Papers by Keyword: CeO2

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Authors: Jin Liang, Hong Chen, You Hua Fan, Zhi Qing Yuan
Abstract: A facile and novel method was developed to fabricate highly porous CeO2 surface on aluminum via a combination of homogeneous precipitation method and in situ growth process. After the introduction of CeO2 film, aluminum exhibited excellent superhydrophobicity with contact angle of 152.9±1.5 o and a sliding angle of 5 o. SEM image of the film showed that the resulting surface exhibits a hierarchical micro-Superscript text and nanostructure, which comprised of nanoleaves that grew perpendicular to the substrate and interleaved together to form a highly porous structure. This porous architecture, along with the low surface energy renders the aluminum superhydrophobicity.
1679
Authors: Norimitsu Murayama, Noriya Izu, Woosuck Shin, Ichiro Matsubara
Abstract: For resistive oxygen sensor elements of Ce1-xZrxO2 (x = 0.0, 0.05, 0.1, 0.2), grain diameter was varied in the range of 86 – 300 nm by changing sintering temperature or changing Zr content. The grain diameter decreased with increasing Zr content. The response time was approximately proportional to the square of the grain diameter. In the relationship between the amplitude of sensor output, An and the frequency, f of sine wave of variation in oxygen partial pressure, the gradient in the high-frequency region of a plot of log An vs. log f in was approximately –0.5. From these results, it was concluded that the sensor response was determined by the oxygen vacancy diffusion rate. The grain diameter of Ce0.8Zr0.2O2 element was 86 nm and the response time at 1073 K was 9 ms, which result opens the door to the technological development of independent control of engine cylinders.
323
Authors: Dan Zhao, Da Liang Li, Xin Qiang Wu, En Hou Han
Abstract: CeO2 nanoparticles with diameter of about 5 nm were prepared by batch supercritical hydrothermal synthesis method at 390 °C without additional treatment. It was found that the characteristics of products depended on the pH value, reactant concentration (C0), and reaction temperature. The reaction time and coexisting cations (Li+, Na+ and K+) had little effect on the size and morphology of CeO2 particles. Uniform CeO2 nanoparticles were synthesized at 390 °C, pH = 9 and C0 = 0.06 M. The mechanism for batch supercritical hydrothermal synthesis of CeO2 nanoparticles is discussed.
773
Authors: Yuji Haga, Pusparatu, Kiyotada Aoyama, Kenichi Komura, Yoichi Nishimura, Yoshihiro Sugi, Jong Ho Kim, Gon Seo
2323
Authors: Isabel Van Driessche, G. Penneman, J.S. Abell, E. Bruneel, Serge Hoste
3517
Authors: Z.M. Shi
Abstract: Stable oxygen concentration in exhausts is a decisive factor in catalytic purification of the vehicle exhausts. Nanostructured CeO2 is generally added into catalytic coating on a ceramic support to adjust the oxygen concentration because it possesses a unique oxygen storage capacity (OSC). However, a small amount of CeO2 gets insufficient when the oxygen concentration fluctuates in a large range. In the present work, the cordierite-CeO2 composite ceramic with oxygen storage capacity was prepared for a support material of catalytic converters. The oxygen storage-release performance of the ceramics, including temperature of releasing oxygen, adsorption process of oxygen and the oxygen storage, was examined by a temperature-programmed gas chromatography. The composition of the ceramics was analyzed by an X-ray powder diffraction (XRD) and a scanning electron microscope (SEM) to validate the reliability of the ceramic as the support material with OSC. Results show that the ceramics consist of α-cordierite and CeO2 phases, the latter of which is uniformly dispersed throughout the cordierite matrix. The ceramic powder with 10-20wt% of CeO2 possesses the expected oxygen storage capacity. It is suggested that this novel cordierite-CeO2 composite ceramic is helpful of improving the purification effect of vehicle exhausts.
1075
Authors: Zhi Jun Zhao, Ruo Yu Wang, Qian Long Zhao, En Peng Wang, Hai Quan Su, Shang Hong Zeng
Abstract: The CuO/CeO2 and CuO/PrO2-CeO2 catalysts were prepared by the hydrothermal method, and characterized via XRD, SEM and N2 adsorption-desorption techniques. The study shows that the BET surface area and pore volume of the CuO/PrO2-CeO2 catalysts increase with the increase of praseodymium content. The CuO/CeO2 catalyst presents higher catalytic activity in compare with the CuO/PrO2-CeO2 catalysts although the addition of praseodymium promotes textural properties of the CuO/CeO2 catalysts, and it proves that the interaction of CuO and CeO2 has a crucial role in CO-PROX.
601
Authors: Audrey Siebert-Timmer, Lukas Bichler
Abstract: Cubic Yttria-stabilized zirconia (c-YSZ) is a candidate material for high temperature applications due to its chemical inertness, high thermal stability and low thermal conductivity. In addition, due to c-YSZ’s high radiation stability, there is a new interest in this ceramic for thermal insulating cladding material in Supercrticial Water Nuclear Reactors (SCWR). However, due to the aggressive environment of supercritical water, the degradation behaviour of the ceramic must be well understood prior to its industrial application. In this research, moderately dense 8 mol% Yttria stabilized zirconia (YSZ) as well as YSZ composites containing 5, 10 and 15 mol% CeO2 were fabricated via Spark Plasma Sintering (SPS) and subjected to static corrosion testing in supercritical water (SCW) at 400°C and 31MPa. Weight loss and crystal lattice changes associated with SCW exposure were studied.
1093
Authors: Emilene Laurentino Santos, R. Muccillo, E.N.S. Muccillo
Abstract: The influence of Mn addition (from 1 up to 10 mol%) on densification and electrical conductivity of CeO2 was studied in detail. Bulk specimens were prepared by the conventional technique of mixing suitable amounts of cerium dioxide and manganese carbonate, followed by pressing and sintering. The apparent density of sintered specimens was determined by the immersion method and electrical characterization was carried out by impedance spectroscopy measurements in the 300 to 550 °C range. High densification (> 95% of the theoretical density) was obtained for small addition of Mn (1 mol%) to CeO2 sintered at 1300 °C for only 0.1 h. Electrical conductivity changes in sintered pellets depend on the sintering procedure, but not on the manganese content.
639
Authors: Jun Ming Yu, Shang Guan Ju, Li Ping Liu, Lei Yang, Jia An, Jie Mi, Mao Qian Miao
Abstract: The dynamic behavior of bed for regeneration of cerium oxide high temperature gas desulfurization sorbent under the atmosphere of O2 was investigated in the fixed bed micro-reactor. O2 concentration during the regeneration can be detected by an oxygen analyzer, and the sulfur content of sorbent in the bed was test using sulfur analyzer. The effects of O2 concentration, regeneration temperature on the dynamic behavior of bed for regeneration of CeO2 desulfurization sorbent were discussed. According to the experimental results, the length and movement speed of regeneration zone are calculated. The results showed that the increase of O2 concentration in inlet gas obviously improves the movement speed of regeneration zone in bed for CeO2 desulfurization sorbent, and the increase of regeneration temperature can decreased the length of the regeneration zone and improved the movement speed of the regeneration zone. The increase of regeneration temperature had a better effect on the improvement of bed utilization of sorbent than that of O2 concentration.
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