• Applied Chemistry for Engineering
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• v.18 no.4
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• pp.303-313
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• 2007

Various commercial catalysts used in chemical related applications have been disposed as an industrial waste when the catalytic activity of catalysts is not good enough to achieve an optimum yield. In addition, the amount of disposed three way catalysts (TWC) has been continuously increased. Considering the physicochemical, environmental, and economical characteristics, the deactivated spent catalysts can be treated in several alternative ways such as regeneration, recycling, and disposal. In view of the environmental and economical matters, the spent catalyst should be regenerated and used for the various purposes, although its activity is not as good as a fresh catalyst. On the other hand, spent catalysts containing noble and metal oxides can be applicable for the catalytic oxidation of volatile organic compounds (VOCs) by applying the proper treatment method. Therefore in this review the quantity of the spent catalysts and the available regeneration methods for the spent catalysts are briefly summarized and especially the proper regeneration method for applying the catalytic oxidation of VOCs and its results are introduced.

• The Microorganisms and Industry
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• v.20 no.1
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• pp.38-41
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• 1994

아미노산은 발효법, 합성법, 효소법, 추출법 등으로 제조되고 있으며, 아미노산 시장의 대부분을 차지하는 glutamic acid, lysine, methionine, glycine, phenylalanine등의 주요 아미노산은 전통적인 발효법과 합성법에 의해 주로 제조되고 있다(1-3). 표 1에 주요 아미노산의 생산량, 제조법, 용도들을 표시하였다. 최근 고정화효소법 및 화학합성법과 효소법을 병행한 반합성법(hybrid process 또는 chemico-enzymatic process라고도 함) 등의 새로운 아미노산 제조법(3-7)이 개발되어 주목되고 있다. 이러한 새로운 아미노산 제조법은 효소를 촉매라는 시각에서 수행하고 있기 때문에 생물촉매법이라 총칭하며, 생물촉매법은 화학반응으로는 곤란한 반응을 효소반응의 도입에 의하여 효율적으로 수행할 수 있는 특징과 각종 연관 아미노산 화합물을 동시에 제조할 수 있다는 대단히 유리한 장점 때문에 새로운 아미노산 제조법으로 점차 기업화되고 잇는 추세이다. 따라서, 본고에서는 생물촉매를 이용한 아미노산의 새로운 제조법에 대하여 소개하고자 한다.

• Journal of the Korean Electrochemical Society
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• v.21 no.4
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• pp.61-67
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• 2018

As emerging the new electric devices, the commercial lithium ion batteries have faced with various challenges. In this regard, many efforts to solve challenges have been tried. In order to solve the above problems in terms of development of a new secondary battery, we successfully demonstrated the two electrocatalysts, such as MCWB and PPY hydrogel, PPY hydrogel and MCWB showed typical H3-type BET isotherm, indicating that micro- and mesopores existed. Especially, in terms of voltage efficiency at the first cycle, PPY hydrogel was higher than that of MCWB, but lower than that of PtC. More interestingly, the PPY hygrogel based seawater battery exhibited charge-discharge reversibility during 20 cycles, and the voltage efficiencies ranged from 70.32 % to 77.35 % in cyclic performance test.

• Journal of the Korean Electrochemical Society
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• v.12 no.1
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• pp.11-25
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• 2009

Fuel cells are expected to be one of the major clean new energy sources in the near future. However, the slow kinetics of electrocatalytic hydrogen oxidation reaction (HOR) and oxygen reduction reaction (ORR), and the high loading of Pt for the anode and cathode material are the urgent issues to be addressed since they determine the efficiency and the cost of this energy source. In this review paper, a new approach was developed for designing electrocatalysts for the HOR and ORR in fuel cells. It was found that the electronic properties of Pt could be fine-tuned by the electronic and geometric effects introduced by the substrate alloy metal and the lateral effects of the neighboring metal atoms. The role of substrate was found reflected in a volcano plot for the HOR and ORR as a function of their calculated d-band centers. This paper demonstrated a viable way to designing the electrocatalysts which could successfully alleviate two issue facing the commercializing of the fuel cell-the cost of electrocatalysts and their efficiency.

• Applied Chemistry for Engineering
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• v.4 no.4
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• pp.692-700
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• 1993

Corrosivities and catalytic activities of platinum-transition metal alloy catalyses loaded on carbon substrate and were studied by electrochemical method using a unit cell. And the analysis of Pt-alloy catalyst was conducted by x-ray diffractometer. Among the catalysts, the Pt-Mo/carbon, Pt-Fe-Co/carbon and Pt-Fe/carbon catalyst showed more excellent cathodic current densities than others. It was found that most of cathodic current density for the Pt-Mo/carbon electrode was $120mA/cm^2$. The current density of the Pt-Fe-Co/carbon was much higher than that of Pt/carbon, reaching $200mA/cm^2$.

• Applied Chemistry for Engineering
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• v.35 no.5
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• pp.361-371
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• 2024

This study reviews recent advancements in Ni-based catalysts for CO₂ methanation, emphasizing high thermal stability and catalytic performance at elevated temperatures. Ni catalysts are preferred for their strong hydrogen adsorption, high activity, and methane selectivity. Strategies such as optimizing metal loading, using efficient supports, and introducing promoters enhance thermal stability by preventing sintering and carbon deposition. The produced methane serves as a valuable feedstock for synthetic fuels and chemicals, improving the economic feasibility of the CO₂ methanation process. These findings underscore the importance of thermal stability in developing effective Ni catalysts for large-scale CO₂ methanation.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.4
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• pp.186-193
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• 2017

Microwave (MW) is an effective method for solubilizing organic solids because it has thermal, non-thermal and ionic conduction effects by dielectric heating and high energy efficiency. In this study, we evaluated the application of MW to the solubilization of cattle manure and investigated the solubilization ratio of cattle manure by solid concentration, MW power and target temperature. And $H_2SO_4$ and NaCl were added to investigated the effects on the MW-assisted solubilization. Also, we evaluated the solubilization efficiency by biochemical methane potential(BMP) test according to the solubilization conditions. Maximum SCOD increment per energy supply was 70.5 mg $SCOD_{increased}/kJ$ at 12% of the solid concentration, MW power of 800 W and the target temperature of $40^{\circ}C$. And SCOD concentration went up 153.2% compared to the initial concentration. In the MW-assisted solubilization with $H_2SO_4$ and NaCl as chemical catalysts, SCOD concentration was increased by 36% and 22.7%, respectively, compared to the result of MW. The methane production was increased by 13.3% and 11.3% with the addition of $H_2SO_4$ and NaCl. Therefore, MW is an effective method for solubilization of cattle manure, and it is necessary to use chemical catalysts to increase the solubilzation efficiency.

• Journal of the Korean Chemical Society
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• v.64 no.1
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• pp.49-53
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• 2020

• Journal of Energy Engineering
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• v.23 no.3
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• pp.157-162
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• 2014

In this research, we investigate electrical performance and electrochemical properties of carbon supported Pt (Pt/C) that is synthesized by polyol method. With the Polyol_Pt/C that is adopted for oxygen reduction reaction (ORR) as cathode of proton exchange membrane fuel cells (PEMFCs), their catalytic activity and ORR performance and electrical performance are estimated and compared with commercial Pt/C(Johnson Mattey) catalyst. Their electrochemically active surface (EAS) area are measured by cyclic voltammetry (CV), respectively. On the other hand, regarding ORR activity and electrical performance of the catalysts, (i) linear sweeping voltammetry by rotating disk electrode and (ii) PEMFC single cell tests are used. The CV measurement demonstrate EAS of Polyol_Pt/C is compared with commercial JM_Pt/C. In case of Polyol_Pt/C, its half-wave potential, kinetic current density are excellent. Based on data obtained by half-cell test, when PEMFC single cell tests are carried out, current density measured at 0.6V and maximum power density of the PEMFC single cell employing Polyol_Pt/C are better than those employing commercial Pt/C. Conclusively, Polyol_Pt/C synthesized by modified polyol process shows better ORR catalytic activity and PEMFC performance than other catalysts.

• Korean Chemical Engineering Research
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• v.57 no.4
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• pp.455-460
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• 2019

Hydrotreating catalysis refers to a various hydrogenation which saturate an unsaturated hydrocarbon, together with removing heteroatoms such as sulfur, nitrogen, oxygen, and trace metals from different petroleum streams in a refinery. Most refineries include at least three hydrotreating units for upgrading naphtha, middle distillates, gas oils, intermediate process streams, and/or residue. Among them, hydrotreating catalysis for residue are the core of the process, because of its complexity. This article reviews recent progress in tackling the issues found in the upgrading residues by hydrotreating, focusing on the chemistry of hydrodemetallization (HDM) and hydrodesulfurization (HDS). We also discuss the composition and functions of hydrotreating catalysts, and we highlight areas for further improvement.