decreased in the order: n-hexadecane oil> mineral oil> therminol oil. The long-term test of DME production was carried out using A and B type catalyst, and n-hexadecane oil and mineral oil, respectively. It was confirmed that the use of A type for the catalyst and n-hexadecane for the reaction medium oil was very useful for the viewpoint of the DME production form the synthesis gas.

Feasibility Study of Employing a Catalytic Membrane Reactor for a Pressurized CO2 and Purified H2 Production in a Water Gas Shift Reaction

  • Lim, Hankwon
    • 청정기술
    • /
    • 제20권4호
    • /
    • pp.425-432
    • /
    • 2014
  • 이 논문은 촉매막반응기(catalytic membrane reactor)에서의 중요한 두 요소인 수소선택도와 수소투과량 및 Ar sweep 유량과 압력이 수성가스전이반응의 성능에 미치는 영향에 대하여 1차원 반응기모델과 반응속도식에 근거한 연구결과를 나타내고 있다. 연소전 이산화탄소 포집의 한 방법으로서, 촉매막반응기를 사용하여 원통부분에서는 고압/고농도의 이산화탄소를 관부분에서는 고순도의 수소를 동시에 얻을 수 있는지에 대한 가능성을 검토하였다. 또한, 고농도의 이산화탄소와 고순도의 수소를 동시에 얻기 위해 필요한 수소투과량, 수소선택도, Ar sweep 유량 및 압력에 대한 지침을 나타내었다. 그 결과 $1{\times}10^{-8}molm^{-2}s^{-1}Pa^{-1}$의 수소투과량과 10000의 수소선택도를 가진 막을 장착한 촉매막반응기에서는 8 atm의 압력과 $6.7{\times}10^{-4}mols^{-1}$의 Ar sweep 유량의 조건하에서 약 90%의 농도를 가진 이산화탄소와 100%의 순도를 가진 수소가 동시에 얻어짐이 밝혀졌다.

Preparation and Permeation of La2Ce2O7 Membrane

  • Park, Jihye;Jung, Miewon
    • 한국세라믹학회지
    • /
    • 제52권4호
    • /
    • pp.269-272
    • /
    • 2015
  • $La_2Ce_2O_7$ and $CeO_2$ membranes were fabricated from the corresponding powders derived from sol-gel process with polyvinyl alcohol binder. These powders and membranes were characterized by XRD, BET, and FE-SEM analysis. Hydrogen and CO gas permeation experiments were performed using Sievert's type equipment. Both fluxes on these membranes were found to decrease with increase of the temperature. This phenomenon was followed by the surface and Knudsen diffusion mechanism. The hydrogen permeability of the $La_2Ce_2O_7$ membrane was found to be $7.27{\times}10^{-5}mol/m^2sPa$, with perm-selectivity of 7.24 at 303 K.

Effects of Metal-Organic Framework Membrane on Hydrogen Selectivity

  • Suh, Jun Min;Cho, Sung Hwan;Jang, Ho Won
    • 센서학회지
    • /
    • 제29권6호
    • /
    • pp.374-381
    • /
    • 2020
  • Hydrogen gas has attracted considerable attention as a promising candidate for future energy resources because of its eco-friendly characteristics; however, its highly combustible characteristics should be thoroughly examined to preclude potential disasters. In this regard, a highly sensitive method for the selective detection of H2 is extremely important. To achieve excellent H2 selectivity, the utilization of a metal-organic framework (MOF) membrane can physically screen interfering gas molecules by restricting the size of kinetic diameters that can penetrate its nanopores. This paper summarizes the various endeavors of researchers to utilize the MOF molecular sieving layer for the development of highly selective H2 sensors. Further, the review affords useful insights into the development of highly reliable H2 sensors.

구형 Ni과 나노 YSZ Powder를 이용하여 제조한 Ni/YSZ Core-shell의 SOFC 연료극 특성 (Characteristics of SOFC Anode of Ni/YSZ Core-shell Manufactured Using sSpherical Ni and Nano YSZ Powders)

  • 최병현;구자빈;설광희;지미정
    • 한국수소및신에너지학회논문집
    • /
    • 제28권1호
    • /
    • pp.40-46
    • /
    • 2017
  • We reviewed the electrical properties of SOFC anode manufactured using spherical Ni and nano YSZ powder. When core-shell is fabricated by using submicron Ni as core and nano-sized YSZ as shell for SOFC anode, the electrical conductivity of the $0.2{\mu}m$ Ni-YSZ core-shell was 3 times higher than that of $1.0{\mu}m$ NiO or $1.0{\mu}m$ Ni-YSZ. Hydrogen selectivity was similar at $800^{\circ}C$, but hydrogen selectivity and methane conversion rate under $750^{\circ}C$ was 10~25% higher, Power density was more than 2 times, ASR was about 1/3, when exposed to $H_2$ atmosphere at $750^{\circ}C$ for a long time, Ni particles did not have any growth or cut off conduction path.

Ni 촉매 상에서 Power to Gas (P2G) 기술의 CO2 메탄화 반응에 관한 연구 (A Study on the CO2 Methanation in Power to Gas (P2G) over Ni-Catalysts)

  • 염규인;서명원;백영순
    • 한국수소및신에너지학회논문집
    • /
    • 제30권1호
    • /
    • pp.14-20
    • /
    • 2019
  • The power to gas (P2G) is one of the energy storage technologies that can increase the storage period and storage capacity compared to the existing battery type. One of P2G technologies produces hydrogen by decomposing water from renewable energy (electricity) and the other produces $CH_4$ by reacting hydrogen with $CO_2$. The objective of this study is the reaction of $CO_2$ methanation which synthesized methane by reacting carbon dioxide and hydrogen. The effect of $CO_2$ conversion and $CH_4$ selectivity on reaction temperature, pressure, and methane contents over 40% Ni catalyst was mainly investigated throughout this study. As a result, the activity of this catalyst appeared to be the highest in $CH_4$ yield at around $400^{\circ}C$ and the selectivity of $CH_4$ increased with increasing reaction pressure. The methane content was not significantly influenced below 3% of all componets. As the space velocity increases from 10,000 to 30,000/hr, the $CO_2$ conversion rate tends to decrease.