• Title/Summary/Keyword: 화학적 반응

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A Study on the Heat Storage System for Chemical Heat Pump Using Inorganic Hydrates (III) -Numerical Analysis of Heat Transfer in Ca(OH)2 Dehydration Packed Bed- (화학열펌프에 있어서의 무기수화물계 축열시스템에 관한 연구(III) -Ca(OH)2 탈수반응층의 전열해석-)

  • Park, Young-Hae;Lee, Young-Sei;Kim, Jong-Shlk
    • Applied Chemistry for Engineering
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    • v.7 no.6
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    • pp.1181-1191
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    • 1996
  • To develope chemical heat pump, which is operated by heat of high temperature using available energy sources such as solar heat and many kinds of waste thermal energy we have studied theoretically the enhancement effects of inserted fins on the rate of heat transfer and reaction in cylinderical $Ca(OH)_2$ packed bed reactor. The results obtained by numerical analysis about profiles of temperature, completion time of reaction and exothermic heat amount released from the reactor read as the inserted copper fins in reator reduce the completion time of dehydration reaction in packed bed by half, and the rate of thermochemical reaction depends on the temperature and concentration, and it is also governed by the boundary conditions and the rate of heat transfer in the particle packed bed.

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Computational Chemistry Study of CO2 Fixation and Cyclic Carbonate Synthesis Using Various Catalysts (촉매를 이용한 이산화탄소 고정화 및 고리형 카보네이트 합성반응에 대한 계산화학적 해석)

  • An, Hye Young;Kim, Min-Kyung;Jeong, Hui Cheol;Eom, Ki Heon;Won, Yong Sun
    • Clean Technology
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    • v.22 no.1
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    • pp.35-44
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    • 2016
  • In this study, a computational chemistry methodology called as molecular modeling was been applied to explain several experiment results mechanistically. The reaction chosen for this study was to remove carbon dioxide, known as a primary greenhouse gas, by an epoxide via the carbon dioxide fixation to produce carbonates. This reaction inherently needs the use of catalysts because it has a significantly high activation barrier (55~59 kcal/mol). Among various types of catalysts, we studied in zeolitic imidazolate framework 90 (ZIF-90)/ionic liquid immobilized ZIF-90 (IL-ZIF-90), polystyrene-supported quaternized ammonium salt, KI/KI-glycine, and dimethylethanolamine (DMEA). First, probable reaction pathways were proposed based on calculated energetics by computational chemistry. The energetics was then used for the thermodynamic interpretation on the activity of catalysts. In the case of ZIF-90/IL-ZIF-90 and KI/KI-glycine, IL-ZIF-90 and KI-glycine showed better yields compared to their counterparts. The calculation proposed interesting results that it is not from the lowering of activation energy but from the unstable intermediates of ZIF-90 and KI-glycine. For DMEA, the calculated activation energy was ~42 kcal/mol, much lower than that of the non-catalytic reaction. A possible reaction pathway was located to confirm the interaction between −NH group from ammonium and oxygen from epoxide for polystyrene-supported quaternized ammonium salt.

Sulfonation of Polyamide Containing Carboxylic Acid (Carboxylic acid를 함유한 sulfonated polynmide의 제조)

  • Jeon, Jong-Young;Lee, Gi-Jo
    • Journal of Sericultural and Entomological Science
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    • v.48 no.1
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    • pp.1-5
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    • 2006
  • Polyamide containing carboxylic acid was sulfonated with chlorosulfonic acid in dichloroethane under various conditions. The impact of the sulfonating agent concentration, the reaction temperature, and the reaction time on the ion exchange capacity was investigated. The mechanical and thermal properties, the contact angle, and the change of poly-dispersity were calculated for studying change of their properties. The reactions were effective, when the temperature was below $10^{\circ}C$ and the concentration of chlorosulfonic acid was below 0.05 mol. The value of ion exchange capacity was increased with reaction time. Thermal and mechanical properties were nearly unchanged according to the degree of sulfonation, but the contact angle was increased with increasing the value of ion exchange capacity.

Comparative Photoluminescence Study of Single-Layer MoS2 Annealed in Hydrogen and Vacuum

  • Ryu, Ye-Jin;Park, Min-Gyu;Ryu, Sun-Min
    • Proceedings of the Korean Vacuum Society Conference
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    • 2014.02a
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    • pp.195.1-195.1
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    • 2014
  • 최근 반자성 물질인 $MoS_2$를 수소 기체 속에서 열처리하게 되면 약한 강자성이 유발된다는 연구가 보고되었다. 본 연구에서는 강자성 발현을 수반하는 물리적 및 화학적 변화를 이해하기 위해서 단일층 $MoS_2$에 대한 라만분광 및 광발광 연구를 수행하였다. 기계적 박리법을 이용하여 $MoS_2$ 결정으로부터 단일층 및 이중층 $MoS_2$를 분리하여 $SiO_2/Si$ 기판에 전사한 후, $200^{\circ}C{\sim}500^{\circ}C$ 영역의 특정 온도에서 1시간 동안 열처리하였다. 배경 기체가 열처리 도중 $MoS_2$에 미치는 영향을 이해하기 위하여 수소 속 반응을 진공 상태와 비교하였다. 라만 스펙트럼에서는 큰 변화가 없었으나, 광발광의 세기는 수소 속 반응 후에 감소하고 진공 속 반응 후에는 증가하는 대조적인 결과를 보였다. AFM 측정으로부터는 열처리 후에 $MoS_2$ 표면에 뚜렷한 변화가 일어나지 않는다는 사실을 확인하였다. 본 발표에서는 수소와 진공 조건에서 관찰된 상이한 광발광 특성과 그래핀/$SiO_2/Si$에서 관찰된 p-형 도핑과의 상관관계를 설명하고자 한다.

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Investigation on Rheological and Mechanical Properties of Propellant with Chemical Structures of HTPB Binder (HTPB 바인더의 화학적 구조에 따른 추진제의 유변학적, 기계적 특성 연구)

  • Kim, Jeong Eun;Ryu, Taeha;Hong, Myung Pyo;Lee, Hyoung Jin
    • Journal of the Korean Society of Propulsion Engineers
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    • v.21 no.1
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    • pp.84-90
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    • 2017
  • It is observed that chemical characteristics of HTPB(Hydroxyl Terminated Polybutadiene) binder such as OH index, molecular weight and functionality and so on, can be different with synthetic batch, which can affect curing reaction of binder in itself or propellant. Finally this reaction can also affect mechanical properties of propellant. And the results suggest that proper degree of curing reaction is necessary to obtain better mechanical properties of propellant.

Effect of Degree of Saponification on the Durability of Paper Coated by Atactic Poly(vinyl alcohol) (혼성배열 폴리비닐알코올로 코팅된 용지의 내구성에 대한 비누화도의 영향)

  • 최원규;류원석
    • Proceedings of the Korean Fiber Society Conference
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    • 2002.04a
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    • pp.414-416
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    • 2002
  • 폴리비닐알코올 (poly(vinyl alcohol), PVA)는 분해되어 대부분의 성분이 물과 이산화탄소로 전환되는 가장 이상적인 환경친화성 고분자이다. PVA만의 특유한 반응인 비누화 과정에 의해 가지가 모두 제거되기 때문에 화학적인 방법에 의해 완벽한 선형고분자를 얻는 것이 가능하다. PVA는 측쇄에 존재하는 히드록시기의 강력한 수소결합 때문에 우수한 반응성 및 결합성을 보유한 유기 고분자로서, 수용성 뿐 아니라 다양한 소재와 상용성이 있는 것으로 알려져 있다(1-4). (중략)

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