CaO／La2O3催化剂电导性质与催化性质的研究

碱土金属氧化物及稀土金属氧化物对甲烷氧化偶联(OCM)均有较好的催化活性,前者具有较强的碱性,后者具有较好的稳定性,而且是产生甲基自由基的活性材料。Becker在较大范围内调变了CaO-La_2O_3的组成,研究了其反应活性及表面酸碱性的关系。结果表明,混合氧化物生成C_2烃的选择性比La_2O_3纯相氧化物的高,据此推测在La_2o_3和CaO间存在一种相互作用,有利于提高C_2烃的选择性。为进一步研究这种二元催化剂的相互作用,我们在较小范围内对La_2o_3进行了调变,通过对其电导、结构及催化性质的研究发现,少量CaO掺杂使C_2烃选择性提高的原因在于有部分Ca~(2+)进入了La_2O_3晶格,产生了O~-离子物种。 1 实验部分 1.1 催化剂合成 采用硝酸盐混合溶解、673K热分解、1373K高温焙烧的方法制备CaO/La_2O_3(记为XLEC)催化剂。根据所含CaO的摩尔百分数0、1、3、5、7、100,分别将其标记为XLEC0、XLEC1、XLEC3、XLEC5、XLEC7、XLECaO。 1.2 活性表征 反应在常压固定床石英反应器内完成,CH_4:O_2=4:1(总流速100mL/min),催化剂40～60目,用量0.2g。产物用2305型氢火焰检测器分析。 1.3 仪器及测试条件 XRD谱及晶胞参数测定在DMAX—Ⅱ型衍射仪上完成,使用CuKα射线辐射。Raman光谱应用SPEX-1403双光栅拉曼光谱仪,光源为A     

三氯化二甘氨酸四水合稀土固体配合物的合成及红外光谱研究

在水溶液中制备出配合物［Ｌｎ（Ｇｌｙ）２．４Ｈ２Ｏ］．Ｃｌ３．ｎＨ２Ｏ（Ｌｎ＝Ｇ，Ｅｒ，Ｙｂ），测定了配合物的红外光谱，并对其主要红外吸收带进行了归属。结果表明，甘氨酸以内盐的形式存在于配合物中，并通过羧基与稀土离子配位。四个水分子参与了配位，在Ｇｄ和Ｅｒ的配合物还有一个不分子未参与配位。推测Ｙｂ配合物为对称的一维无限长链结构，其余两种配合物为不对称的一维无限长链。     

Spectroscopic studies of CO2 trapped in rare gas matrices

Low temperature (5 K) high resolution (0.15 and 0.03 cm⁻¹) absorption spectra of ¹³CO₂ have been recorded in neon, argon, krypton, and xenon matrices, in the ν₃ and ν₂ regions. Diffusion experiments have been performed in krypton and xenon in order to identify vibrational traps which could be responsible for the decrease and shortening of the emission observed after laser excitation: high-frequency structures in the ν₃ region are assigned to dimers and a doubling of the monomer line is due to a site effect. In neon, only a double substitutional site, with a splitting of the degenerate ν₂ vibration, is observed. In argon, as previously reported, a single and a double site are characterized. In krypton and xenon, where ν₂ is not split, only single sites would be predicted. As one of them exhibits a ν₃ line highly sensitive to temperature, we expect a large coupling with the lattice and a fast vibrational relaxation. This site is very likely the vibrational trap we are looking for.     

LnHal2Hn — Neue Phasen in den ternären Systemen Ln/Hal/H (Ln = Lanthanoid,Hal = Br,I) III. Physikalische Eigenschaften

LnHal₂H_n - New Phases in the Ternary System Ln/Hal/H (Ln = Lanthanoid, Hal = Br, I) 111. Physical Properties IR and diffuse reflectance spectra, magnetic susceptibility and electrical resistance as well as photo-electron spectra of GdI₂H_n and CeI₂H_n (n ≦ 1) are reported. GdI₂H_n samples with 0 < n 5 1 are insulators or semiconductors. Compounds with n = 1 are colourless, with n < 1 blue transparent. Phases with n < 0.9 show metallic lustre. This feature and the electrical properties can be understood on the basis of the electronic structure (Extended Hückel calculations, photoelectron- and reflectance spectroscopy). For n ≠ 1, in contrast to the stoichiometric hydride halides, bands approx. 1 eV below the Fermi edge are populated. With decreasing H content they broaden and the density of states increases. CeI₂H_n exhibits a metal-to-semiconductor transition for n = 0.33. According to the susceptibility measurements the ferromagnetic order of GdI₂ successively is suppressed by the incorporation of hydrogen. Simultaneously, correlated regions with spontaneous magnetization are maintained. Temperature dependent X-ray diffraction measurements also indicate the existance of such clusters.     

醋酸纤维素为母体的稀土离子选择性电极的研制

醋酸纤维素为母体的稀土离子选择电极,制备容易,使用方便,可以测定混合稀土,电极的线性范围为1.2×10~(-1)～1×10~(-5)mol/L,适宜的pH范围较宽,测定结果令人满意。     

三维荧光光谱法在多组分稀土分析中的应用

本文研究了HFA-TOPO-Triton X-100体系中铕、钐、铽和镝的三维荧光光谱,拟定了三维荧光光谱法同时测定这四个稀土元素的分析方法。     

Syntheses, structures, and magnetic properties of new rare earth coordination polymers constructed by 1,3,5-benzenetriacetic acid

Three new coordination polymers with formula [Gd(bta)(H₂O)·1.39H₂O] _n (1), [Dy(bta)(H₂O)·1.35H₂O] _n (2) and [Y(bta)(H₂O)₂·0.5H₂O] _n (3) were synthesized by using corresponding rare earth nitrates and 1,3,5-benzenetriacetic acid (H₃bta) under hydrothermal/solvothermal reaction conditions, and characterized by single-crystal X-ray diffraction. In these complexes, the carboxylate groups of bta³⁻ adopt different coordination modes, namely one carboxylate group adopts μ₂-η¹:η¹-bridging and each of the other two carboxylate groups adopts μ₂-η²:η¹-bridging coordination modes in 1 and 2, and one carboxylate group adopts a μ₂-η²:η¹-bridging coordination mode and each of the other two carboxylate groups adopts a μ₂-η¹:η¹-bridging mode for the major component and one carboxylate group adopts a μ₂-η²:η¹-bridging coordination mode, one has a μ₂-η¹:η¹-bridging mode and the third has a monodentate mode for the minor component in 3. The magnetic properties of the complexes 1 and 2 were investigated in the temperature range of 1.8–300 K.     

Mm(NiMnTiCo)5贮氢合金的制备工艺、 电化学性能及相结构研究

用电化学测量、Ｘ射线衍射、透射电子显微镜和能谱分析等技术对不同工艺制备的Ｍｍ（ＮｉＭｎＴｉＣｏ）５贮氢合金的电化学性质和结构进行了详细研究。快淬技术如熔体喷带法可有效改善合金的循环稳定性，但却导致其活化速度和放电容量下降。合金在适当温度下回火可弥补以上不足。不同制备工艺造成合金电化学性能变化的原因在于相结构和显微组织的差别。     

Fluorimetric determination of nucleic acids with terbium and lutetium

In this paper, fluorescence-enhancement of Tb-nucleic acids [fish sperm DNA (fsDNA) and yeast RNA (yRNA)] by Lu³⁺ is studied in detail and is applied to determine nucleic acids. The experiments indicated that under the optimum conditions, a linear relationship was obtained between the fluorescence intensity (I_f) and the concentration of nucleic acids. The linear range is 1.2×10⁻⁸-1.0×10⁻⁴ g/ml for DNA and 3.0×10⁻⁸-8.0×10⁻⁴ g/ml for RNA. The detection limits (signal/noise=3) for DNA and RNA were 4.8×10⁻⁹ and 7.0×10⁻⁹ g/ml, respectively. The mechanism of the co-luminescence effect is also discussed.     

氯化-甘氨酸六水合稀土固体络合物的合成及红外光谱研究

本文用稀土氯化物与甘氨酸反应制备了标题络合物[Ln(Gly)·6H_2O]·Cl_3(Ln=Nd,Sm,Gd,Er,Yb),测定了络合物的红外光谱,对其主要吸收带进行了归属。红外光谱的研究结果表明,甘氨酸以内盐的形式存在于络合物中,通过羧基与稀土离子配位。水分子也参与了配位。并推测,Nd的络合物为双核络合物,其它稀土络合物具有一维无限长链结构。