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Park J.-H.,Chungbuk National University | Cho J.H.,Chungbuk National University | Kang S.E.,Chungbuk National University | Cho K.H.,Korea Research Institute of Chemical Technology | And 3 more authors.
Korean Journal of Chemical Engineering | Year: 2013

A series of xAl-(1-x)Ce oxides (x=0-0. 20) were prepared as supports by the coprecipitation method. 1 wt% Pt was impregnated on the Al-modified Ce oxide supports, which were tested as catalysts for CO oxidation in the absence and presence of H2O vapor. The prepared catalysts were characterized by X-ray diffraction (XRD), N2 sorption, CO temperature-programmed reduction (CO-TPR), 27Al magic-angle spinning (MAS) NMR, and CO-chemisorption analyses. Upon comparison of the catalytic results obtained from the 1 wt% Pt/xAl-(1-x)Ce oxide catalysts, the Pt/0. 10Al-0. 90Ce oxide catalyst was found to exhibit the highest catalytic activity. When water vapor was present in the feed stream, the catalytic activity increased remarkably, and T90% shifted to a temperature ca. 30 °C lower compared to that in dry conditions due to the promotion effect by the water-gas shift reaction. The catalytic activity could be correlated with the Pt dispersion and the amount of surface or lattice oxygen. © 2013 Korean Institute of Chemical Engineers, Seoul, Korea.


Park J.-H.,Chungbuk National University | Cho J.H.,Chungbuk National University | Cho K.H.,Korea Research Institute of Chemical Technology | Lee T.W.,Heesung Catalysts Corporation and 507 1Da | And 2 more authors.
Korean Journal of Chemical Engineering | Year: 2012

CuO catalysts, prepared by the precipitation method using different precipitants such as ammonium hydroxide, sodium hydroxide, sodium carbonate and sodium hydrogen carbonate were applied to CO oxidation. Among the catalysts studied, CuO synthesized with sodium hydrogen carbonate showed the highest activity for CO oxidation. With the water vapor present in the feed gas, the catalytic activity decreased considerably due to reduction in the number of active sites by competitive adsorption between water vapor and CO. The H 2-TPR and CO-TPD results showed that existing Na + cations and HCO 3 - and CO 3/2- anions on the CuO surface could weaken the copper-oxygen bond strength and accelerate the mobility of oxygen on the surface or lattice. Finally, the morphology of the CuO crystals was dependent on the precipitants, and the introduction of Na + cations and various anions resulted in the formation of smaller crystals. © 2012 Korean Institute of Chemical Engineers, Seoul, Korea.


Park J.-H.,Chungbuk National University | Cho J.H.,Chungbuk National University | Kim Y.J.,Chungbuk National University | Kim E.S.,Heesung Catalysts Corporation and 507 1Da | And 2 more authors.
Applied Catalysis B: Environmental | Year: 2014

A monoclinic ZrO2 support was synthesized via a precipitation technique for the investigation of the effects of calcination temperature on methane combustion over Pd/ZrO2 and Pd/γ-Al2O3 catalysts at 600°C, in the absence and presence of water vapor. In comparison with Pd/γ-Al2O3, all the Pd/ZrO2 catalysts studied showed superior performances. With the exception of Pd/ZrO2 (ZrO2 support calcined at 1000°C), all the Pd/ZrO2 catalysts showed higher methane conversions in the presence of water vapor than in its absence. The Pd/ZrO2 catalyst with a ZrO2 support calcined at 900°C exhibited the highest activity as well as the greatest durability under both conditions, in spite of its low surface area. Transmission electron microscopy indicated that the activity of methane combustion is unrelated to Pd particle size. In addition, the results of temperature-programmed decomposition of Pd oxide on Pd/support and X-ray photoelectron spectroscopy showed that the activity of Pd/ZrO2 was strongly dependent on the oxidation state of the Pd species. © 2014 Elsevier B.V.

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