• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1994.05a
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• pp.9-14
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• 1994

알카리금속염 (K$_2$CO$_3$, $K_2$SO$_4$). 알카리 토금속염 (Ba(NO$_3$)$_2$), 철족금속염(Ni(NO$_3$)$_2$, FeSO$_4$) 으로 이루어진 여러가지 혼합물들이 반응온도 700~85$0^{\circ}C$ 하의 촤-수증기 가스화반응에서 나타내는 촉매활성을 열천칭 반응기를 사용하여 측정하였다. 비촉매 가스화반응에서 초기반응성은 수증기 분압에 비례하였다. 촉매 가스화반응에서 단일염 촉매의 경우 $K_2$CO$_3$ 가 가장 큰 활성을 나타내었으며, 다른 염들은 낮은 활성을 보였다. 혼합염의 경우 $K_2$SO$_4$에 철족염을 부가함에 따라 반응속도가 향상되었으며, $K_2$SO$_4$+Ni(NO$_3$)$_2$가 가장 큰 촉매활성을 나타내었다. $K_2$SO$_4$와 Ni(NO$_3$)$_2$ 의 촉매 활성은 담지량에 따라 증가하며, 석탄의 등급에 따라 감소하였다. $K_2$SO$_4$와 Ni(NO$_3$)$_2$의 혼합비는 같은 몰비로 혼합하였을때 가장 큰 활성을 나타내었다.

• Applied Chemistry for Engineering
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• v.24 no.4
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• pp.375-381
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• 2013

Kinetics data were obtained for steam reforming of methane and natural gas over the commercial nickel catalyst. Variables for the steam reforming were the reaction temperature and partial pressure of reactants. Parameters for the Power law rate model and the Langmuir-Hinshelwood model were obtained from the kinetic data. As a result of the reforming reaction using pure methane as a reactant, the reaction rate could be determined by the Power law rate model as well as the Langmuir-Hinshelwood model. In the case of methane in natural gas, however, the Langmuir-Hinshelwood model is much more suitable than the Power law rate model in terms of explaining methane reforming reaction. This behavior can be attributed to the competitive adsorption of methane, ethane, propane and butane in natural gas over the same catalyst sites.

• Clean Technology
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• v.19 no.1
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• pp.51-58
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• 2013

In this study, kinetics data was obtained for steam reforming reaction of ethane over the nickel catalyst. The variables of steam reforming reaction were reaction temperature, partial pressure of ethane, and mole ratio of steam and ethane. Parameters for the power rate law kinetic model and the Langmuir-Hinshelwood model were obtained from the kinetic data. Also, sizing of steam reforming reactor was performed by using PRO/II simulator. For the steam reforming reaction of ethane, Langmuir-Hinshelwood model determining the reaction rate by the surface reaction was better suited than a simple power rate law kinetic model. On water-gas-shift reaction, power rate law kinetic model was well fitted to the kinetic data. Reactor size can be calculated for production of hydrogen through PRO/II simulation.

• Applied Chemistry for Engineering
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• v.23 no.2
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• pp.204-209
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• 2012

In this study, kinetics data was obtained for steam reforming reaction of ethane over the commercial ruthenium catalyst. The variables of ethane steam reforming were the reaction temperature, partial pressure of ethane, and steam/ethane mole ratio. Parameters for the power rate law kinetic model and the Langmuir-Hinshelwood model were obtained from the kinetic data. Also, sizing of steam reforming reactor was performed by using PRO/II simulator. The reactor size calculated by the power rate law kinetic model was bigger than that of using the Langmuir-Hinshelwood model for the same conversion of ethane. Reactor size calculated by the Langmuir-Hinshelwood model seems to be more suitable for the reactor design because the Langmuir-Hinshelwood model was more consistent with the experimental results.

• Applied Chemistry for Engineering
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• v.2 no.1
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• pp.30-37
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• 1991

The production of hydrogen from steam by reduced iron with additives such as CuO, $In_2O_3$, $MoO_3$ and $WO_3$ has been kinetically investigated. It was shown that all additives have a promoting effect on reaction activity in the order of $$MoO_3{\gg}In_2O_3{\sim_=}WO_3{\sim_=}CuO$$. The shrinking core model was applied to predict the complete conversion time and the results were quite comparable with experimental values. The reaction was carried out in a fixed flow reactor packed with reduced iron with 1 wt % of additives under the conditions, $600-750^{\circ}C$, Ar flow rate of 1 L/min and steam partial pressure of 0.085 atm. The apparent activation energies were 14.2, 20.9, 21.3, 22.4 and 27.9 kJ/mol with $MoO_3$, $In_2O_3$, $WO_3$, CuO and without additive, respectively.

• Korean Chemical Engineering Research
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• v.48 no.1
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• pp.80-87
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• 2010

Lignite of low rank coal and petroleum coke of high sulfur content can be high potential energy sources for coal gasification process because of their plentiful supply. The kinetic study of steam gasification has been performed in an atmospheric thermobalance with wood chip, lignite, bituminous, anthracite, pet-coke. The effects of gasification temperature($600{\sim}850^{\circ}C$) and partial pressure of steam(30~90 kPa) on the gasification rate have been investigated. The modified volumetric reaction model was applied to the experimental data to describe the behavior of carbon conversion and to evaluate the needed kinetic parameters. Lignite and wood chip with high volatile content showed high average gasification rates comparing to other fuel and thus they might be proper fuel for gasification processes. The activation energies for wood chip, lignite, bituminous, anthracite, and pet-coke through Arrhenius plot were found to be 260.3, 167.9, 134.6, 82.2, 168.9 kJ/mol, respectively. The expression of apparent reaction rates for steam gasification of various chars have been proposed as basic information for the design of coal gasification processes.

• Korean Chemical Engineering Research
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• v.50 no.3
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• pp.398-402
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• 2012

The catalytic performance of some metal oxides in the vapor phase selective oxidation of $H_2S$ in the stream containing ammonia and water was investigated. Among the catalysts tested $Fe_2O_3/SiO_2$ was the most promising catalyst for practical application. It showed higher than 90% $H_2S$ conversion and very small amount of $SO_2$ emission over a temperature range of $240{\sim}280^{\circ}C$. The effects of reaction temperature, $O_2/H_2S$ ratio, amount of ammonia and water vapor on the catalytic activity of $Fe_2O_3/SiO_2$ were discussed to better understand the reaction mechanism. The $H_2S$ conversion showed a maximum at $260^{\circ}C$ and it decreased with increasing temperature over $280^{\circ}C$. With an increase of $O_2/H_2S$ ratio from 0.5 to 4, the conversion was slightly increased, but the selectivity to elemental sulfur was remarkably decreased. The increase of ammonia amount favored the conversion and the selectivity to elemental sulfur with a decrease in $SO_2$ production. The presence of water vapor decreased both the activity and the selectivity to sulfur, but increased the ATS selectivity.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.6
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• pp.88-95
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• 2003

The weighted sum of gray gas model(WSGGM) is applied to arbitrary mixtures of CO$_2$ and H$_2$0 gases. To evaluate this model, the spectral and total intensities are obtained for two different problem types. One has uniform, parabolic and boundary layer type temperature profiles with uniform partial pressure, and the other has nonuniform partial pressure and temperature profile. The results obtained from the two different problem types show fairly good agreements with the results obtained by the statistical narrow band model(SNB model) which is regarded as the reference solutions. The WSGGM and its data base provided by this study can be used for analysis of radiative transfer by combustion gases with different thermal loadings and chemical compositions.

• Journal of the Korean Ceramic Society
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• v.39 no.7
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• pp.635-641
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• 2002

Electrical conduction of $SrZrO_3$ doped with $Y_2O_3$ was measured as a function of gas atmosphere and temperature by impedance spectroscopy. Hydrogen dissolution, due to an enhanced driving force in the presence of oxygen, results in protonation by water incorporation. Proton conductivity increased with water vapor pressure, ${P_w}^{1/2}$. In the pure hydrogen atmosphere, the dissolution of hydrogen,$H_2(g)=2H_{i}$ +2e', is supposed to be driven by a reduced activity of electrons, ascribable to their trapping in oxygen vacancies. The activation energy of electrical conductivity was 50 kJ/mol, in wet argon atmosphere in the temperature range of $600~900^{\circ}C$, similar to those reported for proton conduction in the literature. Grain boundary effect in proton conduction was substantial in the 10% doped case at temperatures lower than $700^{\circ}C$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.531-534
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• 2004

초전도 coated conductor는 보호층/초전도층/완충층/금속기판의 구조를 가지며 완충층은 다층산화물 박막으로 이루어져 있다. 본 연구에서는 니켈 기판의 원자가 초전도층으로 확산 침투하는 것을 방지하는 YSZ(Yttria Stabilized Zirconia) 박막의 증착방법 및 최적조건에 대하여 소개하고자 한다. 금속타겟을 사용하며 산화반응가스로서 수증기를 사용하는 것을 특징으로 하는 DC reactive sputtering을 이용하여 YSZ를 증착하였으며 기판 온도는 $850^{\circ}C$ 이며 증착시 수증기 분압은 1mTorr이었다. YSZ의 최적두께를 알아보기 위하여 $CeO_2(12.2nm)/Ni$ 상부에 130nm, 260nm, 390nm, 650nm로 두께를 달리하여 YSZ층을 증착하고 SEM으로 박막 표면상태를 관찰한 결과 columnar grain growth를 하며 두께가 두꺼워 질수록 표면조도가 증가함을 알 수 있었다. 4개의 각 시료위에 thermal evaporation 증착법을 이용하여 $CeO_2$를 18.3nm의 두께로 증착한 후 PLD를 이용하여 YBCO 초전도 박막을 300nm 두께로 증착하였고 77K, 0T에서 임계전류가 각각 0, 6A, 7.5A, 5A로 측정되었다. 이는 YSZ층의 두께가 두꺼워질수록 기판 구성원자의 확산방지역할을 충실히 하는 반면에 표면조도는 증가함을 알 수 있었다.