• Korean Chemical Engineering Research
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• v.56 no.1
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• pp.125-132
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• 2018

The direct synthesis of $C_2$ chemical directly from methane was studied by employing catalysts with ordered mesopores in a dielectric barrier discharge plasma reactor. The reaction was carried out using MgO/OMA (ordered mesoporous alumina), $MgO/{\gamma}-Al_2O_3$ and $MgO/{\alpha}-Al_2O_3$ as catalysts. When MgO/OMA was applied, it showed excellent performance in the plasma reactor using pulse-type power supply and the selectivity of $C_2$ chemicals was measured as 67%. The effects of metal oxide type, textural property of support, alumina phase and power supply type on catalytic performance were investigated especially in terms of $C_2$ chemical formation. BET (Brunauer, Emmett, Teller), X-ray diffraction, transmission electron microscope and thermogravimetric analysis were used to investigate the characterization of the catalyst before and after the reaction.

• Polymer(Korea)
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• v.35 no.3
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• pp.244-248
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• 2011

Poly(2,6-dimethyl-1,4-phenylene ether) (PPE) was synthesized by oxidative polymerization using various Cu(I)-amine catalyst system. The effects of catalyst/monomer ratio, different amine ligand, and the content of 2,4,6-trimethylphenol (TMP) additive on the polymer yield and molecular weight were investigated by using gel permeation chromatography. The catalytic activity of various Cu-amine systems on the 2,S-dimethylphenol (DMP) polymerization was monitored and compared each other through oxygen-uptake experiment. In addition, the effect of catalyst removal using aqueous EDTA on the thermal stability of the prepared polymer was elucidated by thermogravimetric analysis.

• Preventive Nutrition and Food Science
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• v.1 no.1
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• pp.111-116
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• 1996

Polyphenol oxidase(PPO) isolated from the crude extract of ascidian, Halocynthia roretzi, showed higher affinity for catechol than tyrosine or DL-DOPA. Successful enzyme assay could be performed at $25^{\circ}C$, 10min. by mixing 0.2ml of crude enzyme extract with 2.8ml of 0.13M catechol in 0.1M sodium phosphate buffer(pH 6.4). The specific activity of PPO which had been purified with a combination of ammonium sulfate treatment, ion exchange chromatography on DEAE-cellulose, and gel filtration on Sepharose 6B was 13-fold disc gel electrophoresis. The activity of PPO was stable from pH 5.0 to 8.0 and showed the peak activity at pH 6.4 .The optimum reaction temperature for PPO oxidation on catechol was 35$^{\circ}C$ and those enzyme were heat stable up to 4$0^{\circ}C$. Molecular weigth of the enzyme was estimated about 170kDa. One molecule was found to be composed of gour subunits. Two of them had molecular weigh of 55kDa and the others 30kDa. The {TEX}$K_{m}${/TEX} values, {TEX}$V_{max}${/TEX} and catalytic efficiency({TEX}$V_{max}${/TEX}/{TEX}$K_{m}${/TEX}) for catechol were 0.12mM, 2.5mM/liter/min. and {TEX}$0.18min^{-1}${/TEX} respectively. The substrate affinity and electrophorectic pattern suggested that the enzyme of ascidian was considered to be not tyosine but catechol oxidase.

• Membrane Journal
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• v.31 no.2
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• pp.120-132
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• 2021

Microbial fuel cell (MFC) is a bio-electrochemical device that generates electricity by utilizing bacterial catalytic activity that degrades wastewater. Proton exchange membrane (PEM) is the core component of MFC that decides its performance, and Nafion membrane is the most widely used PEM. In spite of the excellent performance of Nafion, it has drawbacks such as high cost, biofouling issue, and non-biodegradable property. Recent studies in MFC attempted to synthetize the alternative membrane for Nafion by incorporating various polymers, sulfonating, fluorinating, and doping other chemicals. This review summarizes characteristics and performances of different composite membrane based MFCs, mostly focusing on PEM.

• Journal of Electrochemical Science and Technology
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• v.10 no.3
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• pp.335-343
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• 2019

In this study, $Sr_2Ni_{1.8}Mo_{0.2}O_{6-{\delta}}$ (SNM) with a double perovskite structure was investigated as an alternative anode for use in the $CH_4$ fuel in solid oxide fuel cells. SNM demonstrates a double perovskite phase over $600^{\circ}C$ and marginal crystallization at higher temperatures. The Ni nanoparticles were exsolved from the SNM anode during the fabrication process. As the SNM anode demonstrates poor electrochemical and electro-catalytic properties in the $H_2$ and $CH_4$ fuels, it was modified by applying a samarium-doped ceria (SDC) coating on its surface to improve the cell performance. As a result of this SDC modification, the cell performance improved from $39.4mW/cm^2$ to $117.7mW/cm^2$ in $H_2$ and from $15.9mW/cm^2$ to $66.6mW/cm^2$ in $CH_4$ at $850^{\circ}C$. The mixed ionic and electronic conductive property of the SDC provided electrochemical oxidation sites that are beyond the triple boundary phase sites in the SNM anode. In addition, the carbon deposition on the SDC thin layer was minimized due to the SDC's excellent oxygen ion conductivity.

• Journal of Mushroom
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• v.21 no.4
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• pp.209-214
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• 2023

In this study, Pleurotus ostreatus No.42 was cultured in glucose-peptone-yeast-wheat bran medium using a previously reported novel rotary draft tube bioreactor. Versatile peroxidase (VP), a lignin-degrading enzyme, was isolated from a pellet-type mycelium culture grown in the medium for seven days. The VP was purified by sequentially applying ultra-filtration, DEAE-Sepharose CL-6B column, and Mono Q column. SDS-PAGE analysis revealed the molecular weight of VP to be 36.4 KDa with an isoelectric point of 3.65. The amino acid sequence was confirmed as VTCATGQTT. The purified VP was observed to possess the property of not only oxidizing Mn ions but also decomposing veratryl alcohol, a non-phenolic compound. The catalytic ability of VP is a subject for future research.

• Transactions of the Korean hydrogen and new energy society
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• v.31 no.1
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• pp.57-64
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• 2020

The water-gas shift reaction for the compact reformer was carried out at a gas hourly space velocity of 72,152 h^-1 over the Cu-Nb-CeO₂ catalysts prepared by co-precipitation method. In order to investigate the effect of Nb₂O₅ promotion over a Cu-CeO₂ catalyst, the Nb₂O₅ loading amount was systematically changed from 0 to 5 wt.%. Among the prepared catalysts, the Cu-Nb-CeO₂ (1%) catalyst showed the highest catalytic activity (CO conversion=61% at 400℃) as well as 100% CO₂ selectivity. The high activity and stability of Cu-Nb-CeO₂ (1%) catalyst are correlated to high Brunauer-Emmett-Teller surface area, small metallic Cu crystallite size, and enhanced redox property.

• Applied Chemistry for Engineering
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• v.2 no.4
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• pp.330-339
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• 1991

The acid properties of $V_2O_5-TiO_2/SiO_2$ catalysts and the partial oxidation of o-xylene into phthalic anhydride had been investigated in order to relate the acid property of catalyst to the catalytic activity. $V_2O_5$ had both weak (V=O) and strong (V-O-V) acid sites which gave pyridine desorption peaks at $230^{\circ}C$ and $300^{\circ}C$, respectively, and the amount of weak acid sites at $230^{\circ}C$ decreased with the increase of calcination temperature. On the other hand, the amount of weak acid sites increased considerably by increasing the amount of $TiO_2$ to the $V_2O_5-TiO_2/SiO_5$, and the maximum value was shown at 20 and higher mole % of $TiO_2$ with respect to $SiO_2$. In the oxidation of o-xylene, $V_2O_5-TiO_2/SiO_2$ enhandced more the total conversion and the selectivity to phthalic anhydride than $V_2O_5/SiO_2$, and the higher $TiO_2$ ratio to $V_2O_5$ increased the total conversion but could not change the selectivity to phthalic anhydride. Weak acid sites (V=O) led o-xylene to partial oxidation producing phthalic anhydride by adsorbing o-xylene weakly, while acid sites (V-O-V) led it to total oxidation producing CO and $CO_2$ by adsorbing it strongly.

• Applied Chemistry for Engineering
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• v.25 no.1
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• pp.41-46
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• 2014

The property improvement of polycarbonate coated with a multilayer film composed of an inorganic $SiO_2$ film and a photocatalytic $TiO_2$ film was studied. The $SiO_2$ film as a binder had an excellent light transmission characteristic. After the treatment with atmospheric pressure plasma, the surface of $SiO_2$ film showed the hydrophilicity, which increased the film coating uniformity with a $TiO_2$-containing aqueous solution. When $TiO_2$ film was over 200 nm thick, the absorption effect of UV rays in the range of 180~400 nm suppressed the yellowing phenomena of polycarbonate substrate. The inorganic film improved the heat resistance of polycarbonate substrates. $TiO_2$ film in the outmost under the exposure of UV rays promotes the catalytic oxidation characteristics and yields the capability to the decomposition of organic contaminants, and also increases the self-cleaning properties due to the increase of hydrophilicity. Structural stability of the polycarbonate substrate coated with inorganic $TiO_2$ and $SiO_2$ film was shown. The role of $SiO_2$ film between $TiO_2$ and polycarbonate substrate suppressed the peeling of $TiO_2$ film by inhibiting the photocatalytic oxidation effect of $TiO_2$ film on the polycarbonate substrate.

• Applied Chemistry for Engineering
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• v.26 no.2
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• pp.138-144
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• 2015

Effects of Co/Al and Si/Al molar ratios of cobalt incorporated SAPO-34 catalysts (CoAPSO-34) on their catalytic lifetime were investigated in dimethyl to olefin (DTO) reaction. The property of CoAPSO-34 catalysts was characterized using XRD, SEM, $^{29}Si$ MAS NMR, and $NH_3$-TPD techniques. First, the lifetime of CoAPSO-34 prepared by varying Co/Al molar ratios was improved than that of using the SAPO-34 catalyst, and the optimal Co/Al molar ratio was 0.0025. The total acid site amounts increased from 0.432 to 1.111 mmol/g with increasing Si/Al molar ratios from 0.05 to 0.20 while fixing a Co/Al molar ratio of 0.0025. However, the catalysts with too high acid site amounts were deactivated rapidly with blockages of the pores due to the fast accumulation of polycyclic aromatic hydrocarbons in the cage. Therefore, the CoAPSO-34 catalyst with a proper Si/Al molar ratio of 0.10 was the most superior in terms of the lifetime, which was improved by about 87% as compared with that of the SAPO-34 catalyst.