Papers by Keyword: Ceria

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Authors: Feng Chen, Cheng Bao Liu, Zhi Gang Chen
Abstract: Hierarchical porous ceria with nanocrystalline was successfully synthesized using filter paper as biotemplate. Unique biomorphic microstructures were characterized by Field Emission Scanning Electron Microscope (FESEM), transmission electron microscopy (TEM) and nitrogen absorption-desorption technique. The obtained ceria material showed the repetitious biomimetic structure consisting of fibre with diameter of ca. 1-3 μm and nanopores which had 2-4 nm apertures. The small crystallite diameter (6-8 nm) and the high specific surface area (71.3 m2·g-1) of porous CeO2 were measured by wide-angle X-ray Diffraction (XRD), high resolution TEM (HRTEM) and the BET method. While the concentration of acid fuchsine was 20 mg/L, the porous sample had a higher decoloring rate in a shorter time than others. The decoloring rate can reach 100% after 200 min.
Authors: D. Yang, Ming Fen Wen, Ch.L. Song, Jian Chen, Yong Wan Gu
Abstract: Herein mesoporous CeO2 with high thermal stability was synthesized via a new hydroxycarbonates based hydrothermal threatment approach in present of hexadecyltrimethylammonium bromide (CTAB). IR and XRD prove the coexistence of hydroxycarbonate cerium and CTAB in precursors. TEM micrographs show that non-ordered pore structure is formed in the product, and average particle size of 20 nm is obtained even after calcined at 1173 K. BET results exhibit that the pore structure is stable when the calcination temperature is below 923 K. However, While calcinated at 1173 K, the average particle size is 20 nm, the BET surface area and pore volume can remain as high as 31.07 m2/g and 0.21 cm3 g-1.
Authors: Márcia Caldeira Brant, Felipe da Silva Possa, Fernando Soares Lameiras
Abstract: Powders of Ce0.8Gd0.2O1.9 were synthesized by co-precipitation and amorphous citrate routes and their compositions and structures were compared. Co-precipitation process was carried out at room temperature, while amorphous citrate synthesis was performed at 60-70 °C. The powders obtained were calcined at 700 °C for 1 h. X-ray diffraction analyses showed that a single fluorite structure was formed by both synthesis techniques. Pellets from these powders were prepared by compaction at 30 kN/cm2 and sintered at 1593 °C in air. WDS analysis confirmed the homogeneity of the pellets. The sintered pellets obtained by amorphous citrate and by coprecipitation routes showed relative densities over 97 % of the theoretical density. These results indicated that the citrate amorphous route is an interesting and simple technique to prepare gadolinium-doped ceria powders with high sinterability.
Authors: I. Albinsson, R. Bokalawela, M.A.K.L. Dissanayake, B.E. Mellander, K. Rundgren
Authors: Kenji Higashi, K. Sonoda, Haruhiko Ono, Soichiro Sameshima, Yoshihiro Hirata
Authors: Kenichi Myoujin, Hiroki Ichiboshi, Takayuki Kodera, Takashi Ogihara
Abstract: Spherical samarium doped ceria (Ce0.8Sm0.2O1.9, SDC) powders having high specific surface area (SSA) were successfully synthesized by carbon-assisted spray pyrolysis (CASP). Saccharides, such as monosaccharides and disaccharides, or organic acids were used as carbon sources. The physical and chemical properties of these powders were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), Thermo gravimetry-Differential Thermal Analysis (TG-DTA), and BET. Decarbonized powders obtained by this method exhibit spherical morphologies and nano- and submicron-sizes. The SSA of SDC obtained from CASP was more than seven times higher than that obtained from conventional spray pyrolysis (CSP). The SSA of the decarbonized SDC powders obtained by calcination at 900 °C was estimated to be approximately 70 m2/g by using the BET method. The relative density of SDC obtained from CASP was higher than that obtained from CSP. The relative density of the SDC pellet was highest (96 %) when it was sintered at 1400 °C.
Authors: Yong Guang Wang, Liang Chi Zhang, Altabul Biddut
Abstract: This paper investigates the effects of some chemical factors on the material removal rate (MRR) in chemo-mechanical polishing (CMP) of Si (100) wafers. The CMP was carried out in alkaline slurry using alumina and ceria particles with hydrogen peroxide. When using the alumina particles, the MRR initially decreases with increasing the slurry pH value until pH = 9. Nevertheless, the application of the ceria particles increases the MRR before the pH of the slurry reaches 10. A higher slurry flow rate brings about a greater MRR.
Authors: P. Martin, S. C. Parker, D.C. Sayle, G.W. Watson
Abstract: The aim of this paper is to describe the recent progress in using atomistic simulation techniques to develop simulation models of ceria nanotubes and to model oxygen ion transport at ceria surfaces. The basis of these atomistic techniques is to use the Born Model of Solids where parameterized analytical equations are employed to describe the interactions between atoms. Once these interatomic forces are specified energy minimization and molecular dynamics techniques can be applied to the models.
Authors: Jie Liu, Xin Yong Li, Qi Dong Zhao, Dong Ke Zhang
Abstract: CuO/TiO2, CuO/Ti0.9Ce0.1O2 and CuO/CeO2/TiO2 composite catalysts were prepared and tested for their application in selective catalytic reduction (SCR) of NO with C3H6. The effect of CeO2 species on the catalytic performance was further evaluated. Catalyst characterization including BET surface area, XRD and temperature-programmed reduction of H2 (H2-TPR) suggested that the addition of CeO2 species changed the physicochemical properties of the catalysts obtained. Compared to the impregnation method, the homogeneous precipitation method was an effective approach to preparing the CeO2 doped catalyst, which could promote the activation of C3H6 to react with NO.
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