• Journal of Environmental Science International
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• v.18 no.10
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• pp.1071-1077
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• 2009

A novel pretreatment technique was applied to the conventional Pt/alumina catalyst to prepare for the highly efficient catalyst for the preferential oxidation of carbon monoxide in hydrogen-rich condition. Their performance was investigated by selective CO oxidation reaction. CO conversion with the oxygen-treated Pt/Alumina catalyst increased remarkably especially at the low temperature below $100^{\circ}C$. This result is promising for the normal operation of the proton exchange membrane fuel cell (PEMFC) without CO poisoning of the anode catalyst. XRD analysis results showed that metallic Pt peaks were not observed for the oxygen-treated catalyst. This implies that well dispersed small Pt particles exist on the catalyst. This result was continued by high resolution transmission electron microscopy (HRTEM) analysis. Consequently, it can be concluded that highly dispersed Pt nanoparticles could be prepared by the novel pretreatment technique and thus, CO conversion could be increased considerably especially at the low temperatures below $100^{\circ}C$.

• Bulletin of the Korean Chemical Society
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• v.35 no.2
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• pp.349-352
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• 2014

Anodic alumina oxide (AAO), a self-ordered hexagonal array, has various applications in nanofabrication such as the fabrication of nanotemplates and other nanostructures. In order to obtain highly ordered porous alumina membranes, a two-step anodization or prepatterning of aluminum are mainly conducted with straight electric field. Electric field is the main driving force for pore growth during anodization. However, impurities in aluminum can disturb the direction of the electric field. To confirm this, we anodized two different aluminum foil samples with high purity (99.999%) and relatively low purity (99.8%), and compared the differences in the surface morphologies of the respective aluminum oxide membranes produced in different electric fields. Branched pores observed in porous alumina surface which was anodized in low-purity aluminum and the size; dimensions of the pores were found to be usually smaller than those obtained from high-purity aluminum. Moreover, anodization at high voltage proceeds to a significant level of conversion because of the high speed of the directional electric field. Consequently, anodic alumina membrane of a specific morphology, i.e., meshed pore, was produced.

• Journal of the Korean Institute of Gas
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• v.8 no.3 s.24
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• pp.43-51
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• 2004

In this study, gas permeation and separation characteristics of $CO_2$ and $N_2$ on nano-porous TPABr(Tetrapropylammoniumbromide) templating silica/alumina composite membrane were studied by using GMS (Generalized Maxwell Stefan) model. Since the transport mechanisms of meso-porous alumina support are Knudsen diffusion and viscous diffusion(or poiseulle flow), they can be identified by DGM (dusty gas model). The transport mechanism of TPABr templating silica layer, which would contribute mainly to the separation of $N_2/CO_2$ mixture, showed surface diffusion rather than pore diffusion. Therefore, the oermeationjseparation mechanisms in multi-component suface diffusion were successfully analyzed by the GMS model. In the separation of $N_2/CO_2$ mixture using the composite membrane, $CO_2$, the strongadsorbate, was permeated through the membrane more than Na due to the pore-blocking phenomena of $CO_2$ by adsorption isotherm and solace diffusion.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.03b
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• pp.45-45
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• 2010

Nanoporous anodic alumina membranes (NAAM) with high aspect ratio, self-ordered pore array were fabricated by high-field 2-step anodization method. High voltages of 80, 100, 120 and 140 V as well as 40 V for comparison were applied to an aluminum anode with respect to a Pt cathode immersed both in 0.3M oxalic acid solution in order to investigate the self-ordering characteristics of the nanoporous structure. The pore structures, including interpore distance, pore size, pore density, and porosity as well as the ordering characteristic were analyzed using field-enhanced scanning electron microscopy (FE-SEM) and the corresponding Fourier-transformed images. The nanoporous structure could be produced for all the voltage conditions, but the well-ordered through-hole pore without a branched structure seemed to occur only at 40 and 140 V. It turned out that the growth rate under 140 V high-field anodization was about 40 times higher than under conventional 40 V mild anodization, which enabled the fast fabrication of self-ordered, high aspect ratio NAAMs.

• Proceedings of the Membrane Society of Korea Conference
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• 2003.07a
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• pp.21-24
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• 2003

Methane steam reforming (MSR) was studied in a membrane reactor (MR) with a Pd-based and a porous alumina membranes. MRs showed methane conversion higher than that foresaw by the thermodynamic equilibrium for a traditional reactor (TR). Silica membranes prepared at KRICT were characterized with permeation tests on single gases ($N_2$, $H_2$ and $CH_4$). These silica membranes can be also used for high temperature applications such as $H_2$ separation $CO_2$ hydrogenation for methanol production is another reaction where $H_2O$ selective removal can be performed with these silica membranes.

• Proceedings of the Membrane Society of Korea Conference
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• 1993.10a
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• pp.24-24
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• 1993

세라믹 분리막은 기존의 유기질막에 비하여 고온 분리공정이 가능하고, 기계적 강도가 크며, 화학 물질에 대해서도 안정하므로 유기질막이 사용 되어질 수 없는 공정 조건에서도 사용이 가능하다. 그러나 기존의 제조법으로 제조한 세라믹 분리막은 복합 분리막의 경우, 코팅시 분리막층에 미세균열이 쉽게 발생하고 막의 재현성이 좋지 않기 때문에 새로운 분리막 제조 공정의 개발 필요성이 대두되고 있다. 본 실험은 이러한 목적하에 반도체 공업에서 주로 사용되어지고 있는 화학기상증착법을 이용하여 세라믹 복합 분리막을 제조하였다.

• Proceedings of the Membrane Society of Korea Conference
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• 2004.11a
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• pp.172-175
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• 2004

• Proceedings of the Membrane Society of Korea Conference
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• 1994.04a
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• pp.28-28
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• 1994

세라믹 분림가은 세라믹 고유의 열적, 기계적 특성으로 인해 유기질막이 사용되어질 수 없는 작업환경에서도 사용가능하다는 장점이 있다. 기존의 세라믹 분리막 제조방법으로는 졸겔법등이 있는데, 최근들어 새롭게 주목받고 있는 것이 화학기상중착법 (chemical vapor deposition)에 의한 제조이다. CVD 법은 막의 두께를 비교적 정확하게 조절할 수 있고, 균일한 두께의 막을 제조할 수 있다는 장점이 있다.

• Korean Membrane Journal
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• v.10 no.1
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• pp.26-32
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• 2008

The Gongji stream water of Chuncheon city was filtrated by 2 kinds of tubular alumina ceramic MF membranes with periodic $N_2$-back-flushing. $N_2$-back-flushing time (BT) was changed in $0{\sim}50$ sec at fixed filtration time (FT), or back-flushing period, of 4 min for NCMT-5231 membrane ($0.05\;{\mu}m$). Then, FT was changed in $0{\sim}32$ min at fixed BT of 40 sec for NCMT-7231 $0.1{\mu}m)$). In the viewpoints of total permeate volume ($V_T$), dimensionless permeate flux ($J/J_0$) and resistance of membrane fouling ($R_f$), the optimal $N_2$-BT was 50 sec, which was the longest BT, at 4 min FT for NCMT-5231. It means the longest BT was the most effective to minimize the membrane fouling, and we could acquire the most $V_T$. But the optimal FT for NCMT-7231 was 16 min in the viewpoint of $V_T$, and was 8 min in the viewpoints of $J/J_0$ and $R_f$ at fixed BT of 40 sec. The rejection rates were excellent as $80.6{\sim}96.6\;%$ for turbidity, $35.2{\sim}58.4%$ for $NH_3$-N, $16.3{\sim}45.2%$ for T-P and $16.3{\sim}45.2%$ for $COD_{Mn}$. However, the rejection rate of T-N was very low as $2.7{\sim}13.4%$ and it of TDS below 6.1%.

• Membrane Journal
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• v.22 no.6
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• pp.435-440
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• 2012

In this study, nanoporous HKUST-1 membranes were synthesized by solvothermal method. It is very difficult to prepare uniform and crack-free HKUST-1 layer on macroporous alumina support by in-situ solvothermal method. In this study, continuous and crack-free HKUST-1 membranes could be obtained by spraying solvothermal precursor solution on the heated alumina support, followed by solvothermal synthesis. HKUST-1 membranes were characterized by XRD, FE-SEM and single gas permeation experiments.