• Title/Summary/Keyword: Molecular sieve carbon

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Study on the Properties of Molecular Sieve Made from Carbonized Material with Modifiers (변형제를 이용한 탄화 시료의 분자체 특성 효과에 관한 연구)

  • Kim, Kweon-Ill;Kim, Tae-Hwan;Park, Jong-Gi;Cho, Sung-Chul;Jin, Myeng-Jong
    • Applied Chemistry for Engineering
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    • v.7 no.2
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    • pp.334-340
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    • 1996
  • Carbon adsorbents, having the properties of molecular sieve, were prepared based on coat materials. A couple of modifiers were used to prepare carbon molecular sieve. The effects of modifier concentrations on the characteristics of carbon molecular sieve were investigated. In order to verify the characteristics of carbon molecular sieve, the adsorption rates of oxygen and nitrogen gases on the carbon molecular sieve were measured using Cahn microbalance(model # : D-200). The experimental data were fitted to an adsorption rate equation and gas diffusivities were calculated. The effects of modifier molecular weight and concentration on the characteristics of carbon molecular sieve were shown.

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Studies on Molecular Sieve Characteristics of Activated Carbon Fibers for Selective Gas Separation (선택적 가스분리를 위한 활성탄소섬유의 분자체 특성 연구)

  • 박병배;김도수;박영성
    • Journal of the Korean Ceramic Society
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    • v.38 no.1
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    • pp.1-8
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    • 2001
  • 선택적 가스분리를 위한 분자체탄소(Molecular Sieve Carbon: MSC)로서의 활용을 위해 제조된 활성탄소섬유의 흡착능과 분자체 특성이 다양한 분자크기를 갖는 가스 흡착실험을 통해 조사되었다. 각 활성화 조건별 세공크기분포와 세공발달 전개과정을 유추함으로서, 세공크기분포의 조절이 가능하게 되었으며 활성탄소섬유의 분자체 탄소로서 활용을 용이하게 할 수 있었다. 800, 85$0^{\circ}C$의 온도로 수증기에 의해 활성화한 활성탄소섬유의 경우 burn-off가 각각 50, 40% 정도를 가진 활성탄소섬유가 비교적 작은 분자크기(0.3~0.4nm)의 흡착질에 대한 분자체 특성을 나타냈다. 또한, 다양한 분자크기의 흡착질을 포함하는 혼합가스의 유속과 흡착온도의 조절로서 원하는 흡착질의 선택적 분리를 위해 활성탄소섬유가 갖는 분자체 특성 향상을 보였다.

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Characterization of Carbon Molecular Sieve for Separating CH4 Gas (메탄가스 분리용 탄소분자체 특성 연구)

  • Lee Byum-Suk;Kim Taik-Nam;Kim Yun-Jong
    • Korean Journal of Materials Research
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    • v.14 no.2
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    • pp.157-162
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    • 2004
  • The object of this research is to develop a carbon molecular sieve(below CMS) which can separate selectively to convert mixture gases spout at waste landfill into fuel. And this research is meaningful from the viewpoint of a quality improvement of CH$_4$ gas and an utilization of by-product. CMS was prepared using coconut shell powder as starting material and the effects of activators, temperature and modifier on the reaction were investigated in this research. Also, pore diameter, surface area of CMS and adsorption rate were measured and studied by cahn balance and ASAP2010. Its specific surface area and pore distribution were controlled easily at 800^{\circ}C and adsorption rate was very good. The CMS prepared in this research is shown to be able to separate landfill gases very effectively.

Carbon Molecular Sieve Membranes Dispersed with Nano Particles

  • H.Suda;Ha, K.raya
    • Proceedings of the Membrane Society of Korea Conference
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    • 2004.05a
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    • pp.183-186
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    • 2004
  • Nano particles-containing CMS membranes were prepared by pyrolysis of polyimides dispersed uniformly with precursors and their gas separation performances were examined, to elucidate the permeation mechanism and to further improve the gas separation performance. Consequently, it was suggested that the separation performance could be controlled by doping nano-particles in the CMS membranes, and that optimization of various factors, such as the size, content, and dispersion state of the nano particles would contribute for further improvement of the gas separation performance.

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Preparation, Characterization, and Gas Permeation Properties of Carbon Molecular Sieve Membranes Derived from Dense P84-Polyimide Film

  • Park, Ho-Bum;Nam, Sang-Yong;Jang, Jeong-Gyu;Lee, Young-Moo
    • Korean Membrane Journal
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    • v.4 no.1
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    • pp.25-35
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    • 2002
  • The gas permeation properties have been studied on carbon molecular sieve (CMS) membranes prepared by pyrolysis of P84 polyimide under various conditions. P84 polyimide shows high permselectivities (O$_2$/N$_2$= 9.17 and CO$_2$/N$_2$= 35) for various gas pairs and has a good processibility because it is easily soluble in high polar solvents such as N-methylpyrrolidinone (NMP), dimethylformamide (DMF), and N,N-dimethylacetamide (DMAc). After pyrolysis under Ar flow, the change in the heating rate was found to affect the gas permeation properties to some extent. The permeabilities of the selected gases were shown to be in the order He > CO$_2$> O$_2$> N$_2$for all the CMS membranes, whose order was in accordance with the order of kinetic gas diameters. It also revealed that the pyrolysis temperature considerably influenced the gas permeation properties of the CMS membranes derived from P84 polyimide. The CMS membranes pyrolized at 700$\^{C}$ temperature exhibited the highest permeability with relatively targe loss in permselectivity. This means that the pyrolysis temperature should be varied in accordance with target gases to be separated.

Pyrolytic Carbon Membranes for Air Separations (공기 분리용 열분해 탄소막)

  • Singh, Anshu;Koros, W.J.
    • Membrane Journal
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    • v.7 no.1
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    • pp.15-21
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    • 1997
  • Carbon molecular sieve (CMS) membranes were synthesized by the pyrolysis of polymeric precursors. The CMS materials had oxygen-nitrogen selectivities much higher than those observed for the polymeric precursors. Typically molecular sieving materials have diffusion selectivities much higher than polymeric materials. This has been identified as a result of higher entropic selectivity of the molecular sieving materials. A study of the development of molecular sieving properties as the polymeric precursor is pyrolyzed into a CMS material will offer us an insight into polymeric molecular structures needed for enhanced entropic selectivity membrane materials.

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A New Gas-Chromatograghic Method of Organic Elemental Analysis (가스크로마토그래피에 依한 微量元素分析)

  • Kim, You-Sun;Son, Youn-Soo;Choi, Q.Won
    • Journal of the Korean Chemical Society
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    • v.8 no.4
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    • pp.188-191
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    • 1964
  • A new gas-chromatographic method for determining carbon and hydrogen in organic compounds has been developed. After sample combustion was performed in a regular analytical combustion tube with an internal oxidant (a mixture of silver oxide and manganese dioxide) under a helium flow, the water produced was converted to acetylene by passing through a calcium carbide tube. The carbon dioxide and acetylene were trapped by a molecular sieve 5A column at room temperature. The trapped gases were released under programmed temperature raise up to $340^{\circ}C$ and the released gases were passed through a silica gel column. The adsorption of $CO_2$ and $C_2H_2$ in the molecular sieve 5A trapping column were found to be quantitative and the silica gel column showed an excellent resolution of $CO_2$ and $C_2H_2$ for analytical purpose. The analytical results for various known compounds based on the out-put of the thermal conductivity cell calibrated for the amounts of carbon and hydrogen contents in benzoic acid, showed average errors ${\pm}0.5%$ and ${\pm}0.33%$ for carbon and hydrogen, respectively.

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Hierarchical 5A Zeolite-Containing Carbon Molecular Sieve Membranes for O2/N2 Separation (산소/질소 분리를 위한 다층구조 제올라이트 5A를 함유한 탄소분자체 분리막 제조)

  • Li, Wen;Chuah, Chong Yang;Bae, Tae-Hyun
    • Membrane Journal
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    • v.30 no.4
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    • pp.260-268
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    • 2020
  • Mixed-matrix carbon molecular sieve membranes containing conventional and hierarchically structured 5A were synthesized for application in oxygen (O2)/nitrogen (N2) separation. In general, incorporating 5A fillers into porous carbon matrices dramatically increased the permeability of the membrane with a marginal decrease in selectivity, resulting in very attractive O2/N2 separation performances. Hierarchical zeolite 5A, which contains both microporous and mesoporous domains, improved the separation performance further, indicating that the mesopores in the zeolite can serve as an additional path for rapid gas diffusion without sacrificing O2/N2 selectivity substantially. This facile strategy successfully and cost-effectively pushed the performance close to the Robeson upper bound. It produced high performance membranes based on Matrimid® 5218 polyimide and zeolite 5A, which are inexpensive commercial products.