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91.
SrxBi1-xFeO3- (SBF) series mixed conductors were synthesized using Standard ceramic method. The properties of such materials were characterized by XRD, O2-TPD techniques. Ab-normal crystal phenomena were found and explained and correlated with the oxygen permeation results. By analysis of the critical radius (rc), the degree of openness of the lattice (Fv) and the average metal-oxygen bonding energy of the perovskite lattice (ABE), it was proposed that the oxygen permeation flux is determined mainly by the oxygen diffusion rate in bulk when 1-x≤0.5, and by the concentration of oxygen vacancy when 1-x≥ 0.5. The stability of Sr0.5Bi0.5FeO3- was also investigated, and the high stability of it was attributed to the stable BO6 octahedra. 相似文献
92.
MgAl2O4尖晶石的合成及作为甲烷部分氧化反应的良好催化剂载体 总被引:5,自引:0,他引:5
γ-Al2O3 has been intensively studied as a catalyst support in alkane conversion due to its large surface area. However, it is susceptible to crystal phase transition and favors catalyst sintering while the operaing temperature is higher than 700℃. Therefore, its application in industrial reactions is limited. 相似文献
93.
94.
Let H be a complex Hilbert space and B(H)the algebra of all bounded linear operators on H.An operator A is called the truncation of B in B(H)if A=PABPA*,where PA and PA*denote projections onto the closures of R(A)and R(A*),respectively.In this paper,we determine the structures of all additive surjective maps on B(H)preserving the truncation of operators in both directions. 相似文献
95.
Zhang Xiang Li Wenxin Sun Tongyu Yin Xinmin Qin Zhi Zhao Lili Wu Dingqing Zheng Jiwen Liu Guoxing 《中国物理C(英文版)》1996,20(1):21-25
The yields of known hafnium isotopes produced in 6.3-24.6MeV/u 40Ar+natW reactions were determined by γ-ray spectroscopy following radiochemical separations.The excitation functions,FW values and isotope distributions of hafnium were obtained.It is indicated that synthesis of new heavy neutron-rich isotopes is possible through the reactions induced by heavy ions at HIRFL energy region.The thick target is favorable for increasing the yields of neutron-rich nuclides far from the β-stability. However, further increasing incident energy is not always helpful to synthesize neutron-rich isotopes. 相似文献
96.
王国兴 《浙江大学学报(理学版)》2017,44(5):520-525
图G的一个正常k-边着色是指k种颜色1,2,…,k对图G各边的一个分配,使得任意2条相邻边染以不同的颜色.对于图G的一个正常边染色f和G中任何一个顶点x,Sf(x)或S(x)表示与顶点x关联的边在f下的颜色所构成的集合.若对于图G中任意2个相邻顶点u和v,有S(u)≠S(v),则称f为图G的邻点可区别正常边染色.对图G进行邻点可区别正常边染色所需的最少颜色数,称为G的邻点可区别正常边色数,记为χ'a(G).图G的一个正常k-全染色是指k种颜色对图G的顶点和边的一个分配,使得任意2个相邻的或相关联元素染以不同的颜色.对于图G的一个正常全染色g和G中任何一个顶点 x,使用Cg(x)或C(x)来表示顶点x的颜色(在g下)以及与顶点x关联的边在g下的颜色所构成的集合.若对于G中任意2个相邻顶点u和v,有C(u)≠C(v),则称g为图G的邻点可区别全染色.图G的邻点可区别全染色所需的最少颜色数称为图G的邻点可区别正常全色数,记为χ″a(G).主要讨论了Cartesian积和2种邻点可区别染色之间的关系. 相似文献
97.
共沉淀镍催化剂用于膜反应器中高碳烃类燃料水蒸气重整反应 总被引:1,自引:0,他引:1
采用共沉淀法制备了NiO/La-Al2O3催化剂,利用低温N2物理吸附、程序升温还原、 H2-O2化学吸附和X射线衍射对催化剂进行了表征,并将该催化剂应用于Pd膜反应器中高碳烃类燃料水蒸气重整反应. 结果表明,催化剂中NiO与载体间存在较强的相互作用. 与常规固定床反应器相比,在膜反应器中,由于高渗透性能的Pd金属复合膜能选择分离氢气,结果氢气产率得到了明显的提高,甲烷的生成得到了有效抑制,并且在接近实用的反应条件下,依然能够得到高的氢气产率和回收率. 高碳烃类燃料水蒸气重整反应制氢的过程可以在一个膜反应器中,利用一种催化剂在反应温度低于823 K的温和条件下实现. 相似文献
98.
99.
The molecular assembling behaviours between ferrocene-modified diphenylalanine and β-cyclodextrin were investigated, which showed a reversible morphological conversion by the chemical redox of ferrocenyl moiety. 相似文献
100.
MoO3 / Al2O3、MoO3 / TiO2与NiO-MoO3 / TiO2催化剂上活性相还原行为的XPS考察 总被引:2,自引:0,他引:2
The H_2 reduction behaviours of MoO_3/Al_2O_3, MoO_3/TiO_2 and NiO-MoO_3/TiO_2 samples prepared by impregnation method were studied at various temperatures for different times by XPS technique. The recored XPS spectra of Mo3d from those samples were treated by computer curve fittingprogram to measure the distribution of various molybdenum oxide species with different valence states. The results of computer fitting shows that there areMo(Ⅵ), Mo(Ⅴ)and Mo(Ⅳ) on the all of reduced samples. However, after H_2 reductonin same way, the percentage of low valence species Mo(V) and Mo(IV) on the MoO_3/TiO_2 is much higher than on the MoO_3/Al_2O3 (Fig.2). For example, after H_2 treatment at 500 ℃ for 2 hrs., Mo(IV) species on the surface of MoO_3/TiO_2 sample is about 60% and it is three times higher than what is found on the MoO_3/Al_2O_3 sample. In addition, the reduction of molybdena on TiO_2 support is much easier and faster than on Al_2O_3 support (Fig.3). Addition of NiO further promotes the reduction of molybdena to cause the strting reduction temperature producing Mo(IV) and Mo(V) to be decreased about 100 ℃. and 80% of molyb dena on NiO-MoO_3/TiO_2 support could be reduced to Mo(IV) (Fig.2). A detail discussion about the interaction between molybdena and carries was presented. It was suggested that TiO_2 is certainly involved in the reduction and oxidation process of molybdenum oxide species on the surface of it. 相似文献