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1.
The new compounds YNi2P2 and LnNi2P2 (Ln = La, Ce, Pr, Nd, Sm, Tb, Dy, Ho, Er, Tm) were prépared by sintering the elemental components in silica tubes. Well-developed crystals were obtained using tin as a flux. They crystallize with the ThCr2Si2 (CeGa2Al2)-type structure which was refined from single-crystal X-ray data for EuNi2P2 to a conventional R value of 0.049 for 118 unique structure factors. While the P atoms in formally isotypic EuCo2P2 are isolated from each other, they form pairs in EuNi2P2. This results in a different ratio and an entirely different bonding situation. A comparison of cell volumes shows that Eu in EuNi2P2 has an intermediate valence. 相似文献
2.
有机硒化合物具有生物活性[14],将硒基团引入到有机分子的一般方法是使亲核性的硒金属盐与亲电试剂反应 .二芳基二硒醚是制备有机硒化合物的重要中间体 .当它被还原时转化为硒负离子 ,被卤素等氧化时转化为亲电的硒试剂 .还原二硒醚通常使用NaBH4[5 ],最近报道一些新的方法 ,如使用水合肼 /甲醇钠体系[6 ],Sm/HgCl2 体系[7].本文报道Cp2 TiCl2 /BuiMgBr/THF体系还原二芳基二硒醚 .1 结果与讨论Cp2 TiCl2 与BuiMgBr反应产生的钛氢化物是一种强的还原剂[8].在室温下 ,钛氢化物很容易与二硒醚反应生成… 相似文献
3.
TiO2/H2O2/超声波协同降解壬基酚聚氧乙烯醚溶液 总被引:1,自引:0,他引:1
采用经过处理的锐钛矿型TiO2作为催化剂,在H2O2存在下,以TiO2/H2O2/超声波协同降解壬基酚聚氧乙烯醚反应为模型,探讨了TiO2催化剂用量、H2O2用量、超声波功率、壬基酚聚氧乙烯醚溶液初始浓度、初始pH值对壬基酚聚氧乙烯醚降解率的影响。结果表明,在一定的超声波功率和一定的TiO2用量范围内,壬基酚聚氧乙烯醚降解率随超声波功率和TiO2用量的增大而增大,达到一定值后保持平稳;当H2O2浓度介于一定范围内,增大H2O2用量可提高壬基酚聚氧乙烯醚的降解率,但H2O2用量过多时,反而会使壬基酚聚氧乙烯醚的降解率下降;pH<5时,壬基酚聚氧乙烯醚降解效果较好,且pH值越小,降解率越高;pH>5时,降解率越来越低。TiO2/H2O2/超声波体系降解壬基酚聚氧乙烯醚产生了较强烈的协同效应,在同一时刻三者协同体系的降解率比其3种单独体系的降解率之和高出约60%;在TiO2催化剂用量0.4g/L、H2O2用量0.2g/L、超声波功率600W、降解时间120min的条件下,对初始质量浓度为80mg/L,pH=1的壬基酚聚氧乙烯醚溶液进行降解,其降解率达98%以上。 相似文献
4.
By metal impregnation of selected naturally occurring organic materials followed by controlled carbonization, metal semicoke catalysts can be readily prepared. These catalysts have been tested in the synthesis of hydrocarbons and alcohols from CO/H2 and CO2/H2 mixtures. Fe and Co preparations have been used. Relatively high temperatures are required when using these catalysts, which are quite active for synthesis using CO2 and H2. The pressure (5150 kPa) is very favorable both for the synthesis of liquid hydrocarbons (C5–C30) and alcohols (C1–C5).
. CO/H2 CO2/H2. Fe Co. , CO2 H2. 5150 ) (C5–C30) (C1–C5).相似文献
5.
A new reaction of MgCl2·4H2O with CCl2F2 is investigated by DTA and TG from room temperature to 350 °C. It is observed that MgF2 was obtained between 252 and 350 °C, Below the temperature, MgCl2·4H2O dehydrates and hydrolyzes to MgCl2 and Mg(OH)Cl, which are the real reactants of the reaction with CCl2F2. The formation of MgF2 is ascribed to the reaction of MgCl2 and Mg(OH)Cl with HF, which forms by decomposition of CCl2F2 with the taking part in of H2O released from dehydration of hydrated magnesium chloride on the surface of MgCl2 and Mg(OH)Cl, which catalyzes the decomposition of CCl2F2 in this case. Consequently, the reactions are tested in the fluid-bed condition. It is found that MgF2 formed at temperatures down to 200 °C in a fluid-bed reactor. This reaction may be used as a method of disposing of the environmentally sensitive CCl2F2 (rather than release into the atmosphere). It is also a method for the preparation of MgF2. 相似文献
6.
以活性艳橙溶液为模拟废水,通过H2O2/TiO2超声(US)协同作用光降解活性艳橙溶液,探讨了TiO2催化剂用量、H2O2用量、活性艳橙溶液的初始浓度、pH值、TiO2催化剂锻烧温度等对活性艳橙溶液降解率的影响,并比较了几种不同作用方式对活性艳橙溶液的降解效果.结果表明:UV/H2O2/TiO2/US协同作用降解活性艳橙溶液的效果最好;当活性艳橙溶液的初始浓度为20 mg·L-1,pH=5,TiO2用量为0.4 g·L-1,H2O2用量为0.4 ml·L-1时,降解率可达92.06%. 相似文献
7.
Alkenes a–d interact at ?80°C in 15 min. with the Vilsmeier reagent (Me2N=CHCl)+PO2Cl2? in presence of 30% H2O2 to yield the corresponding epoxides a–d. The reaction could involve the formation of the highly reactive hydroperoxymethylenedimethylammonium salt (Me2N=CHOOH)+PO2Cl?2. 相似文献
8.
BrCF2X (X : Cl, Br, BrCF2) react wth enamines and ynamines. A radical chain mechanism is proposed. Halogen (Br or Cl) - fluorine exchange of α halodifluoromethylketones to α trifluoromethylketones using Bu4+N, F?, 3H2O is examined. 相似文献
9.
The compound V0.4Os0.6B2 was found to crystallize with ReB2-type structure. V2OsB2, Mo2OsB2, and W2OsB2 are isotypic with the crystal structure of Mo2IrB2. The crystal chemistry of complex borides with ReB2- and Mo2IrB2-type structure is discussed. 相似文献
10.
K. Zbudniewek J. Góralski J. Rynkowski 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2012,86(13):2057-2062
The development of industry induced a massive increase in the emission of carbon dioxide into the atmosphere. A large amount of CO2 and its general availability causes that it could be a cheap reactant in a reaction that runs in a way similar to photosynthesis in plants. Pure TiO2 and metal doped TiO2 are the most studied semiconductor catalysts for photoreduction of CO2. The TiO2/SiO2 and Pd/TiO2/SiO2 catalysts were prepared and studied by temperature-programmed desorption, X-ray diffraction analysis, SEM-EDS, temperature-programmed reduction and then used for the methanol synthesis. The photoactivity of Pd/TiO2/SiO2 catalysts in the reduction of CO2 with H2O was tested at room temperature using photoreactor equipped with 16 lamps. The wavelength was characteristic of near ultraviolet. Post-reaction products were identified with gas chromatograph equipped with the flame ionization detector. Pd doping made the catalysts photoactive and the photoactivity of catalysts was changing as follows: 1%Pd/5%TiO2/SiO2 > 1% Pd/10% TiO2/SiO2 > 1% Pd/15% TiO2/SiO2. Optimum ultraviolet radiation time in the photoreduction of CO2 to methanol was 7 h. An addition of Pd does not change the surface of the carrier. 相似文献
11.
Simple 2H-chromenes and 2H-thiochromenes form the [2+2]-adducts, tetrahydro[1]benzo(thio)pyrano[3,4-c] [1,2]diazeto[1,2-a][1,2,4]triazoles, with triazolinediones, whereas their 3- and 4-bromo and the corresponding cycloalkylamino derivatives undergo an overall etectrophilic substitution sequence. 相似文献
12.
Minh Tho Nguyen Debasis Sengupta L. G. Vanquickenborne 《Chemical physics letters》1995,240(5-6):513-520
Potential energy surfaces of the reaction of SiH2 and C2H2 (and C2D2) have been calculated by means of ab initio molecular orbital theory at the QCISD/6-311G++(2df, 2p)//MP2/6-31G(d, p) level with corrections for the triple excitations to the QCISD energies. The barrier heights for the two reaction channels of the adduct, thus calculated, were further utilized for the dynamical calculation of the rate constants in the framework of quantum statistical Rice-Ramsperger-Kassel theory. Contributions of the rate constants of the various pathways to the total rate constant (KT) for the disappearance of the reactants are critically examined and compared with experiment. The pressure dependence of KT(C2H2) is primarily due to the formation of silirene. KT(C2D2) is consistently higher than KT(C2H2). The standard heat of formation of silirene is predicted to be 72.1 ± 3 kcal/mol. Rearrangement of silirene to vinylsilylene requires an activation energy smaller than that to silylacetylene. 相似文献
13.
Intramolecular epoxidation is shown to occur when trimethyl ortho oleate is treated with H2O2. 相似文献
14.
Some K2O-TiO2-GeO2 glasses with a large amount of TiO2 contents (15-25 mol%) such as 25K2O-25TiO2-50GeO2 have been prepared, and their electronic polarizability, Raman scattering spectra, and crystallization behavior are examined to clarify thermal properties and structure of the glasses and to develop new nonlinear optical crystallized glasses. It is proposed that the glasses consist of the network of TiO6 and GeO4 polyhedra. The glasses show large optical basicities of Λ=0.88-0.92, indicating the high polarizabity of TiOn (n=4-6) polyhedra in the glasses. K2TiGe3O9 crystals are formed through crystallization in all glasses prepared in the present study. In particular, 20K2O-20TiO2-60GeO2 glass shows bulk crystallization and 18K2O-18TiO2-64GeO2 glass exhibits surface crystallization giving the c-axis orientation. The crystallized glasses show second harmonic generations (SHGs), and it is suggested that the distortion of TiO6 octahedra in K2TiGe3O9 crystals induces SHGs. 相似文献
15.
V. V. Sinels’nikov N. N. Tolkachev S. S. Goryashchenko N. S. Telegina A. Yu. Stakheev 《Kinetics and Catalysis》2006,47(1):98-105
Possible mechanisms are suggested for propane oxidation on Pt/TiO2/Al2O3 and Pt/CeO2/Al2O3 catalysts in the cyclic reactant supply mode. As compared to the steady-state process, the process conducted as catalyst oxidation-reduction cycles results in a very different product composition: it is more selective toward partial oxidation products and yields much smaller amounts of complete oxidation products. It is established by isothermal and temperature-programmed oxygen desorption that, under the reaction conditions examined, the oxygen desorbed from the catalyst surface into the gas phase makes a negligible contribution to propane oxidation. It is proved by XPS that propane oxidation is due to the chemically bound oxygen of the catalyst. The hypothetical mechanism of the process includes propane activation on Pt followed by the transfer of the activated species to the oxygen-storing component (TiO2 or CeO2), where the intermediates are oxidized by chemically bound oxygen. 相似文献
16.
A new selective brominating system Br2/SO2Cl2/zeolite, has been discovered. Partially cation-exchanged Ca2+-Y zeolite efficiently catalyzes the selective para-bromination of neat chlorobenzene (CB) by Br2/SO2Cl2 affording a CB conversion of ∼89% and a para-selectivity of ∼97%. During the bromination reaction, SO2Cl2 oxidizes HBr, prevents its accumulation within the zeolite pores and yields a more active brominating species. The Ca2+-Y catalyst was found to be stable under the bromination conditions, and can easily be regenerated by calcination. The Br2/SO2Cl2/Ca2+-Y brominating system could be applicable to other activated aromatic compounds such as o-xylene, toluene and fluorobenzene. 相似文献
17.
A rapid method has been described for the quantitative extraction of milligram amounts of Mn/II/ with 2-PRONAPOX into CHCl3. The extraction coefficient /E/ of Mn/II/ between CHCl3 and aqueous solution containing 0.2M NH4Cl shows a maximum value of E=143 at pH 10.5. The percentage extraction is better than 98% in the pH range from 9 to 11 and an equilibration time of 6 min. The effects of anions and cations have been studied. The stoichiometry of metal: reagent determined by substoichiometric extraction and slope ratio method is found to be 12. The decontamination factors for most of the elements are better than 104 in the substoichiometric extraction of Mn/II/. 相似文献
18.
Heinrich Lang Bettina Lühmann Roy Buschbeck 《Journal of organometallic chemistry》2004,689(22):3598-3603
A straightforward method for the preparation of metallo carbosiloxanes of type Si(OCH2CH2CH2SiMe2[OCH2PPh2M(CO)n])4 (n = 3, M = Ni, 7a; n = 4, M = Fe, 7b; n = 5: M = Mo, 7c; M = W, 7d), Si(OCH2CH2CH2SiMe[OCH2PPh2Ni(CO)3]2)4 (8) and Me2Si(OCH2CH2CH2SiMe[OCH2PPh2Ni(CO)3]2)2 (11) is described. The reaction of Si(OCH2CH2CH2SiMeXCl)4 (1: X = Me, 2: X = Cl) or Me2Si(OCH2CH2CH2SiMeCl2)2 (9) with HOCH2PPh2 (3) produces Si(OCH2CH2CH2SiMe2(OCH2PPh2))4 (4), Si(OCH2CH2CH2SiMe(OCH2PPh2)2)4 (5) or Me2Si(OCH2CH2CH2SiMe(OCH2PPh2)2)2 (10) in presence of DABCO. Treatment of the latter molecules with Ni(CO)4 (6a), Fe2(CO)9 (6b), M(CO)5(Thf) (6c: M = Mo; 6d: M = W), respectively, gives the title compounds 7a-7d, 8 and 11 in which the PPh2 groups are datively bound to a 16-valence-electron metal carbonyl fragment.The formation of analytical pure and uniform branched and dendritic metallo carbosiloxanes is based on elemental analysis, and IR, 1H, 13C{1H}, 29Si{1H} and 31P{1H} NMR spectroscopic studies. In addition, ESI-TOF mass spectrometric studies were carried out. 相似文献
19.
用高温熔融法制备了掺杂Sm2O3的CaO-CaF2-B2O3-SiO2(CFBS:Sm)发光玻璃材料, 并借助X射线衍射(XRD)谱、傅里叶变换红外(FTIR)光谱以及光致发光(PL)光谱等分析手段研究了玻璃基体中CaF2的摩尔分数及其结构、红外透过性能以及荧光性能的关系. XRD和FTIR测试表明, 玻璃基体中引入CaF2并未引起非晶结构的变化但其红外透过峰发生移动. 光谱学测试表明, CFBS:Sm发光玻璃在404 nm波长激发下出现对应于Sm3+离子位于566、603和650 nm的特征荧光峰, 其发光颜色为橙红色(x=0.531, y=0.371). 此外, 随着玻璃基体中CaF2摩尔分数的增加, CFBS:Sm发光玻璃的荧光发射强度、荧光寿命(Sm3+的4G5/2能级)和荧光量子效率也表现出增大的趋势. 这种CFBS:Sm发光玻璃中荧光发射强度和荧光寿命的提高主要是由于玻璃基体中的CaF2替代CaO引起基体相互作用和声子能量降低、无辐射跃迁减弱造成的. 相似文献
20.
The interactions in the GeS2-Cr2S3 and Cu2GeS3-Cr2S3 sections were studied by differential thermal analysis and X-ray powder diffraction. The GeS2-Cr2S3 section was shown to be quasi-binary, with a degenerate eutectic; no ternary compound was formed. In the Cu2GeS3-Cr2S3 section, a quaternary phase of variable composition having a homogeneity range of 69–75 mol % Cr2S3 crystallized in the cubic system. The samples of this composition are spin glasses with freezing temperatures of 20–25 K. 相似文献