CO oxidation over CuO catalysts supported on CeO2-ZrO2 prepared by microwave-assisted co-precipitation： The influence of CuO content

CeO2-ZrO2 mixed oxide(Ce0.6Zr0.4O2) prepared by microwave-assisted heating co-precipitation was used as a support to prepare a series of CuO/Ce0.6Zr0.4O2 catalysts with various CuO contents(0 wt.%–15 wt.%) via the method of incipient-wetness impregnation.The obtained CuO/Ce0.6Zr0.4O2 samples were characterized by N2 adsorption,XRD,Raman,TEM and H2-TPR technologies,and their catalytic activities for CO oxidation were investigated.The results showed that the activity of CuO/Ce0.6Zr0.4O2 catalyst was strongly influenced by the content of CuO,and the catalyst with 10 wt.% CuO exhibited the best catalytic activity in CO oxidation,which could be attributed to the high dispersion and reducibility of CuO,and high oxygen vacancy concentration in the catalyst.     

Effect of La2O3-Dopant on Microstructure and Microwave Dielectric Properties of CaO-MgO-Nb2O5-TiO2 System Ceramics

With the development of microwave integratedsystem for wireless communication, requirements ofthe microwave device are combined with high dielec tric constants (εr), low dielectric losses (Q = 1/tanδ) and near zero temperature coefficient for stabili ty and frequency selectivity[1,2]. But it is hard to findmaterials that satisfy all above mentioned requiredcharacteristics. In general, a ceramic with a high di electric constant has a larger positive temperature coef fi…     

Lanthanum Modified Ni/y-Al2O3 Catalysts for Partial Oxidation of Methane

La modified Ni/T-Al2O3 catalysts prepared by co-precipitation method using NaOH-Na2CO3 as a precipitator show high activity and selectivity for the partial oxidation of methane （POM）. Meanwhile, the addition of La is beneficial for the formation of an active component and stability of support. We investigated some factors including calcining temperature, nickel content, and space velocity, which turned out to have a strong influence on catalytic activity and selectivity. By XRD and TPR, it is concluded that Ni^0 reduced from amorphous NiAl2O4 is the major active component for POM.     

Catalytic Reduction of SO2 on CeO2-La2O3 Rare Earth Mixed Compounds

Adding rare earth oxide CeO2 with variable valences to La2O3 formed a mixture of rare earth oxides. By means of dipping CeO2, La2O3 and their mixture, whose carriers were all γ-Al2O3, were used as the catalyst for the reduction of SO2 by CO. The activation process of this catalyst and the impact of temperature and reactant concentration on the activation process were investigated. Using X-ray diffraction, the structure characteristics of catalyst before and after reaction were analyzed to reveal the change of phase structure. The result shows that the rare earth oxide mixtures composing of CeO2 and La2O3, as the catalyst for the reduction of SO2 by CO, diminish activation temperature 50～100℃ less and have higher activity than a single oxide CeO2 or La2O3. The reason possibl is that La2O3 goes into in the lattice of CeO2 to form solid phase complex CeO2-La2O3 and increases the capability of CeO2-La2O3/γ-Al2O3 catalyst to store oxygen, which supplies the redox of CeO2 reaction with a better condition. At the same time, elemental sulfur formed in the redox reaction impels La203 to be transformed to activation phase La2O2S in a lower temperature, which can be explained with the synergism between redox reaction and COS intermediate mechanism reaction.     

Luminescence properties of Mn2） ions doped Lu2CaMg2Si3O1） garnet phosphors

Yttrium aluminum garnet structure phosphors Lu2CaMg2Si3O12:Mn2+ were synthesized by conventional high temperature solid-state reaction in reductive atmosphere. The structure and optical properties of samples were characterized by application of powder X-ray diffraction (XRD) and photoluminescence spectroscopy. Results of X-ray diffraction (XRD) analysis showed that the phosphors mainly presented garnet structure with a few weak peaks of impurity phases. Lu2-xCaMg2Si3O12:xMn2+ (x=0.01-0.8) phosphors showed a broad emission band peaking at around 590 nm under ultraviolet (UV) light of 408 nm when Mn2+ concentration was less than 0.08 mol. With an increase in the Mn2+ concentration (above 0.08), another broad emission band peaking at 720 nm besides 590 nm was observed, which may be due to manganese ion having different valence and occupying different host lattice. The critical quenching concentrations of manganese ion in the wavelength of 590 and 720 nm were about 0.06 and 0.2 mol, respectively. With 408 nm excitation wavelength, emission color of the samples had a red shift trend as the Mn2+ concentration increased. All the results indicated that the Lu2CaMg2Si3O12:Mn2+ phosphors could be applicable to n-UV based white LEDs.     

Effects of Support on Catalytic Behavior of Combustion Catalyst La0.8Sr0. 2CoO3／γ-Al2O3

Combustion catalyst La0.8Sr0.2CoO3 (LSC) is expected to possess relatively high activity for the oxidation of carbon monoxide and many hydrocarbons. If γ-Al2O3 is used as its support, cobalt ions can easily react with γ-Al2O3 at not very high temperature to form spinel CoAl2O4 or spinel-like, which decreases the activity of the combustion catalyst. In this paper, MgAl2O4 and CaAl2O4 were pre-eoated on γ-Al2O3 by impregnation respectively, which formed compound support for LSC. It is shown that, when MgAl2O4 layer is covered on the surface of MgAl2O4 by impregnation, the entering of cobalt ions into γ-Al2O3 lattice is restrained, then LSC formed on the surface of MgAl2O4, which leads to a good catalytic activity of xylene complete oxidation. But the layer of MgAl2O4 should be thick enough to reach 30% (mass fraction) MgO in the support due to large size particle of MgAl2O4 crystalline. If polyvinyl alcohol (PVA) is added into the impregnation solution adequately, MgAl2O4 particles formed on the surface of γ-Al2O3 are getting smaller, and less amount of MgAl2O4 is needed to cover up the surface of γ-Al2O3. If CaAl2O4 layer substituted for MgAl2O4, more closed cover is obtained in virtue of fine particles of CaAl2O4. The activity examination shows that smaller particles of MgAl2O4 or CaAl2O4 Call be more effective to hinder cobalt ions entering the lattice of γ-Al2O3, and better activities will be obtained.     

Synthesis of 2, 6-Bis（1＇-Phenyl-3＇-Methyl-5＇-Oxopyrazole-4＇） Pyridinediacyl and Its Solid-Liquid Extraction Behavior for Ce（Ⅲ）

β-diketone type chelating ligands have high coordinative activity and selectivity, and are widely applied in analytical ehemistry. In order to obtain profounder understanding to the properties of bis(4-aeylpyrazolone-5), A new 4-aeylpyrazol-5-one derivative (H2BPMPP) was syntheszed, whieh eontains a heteroeyelie ring between two 1-phenyl-3-methyl-4-aeylpyrazol-5-one rings. The new compound was eharaeterized by element analyses, UV, IR and ^1H NMR speetra. The equilibrium of the keto-enol tautomerism was studied. The results show that a lower dieleetric constant of solvent favors the enol form whieh has a higher λmax.Due to speeial merits of paraffin wax, the solidliquid extraetion behavior of Ce(Ⅲ) with molten paraffin wax as a diluent was also investigated at higher temperature. The value of the pH1/2 was 3.19 and the value of logKex was 3.467. The ehemieal eomposition of the complex was obtained by the slope analysis method.     

Investigation of Mechanical Property of Oil Tube Steel P110S in High Temperature and High Pressure Environment Containing H2S/CO2

With the exploitation of high sour and deep oil well in china,the corrosion medium containing CO 2,H 2 S,Cl-and organic acid threaten the safety of oil equipment and tube steel severely.In this article,many experiments,including corrosion tests,tensile tests,hydrogen concentration measurement tests and SEM examinations,were performed to investigate the effect of H 2 S partial pressure and loading stress on the mechanical property of oil tube steel P110S in high temperature and high pressure environment containing H 2 S/CO 2.The tensile strength and yield strength during fracture process of P110S steel were obtained experimentally and the fracture morphology was analyzed by SEM.The results indicate that both tensile strength and yield strength decreased after corrosion.The damage of tensile strength and yield strength became serious with an increase in H 2 S partial pressure and loading stress.According to the fracture analysis,the fracture mode exhibited quasi-cleavage and dimple mixed fracture,and the area of quasi-cleavage pattern increased with H 2 S partial pressure and loading stress increasing.According to the results of tensile test and hydrogen concentration measurement test,the tensile property degradation is closely associated with diffusible hydrogen concentration of P110S steel in the H 2 S/CO 2 environment.     

Role of Surface Adsorption in Fast Oxygen Storage/Release of CeO2 -ZrO2 Mixed Oxides

Four kinds of CeO2-ZrO2 mixed oxides, i.e., a physical mixture of ceria and zirconia （CZP）, zirconia-coated ceria （ZCC）, ceria-coated zirconia （CCZ） and a chemical mixture of celia and zirconia （CZC）, were prepared. The oxygen storage capacity （OSC） measurements at 500℃ were performed under transient and stationary reaction conditions. All the curves of CO2 evolution during CO-O2 cycles presented a bimodal shape. The fast peak was primarily the result of the reaction of CO with the oxygen from the oxides, which was mainly determined by the nature of the material The sec- ond peak was mostly related to the CO2 adsorption behavior and was highly influenced by the surface area and the number of surface active sites. As a result, OSC activity of the samples followed in the order of CZC 〉 CCZ 〉 ZCC=CZP.     

Simulation and prediction of the alkalinity in sintering process based on grey least support vector machine

 Prediction of the alkalinity is a difficult problem during the process of sintering .Whether the level of he alkalinity of it is successful or not direct relates to the quality of sinter.By now,there isn’t a very good method due to the high complexity ,high non-linear, strong coupling, high delay-time and etc.A grey support vector machine model was proposed on the basis of the models.The fluctuation of data sequence is weakened by the grey theory and the support vector machine is capable of processing non-linear adaptable information, and the grey support vector machine is a combination of those advantages. The results reveal, the alkalinity of sinter can be accurately predicted through this model by reference to small sample and information. It was concluded that the grey support vector machine model is effective with the advantages of high precision, less samples required and simple calculation.     

Effects of Doping CeO2, Er2O3 on Properties of TiO2-SiO2 Ceramics for Catalyst Supporter of deNOx

Effects of doping CeO2 and Er2O3 on the mechanical strength, thermal expansion coefficient, sintering temperature of TiO2-SiO2 ceramics were investigated. The experimental results and the microscopic analysis of SEM, XRD, TG-DSC, FT-IR and TEM show that adding CeO2 and Er2O3 into TiO2-SiO2 ceramics can prohibit the growth of its crystal grains, make their size uniform and form them into a dense structure, which finally enhance its mechanical behaviors, and the lower thermal expansion coefficient that leads to an excellent property of thermal shock resistance. After the reforming TiO2-SiO2 ceramics doped by CeO2 was sintered at 1380 ℃, the bending strength reached to 83 MPa, and the thermal expansion coefficient was 9.8×10-6/℃ within the temperature range of 25～800 ℃, which provides a promising basis of making equipped honeycomb catalyst of deNOx.     

Dielectric Properties of CeO2 -Doped Ba( Zr, Ti)O3 Ceramics

The influence of additive amount of CeO2 on the properties of Ba(Ti, Zr)O3 (BTZ) capacitor ceramics prepared using conventional solid-state reaction method was investigated. The dielectric constant(ε) increases to a maximum when w( CeO2 ) is about 1.0% and then decreases again at higher doping concentration of CeO2. The dielectric constant gets a maximum while w ( CeO2 ) is about 1. 0%, and the dielectric loss is minimum while w ( CeO2 ) is0.5 %. CeO2 can decrease the curie temperature, widen the εr-T peak and decrease the absolute value of dielectric constant temperature coefficient. The influence mechanism of CeO2 additive on the properties of the BTZ ceramics was discussed. The results show that CeO2 additive influences the properties of BTZ ceramics by means of forming defect solid solution , shifting curie temperature peak effect, segregating in crystal boundary , and impeding grain growth.     

CeO_2包覆对TiO_2传感器材料的氧敏性能的影响

针对CeO2 具有良好的催化性和稳定性 ,以及TiO2 具有优良的氧敏特性 ,采用溶胶 凝胶法制备CeO2 包覆TiO2 材料 ,并在自行设计的实验装置中对材料进行氧敏测试。该材料的温度系数低于纯TiO2 材料 ,且氧敏性能比纯TiO2 材料显著提高。其原因在于壳层中CeO2 颗粒为氧离子进出包覆体内的TiO2 提供通道 ,并利用CeO2 储、放氧能力 ,促进TiO2 电导率变化。     

Preparation, Characterization of CuO／CeO2 and Cu／CeO2 Catalysts and Their Applications in Low-Temperature CO Oxidation

CeO2 was synthesized via sol-gel process and used as supporter to prepare CuO/CeO2, Cu/CeO2 catalysts by impregnation method. The catalytic properties and characterization of CeO2, CuO/CeO2 and Cu/CeO2 catalysts were examined by means of a microreactor-GC system, HRTEM, XRD, TPR and XPS techniques. The results show that CuO has not catalytic activity and the activity of CeO2 is quite low for CO oxidation. However, the catalytic activity of CuO/CeO2 and Cu/CeO2 catalysts increases significantly. Furthermore, the activity of CuO/CeO2 is higher than that of Cu/CeO2 catalysts.     

Catalytic Partial Oxidation of Methane over Ni/CeO2-ZrO2-Al2O3

Nickel catalysts supported on CeO2-ZrO2-CeO2,ZrO2-Al2O3 and Al2O3 were prepared and characterized by means of X-ray diffraction（XRD）,BET areas,H2 temperature-programmed reduction（H2-TPR）,and X-ray photoelectron spectroscopy（XPS）.Through the test of catalytic partial oxidation of methane（CPOM）,Ni/CeO2-ZrO2-Al2O3 displayed the highest activity,which resulted from its largest BET area and best NiO dispersion.Furthermore,Ni/CeO2-ZrO2-Al2O3 maintained a long-time stability in CPOM,which was attributed to its best coking resistance among all the prepared catalysts.     

A rationale for the development of thermally stable nanostructured CeO2-ZrO2-containing mixed oxides

CeO2-ZeO2 solid solutions are extensively used as oxygen storage promoters in the current automotive three-way catalysts. High thermal stability of the textural properties is one of the most important requirements for practical application since temperatures up to 1273 K are easily experienced by these materials under real working conditions. In the present paper, we investigated how hydrothermal treatments applied to cakes of doped and undoped ZrO2-rich CeO2-ZrO2 precursors might improve the thermal stability of the final CeO2-ZrO2 solid solution. A rationale was developed that allowed to correlate the morphology of the hydrothermaUy treated cake with the thermal stability at 1273 K of the final product, which did not depend on the composition of the mixed oxides.     

Preparation and Characterization of Graphite Powder Covered with CeO2

In order to improve the wetting properties of graphite with Al melt and reduce the oxidation of the graphite, by which the segregation of components during the liquid-stir-casting process could be prevented. In this paper, a uniform thin nano-film of CeO2, about 20 nm thick, was successfully prepared onto graphite powder surface by heterogeneous nucleation process. The results show that an obvious chemical reaction did exit between CeO2 film and graphite with the formation of Ce-O-C bond, leading to a shift of the binding energy of C and Ce. The cover with CeO2 film illustrates a distinct change of surface state of graphite with a decrease of angle of contact.     

Fabrication and Mechanical Properties of Sm2O3 Doped CeO2 Reinforced Ti3AlC2 Nano Composite

The fabrication process of Sm2O3 doped CeO2 reinforced Ti3AlC2 nano composites including the nano particle dispersion process by a hetero-coagulation process was developed using in-situ synthesis and densification process of Ti3AlC2. The effects of Sm2O2 doped CeO2 nano particles on mechanical properties of Ti3AlC2 were investigated. It was found that the presence of 20SDC nano particles in Ti3AlC2 was very effective to improve the mechanical properties of Ti3AlC2 without spoiling the unique characteristics of Ti3AlC2temary carbide.     

Effect of CeO2 on Microstructure and Bond Strength of Fe-Ni-Cr Alloy

The more extreme conditions in which metallicmaterials are required to work lead to the developmentof different surface modification materials, such asnickel based alloy, Fe based alloy and Co based al loy, etc. In general, these …     

Effects of ZrO2 Content on Structure and Performance of Cu/CeO2-ZrO2 Catalysts for Water-Gas Shift Reaction

Water-gas shift(WGS)is a critical step in fuelprocessors for preli minary COclean-up and additionalhydrogen generation prior to the CO clean-up stage,which opened up new potential applications for WGScatalysts.Recently several formulations of noble-met-al…