Dispersion and reduction of copper oxide supported on WO3-modified Ce(0.5)Zr(0.5)O2 solid solution.
ABSTRACT XRD (X-ray diffraction), BET (Brunauer-Emmett-Teller), LRS (laser Raman spectra), XPS (X-ray photoelectron spectroscopy), and TPR (temperature-programmed reduction) are used to investigate the surface properties of CuO/WO3/Ce(0.5)Zr(0.5)O2 samples. The results indicate that (1) tungsten oxide can be highly dispersed on Ce(0.5)Zr(0.5)O2 (denoted as CZ hereafter) solid solution, with a dispersion capacity of about 0.8 mmol WO(3)/(100 m2 CZ), and comparatively, the supported tungsten oxide species are preferentially interacted with ceria component on the surface of CZ; (2) for CuO/WO3/CZ samples with a half-monolayer WO3 loading, i.e., xCu-0.4W-CZ series, the surface of CZ is only partially covered by the preloaded WO3) and the supported copper oxide species are dispersed on the remaining surface vacant sites on CZ as well as on top of the preloaded tungsten oxide, while for the samples preloaded with a full-monolayer WO3, i.e., xCu-0.8W-CZ series, only dispersed on the top of the preloaded tungsten oxide monolayer; (3) the effect of the loading amount of WO3 on the reduction property of Cu2+ ions in a series of CuO/WO3/CZ samples has been observed and tentatively attributed to the formation of WO3 monolayer on CZ and the different coordination environments of the dispersed Cu2+ ions are discussed on the basis of the consideration of the incorporation model proposed previously (Chen, Y.; Zhang, L. Catal. Lett. 1992, 12, 51).
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ABSTRACT: Anatase and rutile have the same chemical composition as TiO(2) but different crystalline structures (space group of D(4h)(19)-I4(1) for anatase and D(4h)(14)-P4(2) for rutile, respectively), which result in different surface structures and can be used ideally to investigate the effects of support and surface structure on the properties of their supported catalysts. In this work, anatase- or rutile-supported copper oxide catalysts (signed as Cu-A and Cu-R, thereafter) prepared by the impregnation method were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area, X-ray photoelectron spectroscopy (XPS), and H(2) temperature-programmed reduction (H(2)-TPR) to study the support effect of titania on the physicochemical properties and catalytic properties for the NO reduction by CO of these supported copper oxide catalysts. The results indicated that (1) copper oxide presented different dispersion capacities on anatase or rutile; (2) dispersed copper oxide species on anatase and rutile also showed different reduction behaviors; i.e., one-step reduction for dispersed copper oxide species in Cu-A and stepwise reduction for that in Cu-R; (3) the NO+CO activity test suggested dispersed copper oxide and small CuO particles on rutile are the main active species under the current reaction conditions and copper oxide supported on rutile is more active than that on anatase, which might result from Cu(+) species in Cu-R sample formed during the reaction due to its stepwise reduction behavior.Journal of Colloid and Interface Science 03/2011; 357(2):497-503. · 3.55 Impact Factor
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ABSTRACT: A WO3/CeO2-ZrO2 catalyst system was discovered for selective catalytic reduction of NOx with NH3; the catalyst (10 wt% WO3 loading) showed nearly 100% NOx conversion in a temperature range of 200-500 degrees C, at a space velocity of 90 000 h(-1) in a simulated diesel exhaust containing 550 ppm NOx (NO : NO2 feed ratio at 1.0), 10 vol% H2O and 10 vol% CO2; the catalyst also exhibited high temperature stability.Chemical Communications 04/2008; · 6.38 Impact Factor
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ABSTRACT: XRD, LRS, TPR and in situ NH(3) adsorption FT-IR were used to investigate the dispersion state of the copper oxide and molybdena species of MoO(3)/CeO(2) and CuO/MoO(3)/CeO(2) catalysts as well as their surface acidity. The results showed that the molybdena monolayer modification promoted the dispersion of CuO due to the formation of new tetrahedral vacancies. Meanwhile, CuO changed the structure of molybdenum species and then influenced the surface acidity of the samples. A detail discussion about the possible model of the surface structure of the catalyst was presented. In addition, combining with the in situ NH(3) adsorption FT-IR, the relationships between the activities for ''NO + NH(3) + O(2)'' reaction and surface acid properties (Brønsted and Lewis acid sites) of the catalysts were discussed.Journal of Colloid and Interface Science 08/2011; 364(2):435-42. · 3.55 Impact Factor