一些晶态层状有机-无机混合磷酸锆的制备、表征和层间距分析

酸氢锆和有机磷酸锆是一类具有层状结构的多功能材料 ,具有较高的热稳定性和较好的耐酸碱性能 ,可用作离子交换剂、催化剂及催化剂载体、吸附剂和色谱填充剂等 [1,2]。典型的α-磷酸氢锆具有数十至数百 m2· g-1的比表面 [3]。且无论是晶态、半晶态或是非晶态 ,所有有机基团均位于其表面或层间面上 ,这一优点可以充分发挥活性基团的配位作用。利用有机合成化学的丰富多样性 ,合成含有不同种类有机活性基团的有机膦酸 ,从而将不同种类的有机活性基团引入有机-无机混合磷酸锆层状结构材料 [4～ 6]。这些膦酸盐的另一优点是有机基团的含量比是…     

锆吸氘和氚的动力学同位素效应

应用反应速率分析方法,在高真空金属系统上测定了锆在恒容体系和450～630 ℃范围内吸收氘和氚的p-t曲线。由p-t曲线可知,在同一温度下,锆吸氚的速率低于锆吸氘的速率;而随着温度的升高,由于解吸逆反应的影响,锆吸氚(氘)的反应速率降低。根据p-t曲线计算了吸气反应在不同温度的速率常数,得到锆吸氘和氚的表观活化能分别为(-25.9±0.7)和(-16.8±0.8)kJ·mol^-1。从活化能数据可以看出     

双(烷基环戊二烯基)二硫氰基钛、锆、铪的合成

文献报道了双(环戊二烯基)二硫氰基钛、锆、铪^[1-3]及双(甲基环戊二烯基)二硫氰基钛^[4]的合成。我们利用双(烷基环戊二烯基)二氯化钛、锆、铪与过量硫氰酸钾反应,合成了一系列新的双(烷基环戊二烯基)二硫氰基钛、锆、铪(见表1)。     

惰性气体中熔样-热导法测定锆中氢的含量

锆具有良好的核性能、机械性能和耐腐蚀性能,被广泛用作核电燃料元件的包壳材料。氢可使锆发生脆性断裂,氢在金属缺陷附近富集导致的氢脆,是燃料元件包壳破损的潜在原因[1-2]。因此,准确测定锆中氢的含量对保证核电燃料元件制造质量具有非常重要的意义。氢在金属中扩散系数较大。从热力学角度分析,氢化物分解及氢的析出不需要过高的温度及浴金属,但在无浴或较低温度下析出氢耗时相当长。只有将被测金属加热至高于其熔点的温度或将其熔     

茂钛配合物掺杂的高活性纳米镁粉的加氢性能

镁粉可作为储氢材料和某些化学反应试剂,但普通的工业镁粉不够活泼。文献中陆续出现一些制备活性镁的方法,例如用碱金属还原卤化镁 [1,2],用催化法合成氢化镁后脱氢 [3,4],以及在不同条件下使蒽镁分解 [5]。我们曾报道过用蒽镁真空热解制备高活性纳米镁粉的结 果 [6～ 7],由此得到的镁对氢具有很高的反应活性。将这种镁用于制备双格氏化合物 [8,9]和制备纳米氮化镁 [10],表明这种镁粉比著名的 Rieke镁活性高。 Bogdanovic等曾报道过合成氢化镁后用环辛二烯基镍掺杂对 MgH2的放 /吸氢行为有显著的改善 [11]。本文报道用茂钛配合物 (C…     

LaMg_2Cu_(1-x)Ni_x(x=0～0.90)合金的相结构及储氢性能

利用真空感应熔炼技术制备了LaMg2Cu1-xNix(x=0,0.10,0.25,0.50,0.75,0.90)合金,并在0.06MPa氩气保护下于723K退火6h得到测试所用合金铸锭。XRD表明合金LaMg2Cu1-xNix含有ThCr2Si2型的LaMg2Cu2相和CeMg3型的LaMg3相以及少量未知相,随着x的增加,LaMg2Cu2相的晶胞体积先增加后减小,而LaMg3相的晶胞体积几乎不变。通过SEM观察,发现Ni可以有效的减小合金在吸放氢过程中的粉化。当x0.50时,Ni对合金的吸氢速率降低;而当x≥0.50时,Ni的加入可以极大的提高合金的吸氢速率,合金在50s左右就能达到最大吸氢量的90%。当x=0.50时,合金具有较好的综合储氢性能,合金在473K下吸氢量为3.741wt%,49s就可达到最大吸氢量的90%以上。     

MmB5贮氢合金的结构和性能

近十年未对AB5型合金的研究表明，某些多元取代的LaNi5基合金可作为MH／Ni电池的负极材料，且具有容量大，寿命长等优点[1，2]．LaNi5虽然具有吸放氢量较大、平台氢压平整和压力滞后小等优良性能，但不耐硷腐蚀、吸氢后易粉化，其氢化物的分解氢压较高，故不能作为负板材料．以Co部分地取代Ni可有效地降低氢化物的分解氢压·混合稀土（Mm）取代La，虽容量有所下降，但从原料成本上看是有益的．本工作试图从MmB5多元合金晶体结构的研究，来探讨Mm中La和Ce的相对含量对吸放氢性能和电化学容量的影响．1实验Mllin。合金样品由金属Ni，…     

TiHx(x=2,3,4)的从头计算研究

过渡金属氢化物分子与诸多催化过程密切相关[1].而过渡金属氢化物本身是一种颇有潜力的能源材料,即贮氢材料,如钛系、钒系贮氢材料在工业上已得到了广泛的应用 [2].但对于金属与氢的相互作用的机理研究的报道甚少.     

镧镍铜钴储氢合金的制备与性质

以LaNi₅为代表的镧系储氢合金有优良的吸放氢性能,抗中毒能力强,因而受到广泛重视^[1]. 目前已开发出许多二元及多元镧系合金,并研究了部分合金的表面性质^[1～4],但结果并不一致. 本文制备了四元合金LaNi₄Cu_0.5Co_0.5,通过X 射线光电子能谱(XPS)、扫描电镜(SEM)和吸氢测试等方法研究该合金的性质。     

大量铌、钽、钛中微量锆的分离和测定

1-苯基-3-甲基-4-苯甲酰基毗唑酮^[5](PMBP)在分析化学上已广泛应用^[1~5].本文着重报导在硫酸-硝酸溶液中,有柠檬酸和过氧化氢存在下,微克量锆和100毫克铌共存时,以PMBP萃取完全的适宜条件(用硝酸反萃取,加入高氯酸于反萃液中,加热破坏有机物后以偶氮胂Ⅲ进行光度测定^[5,6].在确定了的适宜条件下,大量钽、钛等离子不影响锆的萃取和测定.铌、钽、钛、铌-钛合金、锡化三铌和金红石精矿中微量锆用本法分离和测定,得到较满意结果.     

Physico-chemical properties of Chitosan films

Chitosan films obtained by dry phase inversion were prepared from an aqueous solution of chitosan in acetic acid. The films, of thickness less than 20 μm, were transparent, very flexible and had smooth surfaces. Increasing the film thickness induced an increase of the internal tensions and the consequent formation of a rough surface. Structural investigations by X-ray diffraction and Fourier transform IR analysis, showed that the chitosan films, as prepared, are amorphous. Further annealing to evaporate acetic acid and water traces, changed the amorphous phase into a more ordered phase, characterized by diffraction peaks at 2θ values of 9, 17, 20 and 23 degrees. Thermal investigations by TG, DTG, and DTA revealed that the decomposition of the chitosan films as prepared proceeds in two stages, starting from 180°C and 540°C.     

Pyrazoles as molecular probes to study the properties of co-crystals by solid state NMR spectroscopy

Equimolar mixtures of 3,5-dimethylpyrazole (1) with four NH-imidazoles (2–5) have been studied by¹³C and ¹⁵N CPMAS NMR and by DSC. In three cases, the solid mixture behaves as the sum of the individual components [imidazole (2), 2-methylimidazole (3) and 2,4(5)-dimethylimidazole (5)]. In one case [4,5-dimethylimidazole (4)], the mixture corresponds to a new species in which the dynamic behavior of1 no longer exists.     

Aqueous p-nitrotoluene oxidation induced with direct glow discharge plasma

A plasma induced degradation process has been studied to treat 4-nitrotoluene (4-NT) present as an aqueous pollutant. The plasma was locally generated from a glow discharge around a tip of a platinum anode in an electrolytic solution. The influence of initial pH and Fe²⁺ on the degradation was examined. Major intermediates resulting from the degradation process were identified. Amongst the aromatic intermediates, p-hydroxybenzoic acid was the predominant degradation product. The formation of oxalic acid, malic acid was also observed. The final products of degradation were NH ₄ ⁺ , NO ₃ ⁻ and CO₂. Based on the analysis of intermediates and the kinetic considerations, the degradation was shown to follow a pseudo-first order reaction hence, a possible reaction pathway was proposed.     

Catalytic air oxidation of manganese in synthetic waters

An attempt was made to study the oxidation of manganese by air in synthetic waters. A series of batch experments were performed at differnet values of concentration, temperature and pH. Unoxidized manganese in the solution was determined by formaldoxime spectrometric method. Results of these studies indicated that the air oxidation of manganese soluble in water can be effectively performed in basic media and that oxidation yield increasedwith an increase in pH and concentration. The yield was very high in the presence of manganese dioxide, sepiolite or clinoptilolite in solution and, the oxidation was almost completed especially at high values of pH and concentration. The reaction was found to be first order with respect to Mn²⁺ with a very low activation energy. A yield of 62% was obtained for the air oxidation of wastewater taken from the treatment plant of Corum Municipality.     

Zur Kenntnis der Reaktionsfähigkeit des Thiomorpholins und alkylsubstituierter Thiomorpholine, 4. Mitt.

Thiomorpholine as well as alkyl substituted thiomorpholines and their Sdioxides, respectively, are transformed into the corresponding N-Aminothiomorpholines by nitrosation (1–5) followed by the reduction with zinc in acetic acid/acetic acid anhydride under simultaneous formation of the corresponding N-acetyl derivates, and hydrolysis by hydrochloric acid (6–9). Examples of this method are described. 4-Aminothiomorpholines and their Sdioxides react with aldehydes or ketones to give azomethines (10–31). Acylation with mono-and dicarbonic acid chlorides leads to the N-acyl derivatives32–44.Mannich condensation is also possible. By oxidation with yellow mercury oxide tetracenes are formed (46–47).

Teil der DissertationM. Schmitz, Techn. Hochschule Aachen, 1975.     

Präparation und röntgenographische Untersuchung eines neuen Kupfer-Oxoaluminats: Cu2Al4O7

Solid state reaction of CuO and Al₂O₃ with a flux of PbO about 930°C and reaction time of 8d gives the new compound Cu₂Al₄O₇. The red single crystals were examined by energydispersive microanalysis and X-ray diffraction methods. Cu₂Al₄O₇ has cubic symmetry, space group ,a=908.0 pm. The typical coordination of Cu⁺ (CN=6 and CN=12) and the interstitial arrangement of the AlO₄-tetrahedra are discussed with respect to related compounds.

     

Beiträge zur Chemie der Pyrrolpigmente, 39. Mitt.: Ein Kraftfeldmodell zur konformationsanalytischen Untersuchung von Gallenfarbstoffen

A force field model was designed with respect to the special needs of bile pigments. It is parametrized and tested using partial structures of bile pigments as well as an integral pigment; the solution structures of the molecules were previously deduced using independent experimental methods.

38. Mitt::Falk, H., Schlederer, T., Wolshann, P., Mh. Chem.112, 199 (1981).     

Kinetics and mechanism of oxidation of xylitol and galactitol by hexacyanoferrate(III) ion in aqueous alkaline medium

Kinetics of oxidation of xylitol and galactitol by hexacyanoferrate(III) ion in aqueous alkaline medium is reported. The reaction rate is of first order with respect to hexacyanoferrate(III) in each substrate. The reaction is first order at lower concentrations of xylitol and galactitol and tends towards zero order as the concentration increases. Similarly first order kinetics was obtained with respect to hydroxide ion at lower concentrations and tends to lower order at higher concentration in the oxidation of xylitol; in the oxidation of galactitol the reaction is first order with respect to hydroxide ion even up to manyfold variation. The course of reaction has been considered to proceed through the formation of an activated complex between [K Fe(CN)₆]^2– and substrate anion which decomposes slowly into radical and [K Fe(CN)₆]^3–. A probable reaction mechanism is proposed.

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Kinetik und Mechanismus der Oxidation von Xylit und Galaktit mit Hexacyanoferrat(III) in wäßriger, alkalischer Lösung

Zusammenfassung Das Geschwindigkeitsgesetz der Titelreaktion ist in beiden Fällen erster Ordnung bezüglich Hexacyanoferrat(III). Die Oxidation ist erster Ordnung bei niedrigen Konzentrationen von Xylit und Galaktit und geht bei Erhöhung der Konzentration gegen null. In gleicher Weise wurde eine Kinetik erster Ordnung bezüglich Hydroxyl bei niedrigen Konzentrationen und eine erniedrigte Ordnung bei höheren Konzentrationen für die Oxidation von Xylit beobachtet; bei Galaktit bleibt die Oxidation auch bei höheren Hydroxyl-Konzentrationen erster Ordnung. Es wird angenommen, daß die Reaktion über einen aktivierten Komplex zwischen [KFe(CN)₆]^2– und dem Substrat-Anion verläuft; dieser Komplex zerfällt in [KFe(CN)₆]^3– und ein Substrat-Radikal. Ein möglicher Reaktionsmechanismus wird vorgeschlagen.

     

Hydrazyl,Nitronyl-, and imino-nitroxides: Synthesis,properties and reaction with nitric oxide and nitrogen dioxide

Ten novel and stable free radicals of nitronyl-, imino-nitroxide and hydrazyl type compounds were synthesized and their physico-chemical properties investigated. UV-Vis and ESR spectroscopic data, as well as the lipophilicities and specific hydrophobic areas of the compounds are compiled. The reaction of these radical compounds with nitric oxide and nitrogen dioxide was also investigated. The radicals synthesized, show selectivity in their reaction with these nitric oxides, depending on their structure (nitronyl-nitroxide radicals react with NO, while hydrazyl radicals react with NO₂). The processes are easily monitored by UV-Vis or ESR spectroscopy.     

Kinetische und thermodynamische Untersuchungen im System AgCl-LiCl-NaCl

In the ternary system silver chloride-lithium chloride-sodium chloride the kinetics of the galvanic deposition of silver on graphite electrodes was investigated as well as its dissolution without current in the molten salt saturated with chlorine gas.In addition the emf-values were measured in the temperature range between 923 K and 1,173 K by means of, the formation cell graphite/Ag(s)/AgCl(l)–LiCl(l)–NaCl(l)/Cl₂ graphite From these data the partial molar free excessGibbs energies were calculated. Using the equation for a multicomponent system as suggested byRedlich-Kister ¹ G _AgCl ^E values were obtained by a non-linear fitting process, where the fit was performed for all investigated temperatures and over the entire concentration range in the ternary system. With the parameters obtained the partial and integral excess valuesG _i ^E ,G ^E ,H _i ^E ,H ^E ,S _i ^E andS ^E were calculated.