• Applied Chemistry for Engineering
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• v.9 no.7
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• pp.1070-1078
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• 1998

Thermodynamic analysis on carbon dioxide reforming of methane was performed using a computer program which can handle condensed species in the products, and the reforming experiments were conducted over $Al_2O_3$, $La_2O_3$, ZSM-5, MCM-41, KIT-1 supported nickel catalysts, and a commercial ICI 46-1. It was estabished that a system which consists of $CH_4$, $CO_2$, CO, $H_2$, $H_2O$, and C is appropriate for theoretical equilibrium calculations and addition of water vapor or oxygen was found to diminish the contribution of carbon dioxide in reforming. Silicate molecular sieve-supported catalysts such as Ni/ZSM-5, Ni/MCM-41, Ni/KIT-1 were effective for high $CH_4$ and $CO_2$ conversions as well as for high CO yield. Coke formation was suppressed when CaO was added as a promoter. Ni/Ca/KIT-1 which contains 10% Ni with 3% Ca showed conversion approaching equilibrium levels above $650^{\circ}C$ and maintained constant activity over 20 h. Despite increased space velocity, relatively high conversion and CO yield were observed.

• Journal of Energy Engineering
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• v.12 no.2
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• pp.145-153
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• 2003

In order to develop the carbonation process as a core technology of zero emission coal power plant, study on characterization of methane steam reforming (MSR) which is main reaction of this process was carried out. The effects of gas hourly space velocity (GHSV), steam/carbon (S/C) ratio and pressure in the MSR using reforming catalyst were investigated. The equilibrium composition of the gases produced in the MSR were obtained below GHSV 7,000 hr$\^$-1/. The operating conditions of carbonation process using hybrid reaction (MSR+CO$_2$ adsorption using CaO) were 700∼800$^{\circ}C$ and S/C ratio of 2.5∼3. The equilibrium mixture of gases composed of 75∼78% H$_2$ and 8∼9％ CO$_2$ at atmospheric pressure and 60∼78% H$_2$ and 9∼l1% CO$_2$ at 1∼30 atm respectively under above operating conditions.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.3
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• pp.248-254
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• 1998

In the present study the glow discharge characteristics of $CO_2$ in a parallel plate electrode system were investigated, and the decomposition properties of $CO_2$ concerned with the discharge characteristics were discussed. The results show that $CO_2$ concentration decreases with increase in discharge power and decrease in gas pressure. The maximum conversion of $CO_2$ by glow discharge was 52% under the conditions of gas pressure, 10m Torr and 290W of discharge power.

• Applied Chemistry for Engineering
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• v.7 no.1
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• pp.26-33
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• 1996

This study is related to the investigation of the characteristics of phase transfer catalysts on the addition reaction of carbon dioxide and phenyl glycidyl ether(PGE). Quaternary ammonium salts showed a good conversion of PGE at l atm of $CO_2$. Among the quaternary ammonium salts tested, the ones with higher alkyl chain length and with more hydrophilic counter anion showed higher catalytic activity. Polyethylene glycol and crown ether were also effective catalysts when they are used with NaI. High pressure of $CO_2$increased the conversion of PGE by increasing solubility of $CO_2$in NMP. A mechanism of the reaction involving the role of phase transfer catalyst was also proposed.

• Korean Chemical Engineering Research
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• v.50 no.2
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• pp.217-222
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• 2012

The synthesis of dimethyl carbonate(DMC) is a promising reaction for the use of naturally abundant carbon dioxide. DMC has gained considerable interest owing to its versatile chemical reactivity and unique properties such as high oxygen content, low toxicity, and excellent biodegradability. In this study, the synthesis of DMC through the transesterification of ethylene carbonate(EC) with methanol was investigated by using ionic liquid and metal oxide catalysts. The screening test of different catalysts revealed that choline hydroxide ([Choline][OH]) and 1-n-butyl-3-methyl imidazolium hydroxide([BMIm][OH]) had better catalytic performance than metal salts catalysts such as MgO, ZnO and CaO. The effects of reaction parameters such as reaction temperature, MeOH/EC mole ratio, and carbon dioxide pressure on the reactivity of [Choline][OH] catalyst were discussed. High temperature and high MeOH/EC mole ratio were favorable for high conversion of EC. However, the yield of DMC showed a maximum when carbon dioxide pressure was 1.34 MPa, and then it decreased for higher carbon dioxide pressure. Zinc chloride($ZnCl_2$) was used as co-catalyst with the ionic liquid catalyst. The mixed catalyst showed a synergy effect on the EC conversion and DMC yield probably due to the acid-base properties of the catalysts.

• Applied Chemistry for Engineering
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• v.2 no.2
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• pp.165-174
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• 1991

The kinetics and the mechanism for the selective oxidation of ethylene on the supported monolithic silver catalyst were experimentally investigated in a fixed bed tubular reactor. The formation rates of ethylene oxide and carbon dioxide were measured at the atmospheric pressure with various combinations of partial pressures of ethylene and oxygen at temperature range of $225-300^{\circ}C$, conversion with 1.2-7.5 %, and then the mechanism of the selective oxidation of ethylene was verified. Their formation rates fitted with the Langmuir-Hinshelwood mechnism. The ethylene oxide and carbon dioxide are produced by reation of adsorbed ethylene with monoatomic oxygen adsorbed on the active sites of Ag-surface, and their formation rate equation are expressed as : $R_{EO}={\frac{k_1K_0{^{1/2}}K_EK_SP_{02}{^{3/2}}P_E}{(1+{\sqrt{K_0P_{02}}}+K_EP_E+K_PP_P)^2(1+{\sqrt{K_SP_{02}})^2}}$ $R_C={\frac{k_2K_0{^3}K_EK_S{^{7/2}}P_{02}{^{13/2}}P_E}{(1+{\sqrt{K_0P_{02}}}+K_EP_E+K_PP_P)^7(1+{\sqrt{K_SP_{02}})^7}}$ The activation energies of ethylene oxide and dioxide and carbon dioxide formations can be estimated to be 12.25 and 17.85 Kcal/mol, respectively.

• Applied Chemistry for Engineering
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• v.5 no.4
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• pp.580-587
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• 1994

The oxidative coupling of methane was studied kinetically using $Na^+(50wt%)/MgO$ catalyst at 710, 730, 750, 770 and $790^{\circ}C$ in a fixed bed flow reactor at the atmospheric pressure under differential conversion conditions. Through curve fitting, it was found that the Langmuir-Hinshelwood type mechanism was fitted to this reaction rather than Rideal-Redox type or Eley-Rideal type mechanism. Therefore, it was proposed that the $O_2{^-}$ or $O_2{^{2-}}$ species on the surface was related to the production of $CH_3{\cdot}$. The estimated activation energy of $CH_3{\cdot}$ production was about 39.3kcal/mol. Moreover, as the result of curve fitting, the stoichiometric coefficient of $O_2$ for the production of $CH_3{\cdot}$ to produce $CO_x$was approximately 1.5. Accordingly, it could be concluded that the $CH_3O_2{\cdot}*$ was prouduced through the partial oxidation of $CH_3{\cdot}$ with the surface oxygen.

• Korean Chemical Engineering Research
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• v.47 no.6
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• pp.727-733
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• 2009

Effects of $Ca(OH)_2$ concentration(0.16~0.64 wt%), total volumetric flow rate(3~6 L/min) and $CO_2$ volume fraction(0.3~0.6) on morphology of the precipitated $CaCO_3$ and the mean particle size of the precipitated $CaCO_3$ were investigated in the slurry bubble column reactor. Experiments were carried out in acrylic reactor($0.11m-ID{\times}1.0m-high$) with a internal tube($0.04m-ID{\times}1.0m-high$). The calibration curve on the mass ratio of $CaCO_3$ to $Ca(OH)_2$ was obtained by FT-IR for the conversion of $Ca(OH)_2$ with the reaction time. The reaction rate of $Ca(OH)_2$ increased with increasing the volumetric flow rate of $CO_2$. From SEM images, the crystal size of $CaCO_3$ increased with increasing the reaction rate in the saturated concentration of $Ca(OH)_2$ (0.16 wt%). In addition, the crystal size of precipitated $CaCO_3$ decreased with increasing the concentration of $Ca(OH)_2$, but the mean particle size of precipitated $CaCO_3$ increased with increasing the concentration of $Ca(OH)_2$.