• Title/Summary/Keyword: Chemical reaction process

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A Study on the Hypochlorination Reaction for Improvement of Epichlorohlydrin Production Process : Reduction of Side Reacion (ECH 생산공정 개선을 위한 Hypochlorination 반응에 관한 연구 : 부반응 억제)

  • Lee, Chul Haeng;Jeon, Sang Jun;Lee, Tai-yong;Wong, Won Hi;Yun, Chang Han;Kim, Young Sub;Cho, Byong Nam;Kim, Yeon Seok
    • Clean Technology
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    • v.9 no.1
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    • pp.29-35
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    • 2003
  • The methods for improving epichlorohydrin process was investigated by carrying out experiments on hypochlorination reaction, from which dichlorohydrin is produced by reacting with allyl chloride and chlorine. As the recycle water from PVC plant was used instead of industrial water for reaction, the effect of recycle water on the reaction yield was studied. It was shown from this experiment that the recycle water rarely affected on the ratio between products. TCPA, which was almost of byproducts, could be removed before purification process using "extractant A". This could prevent additional side reaction by TCPA and reduced energy to separate it in purification part. The change of product yield was observed as the chlorine gas addition decreases which reacted with allyl chloride. It seems that the yield of major products didn't change almost, but the byproducts showed rather reduced trend with decreasing chlorine gas.

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An Establishment of Expert System for Fault Diagnoses of the Cooling System In the Xylene Oxidation Reaction Process (크실렌 산화공정 냉각장치의 고장진단 전문가시스템의 구축)

  • 심종칠;김창은;주용준
    • Journal of the Korean Society of Safety
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    • v.11 no.4
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    • pp.54-63
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    • 1996
  • We establish an expert system for the xylene oxidation reaction process of chemical plants using HAZOP(Hazard and Operability Studies). Our research focus Is only reduced to the cooling system of the total chemical plant due to lack of information. This expert system shows the priority of reasons for the system failure using confidence factor.

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A DFT Study for the Reaction Pathway(s) of Polycyclic Aromatic Hydrocarbons I: Phenanthrene Degradation with two OH Radicals (다고리 방향족 탄화수소의 반응 경로에 대한 DFT 연구 I: 2개의 OH 라디칼에 의한 페난트렌의 분해 반응)

  • Lee, Min-Joo;Lee, Byung-Dae
    • Journal of the Korean Chemical Society
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    • v.65 no.1
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    • pp.9-14
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    • 2021
  • In this study, the DFT calculation was performed using the B3LYP/6-31G(d,p) basis sets for the reaction process in which phenanthrene decomposes due to the chain reaction of two OH radicals on phenanthrene in the gaseous state of 298 K at 1 atm. As a result of the calculation, even when two OH radicals act on phenanthrene in a chain, the reaction for producing phenanthren-9-ol is predicted to be more advantageous than the reaction for producing phenanthren-1-ol. On the other hand, it was predicted that the OH addition process at room temperature would be advantageous for the priority of the OH addition and H abstraction process.

An Evaluation of Thermal Stability of Raw Materials in the Vinyl Acetate Polymerization Process (비닐아세테이트 중합공정에서 원료물질의 열적 안정성 평가)

  • Lee, Keun-Won;Han, In-Soo;Lee, Jung-Suk
    • Journal of the Korean Society of Safety
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    • v.25 no.3
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    • pp.61-65
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    • 2010
  • Most of the chemical reactions performed in the chemical industry are exothermic, meaning that thermal energy is released during the reaction. It is also important to understand the thermal hazards such as thermal stabilities and runaway reactions, which are governed by thermodynamics and reaction kinetics of the mixed materials. The paper was described the evaluation of thermal behavior caused by an exothermic batch process in manufacture of the vinyl acetate resin. The aim of the study was to evaluate the thermal stabilities of raw materials with operating conditions such as a reaction inhibitor, heating rate, reaction atmosphere and the mount of methanol charged in the vinyl acetate polymerization process. The experiments were performed in the differential scanning calorimeter(DSC), C 80 calorimeter, and thermal screening unit($TS^u$). It was suggested that we should provide the thermal characteristics for raw materials to present safe precautions with operating conditions in the vinyl acetate polymerization process.

Study of Solvent Effects in Diels-Alder Reaction through Charge Transfer Formation by Using Semi-empirical Calculations

  • Shihab, Mehdi Salih
    • Bulletin of the Korean Chemical Society
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    • v.29 no.10
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    • pp.1898-1904
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    • 2008
  • Study of computational model of the concerted Diels-Alder reaction between 9,10-dimethyl anthracene (as donor) and tetracyanoethylene (as acceptor) in absence and in presence of aromatic solvents (benzene, mesitylene and hexamethylbenzene, as donors) using an AM1 semi-empirical method. AM1 method used to study the neutral charge transfer complex models that could be expected between donor and acceptor during the course of the concerted Diels-Alder reaction. Calculated enthalpies of reaction of the charge transfer complexes models showed physical and chemical meaning for explain the effect of aromatic solvents on the kinetic process of concerted Diels-Alder reaction that contains tetracyanoethylene.

The Improved Synthesis of 1-Chloro-2-iodoperfluorocycloalkenes and 2,2'-Dichloroperfluorocycloalkenyls (1-Chloro-2-iodoperfluorocycloalkenes와 2,2'-Dichloroperfluorocycloalkenyls 합성의 개량)

  • Sam Kwon Choi;Jeseph D. Park
    • Journal of the Korean Chemical Society
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    • v.21 no.3
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    • pp.180-186
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    • 1977
  • The preparation of 1-chloro-2-iodoperfluorocycloalkenes was achieved with a short reaction time and a high yield when the starting compound was iodinated via the metalation process using an alkyllithium reagent. Especially, the high yield of 1-chloro-2-iodo-perfluorocyclohexene was obtained when 1,2-dichloroperfluorocyclohexene was iodinated via the same reaction conditions. The coupling reaction of 1,2-dihaloperfluorocycloalkenes was also achieved with a lower reaction temperature and a shorter reaction time when the equal slurry mixture of fluorocycloolefines and DMF was reacted at a high pressure in a sublimer. The yield of the coupling product was greatly improved by this process. For a typical example, the coupling reaction of the 1-chloro-2-iodotetrafluorocyclobutene was proceeded with a higher yield of the product than that of the reported reaction, when the present method was adopted. A plausible reaction mechanism of the present coupling reactiont was proposed and the physical characteristics of the coupling product were confirmed.

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Theoretical Studies on the Gas-phase Reaction of Methyl Formate with Anions$^\dag$

  • Lee, Ik-Choon;Chung, Dong-Soo;Lee, Bon-Su
    • Bulletin of the Korean Chemical Society
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    • v.10 no.3
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    • pp.273-278
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    • 1989
  • The gas-phase reactions of methyl formate with anions, $-NH_2,\;-OH,\;-CH_2CN$, are studied theoretically using the AM1 method. Stationary points are located by the reaction coordinate method, refined by the gradient norm minimization and characterized by the determination of Hessian matrix. Potential energy profiles and the stationary point structures are presented for all conceivable processes. Four reaction paths are found to be possible: formyl proton and methyl proton abstractions, carbonyl addition, and $S_N2$ process. For the most basic anion $-NH_2$ the proton abstraction path is favored, while in other case, $OH\;and\;-CH_2CN$, the carbonyl addition paths are favored. In all cases the $S_N2$ process is the most exothermic, but due to the relatively high activation barrier the process can be ruled out.

Mechanism of the Electrode Reduction of Cupferron in Neutral and Alkaline Media (중성 및 알카리성수용액에서 Cupferron 의 전극환원메카니즘)

  • Hwang, Kum-Sho;Hwang, Jung-Ui
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.11 no.1
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    • pp.32-55
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    • 1975
  • The ammonium salt of N-Nitrosophenylhydroxiamine, namely Cupferron, is a well-known analytical reagent which precipitates a great number of metal ions in acid medium. Various structures of electrode reduction for N-Nitrosophenylhydroxiamine have been suggested in acid and alkaline media by many researchers, but not in neutral medium. So the mechanism of electrode reaction of Cupferron was investigated by both chronopotentiometric and polarographic methods. It was estimated that the reduction of Cupferron occurs in a three-step mechanism through which a chemical step is interposed between two charge transfer, the ECE (charge transfer-chemical reaction-charge transfer) mechanism, over a range of neutral and alkaline media. The chemical reaction of the process was assumed to be acid-base catalyzed from the fact that kapp (over all rate constant) of chemical reaction is pH dependent.

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Hg(0) Removal Using Se(0)-doped Montmorillonite from Selenite(IV)

  • Lee, Joo-Youp;Kim, Yong Jin
    • Bulletin of the Korean Chemical Society
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    • v.34 no.12
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    • pp.3767-3770
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    • 2013
  • Potassium methylselenite ($KSeO_2(OCH_3)$) was reduced to elemental selenium, Se(0), and then doped onto montmorillonite K 10 (MK10) clay to examine the interaction between elemental mercury (Hg(0)) vapor and Se(0) in an effort to understand the possible heterogeneous reaction of Hg(0) vapor and Se(0) solid. The clay was used as a cost-effective support material for uniform dispersion of Se(0). The Se(0)-doped MK10 showed an excellent reaction performance with Hg(0) under an inert nitrogen gas at 70 and $140^{\circ}C$ in our lab-scale fixed-bed system. However, the precursor, $KSeO_2(OCH_3)$-doped MK10 showed a negligible reaction performance with Hg(0), suggesting that the oxidation state of selenium plays a key role in the reaction of Hg(0) vapor and selenium compounds.

Chemical Reaction between Aluminium and graphite Crucible During the Fabrication of Spherical Monosized Al particles

  • Kwon, Hansang
    • Journal of Powder Materials
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    • v.25 no.2
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    • pp.99-103
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    • 2018
  • Spherical monosized pure aluminum (Al) particles are successfully fabricated by the pulsated orifice ejection method (POEM). The surface reaction between Al and the graphite crucible is investigated by analysing the microstructure and chemical composition of the materials. No significant chemical reaction occurs between Al and the graphite owing to the crystalline Al oxide (${\gamma}-Al_2O_3$) layer generated in the initial state. The ${\gamma}-Al_2O_3$ layer is clearly observed in all regions between the Al particles and graphite via transmission electron microscopy and confirmed by the selected area diffraction pattern. The morphology of the ${\gamma}-Al_2O_3$ layer perfectly follows the surface morphology of the graphite crucible, which showed nanoscale roughness. This implies that molten Al could not directly contact graphite even though the surface of the crucible became rough to some extent. However, this passivation phenomenon allowed the successful fabrication of monosized pure Al particles. Therefore, POEM is a useful process at least to manufacture monosized pure Al particles.