• 공업화학
• /
• 제27권1호
• /
• pp.56-61
• /
• 2016

본 연구에서는 천연 광물질 촉매를 사용하여 $CO_2$ 석탄가스화의 반응특성을 조사하였다. Meng Tai지역의 갈탄에 4종류의 천연 광물질(Dolomite, Silica sand, Olivine, Kaolin)을 각각 5 wt%로 물리적으로 혼합한 후 Thermogravimetric Analyzer (TGA)를 이용하여 800, 850, $900^{\circ}C$에서 $CO_2$ 가스화 반응을 수행하였다. 실험 결과를 Volumetric Reaction Model (VRM), Shrinking Core Model (SCM), Modified Volumetric Reaction model (MVRM)을 이용하여 분석하였다. MVRM이 가장 적합하였다. 반응 온도가 올라감에 따라 반응속도상수가 커졌다. 천연 광물질 촉매를 사용할 경우가 촉매를 혼합하지 않은 경우에 비해 반응속도상수는 커지고 활성화 에너지 값이 낮아졌다. Silica sand를 혼합한 시료의 활성화 에너지 값은 114.90 kJ/mol로 가장 낮은 활성화 에너지 값을 보였다. Kaolin을 혼합한 시료의 경우 $850^{\circ}C$와 $900^{\circ}C$에서 각각 가장 높은 반응속도상수를 보여주다가 $800^{\circ}C$에서 낮은 반응속도상수를 나타냈다. 따라서 Kaolin을 혼합한 경우, 반응 온도가 높아질수록 $CO_2$ 가스화에 좋은 효과가 있을 것이다.

• 한국환경과학회지
• /
• 제6권4호
• /
• pp.399-407
• /
• 1997

The pyrolysis reactions of atomic hydrogen with chloroform were studied In a 4 cm 1.6. tubular flow reactor with low flow velocity 1518 cm/sec and a 2.6 cm 1.4. tubular flow reactor with high flow velocity (1227 cm/sec). The hydrogen atom concentration was measured by chemiluminescence titration with nitrogen dioxide, and the chloroform concentrations were determined using a gas chromatography. The chloroform conversion efficiency depended on both the chloroform flow rate and linear flow velocity, but 416 not depend on the flow rate of hydrogen atom. A computer model was employed to estimate a rate constant for the initial reaction of atomic hydrogen with chloroform. The model consisted of a scheme for chloroform-hydrogen atom reaction, Runge-Kutta 4th-order method for Integration of first-order differential equations describing the time dependence of the concentrations of various chemical species, and Rosenbrock method for optimization to match model and experimental results. The scheme for chloroform-hydrogen atom reaction Included 22 elementary reactions. The rate constant estimated using the data obtained from the 2.6 cm 1.4. reactor was to be 8.1 $\times$ $10^{-14}$ $cm^3$/molecule-sec and 3.8 $\times$ $10^{-15}$ cms/molecule-sec, and the deviations of computer model from experimental results were 9% and 12% , for the each reaction time of 0.028 sec and 0.072 sec, respectively.

• 대한환경공학회지
• /
• 제32권11호
• /
• pp.1046-1053
• /
• 2010

본 연구의 목적은 생활폐기물에 저품위 무연탄의 혼합 후 열분해 반응 특성을 연구하는데 목적이 있다. 반응 변수로 혼합율, 반응온도, 승온속도에 따른 열분해조건을 고찰하였다. 그 결과, 저품위 무연탄 20 wt.%를 첨가한 혼합 시료가 3,500 kcal/kg 이상의 저위발열량 확보를 위한 최적의 혼합비로 나타났다. 가장 높은 반응속도상수 도출을 위해서는 $700^{\circ}C$의 조건에서 이루어 질 것으로 판단되었다. 또한 시간당 온도의 비가 증가할수록 반응속도상수가 선형적으로 높게 나타났으나, 열분해 시 전력비 상승 및 열분해 생성 char의 수율 등을 고려하여 더 낮은 승온속도에서 열분해가 이루어져야 할 것으로 판단된다.

• 공업화학
• /
• 제26권3호
• /
• pp.372-376
• /
• 2015

6M HCl 용매 하에서 6-메틸퀴놀린과 chromium(VI) trioxide의 반응을 통하여 6-MQCC(크롬(VI)-6-메틸퀴놀린) 착물을 합성하였다. 적외선분광광도법(IR), 유도결합 플라즈마(ICP) 등으로 구조를 확인하였다. 여러 가지 용매 하에서 6-MQCC을 이용하여 벤질 알코올의 산화반응을 측정한 결과, 용매의 유전상수 값이 증가함에 따라 반응수율이 증가했다. 그 순서는 DMF > 아세톤 > 클로로포름 > 시클로헥센이었다. 산($H_2SO_4$) 촉매를 이용한 DMF 용매 하에서, 6-MQCC은 벤질 알코올(H)과 그의 유도체들($p-OCH_3$, $m-CH_3$, $m-OCH_3$, m-Cl, $m-NO_2$)을 효과적으로 산화시켰다. 전자받개 그룹들은 반응속도가 감소한 반면에 전자주개 치환체들은 반응속도를 증가시켰고, Hammett 반응상수(${\rho}$) 값은 -0.69 (308 K)이었다. 본 실험에서 알코올의 산화반응 과정은 속도결정단계에서 수소화 전이가 일어났다.

• 공업화학
• /
• 제27권1호
• /
• pp.110-114
• /
• 2016

6M HCl 용매 하에서 피라진과 chromium (VI) trioxide의 반응을 통하여 PZCC (크롬 (VI)-피라진 착물)을 합성하였다. 적외선분광광도법(IR), 유도결합 플라즈마(ICP) 등으로 구조를 확인하였다. 여러 가지 용매 하에서 PZCC을 이용하여 벤질알코올의 산화반응을 측정한 결과, 용매의 유전상수 값이 증가함에 따라 반응수율이 증가했다. 그 순서는 N,N'-디메틸포름아미드 > 아세톤 > 클로로포름 > 시클로헥센이었다. 산($H_2SO_4$) 촉매를 이용한 N,N'-디메틸포름아미드 용매 하에서, PZCC은 벤질알코올(H)과 그의 유도체들($p-OCH_3$, $m-CH_3$, $m-OCH_3$, m-Cl, $m-NO_2$)을 효과적으로 산화시켰다. 전자받개 그룹들은 반응속도가 감소한 반면에 전자주개 치환체들은 반응속도를 증가시켰고, Hammett 반응상수(${\rho}$)값은 -0.70 (308 K)이었다. 본 실험에서 알코올의 산화반응 과정은 속도결정단계에서 수소화 전이가 일어났다.

• Bulletin of the Korean Chemical Society
• /
• 제12권4호
• /
• pp.429-433
• /
• 1991

The photoinduced electron transfer reactions of N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) in various polar solvents were studied by measuring time-resolved fluorescence. The temperature dependence on the fluorescence decay rate in acetonitrile, methanol, ethanol and buthanol was carried out to obtain the activation energy and Arrehnius factor for the photoinduced electron transfer reaction. It was found that as the dielectric constant of the solvent increases, the activation energy and the reaction rate increase. This implys that the Arrehnius factor is important in controlling the photoinduced electron transfer reaction rate. In water, TMPD exists in three forms (cationic, protonated and neutral forms) due to the high dielectric constant and strong proton donating power of water. The photoinduced electron transfer reaction was found to be very fast (< 50 ps) and also the long liverd component in the fluorescence decay profile attributable to the photoexcited protonated form of TMPD was observed. Probably, the reaction pathway and the reaction coordinate seem to be different depending on the solvents studied here.

• Elastomers and Composites
• /
• 제50권2호
• /
• pp.92-97
• /
• 2015

A study on reaction kinetics for a PTMG/TDI prepolymer with 2,2'-dichloro-4,4'-methylenedianiline (MOCA), of which formulations may be generally used for fabricating high performance polyurethane elastomers, was peformed using non-isothermal differential scanning calorimetry (DSC). A number of thermograms were obtained at several constant heating rates, and analysed using Flynn-Wall-Ozawa (FWO) isoconversional method for activation energy, $E_a$ and extended-Avrami equation for reaction order, n. Urea formation reaction of the present system was observed to occur through the simple exothermic reaction process in the temperature range of $100{\sim}130^{\circ}C$ for the heating rate of $3{\sim}7^{\circ}C/min$. and could be well-fitted with generalized sigmoid function. Though activation energy was nearly constant as $53.0{\pm}0.5kJ/mol$, it tended to increase a little at initial stage, but it decreases at later stage by the transformation into diffusion-controlled reaction due to the increased viscosity. Reaction order was evaluated as about 2.8, which was somewhat higher than the generally well-known $2^{nd}$ order values for the various urea reactions. Both the reaction order and reaction rate explicitly increased with temperature, which was considered as the indication of occurring the side reactions such as allophanate or biuret formation.

• 한국연소학회지
• /
• 제11권2호
• /
• pp.28-36
• /
• 2006

A constant volume combustion chamber was used to investigate the combustion characteristics. of homogeneous charge of methane-air mixture under various initial pressure, equivalence ratio and ignition times. The constant volume combustion chamber(CVCC) mostly has been studied by the experiments of visualization until now. So it is needed the numerical analysis of fluid and combustion characteristics in chamber by the more detail simulation. In this paper, the numerical analysis is tried to approach basically the homogeneous charge combustion phenomena under the various conditions, and the combustion phenomena in chamber is numerically analyzed by the commercial FIRE code. As a results, the combustion phenomena which were mean temperature, OH radical and reaction rate in chamber were investigated and it showed that the smallest flame growth occurs for the lean state and the increase of initial charged pressure condition due to the reduced OH radical.

• Journal of Pharmaceutical Investigation
• /
• 제20권3호
• /
• pp.145-152
• /
• 1990

Zirconium pyrithione complex was prepared by reaction of sodium-pyrithione solution and zirconyl chloride solution. The physico-chemical properties of the complex was examined by means of IR, XRD, DSC and NMR. And the stability of Zr-complex was investigated on the basis of accelerated stability analysis under conditions of temp. elevation, UV radiation and pH dependence. The result indicates that the ratio of the ligand to metal in Zr-pyrithione complex was determined 4:1, and its stability constant was $4.643{\times}10^4$. The rate order of decomposition of the complex was apparent first-order reaction of which rate constant and the decomposition rate was not only accelerated by effect of heat and UV radiation but was catalyzed by specific acid-base catalysis considered the pH dependence for the hydrolysis of the complex and the suspension was most stable over the range pH 4-8 indicating that solvent catalysis is the primary made of reaction in this region.

• 한국환경보건학회지
• /
• 제35권6호
• /
• pp.532-537
• /
• 2009

The tropospheric ozone production mechanism for the gas phase additive oxidation reaction of hydroxyl radical (OH) with isoprene (2-methyl-1,3-butadiene) has been studied using cavity ring-down spectroscopy (CRDS) at total pressure of 50 Torr and 298 K. The applicability of CRDS was confirmed by monitoring the shorter (~4%) ringdown time in the presence of hydroxyl radical than the ring-down time without the photolysis of hydrogen peroxide. The reaction rate constant, $(9.8{\pm}0.1){\times}10^{-11}molecule^{-1}cm^3s^{-1}$, for the addition of OH to isoprene is in good agreement with previous studies. In the presence of $O_2$ and NO, hydroxyl radical cycling has been monitored and the simulation using the recommended elementary reaction rate constants as the basis to OH cycling curve gives reasonable fit to the data.