• Title/Summary/Keyword: microreactor

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Transport Phenomena in a Steam Methanol Microreformer for Fuel Cell (마이크로 연료전지용 수소개질기내 전달현상 특성 연구)

  • Suh, Jeong-Se
    • Proceedings of the SAREK Conference
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    • 2008.11a
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    • pp.3-8
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    • 2008
  • Effect of external heating rate on the conversion efficiency for the steam reforming of methanol is investigated numerically considering both heat and mass transfer of the species in a packed bed microreactor. In a results from the numerical simulation, the conversion efficiency of methanol has been obtained for the external heating rate. The axial variation of mole fraction of methanol has been additionally presented for several cases of external heating rates. The results show that for the constant inlet temperature condition the conversion efficiency of methanol increases with external heating rate over the range of operating conditions.

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Recent Research Trend in Oxide Semiconductor Gas Sensors for Indoor Air Quality Monitoring (산화물 반도체를 이용한 실내 공기질 가스 센서 연구동향)

  • Lee, Kun Ho;Lee, Jong-Heun
    • Prospectives of Industrial Chemistry
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    • v.23 no.3
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    • pp.32-41
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    • 2020
  • 사람들은 대부분의 시간을 실내에서 보내고 있으며, 실내에 존재하는 유해가스는 미량의 농도에도 불구하고 심각한 질환을 일으킬 수 있다. 금속산화물 반도체 가스센서는 감도가 우수하고, 구조가 간단하며, 초소형화가 가능한 장점이 있어 고가의 대형 장비를 사용하지 않고 실내 유해가스를 측정하는 데 효과적으로 이용될 수 있다. 본 기고문에서는 금속산화물 반도체를 이용한 가스 센서의 검지 원리를 고찰하고, 나노 구조 조절, 마이크로 리액터 및 이중층 구조를 이용한 가스 개질 등 실내 유해가스 측정을 위한 다양한 센서 설계방법을 소개하고자 한다.

Modeling and Simulation of the Photocatalytic Treatment of Wastewater using Natural Bauxite and TiO2 doped by Quantum Dots

  • Becheikh, Nidhal;Eladeb, Aboulbaba;Ghazouani, Nejib
    • International Journal of Computer Science & Network Security
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    • v.22 no.6
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    • pp.91-96
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    • 2022
  • The photocatalytic degradation of salicylic acid takes place in several stages involving coupled phenomena, such as the transport of molecules and the chemical reaction. The systems of transport equations and the photocatalytic reaction are numerically solved using COMSOL Mutiphysics (CM) simulation software. CM will make it possible to couple the phenomena of flow, the transport of pollutants (salicylic acid) by convection and diffusion, and the chemical reaction to the catalytic area (bauxite or TiO2 doped by nanoparticles). The simulation of the conversion rate allows to correctly fit the experimental results. The temporal simulation shows that the reaction reaches equilibrium after a transitional stage lasting over one minute. The outcomes of the study highlight the importance of diffusion in the boundary layer and the usefulness of injecting micro-agitation into the microchannel flow. Under such conditions, salicylic acid degrades completely.

Microfluidic Assisted Synthesis of Ag-ZnO Nanocomposites for Enhanced Photocatalytic Activity (광촉매 성능 강화를 위한 미세유체공정 기반 Ag-ZnO 나노복합체 합성)

  • Ko, Jae-Rak;Jun, Ho Young;Choi, Chang-Ho
    • Clean Technology
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    • v.27 no.4
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    • pp.291-296
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    • 2021
  • Recently, there has been increasing demand for advancing photocatalytic techniques that are capable of the efficient removal of organic pollutants in water. TiO2, a representative photocatalytic material, has been commonly used as an effective photocatalyst, but it is rather expensive and an alternative is required that will fulfill the requirements of both high performing photocatalytic activities and cost-effectiveness. In this work, ZnO, which is more cost effective than TiO2, was synthesized by using a microreactor-assisted nanomaterials (MAN) process. The process enabled a continuous production of ZnO nanoparticles (NPs) with a flower-like structure with high uniformity. In order to resolve the limited light absorption of ZnO arising from its large band gap, Ag NPs were uniformly decorated on the flower-like ZnO surface by using the MAN process. The plasmonic effect of Ag NPs led to a broadening of the absorption range toward visible wavelengths. Ag NPs also helped inhibit the electron-hole recombination by drawing electrons generated from the light absorption of the flower-like ZnO NPs. As a result, the Ag-ZnO nanocomposites showed improved photocatalytic activities compared with the flower-like ZnO NPs. The photocatalytic activities were evaluated through the degradation of methylene blue (MB) solution. Scanning electron microscopy (SEM), x-ray diffraction (XRD), and energy-dispersive x-ray spectroscopy (EDS) confirmed the successful synthesis of Ag-ZnO nanocomposites with high uniformity. Ag-ZnO nanocomposites synthesized via the MAN process offer the potential for cost-effective and scalable production of next-generation photocatalytic materials.

The Study of the Photocatalytic Degradation for Microreactor (마이크로 반응기를 이용한 광촉매 분해특성 연구)

  • Choi B.C.;Kim H.T.
    • Journal of Energy Engineering
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    • v.14 no.2 s.42
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    • pp.105-111
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    • 2005
  • In this study, the photocatalytic degradtion of D-glucose with the micro channel reactor was performed on the various experimental conditions. To apply the $TiO_2$ coating on the micro channel reactor, $TiO_2$ solution was synthesized by hydrolysis of titanium oxysulfate. The feeding rate was proportional to degradation rate of D-glucose solution over the micro channel reactor. Also, the reaction rate constant and Langmuir adsorption coefficient were calculated under various experimental conditions. And the results of these system photonic efficiencies were calculated. This study aims to understand the photocatalytic degradation characteristics on $TiO_2$ coating in the micro channel reactor experimented by the feed batch reaction system.

Hydrogenation of Naphthalene in a Tubing Bomb Microreactor (소형 회분식반응기를 이용한 나프탈렌수소화반응 연구)

  • 이영우
    • Journal of Energy Engineering
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    • v.5 no.1
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    • pp.80-86
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    • 1996
  • Naphthalene hydrogenation reaction was performed as a model reaction for coal liquefaction. Product distributions of tetralin and decalin are sensitive to reaction temperature and hydrogen pressure. At 380$^{\circ}C$, hydrogenation reaction using sulfided pellet catalysts gives poor reproducibility and several experimental methods are tried to examine its cause. It was inferred that H$_2$S had, most possibly, a great effect on this phenomena and the effect of H$_2$S was systematically investigated at 250$^{\circ}C$. It is possible that the intermediate hydroaromatic compound (tetralin) is maximized by changing the partial pressure of H$_2$S. It was identified that the partial pressure of H$_2$S could be another important factor in addition to the reaction time and temperature in coal liquefaction using sulfided catalysts.

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Activity of $V_2O_5/TiO_2$Catalyst Using Domestic Pigment Titania as Support for Nitric Oxide Reducton (국내 안료용 타이타니아를 담체로 이용한 $V_2O_5/TiO_2$ 촉매상에서 질소산화물 제거활성)

  • 이정빈;이인영;김동화;엄희문;지평삼;추수태;남인식
    • Journal of Korean Society for Atmospheric Environment
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    • v.15 no.6
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    • pp.791-797
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    • 1999
  • The activity of domestic pigment titania$(TiO_2)$ impregnated with vanadia$(V_2O_5)$ was investigated in the laboratory microreactor. The meta-titanic acid$(TiO(OH)_2)$ which was produced at Hankook Titanium was selected as the precursor for support. The domestic pigment $TiO_2$ showed higher activity in the reduction of NO with $NH_3$ than the foreign commercial $TiO_2$. $WO_3$ were added to domestic $V_2O_5/TiO_2$ catalytic system to improve the catalytic activity at higher reaction temperature between 400~50$0^{\circ}C$ Also, the deactivation of domestic $V_2O_5/TiO_2$ and $WO_3-V_2O_5/TiO_2$ catalyst by $SO_2$ and $H_2O$ was investigated.

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Pyrolysis of PE plastics in the batch type microreactor (회분식 미분반응기를 이용한 PE계 플라스틱의 열분해특성 연구)

  • Kim, Sang-Hoon;Jang, Hyun-Tae;Cha, Wang-Seog
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.8 no.3
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    • pp.632-638
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    • 2007
  • Pyrolysis experiments of HDPE and LDPE were carried out in the stainless steel reactor of internal volume of 40 $cm^3$. Pyrolysis reactions were performed at temperature $410{\sim}460^{\circ}C$ and the pyrolysis products were collected separately as liquid and gas products. The molecular weight distributions(MWDs) and composition of each product were determined by HPLC-GPC and GC analysis. It was represented that the yield and the molecular weight of liquid product were decreased with the increase of reaction temperature and time. The chain-end scission rate parameters, respectively, were determined to be 63.0kcal/mole of HDPE, 45.7kcal/mole of LDPE by the Arrhenius plot.

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Microflow Photochemistry - Acetone sensitized Addition of Isopropanol to (5R)-5-Menthyloxy-2-(5H)-furanone

  • Aida, Shin;Nishiyama, Yasuhiro;Kakiuchi, Kiyomi;Hoffmann, Norbert;Fon, Adeline;Oelgemoller, Michael
    • Rapid Communication in Photoscience
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    • v.2 no.3
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    • pp.68-71
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    • 2013
  • Acetone sensitized photoadditions of isopropanol to (5R)-5-menthyloxy-2-(5H)-furanone were investigated in two different microflow reactor systems. Setup A employed a commercially available glass reactor under a UVB-panel. Setup B utilized a FEP microcapillary wrapped tightly around a Pyrex cylinder with a single UVB fluorescent tube at its center. The reactions under flow conditions were subsequently compared to analogue reactions conducted in a batch chamber reactor. Overall, the microflow systems gave faster conversions and higher isolated yields. The flexible microcapillary setup, however, showed the best performance and promise in terms of future scale-up and reactor optimization.

New Materials Based Lab-on-a-Chip Microreactors: New Device for Chemical Process

  • Kim, Dong-Pyo
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2012.05a
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    • pp.51-51
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    • 2012
  • There is a growing interest in innovative chemical synthesis in microreactors owing to high efficiency, selectivity, and yield. In microfluidic systems, the low-volume spatial and temporal control of reactants and products offers a novel method for chemical manipulation and product generation. Glass, silicon, poly(dimethylsiloxane) (PDMS), and plastics have been used for the fabrication of miniaturized devices. However, these materials are not the best due to either of low chemical durability or expensive fabrication costs. In our group, we have recently addressed the demand for economical resistant materials that can be used for easy fabrication of microfluidic systems with reliable durability. We have suggested the use of various specialty polymers such as silicon-based inorganic polymers and fluoropolymer, flexible polyimide (PI) films that have not been used for microfluidic devices, although they have been used for other areas. And inexpensive lithography techniques were used to fabricate Lab-on-a-Chip type of microreactors with differently devised microchannel design. These microreactors were demonstrated for various synthetic reactions: liquid, liquid-gas organic chemical reactions in heterogeneous catalytic processes, syntheses of polymer and non-trivial inorganic materials. The microreactors were inert, and withstand even harsh conditions, including hydrothermal reaction. In addition, various built-in microstructures inside the microchannels, for example Pd decorated peptide nanowires, definitely enhance the uniqueness and performance of microreactors. These user-friendly Lab-on-a-Chip devices are useful alternatives for chemist and chemical engineer to conventional chemical tools such as glass.

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