• Applied Chemistry for Engineering
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• v.18 no.6
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• pp.643-649
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• 2007

Lipase-catalyzed esterification of structural butanol isomers and n-butyric acid was investigated in supercritical carbon dioxide. The experiments were performed in a high pressure cell for 5 hrs with a stirring rate of 150 rpm at 323.15 K and 130 bar. The Candida Antarctica lipase B (CALB) was used in whole system as a catalyst. The experimental results were analyzed by GC-FID using a INNOWax capillary column. The conversion yield and the tendency of the esterification in supercritical carbon dioxide were compared with estimated results by molecular dynamics simulation. Based on the Ping-Pong Bi-Bi mechanism with competitive inhibition, each step of the reaction was optimized; using this result the transition state was predicted. Conformational preference of isomers was also analyzed using molecular dynamics simulations. This kind of approach will be further extended to the prediction of enzyme-catalyzed reactions using computers.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.16 no.4
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• pp.479-490
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• 2018

The granite melting concept, which was suggested by Gibb's group for the closing of a deep borehole, was experimentally checked for KURT granite. The granite melting experiments were performed in two pressure conditions of atmospheric melting with certain inorganic additives and high pressure melting formed by water vaporization. The results of atmospheric tests showed that KURT granite started to melt at a lower temperature of $1,000^{\circ}C$ with NaOH addition and that needle shaped crystals were formed around partially melted crystals. In high pressure tests, vapor pressure was increased by adding water with maximum pressure of about 400 bars. KURT granite was partially melted at $1,000^{\circ}C$ when vapor pressure was low. However, it was not melted at vapor pressures higher than 200 bars. Therefore, it was determined that high pressure with a small amount of water vapor more effectively decreased the melting point of granite. Meanwhile, high temperature and high pressure vapor caused severe corrosion of the reactor wall.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.595-596
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• 2008

가스 하이드레이트의 생성속도와 전환율을 높이며, 동시에 생성유도시간을 억제하기 위한 방법으로 다공질 물질을 활용하여 공극 내에 물을 함침시킨 후 가스와 반응시키는 제조방법을 개발하였다. 내용적 10 L 의 대용량 고압 반응기를 제작하여 실험을 수행하였으며, 장치 대형화에 따른 다공질 실리카겔의 다짐현상에 의한 발열제어 등에 대한 문제점은 특별히 나타나지는 않았다. 하이드레이트 형성을 위한 구동력이 높을수록 생성속도가 좋아지는 것을 확인하였다. 일반 벌크상 하이드레이트 제조법과 비교하여 매우 높은 생성속도 및 전환율, 거의 제거된 생성유도시간 등은 응용기술로 활용하기에 매우 바람직한 특성으로써 선택적인 가스분리, 가스저장 매체로 활용이 가능하다.

• Clean Technology
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• v.8 no.1
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• pp.39-44
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• 2002

In order to recycle poly(ethylene terephthalate), methanolysis has been investigated at elevated temperature and under high pressure without catalyst to afford dimethyl terephthalate and ethylene glycol. The reaction was carried out under 62 atm, $310^{\circ}C$ for 50min to obtain 98% dimethyl terephthalate. The method has been suggested as a simple and economical one to recycle the poly(ethylene terephthalate).

• Journal of the Korean Chemical Society
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• v.35 no.1
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• pp.64-69
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• 1991

Kinetics of the reaction of p-methylphenacyl arenesulfonates with pyridine in acetonitrile were investigated by an electric conductivity method at 1∼2000 bars and 35∼55$^{\circ}C$. The rates of these reactions were increased with raising pressures and temperatures. The activation enthalpy(${\Delta}H^{\neq}$), entropy(${\Delta}S^{\neq}$) and activation volume(${\Delta}V^{\neq}$) of the reaction were obtained with the rate constants. Activation volume and entropy were both negative valued, and activation enthalpy was positive. The acteivation parameters (${\Delta}V^{\neq}$ and ${\Delta}S^{\neq}$) were decreased with increasing pressure. From all of the above results, it was found that this reaction proceeds on the S$_N$2 in which C${\cdots}$O bond breaking is more advanced as pressure increases.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.220-220
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• 2010

clathrate compound란 호스트 분자가 수소 결합에 의하여 3차원 골격구조를 만들고, 이 격자 내부의 동공으로 저분자량의 기체 게스트 분자가 포집되며 형성되는 고체 결정 화합물이다. 현재까지 다양한 호스트 분자가 clathrate 화합물을 형성하는 것으로 보고되어 있으며, 이 중 유기물인 hydroquinone 역시 clathrate compound를 형성할 수 있는 것으로 알려져 있다. clathrate compound는 작은 고체 부피 내부에 막대한 양의 기체 분자를 저장할 수 있는 특성을 지니고 있기 때문에, 에너지 가스의 저장/수송이나 혼합 가스의 선택적 분리와 같은 다양한 응용을 위한 연구가 활발히 진행되고 있다. 본 연구에서는 clathrate compound를 형성하는 유기 호스트 분자인 hydroquinone을 이용하여 다양한 기체분자들에 대한 포집 거동을 파악하였다. 순수 기체로는 $N_2$, $H_2$, $CO_2$, $CH_4$의 4종류를 가지고 고압 반응기에서 50bar의 압력, 상온에서의 반응 조건으로 반응을 시켰다. 이렇게 형성된 반응 샘플들은 clathrate 형성 여부(기체의 포집 여부)를 확인하기 위하여 x-ray 회절을 통한 고체 결정 구조 분석을 수행하였다. 또한 순수 기체 이외에 다양한 비율(20%, 40%, 60%, 80%)의 조성을 갖는 $CO_2+N_2$ 혼합가스를 이용하여 clathrate compound의 형성과 조성 분석을 수행하였는데, x-ray 회절 분석과 13C 고체 NMR 분석을 통해 미세 구조 분석 연구를 수행하였고, Raman분석을 통하여 그 조성을 확인하였다. 본 연구에서 얻어진 결과는 기체의 저장/수송이나 혼합 가스의 선택적 분리와 같은 응용 분야에서 중요한 정보를 제공할 수 있을 것으로 기대된다.

• Journal of the Korean Chemical Society
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• v.39 no.8
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• pp.598-603
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• 1995

Kinetics for the reaction of para-substituted benzyl bromides with 3-picoline have been studied with the changes of substituent, pressure and temperature. The activation parameters and the Hammett ρ-values were determined from the values of rate constants. The results of these studies showed that the positive charge developed in the reaction center and bond cleavage was greater than bond formation. The reaction rate and the ability of charge transfer were increased with elevating pressure. The effect of pressure for the charge transfer was more enhanced at low temperatures.

• Clean Technology
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• v.20 no.4
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• pp.425-432
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• 2014

The effect of two important parameters of a catalytic membrane reactor (CMR), hydrogen selectivity and hydrogen permeance, coupled with an Ar sweep flow and an operating pressure on the performance of a water gas shift reaction in a CMR has been extensively studied using a one-dimensional reactor model and reaction kinetics. As an alternative pre-combustion $CO_2$ capture method, the feasibility of capturing a pressurized and concentrated $CO_2$ in a retentate (a shell side of a CMR) and separating a purified $H_2$ in a permeate (a tube side of a CMR) simultaneously in a CMR was examined and a guideline for a hydrogen permeance, a hydrogen selectivity, an Ar sweep flow rate, and an operating pressure to achieve a simultaneous capture of a concentrate $CO_2$ in a retentate and production of a purified $H_2$ in a permeate is presented. For example, with an operating pressure of 8 atm and Ar sweep gas for rate of $6.7{\times}10^{-4}mols^{-1}$, a concentrated $CO_2$ in a retentate (~90%) and a purified $H_2$ in a permeate (~100%) was simultaneously obtained in a CMR fitted with a membrane with hydrogen permeance of $1{\times}10^{-8}molm^{-2}s^{-1}Pa^{-1}$ and a hydrogen selectivity of 10000.

• Applied Chemistry for Engineering
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• v.22 no.3
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• pp.249-254
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• 2011

A nonthermal plasma reactor in conjunction with a tubular type with a ferroelectric (high-dielectric ceramic) pellet layer was designed and constructed. $SrBiTaO_9$ (SBT) pellets with 2.0 mm in diameter were held within the tube arrangement by two metal mesh electrodes (20 mm separation) connected to a high-voltage AC power supply. The dielectric constant of SBT pellets was 150 at room temperature and 500 at curie temperature ($335^{\circ}C$). The generation rate of ozone in the plasma reactor almost linearly increased with increasing applied voltage. In the case of the plasma reactor packed with SBT pellets the generation rate of ozone sharply increased at the applied voltage more than 20 kV. The ozone generation rate at the negative corona discharge was higher than that of the positive corona discharge. However, the destruction efficiency of toluene and methylene chloride was not increased in proportion to ozone concentration.

• Korean Chemical Engineering Research
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• v.58 no.4
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• pp.581-587
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• 2020

In this study, a new reaction system is proposed to solve the problems of the existing 2,3-Butanediol (2,3-BDO) dehydration reaction system. It was confirmed that the reaction system did not wok as it should operate properly when using a furnace, which is commonly used in commercial processes, to raise the reactant, 2,3-BDO, to the reaction temperature, 360 ℃, at near atmoshperic pressure. It is because of the substance considered to be oligomers of 2,3-BDO. It can lead to safety problems, such as blockages inside the furnace's tube and explosions, as well as tricky maintenance issues in the reaction system. To solve it, the temperature of reactant can be brought down by using a heat exchanger with High Pressure (HP) steam instead of the furnace, which has a hot spot problem through the vacuum operation and reduce the reaction temperature. It can be seen that the reactor performance is almost similar under the vacuum operation and the lower reaction temperature, 330 ℃, by using a reaction kinetics. This result explains why the new reaction system is proposed.