WxC-MCM-48催化剂的合成、表征及加氢脱硫催化性能

以正硅酸乙酯(TEOS)为硅源，十六烷基三甲基溴化铵(CTAB)为表面活性剂，仲钨酸铵为钨源，采用水热晶化法一步合成了不同钨含量(以Si、W物质的量比n_Si/n_W表示)的WO₃-MCM-48，然后经甲烷/氢气(V/V=1/4)混和气体程序升温还原碳化(TPC)，制备出了W_xC-MCM-48(x=1、2)催化剂，采用XRD、N₂吸附-脱附和NH₃-TPD对样品的结构进行了表征，用噻吩作为模型化合物，对W_xC-MCM-48催化剂的加氢脱硫催化活性进行了评价。结果表明，在一定钨含量的条件下，WO₃-MCM-48和W_xC-MCM-48样品仍然保持MCM-48的三维立方有序介孔结构，n_Si/n_W=30～15时，碳化钨的物相为W₂C；n_Si/n_W=7.5时，碳化钨为W₂C和WC物相，W_xC-MCM-48催化剂表现出了良好的加氢脱硫催化性能。     

一种新的光致变色膜：Na2WO4-PAA-Glycerol体系研究

A method for preparing Na₂WO₄-PAA-Glycerol photochromic films was reported. The film was composed of Na₂WO₄, PAA and Glycerol, which were coated on a glass substrate. The film turned blue in the sun, and bleached to transparent in the darkness. The UV-Visible spectra showed strong absorbance at 300～500 nm, and the ABS changed signifanctly at 500～800 nm. The film showed the best photochromic behavior when n_Na2WO4∶n_PAA is 4%～5%. The mechanism was suggested that after irradiation, poly tunstate produced by Na₂WO₄ and PAA formed the tungsten blues. The tungsten blues were bleached due to oxidation back to poly tunstate by oxygen. The film showed not only an excellent photochromism property with rapid response and good reversibility, but also the simple techniques and good stability.     

Breaking symmetry: spontaneous resolution of a polyoxometalate

A chiral polyoxometalate [Hf(PW11O39)2]10- (1) has been prepared and structurally characterized. It crystallizes in the chiral space group P2(1)2(1)2, as a conglomerate of two enantiomerically pure crystals in the absence of any chiral source. The absolute configuration of 1 was determined from the Flack parameter by X-ray crystallography. The structure of 1 comprises two lacunary [PW11O39]7- units, each functioning as a tetra-dentate ligand sandwiching an 8-coordinate HfIV centre in a distorted square antiprismatic geometry. Optically active crystals of both enantiomers were spectroscopically distinguishable by means of solid state circular dichroism spectroscopy. This hafnium-substituted polyoxometalate (POM), 1, shows that spontaneous chiral resolution, a rare phenomenon, can be operable in POM systems.     

WC/纳米碳管复合材料制备及其电化学性能

碳化钨具有类铂催化性能和较强的抗中毒能力, 但其催化活性远低于铂等贵金属催化剂. 如何提高其催化活性是碳化钨应用研究所面临的主要难点与热点之一. 为寻找改善碳化钨催化性能的技术方法, 本文将表面修饰与原位还原碳化技术相结合, 成功制备了碳化钨/纳米碳管复合材料, 采用XRD, HRTEM等手段对其形貌和晶相组成进行了表征, 并应用粉末微电极对其电催化性能进行了评价. 实验结果表明, 样品由碳化钨颗粒和纳米碳管组成, 碳化钨为形态不规则纳米颗粒, 均匀地生长于纳米碳管的外表面; 在碱性溶液中, 复合材料对对硝基苯酚的电催化性能明显强于具有介孔结构的纯碳化钨样品. 这说明将碳化钨复合到纳米碳管的外表面是提高碳化钨电催化活性的有效技术方法之一.     

Synthesis and structures of germanium-containing tungsten carbyne complexes Ph3gec≡w(ch2but)3 and Ph3GeC≡W(CH2SiMe3)3

New germanium-containing tungsten carbyne complexes Ph₃GeC≡W(CH₂R)₃ (R = Bu^t or SiMe₃) were synthesized by the reaction of the alkoxy derivative Ph₃GeC≡W(OBu^t)₃ with alkyllithium reagents RCH₂Li. The new compounds were isolated in individual form as crystals in 95 and 90% yields, respectively, and were characterized by elemental analysis, ¹H and ¹³C NMR spectroscopy, and X-ray diffraction. X-ray diffraction study showed that the coordination environment of the W and Ge atoms in the Ph₃GeC≡ W(CH₂Bu^t)₃ and Ph₃GeC≡W(CH₂SiMe₃)₃ complexes can be described as a distorted tetrahedron. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 213—216, February, 2006.     

Triangular telluride complexes containing a cluster fragment [M3(µ3-Te)(µ2-Te2)3]4+ (M = Mo, W): Study of specific non-valence interactions

Various synthetic approaches are used to obtain new triangular complexes with rare cluster nuclei M₃Te₇ ⁴⁺ (M = Mo, W), as well as with partial substitution for chalcogen W₃Te_3.8Se _3.2 ⁴⁺ . The crystalline structure has been identified for K₅{[Mo₃Te₇(CN)₆]₂I}·2.5H₂O (I), K₃{[Mo₃Te₇(CN)₆]SeCN}·3.25H₂O (II), Cs₂K{ [W₃Te₇(CN)₆]Br_0.8Cl_0.2}·2.5H₂O (III), Cs₃{ [W₃Te₇(CN)₆]Br}·2H₂O (IV), Cs_1.59K_1.41{[W₃Te_3.8Se_3.2× ×(CN)₆]Br}·1,5H₂O (V), [W₃Te₇((EtO)₂PS₂)₃]Br (VI). The compounds are characterized by IR methods and electronic spectroscopy, electrospray-mass-spectrometry. The crystalline structure of this class of compounds is analyzed. Specific non-valence interactions in these systems are considered in detail.     

Hydrodeoxygenation of glycerol into propanols over a Ni/WO3–TiO2 catalyst

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Effect of WO3 particle size on the type and concentration of surface oxygen

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