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51.
加氢脱氮催化剂中硫化钼结构的表征 总被引:1,自引:0,他引:1
众所周知,重油加氢脱氮(HDN)所用Mo-Ni/Al2O3催化剂需经预硫化后始有显著的活性,关于硫化的条件工业上已较成熟,但在持续反应过程中硫化催化剂的结构与活性间的关系则很复杂,如硫化钼的价态和结构、金属组分和担体间的相互作用、反应条件及原料对催化剂组分的影响,以及硫化态催化剂中MoS2结晶的形貌等都可以引起催化剂活性本质的变化. 相似文献
52.
Mao Jiang-Gao Huang Jin-Shun Ma Jian-Fang Ni Jia-Zuan 《Transition Metal Chemistry》1997,22(3):277-280
The reaction of diglycolic acid, O(CH2CO2H)2, with Cu(NO3)2·2H2O and lanthanoid nitrate hydrate produces a series of novel Ln–Cu mixed metal complexes, [Ln2Cu3{O(CH2CO2)2}6]·nH2O (Ln=La, Nd, n=9; Ln=Er, n=6), which have been characterized by elemental analysis, i.r. spectroscopy, magnetic measurements and X-ray crystallography. The Ln3+ and Cu2+ ions are connected by the carboxylate groups of the ligands, resulting in the formation of a complicated network. 相似文献
53.
54.
Metz AW Ireland JR Zheng JG Lobo RP Yang Y Ni J Stern CL Dravid VP Bontemps N Kannewurf CR Poeppelmeier KR Marks TJ 《Journal of the American Chemical Society》2004,126(27):8477-8492
A series of low-melting, thermally stable cadmium metal-organic chemical vapor deposition (MOCVD) precursors have been synthesized, structurally and spectroscopically characterized, and implemented in growth of highly conductive and transparent CdO thin films. One member of the series, bis(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)(N,N-diethyl-N',N'-dimethyl-ethylenediamine)cadmium(II), Cd(hfa)(2)()(N,N-DE-N',N'-DMEDA), represents a particularly significant improvement over previously available Cd precursors, owing to the low melting point and robust thermal stability. High-quality CdO films were grown by MOCVD on glass and single-crystal MgO(100) between 300 and 412 degrees C. Film growth parameters and substrate surface have large effects on microstructure and electron carrier transport properties. Enhanced mobilities observed for highly biaxially textured films grown on MgO(100) vs glass are attributed, on the basis of DC charge transport and microstructure analysis, to a reduction in neutral impurity scattering and/or to a more densely packed grain microstructure. Although single-grained films grown on MgO(100) exhibit greater mobilities than analogues with discrete approximately 100 nm grains and similar texture, this effect is attributed, on the basis of charge transport and Hall effect measurements as well as optical reflectivity analysis, to differences in carrier concentration rather than to reduced grain boundary scattering. Unprecedented conductivities and mobilities as high as 11,000 S/cm and 307 cm(2)/V.s, respectively, are obtained for epitaxial single-grained films (X-ray diffraction parameters: fwhm(omega) = 0.30 degrees, fwhm(phi) = 0.27 degrees ) grown in situ on MgO(100) at a relatively low temperature (400 degrees C). 相似文献
55.
56.
硝酸镧与冠醚(2, 2)配合物的晶体及电子结构研究 总被引:1,自引:0,他引:1
用X-射线单晶衍射法测定了硝酸镧与冠醚(2,2)配合物的晶体结构,发现其具有与报道的Eu(NO_3)_3(2,2)配合物不同的配位方式.晶体属于三斜晶系,空间群P(?),晶胞参数为a=10.312(2)(?);b=12.745(3)(?);c=8.917(2)(?);α=103.79(2)°;β=112.73(2)°;γ=83.68(2)°;V=1049.5(5)(?)~3;F(000)=587.88;Z=2.结构用重原子法解出;R值为0.0292.用INDO法计算了配合物的净电荷分布,电子结构、键级.结果表明,镧与配位原子间的键具有一定程度的共价性.镧的5d轨道对共价性的贡献最大,而4f轨道基本上不参与成键.La-N比La-O(醚)间存在较强的作用,增大了配合物的稳定性. 相似文献
57.
58.
PdH2、YH2分子的结构与势能函数 总被引:6,自引:0,他引:6
用密度泛函理论的B3LYP方法,对钯和钇原子采用SDD收缩价基函数,氢原子采用6-311++G**全电子基函数,对PdH2和YH2体系的结构进行优化计算,得到PdH2分子最稳态为C2v构型,电子组态为1A1,平衡核间距RPdH=0.1692 nm,键角∠HPdH=29.4°,离解能De=5.5212 eV,基态简正振动频率:ν1(b2)=1470.1 cm-1、ν2(a1)=1007.9 cm-1、ν3(a1)=2907.0 cm-1.YH2分子最稳态也为C2v构型,电子组态2A1,RYH=0.1962 nm,∠HYH=114.3°,De=5.6691 eV,基态简正振动频率:ν1(b2)=1457.9 cm-1、ν2(a1)=476.0 cm-1、ν3(a1)=1506.3 cm-1.由微观过程的可逆性原理分析了分子的可能离解极限.并用多体项展式理论方法分别导出基态PdH2和YH2分子的势能函数,其等值势能面图准确地再现了PdH2和YH2分子的结构特征和离解能,由此讨论了Pd + H2和Y + H2分子反应的势能面静态特征. 相似文献
59.
Yan-Cong Chen Yan Meng Yan-Jie Dong Xiao-Wei Song Guo-Zhang Huang Chuan-Lei Zhang Zhao-Ping Ni Jakub Navaík Ondej Malina Radek Zboil Ming-Liang Tong 《Chemical science》2020,11(12):3281
Among responsive multistable materials, spin crossover (SCO) systems are of particular interest for stabilizing multiple spin states with various stimulus inputs and physical outputs. Here, in a 2D Hofmann-type coordination polymer, [Fe(isoq)2{Au(CN)2}2] (isoq = isoquinoline), a medium-temperature annealing process is introduced after light/temperature stimulation, which accesses the hidden multistability of the spin state. With the combined effort of magnetic, crystallographic and Mössbauer spectral investigation, these distinct spin states are identified and the light- and temperature-assisted transition pathways are clarified. Such excitation-relaxation and trapping-relaxation joint mechanisms, as ingenious interplays between the kinetic and thermodynamic effects, uncover hidden possibilities for the discovery of multistable materials and the development of multistate intelligent devices.Two new two-stage manipulation protocols, namely light- and temperature-assisted spin state annealing (LASSA/TASSA), are applied to a spin crossover coordination polymer, [Fe(isoq)2{Au(CN)2}2], revealing the hidden multistability of spin states. 相似文献
60.
A novel method for the determination of trace amounts of Al(III) based on resonance Rayleigh scattering (RRS) has been developed. In the presence of some surfactants, Al(III) can react with morin and form an Al(III)-morin-surfactant complex, which results in the enhancement of RRS intensity and the appearance of the corresponding RRS spectral characteristics. Their maximum scatter peaks are at 476 nm for the cetyltrimethylammonium bromide (CTAB) system, 489 nm for the cetylpyridinium chloride (CPC) system, 474 nm for the Triton X-100 system, and 473 nm for the Tween-20 system. The enhanced RRS intensity is directly proportional to the concentration of Al(III). The detection limits are in the range of (0.50-1.2)×10−7 mol l−1 depending on the surfactant. The characteristics of RRS spectra of the complexes, the optimum conditions of these reactions and the influencing factors have been investigated. The method has high selectivity, and was successfully applied to the determination of Al(III) in natural and biological samples. Furthermore, according to different complexation capacity of Al(III)-morin-CTAB system under two pH conditions, speciation analysis of Al(III) in natural waters was explored. The labile monomeric Al fraction (mainly inorganic Al, Ali) is determined at acidic pH and the total monomeric Al fraction (Ala) is determined at alkaline pH. The results are in agreement with those obtained by Driscoll’s 8-hydroxyquinoline extraction-ion exchange method. 相似文献