• Korean Membrane Journal
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• v.2 no.1
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• pp.48-55
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• 2000

In order to improve organic vapor separation efficiency of polydimethylsiloxane (PDMS) membrane, various zeolites (zeolite 4A, zeolite 13X and natural zeolite) were introduced into a thin PDMS film. The measurements of permeability and selectivity of zeolite-filled PDMS membranes were carried out with a CO$_2$gas and a CO$_2$gas/acetic acid vapor mixture, respectively. The CO$_2$permeability of zeolite-filled membranes decreased with increasing zeolite content and then recovered up to 30 wt% content. The effect of zeolite type on the improvement of CO$_2$permeability was found to be in the order of zeolite 13X > natural zeolite > 4A. The CO$_2$selectivity of zeolite-filled membranes was enhanced up to 9 times compared with the selectivity of a pure (unfilled) PDMS membrane. The effect of zeolite type on the improvement of CO$_2$selectivity was found to be in the order of natural zeolite > zeolite 13X > zeolite 4A.

• Journal of Environmental Science International
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• v.9 no.4
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• pp.311-318
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• 2000

To improve $CO_2$pemselectivity, a modified silica membrane was prepared by chemical vapor deposition with tetraethoxysilane(TEOS)-ethanol-water, and TEOS-ethanol-water-HCI solution at 300-$600^{\circ}C$. The silica was effectively deposited in the mesopores of a ${\gamma}$-alumina film coated on a porous $\alpha$-alumina tube by evacuating the reactants through the porous wall. In this membrane, $CO_2$interacts, to some extent, with the pore wall, and $CO_2$/$N_2$selectivity then exceeds the value of the Knudsen diffusion mechanism, while the membrane derived from TEOS alone has no $CO_2$selectivity. The silica membrane prepared from TEOS-ethanol-water-HCI solution showed that $CO_2$permeance was $2.5$\times$10^{-7}mol/s^{-1}.m^{-2}.Pa^{-1} at 30{\circ}C$ and $CO_2$/$N_2$selectivity was approximately 3. The $CO_2$permeance and selectivity was improved by enlarging the surface diffusion with modification of chemical affinity of the silica pores.

• Membrane Journal
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• v.28 no.2
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• pp.105-112
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• 2018

In this study, PTMSP-GO composite membranes were prepared by the addition of GO (graphene oxide) into PTMSP [poly (1-trimethylsilyl-1-propyne)] having high gas permeability, to study of gaseous membrane using GO. Gas permeation properties for $N_2$, $CH_4$, $CO_2$ were investigated by increasing the amount of GO in the PTMSP. PTMSP-GO composite membranes had higher gas permeability in the order of $N_2$ < $CH_4$ < $CO_2$. The gas permeation tendency of $N_2$, $CH_4$, and $CO_2$ increased as the content of GO increased from 0 to 10 wt%, but the gas permeability decreased as increased from 10 to 30 wt%. In the range of low GO contents, the gas permeability decreased due to the decrease of diffusivity because GO acts as a barrier in the composite membrane, and the gas permeability increased due to the void at the interface above the content range. And $CO_2$ has an affinity with -COOH of GO, the selectivity ($CO_2/N_2$) and the selectivity ($CO_2/CH_4$) gradually increase with increasing GO content. And the selectivity($CO_2/N_2$) showed the highest selectivity at 10.6 for PTMSP-GO 10 wt% and the selectivity ($CO_2/CH_4$) showed the highest selectivity at 3.4 for PTMSP-GO 20 wt%. However, above a certain amount of GO, selectivity ($CO_2/N_2$) and selectivity ($CO_2/CH_4$) decreased because the coagulation phenomenon between GO was increased and the solubility effect of $CO_2$ decreased. The PTMSP-GO 20 wt% composite membrane exhibited enhanced gas permeation characteristics with increased $CO_2$ permeability and selectivity ($CO_2/CH_4$) over PTMSP membrane.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2010.04a
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• pp.199-199
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• 2010

Polymeric membranes have been widely used to separate gas mixtures, such as $O_2/N_2,\;CO_2/CH_4,\;CO_2/N_2$, and olefin/paraffin. The permeation selectivity is the ratio between composition ratio at the permeate side and composition ratio at the feed side. In addition, the permeation selectivity is a product of solubility selectivity and diffusivity selectivity. We present a novel idea and describe its experimental result, which was achieved by preparing polymer gel films that included a room temperature ionic liquid (RTIL) in a polymer matrix. It is known that $CO_2$ can dissolve easily in imidazolium-based RTILs. We prepared polymer-ionic liquid gel films using an ionic liquid, 1-ethyl-3-methylimidazolium acetate ([emim] acetate, C-tri) and a host polymer, poly (vinyl acetate) (PVAc, Aldrich).

• Membrane Journal
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• v.25 no.1
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• pp.27-31
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• 2015

PEBAX[poly(ether-block-amide)]-NaY zeolite composite membrane was studied on the permeability of penetrant $H_2$, $N_2$, $CO_2$ and $CH_4$ and the selectivity. When the NaY zeolite contents of PEBAX-NaY zeolite membranes were increased, the permeability of $H_2$ was increased, but the permeability of $N_2$, $CH_4$ and $CO_2$ was decreased. By the addition of NaY zeolite into PEBAX, the gas selectivity for $H_2$, $N_2$ and $CO_2$ was decreased except the increase of selectivity of $H_2/N_2$. $CO_2/N_2$, $H_2/CO_2$ and Gas/$CH_4$. The highest selectivity among these gases was from $CO_2$. In particular, the gas selectivity for $CO_2$ was the greatest with a value of 12~156.

• Journal of the Korean Chemical Society
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• v.55 no.5
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• pp.824-829
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• 2011

In Fischer-Tropsch Synthesis, because of few reactants ($H_2$, CO), scarce operating parameters affected on efficiency especially the selectivity of products. In this research, effect of operating parameters on the selectivity of Co-Mn-$TiO_2$ Fischer-Tropsch synthesis catalyst were studied by design of experimental procedure and Taguchi method. According to this research, interactions between operating factors have a crucial effect on light products selectivity. Among these interactions, (temperature${\times}$feed ratio) has the main influence on light hydrocarbons selectivity. It was concluded that temperature and feed ratio ($H_2$/CO) were the most integral operating parameters for much greater selectivity of light hydrocarbons.

• Membrane Journal
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• v.28 no.4
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• pp.233-242
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• 2018

To study gas membrane using GO (graphene oxide), the PEBAX [poly(ether-block-amide)]-GO polymer composite membrane was prepared by adding GO to PEBAX. Through this composite membrane, gas permeation characteristics for $H_2$, $N_2$, $CH_4$, and $CO_2$ were studied. As a result of the gas permeation test, the permeability of $N_2$, $CH_4$, and $CO_2$ to PEBAX-GO composite membranes gradually decreased as the GO content increased. On the other hand, the gas permeability of $H_2$ increased with the increase of GO content, and it was 21.43 barrer at the GO content of 30 wt%, which was about 5 times higher than that of PEBAX membrane. This is because the GO was easier to operate with a fast and selective gas transport channel for $H_2$ than other gases. The increased selectivity ($H_2/N_2$) and selectivity ($H_2/CH_4$) were influenced by the diffusion selectivity by the permeate gas size. The increased selectivity ($CO_2/N_2$) and selectivity ($CO_2/CH_4$) were more influenced by the solubility selectivity due to the affinity of $CO_2$ and GO for -COOH.

• Korean Membrane Journal
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• v.5 no.1
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• pp.43-53
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• 2003

The selectivity of a gas in the carbon molecular sieve membrane (CMSM) can be expressed as the ratio of the product of the diffusivity and the solubility of two different gases. The diffusivity is also expressed as the product of the entropy and the total energy (kinetic and potential energy) in the nano-sized pore of the membrane. The present study calculates the entropic-energy and selectivity of penetrant gases such as H$_2$, O$_2$, N$_2$, and CO$_2$ from the gas-in-a box theory to physically analyze the diffusivity of penetrant gas in slit-shaped pore of CMSM focusing on the restriction of gas motion based on the size difference between penetrant gas pairs. The contribution of each energy term is converted to entropic term separately. By the conjugated calculation for each entropic-energy, the entropic effects on diffusivity-selectivity for gas pairs such as H$_2$/N$_2$, CO$_2$/N$_2$, and O$_2$/N$_2$ were analyzed within active pore of CMSM. In the activated diffusion domain, the calculated value of entropic-selectivity lies between 9.25 and 111.6 for H$_2$/N$_2$, between 3.36 and 6.0 for CO$_2$/N$_2$, and between 1.25 and 16.94 for O$_2$/N$_2$, respectively. The size decrement of active pore in CMSM had the direct effect on the reduction of translational entropic-energy and the contribution of vibrational entropic-energy for N$_2$, O$_2$, and H$_2$ was almost negligible. However, the vibrational entropic term of CO$_2$ might extravagantly affect on the entropic-selectivity.

• Bulletin of the Korean Chemical Society
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• v.18 no.8
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• pp.827-831
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• 1997

A novel ONNO-type tetradentate ligand, 1,3-diaminopropane-N,N'-di-α-(β-methyl)-pentanoic acid (H2apmp) and its cobalt(Ⅲ) complexes, [Co(apmp)X2]n+, (X=Cl-, NO2-, H2O, X2=CO32-, en, L-phenylalanine) have been synthesized. During the preparation of the dichloro cobalt(Ⅲ) complex of apmp, [Co(apmp)Cl2]-, the ligand has coordinated to the cobalt(Ⅲ) ion in a geometric selectivity to give only the uns-cis isomer and, during the substitution reaction between L-phenylalanine and [Co(apmp)Cl2]-, the L-phenylalanine has coordinated to the cobalt(Ⅲ) ion in a geometric selectivity to give only an uns-cis-meridional isomer. It is of interest that this is a rare case of the [Co(ONNO ligand)X2]n+-type complex preparations, which gives only an uns-cis isomer with geometric selectivity.

• Applied Chemistry for Engineering
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• v.29 no.1
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• pp.67-76
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• 2018

In this study, PDMS-HNT and PDMS-mHNT composite membranes were prepared by the addition of halloysite nanotube (HNT) and modified HNT (mHNT) to PDMS. To investigate the physico-chemical characteristics of composite membranes, analytical methods such as FT-IR, XRD, TGA, and SEM were utilized. The gas permeability and selectivity properties of $N_2$ and $CO_2$ were evaluated. In particular, the PDMS-HNT with 10 wt% HNT and PDMS-mHNT with 5 wt% mHNT showed the highest $CO_2/N_2$ selectivity and $CO_2$ permeability at $35^{\circ}C$, respectively. Overall, PDMS-HNT and PDMS-mHNT composite membranes improved the $CO_2/N_2$ selectivity compared to that of using PDMS membrane.