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61.
Elena V. Frolova M. Ivanovskaya V. Sadykov G. Alikina A. Lukashevich S. Neophytides 《Progress in Solid State Chemistry》2005,33(2-4):317-325
Structural peculiarities of Ce–Zr–La–O and Ce–Zr–La–O/Ru samples in mean of catalytic properties are compared. The samples (Ce:Zr = 1:1, La = 10÷30 mol.%, Ru = 1.5 wt.%) were obtained by sol–gel method (X-samples) and co-precipitation (P-samples). It is shown that Ce0.45Zr0.45La0.1O2−δ/Ru X-samples are characterized by high thermal stability and the highest catalytic activity in partial methane oxidation reaction. According to XRD, BET, FTIR, EPR and XPS data it is concluded that the difference in the samples catalytic activity is caused by various disposition of Ru-containing phase on the support surface. The distinction in the dimension of Ru-containing particles (3D or 2D) is conditioned by structural peculiarities of Ce0.45Zr0.45La0.1O2−δ and Ce0.35Zr0.35La0.3O2−δ P- and X-samples. 相似文献
62.
Stefan?DiethelmEmail author Joseph?Sfeir Frank?Clemens Jan?Van herle Daniel?Favrat 《Journal of Solid State Electrochemistry》2004,8(9):611-617
Dense planar and tubular oxygen separation membranes of La0.6Ca0.4Fe0.75Co0.25O3– were investigated as reactors for the partial oxidation (POX) of methane to syngas. Their permeation properties were measured in an air/argon
pO2 gradient as a function of temperature. At 900 °C, the oxygen flux through a 1.26-mm-thick membrane was 0.075 mol/cm2·s and through a 0.25-mm-thick tube, 0.24 mol/cm2·s.For the POX measurements, a catalyst was added to the membrane and methane was introduced on the argon side. This resulted in a gradual increase of the oxygen flux with increasing concentration of methane, reaching 2 mol/cm2·s at 900 °C with pure methane. For the planar reactor, the CO selectivity reached 99% and the CH4 conversion 75% at 918 °C with pure methane. For the tubular reactor, the CO selectivity and CH4 conversion were 83 and 99%, respectively, under the same conditions. After 1,400 h of operation in a tubular POX reactor, the membrane was examined revealing phase demixing and local decomposition.Presented at the OSSEP Workshop Ionic and Mixed Conductors: Methods and Processes, Aveiro, Portugal, 10–12 April 2003 相似文献
63.
The silver iodate(VII), Ag5IO6, was obtained by reacting a stoichiometric mixture of Ag2O and KIO3, at elevated oxygen pressure, adding a small portion of distilled water. The synthesis was done at 673 K and 270 MPa of oxygen pressure. The crystal structure was solved by direct methods based on single crystal diffraction data ( , Z = 6, a = 5.9366(1), c = 32.1471(6) Å, 323 independent reflections, R1 = 2.31 %). According to conductivity measurements, Ag5IO6 is semiconducting with a specific resistance of 0.08 Ωcm at 300 K. The activation energy was determined as 7.4(1) meV in the temperature range of 220 – 300 K, and 4.3(1) meV in the temperature range of 90 – 180 K. The optical band gap for Ag5IO6 is 1.4 eV. Ag5IO6 is diamagnetic with a magnetic susceptibility of ?4.4×10?4 emu/mol. 相似文献
64.
纳米碳管电极上氧的电催化还原 总被引:5,自引:0,他引:5
以聚四氟乙烯为粘结剂制成了多壁纳米碳管(MWNT)电极.采用恒电位阶跃法和循环伏安法研究了MWNT电极在碱性溶液中的电化学行为,并对碱性溶液中溶解氧在该电极上的电化学还原行为进行了研究.实验结果表明: MWNT电极具有比石墨电极更高的孔隙率和电化学表面积;MWNT电极上O2还原成的反应为准可逆过程;在5~50 mV•s-1的扫描速率范围内,阴极峰电流与扫描速度成线性关系,表明MWNT电极上O2还原成的反应受吸附控制;对碱性溶液中的氧还原反应, MWNT比石墨具有更高的催化活性. 相似文献
65.
Jie Hu Haoshan Hao Changping Chen Delin Yang Xing Hu 《Journal of membrane science》2006,280(1-2):809-814
The oxygen permeation properties of mixed-conducting ceramics SrFeCo0.5O3−δ (SFCO), Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCFO), La0.2Sr0.8Co0.8Fe0.2O3−δ (LSCFO) and Ba0.95Ca0.05Co0.8Fe0.2O3−δ (BCCFO) were studied by thermogravimetric method in the temperature range 600–900 °C. The results show that the oxygen adsorption rate constants ka of all material are larger than oxygen desorption rate constants kd and both ka and kd are not strongly dependent on temperature in the studied temperature range. The oxygen vacancy contents δ(N2) and δ(O2) in nitrogen and oxygen and their difference Δδ = δ(N2) − δ(O2) play an important role in determining the temperature behavior of oxygen permeation flux JO2. 相似文献
66.
Jorge Pavez Maritza Páez Armelle Ringuedé Fethi Bedioui José H. Zagal 《Journal of Solid State Electrochemistry》2005,9(1):21-29
We studied the electrocatalytic activity of cobalt tetra-aminophthalocyanine (CoTAPc) for the reduction of molecular oxygen (O2) on adsorbed monomeric and on electropolymerized films of different thicknesses on glassy carbon (GC) electrode. The polymeric films, denoted poly-CoTAPc, were first characterized by electrochemical impedance spectroscopy and it appears that the types of phenomena revealed to be occurring depend less on the film thickness in basic than in acid media. For O2 reduction, the results showed that poly-CoTAPc is more active than the monomeric CoTAPc adsorbed on GC. Indeed, rotating ring-disk electrode data showed that polymeric CoTAPc promotes the four-electron reduction of O2 to water in parallel to a two-electron reduction to give peroxide. On monomeric and thin films of poly-CoTAPc, a two-electron reduction mechanism predominates. In basic media the activity increases very slightly with thickness, whereas in acid media this increase is more pronounced. This parallels the observed behavior revealed by electrochemical impedance spectroscopy. 相似文献
67.
E Gaudin 《Journal of solid state chemistry》2003,175(1):124-131
The compound La2Ca2MnO6(O2) has been synthesized from La2Ca2MnO7 heated at 1123 K under high pressure (4 GPa) with KClO3 as oxygen source. The crystal structure has been refined from X-ray powder data in the space group. The unit-cell parameters are a=5.6335(2) Å and c=17.4879(8) Å. Perpendicular to the c-axis, the structure is built up by the periodic stacking of two close packed [LaO3] layers separated by a layer of composition [Ca2O2] containing (O2)2− peroxide ions. This oxide belongs to the family of compounds formulated as [A′2O2−δ][AnBn−1O3n] for n=2 and δ=0. It is the first member of the series where the thickness of the perovskite slab corresponds to one [BO6] (B=Mn) octahedron. The structural relationships with La2Ca2MnO7 are discussed and the magnetic properties show that in both phases manganese is tetravalent. 相似文献
68.
甲基丙烯酸八氟戊酯乙烯基咪唑共聚物的合成及与钴卟啉复合物的氧结合性能 总被引:3,自引:0,他引:3
研究了甲基丙烯酸八氟戊酯单体及其与乙烯基咪唑共聚物的合成与表征 ,以及该共聚物与氧载体钴卟啉配位复合物的氧结合性能 .共聚物分子量和乙烯基咪唑含量分别由GPC和元素分析方法测定 ,结果为5 0× 10 4 和 2 5mol % .共聚物中的咪唑基与钴卟啉在溶液中配位 ,复合物具有快速、可逆的氧结合特性 .溶剂对复合物的氧结合性能影响较大 ,复合物在四氢呋喃中的氧结合亲合力大于在N ,N 二甲基甲酰胺中的亲合力 相似文献
69.
S. Canulescu Th. Lippert A. Wokaun R. Robert D. Logvinovich A. Weidenkaff M. Dbeli M. Schneider 《Progress in Solid State Chemistry》2007,35(2-4):241-248
Perovskite thin films with a nominal composition of La0.6Ca0.4Mn1−xFexO3 (x = 0, 0.2) were deposited by pulsed reactive crossed beam laser ablation. The film properties, such as electrical conductivity and magnetoresistance are studied as a function of the oxygen content and substrate type. The oxygen content of the thin films was determined by Rutherford Backscattering and controlled by varying the background gas pressure, pressure of the gas pulse and by using alternatively O2 and N2O as the gas pulse.
LaAlO3 and SrTiO3 were used as substrates at deposition temperature of 650 °C. The grown films were analyzed by X-ray diffraction in order to optimize the growth conditions, i.e. to obtain epitaxial thin films. Thin films doped with 20% Fe were grown under the same experimental conditions as the undoped LCMO films and the effect of the doping on the structural and transport properties of the thin films has been investigated.
The temperature of the metal–insulator transition was measured as a function of the oxygen content and substrate type. 相似文献
70.
Two novel copper(I) complexes with Cu‐O bonds, [Cu2L2(PPh3)2](BF4)2 ( 1 ) and [Cu(L)(dppeo)](BF4) ( 2 ) ( L = 6‐(4‐diethylmethylphosphonatephenyl)‐2,2′‐bipyridine, dppeo = bis(diphenylphosphino)ethane monoxide), have been prepared and their structures characterized. In the binuclear complex 1 , the ligand L serves as tridentate donor with the N, N′ and O as coordination atoms, and the two CuI atoms are bridged through both P = O donor atoms in different ligand L with a triphenylphosphine molecule as auxiliary ligand. While in mononuclear complex 2 , both ligands L and dppeo behave as bidentate with N∧N from L and P∧O from dppeo chelating to CuI atom. 相似文献