• Bulletin of the Korean Chemical Society
• /
• v.23 no.6
• /
• pp.799-803
• /
• 2002

Partial oxidation of methane has been conducted over $CeO_2$and it has been found that $CeO_2$has an extraordinary catalytic activity in the reaction. Its activity was strongly dependent on the $CH_4/CO_2$ ratio. Total combustion was dominant with stoichiometric feed ratio$(CH_4/O_2=$ 2.0) but partial oxidation was achieved between the $CH_4/O_2$ ration of 3.8 4.3 and the period depended upon the feed composition. The proposed raaction mechanism it that oxygen vacancies in raduced deria are supplied with oxygen molecules from the reactant, and then activate adsorbed oxygen, followed by releasing activated axygen species reacting with methane to produce $H_2$ and CO.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09b
• /
• pp.857-858
• /
• 2006

In order to clarify the wear resistance as cutting tools, the effect of oxygen addition on oxidation behavior of the ${\beta}-Si_3N_4$ ceramics with 5 mass% $Y_2O_3$ and 2 or 4 mass% $Al_2O_3$ was investigated by performing oxidation tests in air at $1300^{\circ}$ to $1400^{\circ}C$ and cutting performance tests. From test results, we could conclude that the mechanical properties of ${\beta}-Si_3N_4$ ceramics depending on oxygen introduction are much effective on cutting performance improvements of ${\beta}-Si_3N_4$ ceramics.

• Bulletin of the Korean Chemical Society
• /
• v.28 no.12
• /
• pp.2442-2444
• /
• 2007

CO adsorbates on the surface of Pt supported on carbon catalysts (Pt/C) were investigated by CO stripping voltammetry. Three types of CO adsorbed samples were prepared: by methanol dehydrogenation only (COm), by CO gas bubbling only (COg), and by methanol dehydrogenation followed by CO gas bubbling (COm+g). Our coverage data show that CO gas can be adsorbed on Pt/C catalyst already saturated with CO adsorbates by methanol dehydrogenation. The COm+g sample showed the properties of both COm as well as COg samples in terms of the potential although the CO adsorbed by dehydrogenation was completely exchanged with CO in the electrolyte solution. Therefore, the oxidation pathways of CO on Pt/C were observed to depend on the initial adsorption conditions of CO more strongly than on the CO coverage. Our results imply that an initial CO poisoning condition in fuel cell operation is an important factor to determine the difficulty in removing the adsorbed CO and confirm that the properties of the adsorbed CO do not change even with chemical replacement with CO in different conditions. In addition, our results indicate a low CO surface mobility on the Pt in an electrolyte solution.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.08a
• /
• pp.70-70
• /
• 2013

As the costs of carbon-footprinetd fuels grow continuously and simultaneously atmospheric carbon dioxide concentration increases, solar fuels are receiving growing attention as alternative clean energy carriers. These fuels include molecular hydrogen and hydrogen peroxide produced from water, and hydrocarbons converted from carbon dioxide. For high efficiency solar fuel production, not only light absorbers (oxide semiconductors, Si, inorganic complexes, etc) should absorb most sunlight, but also charge separation and interfacial charge transfers need to occur efficiently. With this in mind, this talk will introduce the fundamentals of solar fuel production and artificial photosynthesis, and then discuss in detail on photoelectrochemical (PEC) water splitting and CO2 conversion. This talk largely divides into two section: PEC water oxidation and PEC CO2 reduction. The former is very important for proton-coupled electron transfer to CO2. For this oxidation, a variety of oxide semiconductors have been tested including TiO2, ZnO, WO3, BiVO4, and Fe2O3. Although they are essentially capable of oxidizing water into molecular oxygen, the efficiency is very low primarily because of high overpotentials and slow kinetics. This challenge has been overcome by coupling with oxygen evolving catalysts (OECs) and/or doping donor elements. In the latter, surface-modified p-Si electrodes are fabricated to absorb visible light and catalyze the CO2 reduction. For modification, metal nanoparticles are electrodeposited on the p-Si and their PEC performance is compared.

• Korean Journal of Materials Research
• /
• v.23 no.2
• /
• pp.123-127
• /
• 2013

The electrolytic reduction of a spent oxide fuel involves liberation of the oxygen in a molten LiCl electrolyte, which is a chemically aggressive environment that is too crosive for typical structural materials. Therefore, it is essential to choose the optimum material for the process equipment for handling a molten salt. In this study, the corrosion behavior of pyro-carbon made by CVD was investigated in a molten LiCl-$Li_2O$ salt under an oxidation atmosphere at $650^{\circ}C$ and $750^{\circ}C$ for 72 hours. Pyro-carbon showed no chemical reactions with the molten salt because of its low wettability between pyro-carbon and the molten salt. As a result of XRD analysis, pyro-carbon exposed to the molten salt showed pure graphite after corrosion tests. As a result of TGA, whereas the coated layer by CVD showed high anti-oxidation, the non-coated layer showed relatively low anti-oxidation. The stable phases in the reactions were $C_{(S)}$, $Li_2CO_{3(S)}$, $LiCl_{(l)}$, $Li_2O$ at $650^{\circ}C$ and $C_{(S)}$, $LiCl_{(l)}$, $Li_2O_{(S)}$ at $750^{\circ}C$. $Li_2CO_{(S)}$ was decomposed at $750^{\circ}C$ into $Li_2O_{(S)}$ and $CO_{2(g)}$.

• Journal of Korean Society on Water Environment
• /
• v.38 no.6
• /
• pp.267-274
• /
• 2022

This paper is a result of research conducted on the 800,000 m³/d capacity of A Water Treatment Plant (WTP) and 400,000 m³/d capacity of B WTP plant in operation in the Nakdong River region. We evaluated the effect of algae broom on the WTP operation based on the running data of both WTP and the data on the pre-oxidation process field test for algae control using sodium permanganate (SPM) at the B WTP. The study results showed that during the algal bloom period, the coagulant dose increased by 102% in A WTP and 58% in B WTP, respectively, and the chlorine dose also increased by 38% and 29%, respectively, which may affect Total trihalomethane (THM) production. Data such as algal populations and Chl-a, residual chlorine and THM, algal populations, and ozone dose appeared also highly correlated, confirming that algal broom affects WTP operations, including water quality and chemical dosage. As a result of the field test of B WTP, THMs appeared lower than that of the control, suggesting the possibility of the SPM pre-oxidation process as an alternative to algae-related water quality management. Furthermore, in terms of GHG emissions due to energy consumption, it was observed that the pre-oxidation process using SPM was approximately 10.8%, which is a very low ratio compared to the pre-ozonation process. Therefore, these results suggest that the SPM pre-oxidation process can be recommended as an alternative to low-carbon water purification technology.

• Korean Journal of Metals and Materials
• /
• v.48 no.10
• /
• pp.907-913
• /
• 2010

Hot-rolled steel plates of SPHC and SS400 were oxidized at 600, 750 and $900^{\circ}C$ for 2 hr in air. With an increase in the oxidation temperature, their oxidation rates increased, and this was accompanied by the formation of pores and cracks in the thickened oxide scales, which were non-adherent. SPHC steels manufactured by either an arc furnace or a blast furnace displayed similar oxidation rates, indicating that their oxidation rates were insensitive to the manufacturing process. Medium-carbon SS400 steel displayed somewhat faster oxidation rates than low-carbon SS400 steel, indicating that the carbon content did not significantly influence the oxidation rates.

• Proceedings of the KIEE Conference
• /
• 1988.07a
• /
• pp.363-366
• /
• 1988

A new $NH_{3}-O_{2}$ oxidation method was estimated by the electrical properties of the fabricated n-MOS transistor. For the C-V characteristic curves the Qox are almost equal to Qss and no hysteresis phenomena are observed. The Id-Vds characteristics show that $NH_{3}-O_{2}$ oxidation method is superior to Dry oxidation.

• Bulletin of the Korean Chemical Society
• /
• v.8 no.4
• /
• pp.254-257
• /
• 1987

Palladium dichloro complexes catalysed the oxidation of cyclopentene by dioxygen in tetralin solvent at ambient temperature. Cyclopentanone formed mainly together with autoxidation products from both cyclopentene and tetralin. The oxidation seems to proceed by co-oxidation mechanism, where tetralin was first oxidized to its hydroperoxide which then oxidized cyclopentene to cyclopentanone. Mechanism of the other by-products formations has been discussed.

• Entomological Research
• /
• v.48 no.5
• /
• pp.453-456
• /
• 2018

The lipids of Clanis bilineata larvae meat (CBLM) are susceptible to oxidation, and thus the commercial and consumption values of CBLM decrease during frozen storage. In the present study, peroxide values (PV), thiobarbituric acid-reactive substances (TBARS), free fatty acid (FFA) content, fatty acid composition, and likeness (palatability) score of CBLM were determined to investigate the effect of glutathione on the oxidation of CBLM lipids. Glutathione decreased the PV, TBARS, and FFA content, maintained fatty acid composition, and increased the likeness (palatability) score of the CBLM, indicating that glutathione can be used as a cryoprotectant to extend the shelf life of CBLM.