• Bulletin of the Korean Chemical Society
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• v.28 no.5
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• pp.805-810
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• 2007

Molecular recognition for a specific cation depending on the change of the oxidation state of the metal catalyst component contained in the hydrogel network has been studied in a self-oscillating hydrogel. The selfoscillating hydrogels are synthesized by the copolymerization of N-isopropylacrylamide (NIPAAm), lead methacrylic acid (Pb(MAA)2), and Ru(bpy)3 2+ monomer as a metal catalyst component. The recognition for a specific cation (in this study, Ca2+ has been used) is characterized by the adsorbed amount of Ca2+ into the gel. The recognition of the gels for Ca2+ is higher at the temperature below the LCST, and also higher at the oxidized state than at reduced state of the metal catalyst component which corresponds to a more swollen state. Moreover, a propagating wave induced by a periodic change of the oxidation state with the diffusion phenomena in the oscillating hydrogel shows a possibility for temporal and site-specific molecular recognition due to the local swelling of the gel.

• Applied Chemistry for Engineering
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• v.9 no.4
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• pp.497-503
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• 1998

The catalytic oxidation of 1.2-dichloroethane was investigated over precious metal supported on alumina using a fixed bed microreactor. Among the catalysts tested, the conversion of 1.2-dichloroethane decreased in the following order : Ru > Pt > Pd $${\sim_=}$$ Rh and Pt was found to be the most active catalyst for the complete oxidation of 1.2-dichloroethane to $CO_2$. Major products containing carbon were vinyl chloride and $Co_2$ at temperature ranging from 200 to $400^{\circ}C$. The presence of vinyl chloride in products suggests that the first step in the oxidation of 1.2-dichloroethane is dehydrochlorination and the second is oxidation of vinyl chloride to $CO_2$. To investigate the effect of HCl on the activity of the complete oxidation, some experiments were conducted by adding HCl to the feed. The presence of HCl increased the conversion of 1.2-dichloroethane below $300^{\circ}C$ owing to the increase of surface acidity, but it didn't affect the conversion above $300^{\circ}C$. The reversible adsorption of HCl onto catalyst surface inhibited the complete oxidation to $CO_2$.

• Applied Chemistry for Engineering
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• v.21 no.1
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• pp.1-5
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• 2010

Cu(II)-organic complexes were synthesized with Lewis base organic ligands including diamine, aminothiol, and dithiol to determine the reactivity for DFP hydrolysis. Results show that the aminothiol catalyst enhances the hydrolysis of DFP in three folds compared to diamine type because aminothiol has higher basicity than diamine. Due to low solubility of Cu(II)(1,2-ethane dithiol)$(NO_3)_2$, it is impossible to compare directly the rates in homogeneous condition. However, the rate of dithol complex is even 1.6 times faster than that of the diamine type. The reactivity of zeolite for DFP hydrolysis is also evaluated. NaY type does not promote the hydrolysis, but RuNaY shows relatively lower reactivity than those of Cu(II)-organic ligands complexes.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.12
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• pp.2263-2273
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• 2000

Catalytic wet air oxidation of acetic acid over Mn-Ce based catalysts deposited on various supports ($SiO_2$, $TiO_2$, $ZrO_2$), $ZrSiO_4$, $ZrO_2(10wt%)/TiO_2$) have been carried out in high pressure microreactors. Also, promotional effects by small addition(O.5~1.0 wt%) of p-type semiconductors (CoO, $Ag_2O$, SnO) have been investigated. From the screening tests for initial activity ranking, both Mn(2.8)-Ce(7.2 wt%) and Ru(O.4)Mn(2.7)-Ce(6.9 wt%) supported on $TiO_2$ were selected as the promising reference candidates. In $Mn-Ce/TiO_2$ reference catalyst, addition of small amount of each p-type semiconductor (Co, Sn and Ag) resulted in activity promotional effect and the degree of the increase was in the following order: Co> Ag > Sn. Especially, $Mn-Ce/TiO_2$ promoted with 0.5 wt% Co gave the 2.6 folds activity increase compared to the reference case attributing to the surface area increase as well as synergy effect. In $Ru-Mn-Ce/TiO_2$ reference catalyst, only Co(1.0 wt%) promoted case showed a little reaction rate increase.

• Journal of Electrochemical Science and Technology
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• v.1 no.1
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• pp.19-24
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• 2010

Alloying degree is an important structural factor of PtRu catalysts for direct methanol fuel cells (DMFC). In this work, carbon supported PtRu catalysts were synthesized by reduction method using anhydrous ethanol as a solvent and $NaBH_4$ as a reducing agent. Using anhydrous ethanol as a solvent resulted in high alloying degree and good dispersion. The morphological structure and crystallanity of synthesized catalysts were characterized by X-ray diffraction (XRD), high resolution transmission electron microscope (HR-TEM). CO stripping and methanol oxidation reaction were measured. Due to high alloying degree catalyst prepared in anhydrous ethanol, exhibited low onset potential for methanol oxidation and negative peak shift of CO oxidation than commercial sample. Consequently, samples, applying ethanol as a solvent, exhibited not only enhanced CO oxidation, but also increased methanol oxidation reaction (MOR) activity compared with commercial PtRu/C (40 wt%, E-tek) and 40 wt% PtRu/C prepared in water solution.

• Korean Chemical Engineering Research
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• v.50 no.5
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• pp.802-807
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• 2012

The autothermal reforming of methane to syngas has been carried out in a reactor charged with both a Ni (15 wt%)-Ru (1 wt%)/$Al_2O_3$-MgO metallic monolith catalyst and an electrically-heated convertor (EHC). The standalone type reactor has a start-up time of less than 2 min with the reactant gas of $700^{\circ}C$ fed to the autothermal reactor. The $O_2/CH_4$ and $H_2O/CH_4$ ratio governed the methane conversion and temperature profile of reactor. The reactor temperature increased as the reaction shifted from endothermic to exothermic reaction with decreasing $H_2O/CH_4$ ratio. Also the amount of $CO_2$ in the products increases with increasing $H_2O/CH_4$ ratio due to water gas shift reaction. The 97% of $CH_4$ conversion was obtained and the reactor temperature was maintained $600^{\circ}C$ at the condition of $GHSV=10,000\;h^{-1}$ and feed ratio ($H_2O/CH_4=0.6$ and $O_2/CH_4=0.5$). In this condition, the maximum flow rate of the syngas generated from the reactor charged with 170 cc of the metallic monolith catalyst is $0.94\;Nm^3/h$.

• Korean Chemical Engineering Research
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• v.47 no.3
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• pp.362-367
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• 2009

Recently, the use of formic acid as a fuel for direct liquid fuel cells has emerged as a promising alternative to methanol. In the work presented herein, we evaluated direct formic acid fuel cells(DFAFCs) with various components under operating conditions, for example, the thickness of the proton exchange membrane, concentration of formic acid, gas diffusion layer, and commercial catalyst. The thickness of the proton exchange membrane influenced performance related to the fuel cross-over. To optimize the cell performance, we investigated on the proper concentration of formic acid and catalyst for the formic acid oxidation. Consequently, membrance-electrode assembly(MEA) consisted of $Nafion^{(R)}$-115 and the Pt-Ru black as a anode catalyst showed the maximum performance. This performance was superior to the DMFCs' one.

• Journal of the Korean Electrochemical Society
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• v.23 no.4
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• pp.97-104
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• 2020

One of the main challenges of electrochemical water splitting technology is to develop a high performance, low cost oxygen-evolving electrode capable of substituting a noble metal catalyst, Ir or Ru based catalyst. In this work, CoFe₂O₄ nanoparticles with sub-44 nmsize of a inverse spinel structure for oxygen evolution reaction (OER) were synthesized by the injection of KNO₃ and NaOH solution to a preheated CoSO₄ and Fe(NO₃)₃ solution. The synthesis time of CoFe₂O₄ nanoparticles was controlled to control particle and crystallite size. When the synthesis time was 6 h, CoFe₂O₄ nanoparticles had high conductivity and electrochemical surface area. The overpotential at current denstiy of 10 mA/㎠ and Tafel slope of CoFe₂O₄ (6h) were 395 mV and 52 mV/dec, respectively. In addition, the catalyst showed excellent durability for 18 hours at 10 mA/㎠.

• Applied Chemistry for Engineering
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• v.32 no.4
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• pp.409-416
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• 2021

Dimensionally stable electrodes are one of the important components in electrochemical water treatment processes. In the manufacturing of the dimensionally stable electrodes, the type of metal catalyst coated on the surface of the metal substrate, the coating and sintering methods substantially influence their performance and durability. In this study, using Ir-Ru-Ta ternary metal coating, various electrodes were prepared depending on the coating method under the same pre-treatment and sintering conditions, and its performance and durability were studied. As a coating method, brush and spray coating were used. As a result, the reduction in the amount of catalyst ink was achieved because more amount of metal could be coated for the electrode using spraying with the same amount of catalyst ink. In addition, the spray_2.0_3.0 electrode prepared by a specific spray coating method shows the phenomenon of cracking and the uniform coating of the ternary metal on the surface of the coating layer, and results in a high electrochemically active specific surface area, and the decomposition performance of 4-chlorophenol was superior to the other electrodes. However, it was found that there was no significant difference in durability depending on the coating method.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.158.2-158.2
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• 2011

DME is acronym of dimethyl ether, which is spotlighted as an ideal fuel to produce hydrogen due to its high hydrogen/carbon ratio, high energy density and easiness to carry. In this research, we calculated thermodynamic hydrogen (or syngas) yield from DME autothermal reforming and compared to other fuels. The reforming efficiency was about 80% above $700^{\circ}C$. Lower OCR has higher reforming efficiency but, it requires additional heat supply since the reactions are endothermic. SCR has no significant effect on the reforming efficiency. The optimized condition is $700^{\circ}C$, SCR 1.5, OCR 0.45 without additional heat supply. Comparing to other commercial gaseous fuels (methane and propane), DME has higher selectivity of $H_2O$ and $CO_2$ than the others due to the oxygen atom in the molecule. To apply DME autothermal reforming to real system, a proper catalyst is required. Therefore, it is performed the experiment comparing various novel metal catalysts based on CGO. Experiments were performed at calculated condition. The composition of product was measured and reforming efficiency was calculated. The catalysts have similar efficiency at high temperature(${\sim}800^{\circ}C$) but, CGO-Ru has the highest efficiency at low temperature ($600^{\circ}C$).