• Bulletin of the Korean Chemical Society
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• v.15 no.8
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• pp.616-622
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• 1994

The oxidation of carbon monoxide by gaseous oxygen in the presence of a powdered $Nd_{1-x}Sr_xCoO_{3-y}$ solid solution as a catalyst has been investigated in the temperature range from 150$^{\circ}$C to 300$^{\circ}$C under various CO and $O_2$ partial pressures. The site of Sr substitution, nonstoichiometry, structure, and microstructure were studied by means of powder X-ray diffraction and infrared spectroscopy. The electrical conductivity of the solid solution has been measured at 300$^{\circ}$C under various CO and $O_2$ partial pressures. The oxidation rates have been correlated with 1.5-and 1.2-order kinetics with and without a $CO_2$ trap, respectively; first-and 0.7 order with respect to CO and 0.5-order to $O_2$. For the above reaction temperature range, the activation energy is in the range from 0.25 to 0.35 eV/mol. From the infrared spectroscopic, conductivity and kinetic data, CO appears essentially to be adsorbed on the lattice oxygens of the catalyst, while $O_2$ adsorbs as ions on the oxygen vacancies formed by Sr substitution. The oxygen vacancy mechanism of the CO oxidation and the main defect of $Nd_{1-x}Sr_xCoO_{3-y}$ solid solution are supported and suggested from the agreement between IR data, conductivities, and kinetic data.

• Corrosion Science and Technology
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• v.12 no.3
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• pp.119-124
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• 2013

Nano-multilayered, crystalline AlTiSiN thin films were deposited on WC-TiC-Co substrates by the cathodic arc plasma deposition. The deposited film consisted of wurtzite-type AlN, NaCl-type TiN, and tetragonal $Ti_2N$ phases. Their oxidation characteristics were studied at 800 and $900^{\circ}C$ for up to 20 h in air. The WC-TiC-Co oxidized fast with large weight gains. By contrast, the AlTiSiN film displayed superior oxidation resistance, due mainly to formation of the ${\alpha}-Al_2O_3$-rich surface oxide layer, below which an ($Al_2O_3$, $TiO_2$, $SiO_2$)-intermixed scale existed. Their oxidation progressed primarily by the outward diffusion of nitrogen, combined with the inward transport of oxygen that gradually reacted with Al, Ti, and Si in the film.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.04a
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• pp.73-73
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• 2007

Amorphous BON and Si-DLC thin films were synthesized by the RF plasma enhanced CVD method, and their oxidation behavior was studied up to $500^{\circ}C$ in air. The oxidation of both films was accompanied by evaporation of volatile species. The oxidation of BON film was preceded by nitrogen escape from the film, and oxygen penetration into the film. The oxidation of Si-DLC film was preceded by carbon escape probably as CO or $CO_2$from the film, and oxygen penetration into the film. The inwardly transported oxygen simply stayed in the oxidized BON and Si-DLC thin films.

• Bulletin of the Korean Chemical Society
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• v.12 no.1
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• pp.35-39
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• 1991

The catalytic activity of $Nd_{1-x}Sr_xCoO_{3-y}$, $0{\leq}x{\leq}0.75$ and $0.001{\leq}y{\leq}0.103$, on the oxidation of carbon monoxide has been investigated from the structure analyses of the catalysts by X-ray diffraction and infrared spectroscopy and the measurements of the oxidation and adsorption rates of carbon monoxide. The catalytic activity is found to be correlated with Sr substitution (x) and nonstoichiometry (y). The oxidation power of carbon monoxide increases continuously with increasing Sr substitution without oxygen, but increases with Sr substitution up to x = 0.25 and then is almost constant at larger x values up to x = 0.75 with oxygen. This change of catalytic activity is explained by the oxidation-reduction properties of the catalyst due to the variation of nonstoichiometry.

• Journal of the Korean Chemical Society
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• v.28 no.2
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• pp.102-108
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• 1984

The catalytic oxidation of CO has been investigated on $ZnCe_{1+y}O_2$ at temperatures from 300 to $500^{\circ}C$ under various P_{CO} and PO_2 conditions. The oxidation rates have been correlated with 1.5-order kinetics: first order with respect to CO and 0.5 order with respect to O2. CO appears to be absorbed essentially on the O lattice of $ZnCe_{1+y}O_2$ as a molecular species, while $O_2$ adsorbs on an O vacancy as an ionic species. The conductivity data show that CO adsorption contributes electron to the conduction band and the adsorption process of $O_2$ withdraws it from an O vacancy. The oxidation mechanism and the defect model of $ZnCe_{1+y}O_2$ are inferred at given temperature and $PO_2'$s from the agreement between the conductivities and kinetic data. It is suggested that CO absorption is the rate-controlling.

• Journal of the Korean institute of surface engineering
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• v.37 no.6
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• pp.360-365
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• 2004

Ti$_3$SiC$_2$ material was synthesized via the powder metallurgical route, and oxidation tested between 900 and $1200^{\circ}C$ in air for up to 100 hr. The oxidation of $Ti_3$$SiC_2$ material resulted in the formation of $TiO_2$and $SiO_2$, accompanying the evolution of CO or $CO_2$ gases from the initial stage of oxidation. The oxidation resistance of $Ti_3$$SiC_2$ mainly owes the protectiveness of highly stoichiometric $SiO_2$. During the initial stage of oxidation, the dominant reaction was the inward transport of oxygen into the matrix. As the oxidation progressed, an outer $TiO_2$ layer and an inner ( $TiO_2$ + $SiO_2$) mixed layer formed. Between these layers and inside the oxide scale, numerous fine voids formed. Numerous, fine oxide grains formed at $900^{\circ}C$ developed into the outer coarse $TiO_2$ grains and an inner fine ($TiO_2$ + $SiO_2$) mixed grains at the higher temperatures. The oxidation resistance of$ Ti_3$SiC$_2$ progressively deteriorated as the oxidation temperature increased, forming thick scales above $1000^{\circ}C$. The outer coarse $TiO_2$ grains formed above $1100^{\circ}C$ grew rapidly mainly along (211).

• Journal of the Korean Applied Science and Technology
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• v.33 no.1
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• pp.129-135
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• 2016

CO oxidation was performed with Cu-Mn and Cu-Zn co-precipitated catalysts as differential precipitant, metal ratio and calcination temperature. The effects of differential metal mole ratio and calcination temperature in mixed metal oxide catalyst were investigated with CO oxidation reaction. Physiochemical properties were studied by XRD, $N_2$ sorption and SEM. 2Cu-1Mn with $Na_2CO_3$ catalyst calcined at $270^{\circ}C$ has a large surface area $43m^2/g$ and the best activity for CO oxidation. $Cu_{0.5}Mn_{2.5}O_4$ in XRD peak shows the lower activity than others. The catalytic activity over the catalyst calcined $270^{\circ}C$ displayed the highest conversion, and it was better activity comparing with Pt catalysts CO conversion.

• Macromolecular Research
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• v.17 no.8
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• pp.603-608
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• 2009

Novel ultra-high molecular weight polyethylene (UHMWPE)/zirconia composites were previously prepared by the in situ polymerization of ethylene using a Ti-based Ziegler-Natta catalyst supported on to the surface of zirconia, as a bearing material for artificial joints. Tribological tests revealed that a uniform dispersion of zirconia in UHMWPE markedly increased the wear resistance. The effects of zirconia content on the oxidation behavior of the ${\gamma}$-ray-treated UHMWPE/zirconia composite surfaces were examined. The oxidation index that estimates the oxidation degree as the content of total carbonyl compounds was monitored using Fourier transform infrared spectroscopy-attenuated total reflectance. The changes in the surface composition due to the oxidation were confirmed by electron spectroscopy for chemical analysis. The extent of oxidation decreased with increasing zirconia content, which was attributed to the increased crystallinity as well as the decreased polymer portion of the UHMWPE/zirconia composites.

• Journal of Electrochemical Science and Technology
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• v.7 no.2
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• pp.91-96
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• 2016

Oxidation behaviours of ash free coal (AFC), carbon, and H₂ fuels were investigated with a coin type molten carbonate fuel cell. Because AFC has no electrical conductivity, its oxidation occurs via gasification to H₂ and CO. An interesting behaviour of mass transfer resistance reduction at higher current density was observed. Since the anode reaction has the positive reaction order of H₂, CO₂ and H₂O, the lack of CO₂ and H₂O from AFC results in a significant mass transfer resistance. However, the anode products of CO₂ and H₂O at higher current densities raise their partial pressure and mitigate the resistance. The addition of CO₂ to AFC reduced the resistance sufficiently, thus the resistance reduction at higher current densities did not appear. Electrochemical impedance results also indicate that the addition of CO₂ reduces mass transfer resistance. Carbon and H₂ fuels without CO₂ and H₂O also show similar behaviour to AFC: mass transfer resistance is diminished by raising current density and adding CO₂.

• Korean Journal of Microbiology
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• v.21 no.1
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• pp.27-35
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• 1983

The stoichiometry between the consumption of CO and $O_2$ and the production of $CO_2(2CO+O_2{\rightarrow}2CO_2)$) showed that Pseudomonas carboxydohydrogena grows as a typical aerobic CO oxidizer with CO. The optimal concentration of CO for growth was found to be 30% in gas mixture with air. The initial buffer concentration of the culture medium did not affect the growth of this bacterium. P. carboxydohydrogena is an obligate aerobe and dose not use nitrate as a terminal electron acceptor. The CO dehydrogenase is an inducible and soluble enzyme. The reaction rate and stability were maximal at pH7.5, and the Arrhenius plot revealed an activation energy of 37.7kJ/mol (9.0 Kcal/mol). The crude enzyme used methylene blue, thionin, and toluylene blue as electron acceptors for the oxidation of CO to $Co_2$ under anaerobic conditions. It was found that water must be the source of the second oxygen atom for CO oxidation.