• Korean Chemical Engineering Research
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• v.45 no.6
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• pp.582-590
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• 2007

In view of the analysis of the phenomena and the prediction of the performance, mathematical modelling and simulation of a high temperature pilot reactor for water gas shift reaction (WGSR) has been carried out. Multiscale simulation incorporated computational fluid dynamics (CFD) technique, which has the capability to deal with the reactor shape, fluid and energy transport with extensive degree of accuracy, and process modeling technique, which, in turn is responsible for reaction kinetics and mass transport. This research employed multiscale simulation and the results were compared with those from process simulation. From multiscale simulation, the maximum conversion of was predicted approximately 0.85 and the maximum temperature at the reactor was calculated 720 K, resulting from the heat of reaction. Dynamic simulation was also performed for the time transient profile of temperature, conversion, etc. Considering the results, it is concluded that multiscale simulation is a safe and accurate technique to predict reactor behaviors, and consequently will be available for the design of commercial size chemical reactors as well as other commercial unit operations.

• Journal of the Korean Chemical Society
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• v.6 no.2
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• pp.148-154
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• 1962

The reactions between organic halides$(CCl_4,\;C_6H_5Br,\;C_6H_5Cl,\;C_6H_5I)$ and amines $(C_6H_5NH_2,\;R_2NH,\;R_3N,\;(CH_2)_5NH,\;pyridine)$ were studied under mixed u.v. irradiation. The modes of reactions were examined by means of gas chromatography and product-reactant ratio determination. The reaction of $CCl_4$ with amines give chloroform and hexachloroethanes, and the reaction of aromatic halides with amines gave biphenyl and benzene. In each series of reaction there obtained mainly corresponding amine hydrohalides, but no amination products. The reactivity was in the order of the basicity of amines and of the reactivity of organic hahides, except in the case of cyclic tertiary amine. The result was interpreted as a non-chain photodecomposition process. A competitive proton abstraction reaction path via the formation of a change transfer complex was proposed as the reaction mechanism.

• Bulletin of the Korean Chemical Society
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• v.17 no.1
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• pp.29-33
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• 1996

Mono-, or di-substituted chlorodicyanovinyl benzene compound was reacted with an excess amount of ethylenediamine to give corresponding imidazoline product with high reaction yield. This reaction occurs by stable imidazoline ring-forming process through nucleophilic attack of terminal amine on the enaminonitrile adduct, the reaction intermediate, toward electropositive enamine carbon, which is accompanied by the release of neutral malononitrile moiety. The similar reaction with 1,2-phenylenediamine produced stable enaminonitrile-amine adduct at lower temperature which could be cyclized intramolecularly to thermally stable benzimidazole at elevated temperature in solution or in solid state. From the difunctional compound of both reactants, poly(enaminonitrile-amine) could be prepared as a new soluble precursor polymer for well-known polybenzimidazole (PBI). The thermal cyclization reaction accompanying the release of malononitrile molecules was studied using thermalanalysis and infrared spectroscopy.

• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3559-3564
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• 2013

Alumina particles were grafted onto the surface of manganese oxide particles via the coprecipitation process using surfactant and cosurfactant. The phase of Mn/Al salts (Phase I) and the phase of precipitation agent (Phase II) were prepared in aqueous surfactant solution, separately. Phase II was added into Phase I and the reaction was performed to form the precursors of composites through hydrogen bonding between $Mn(OH)_2$ and $Al(OH)_3$ prepared by the reaction of Mn/Al salts with the precipitation agent. The alumina-grafted manganese oxide particles were obtained as a final product after calcination. The concentrations of Al salt and surfactant were varied to investigate their effects on the formation and the crystallinity of composites. In addition, the crystal structure of products could be controlled by changing the calcination temperature. Through thermal analyses, it was found that the thermal stability of manganese oxide was improved by the introduction of alumina on its surface.

• Bulletin of the Korean Chemical Society
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• v.12 no.6
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• pp.692-698
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• 1991

The reaction path Smoluchowski equation approach developed in a recent work to calculate the rate constant for a diffusive multidimensional barrier crossing process is extended to incorporate the configuration-dependent diffusion matrix. The resulting formalism is then applied to the investigation of stilbene photoisomerization dynamics. Adapting a model two-dimensional potential and a model diffusion matrix proposed by Agmon and Kosloff [J. Phys. Chem.,91 (1987) 1988], we derive an eigenvalue equlation for the relaxation rate constant of the stilbene photoisomerization. This eigenvalue equation is solved numerically by using the finite element method. The advantages and limitations of the present method are discussed.

• Bulletin of the Korean Chemical Society
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• v.20 no.5
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• pp.551-555
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• 1999

11-Deoxydaunomycinone 15 and 10-fluoroanthracyclinone derivatives 9, 10 were obtained. Naphthalenone 4 prepared from 2-(2,4-pentadienyl)-1,3-dioxane 2 with methyl vinyl ketone and hydrolysis with HClO4 was condensed with phthalidesulfone 5 through Michael type reaction, and was converted to 7 by epoxidation. Epoxide 7 was transformed to trione 12 using reduction-oxidation or hydrofluorination process, and then to 15 by introducing several functional groups. Compound 8 obtained in the course of the reaction of epoxide 7 and HF/ Pyr was used for the synthesis of compounds 9, 10.

• Bulletin of the Korean Chemical Society
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• v.32 no.2
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• pp.407-410
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• 2011

An isolable activated ester, diethyl thiophosphoryl [(Z)-(2-aminothiazol-4-yl)-2-(methoxyimino)acetate (9a, DAMA) was prepared in high purity, which was at least stable for 7 d at $25^{\circ}C$ and 6 months at $5^{\circ}C$. Its reaction with 7-ACA (4) in the presence of tributylamine in i-PrOH provided cefotaxime (1) of high purity in good yield. Preparation of DAMA and its reaction with 7-ACA (4) to 1 was performed in one-pot manner, respectively with minimal unit operations of stirring and filtration.

• Journal of the Korean institute of surface engineering
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• v.23 no.2
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• pp.1-10
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• 1990

Metal-Organic Vapor Phase Epitaxy (MOVPE) is an epitaxial process utilizaing ane or more of organometallice as reactnte to grow compound semicond semiconductror layers. MOVPE is basically a cold wall process in which reactants are delivered without reacting with each other to the heated substrate where reactants are thermally decomposed to from compound semiconductors through chemical reaction. Since reactants are delivered as gas phase and the formation of the single crystal compunds depends on the thermal decomposition of the reactants, details of MOVPE relies on the hydrodynamics and pyroltsis and chemical reation of reactants inside on reaction chamber. It has been demonstrated that MOVPE is capable of growing virtually all of the III-V, II-VI and IV-VI compound semiconductrs, fabricating ultrathin epilayers, for ming abrupt hetrointerfaces with monolayer transition width, and is suitable for multi-wafer operation yilding a high throghtput. Overiew of reactror componts and layer, characteristics, and status of MOVPE are discussed.

• Korean Chemical Engineering Research
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• v.53 no.2
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• pp.253-261
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• 2015

The kinetics of the transesterification of dimethyl terephthalate (DMT) with diethylene glycol (DEG) was studied in a batch reactor. bis-hydroxyethoxytethyl-terephthalate (BHEET), which is polyester polyol monomer, can be produced by the transesterification reaction. Zinc acetate was used as a catalyst. Previous kinetic studies was carried out in a semi-batch reactor where generated methanol was removed so that reverse reactions were not considered in the kinetic expressions, resulting in inaccuracy of the kinetic model. Mathematical models of a batch reactor for the tranesterification reaction, which took the reverse reaction into account, were developed and used to characterize the reaction kinetics and the composition distribution of the reaction products. More accurate models than previous ones were obtained and found to have a good agreement between model predictions and experimental data. Effect of process variables on the esterification reaction was investigated based on the experimental and simulation results.

• Korean Chemical Engineering Research
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• v.61 no.1
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• pp.168-174
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• 2023

In commercial production processes of methyl methacrylate, there is a methacryl aldehyde as an intermediate or impurities. The existence of impurities is critical factor because of significant decrease of the conversion rate and selectivity of the entire chemical reaction. This study found that an acid was the main cause of the decrease in reactivity among various impurities because an acid rapidly lowers the activity of a catalyst and promotes a side reaction, the hetero Diels-Alder reaction. Therefore, the pretreatment methods with the removal of acid were comparatively evaluated by the selective hydrogenation reaction of the carbonyl group of the reactants. Based on several experimental conditions, we believe that proposed effective pretreatment improves productivity with appropriate economical process.