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31.
F-doped TiO2 (FTO) powders were synthesized by spray pyrolysis (SP) from an aqueous solution of H2TiF6. The resulting FTO powders possessed spherical particles with a rough surface morphology and a strong surface acidity. The fluorine concentrations in the FTO powders calculated from XPS spectra significantly depended on SP temperature and ranged from 2.76 to 9.40 at.%. The FTO powder prepared at SP temperature of 1173 K demonstrated the highest photocatalytic activity for the decomposition of gas-phase acetaldehyde under both ultraviolet (UV) and visible light (vis) irradiations, and it was higher than that of commercial P 25. This high photocatalytic activity was ascribed to several beneficial effects produced by F-doping: enhancement of surface acidity, creation of oxygen vacancies, and increase of active sites. It was interesting to point out that the vis photocatalytic activity of FTO powders was achieved by the creation of surface oxygen vacancies rather than the improvement of optical absorption property of bulk TiO2 in vis region. 相似文献
32.
A simple and advantageous method for the determination of titanium using graphite furnace atomic absorption spectrometry with slurry sampling has been developed. Titanium is one of the refractory elements that form thermally stable carbides in the graphite tube, which leads to severe memory effects. Trifluoromethane (Freon-23) was applied in the purge gas during the atomization step or alternatively just prior to the atomization to successfully eliminate the problems of carbide formation and increase the lifetime of the furnace tube which could be used for more than 600 heating cycles. A flow rate of 40 mL min–1 (5% of Freon in argon) was used to obtain symmetrical peaks with no tailing. However, when the gas flow rate was too high (250 mL min–1) the peak-tailing and memory effects reappeared. Ti was determined in various materials covering a wide range of concentrations, from 2.8 g g–1 to 12% (m/m) Ti. The accuracy of the method was confirmed by analyzing certified reference materials (CRMs) or by comparing the results with those obtained using inductively coupled plasma–atomic emission spectrometry (ICP–AES) after decomposition of the samples. The materials analyzed were soil, plant, human hair, coal, urban particulate matters, toothpaste, and powdered paint. 相似文献
33.
Caesium heptaiodo‐dititanate(III), CsTi2I7, is obtained from CsI, Ti and TiI4 at 250 °C in a sealed tantalum ampoule as dark red single crystals. The crystal structure (trigonal, R‐3, a = 1706.6(3), c = 2088.3(5) pm, Z = 12, R1 = 0.0619) contains [TiI4] tetrahedra sharing common vertices (with Ti—I—Ti angles of 180°) to isolated ditetrahedra [Ti2I7]—. It may also be described as a cubic closest packing of alternating CsI3 and I4 layers between which neighbouring tetrahedra are occupied in a way that [Ti2I7]— ditetrahedra are achieved. http://www.gerdmeyer.de 相似文献
34.
A series of novel phenoxy-phosphinimine ligands (L): L = 2-(Ph2PNR), 4, 6-(CMe3)2-C6H2OH [2, R = SiMe3; 3, R = Ph] have been prepared in the yield of 65-71%. And bis(phenoxy-phosphinimide) group 4 complexes of the type L2MCl2 [4, M = Ti, R = SiMe3; 5, M = Zr, R = SiMe3; 6, M = Ti, R = Ph; 7, M = Zr, R = Ph] have been synthesized by the reaction of the ligands with TiCl4 and ZrCl4. The structure of complex 7 has been determined by X-ray crystallography. The complexes 4-7 showed inactive to ethylene polymerization in the presence of modified methylaluminoxane (MMAO) and i-Bu3Al/Ph3CB(C6 F5)4. These results should be caused by overdoing the steric congestion around central metal. 相似文献
35.
Chao Chen Yu-Lin Yang Kun-Lin Huang Zhen-Hua Sun Wei Wang Zhuo Yi Yun-Ling Liu Wen-Qin Pang 《Polyhedron》2004,23(18):3033-3042
With a hydrothermal technique, a layered titanium phosphate with the formula Ti2(H2PO4)(HPO4)(PO4)2 · 0.5C6N2H16 (denoted TP-J2) has been prepared by treating the Ti/H3PO4/H2O/1-methylpiperazine system directly. The as-synthesized products were characterized by powder X-ray diffraction, CP-MAS solid-state 31P NMR spectroscopy, thermogravimetric and differential thermal analyses (TG-DTA). The structure was solved by single-crystal X-ray diffraction analysis and it presents an extended γ-phase intercalated with organic amine. Crystal data: triclinic, , a = 8.106 (2) Å, b = 8.197 (2) Å, c = 11.658 (2) Å. = 78.32 (3)°, β = 80.85 (3)°, γ = 77.90 (3)°, Z = 2. Additionally, the intercalation behavior of TP-J2 with n-alkyl monoamine (n = 2, 3, 4, 6, 8, 10 and 12) was investigated. Owing to the strong brønsted base, N,N′-dimethylpiperazine, resides in the interlayer, it presented unusual features of TP-J2 in contrast with that of γ-Tip. 相似文献
36.
Biing-Jiun Uang I-Pin Fu Chyuan-Der Hwang Chun-Wei Chang Chun-Tzu Yang Der-Ren Hwang 《Tetrahedron》2004,60(46):10479-10486
A highly enantioselective addition of trimethylsilylcyanide to aldehydes catalyzed by chiral titanium complexes is described. The chiral titanium complexes were prepared in situ from Ti(OiPr)4 and β-hydroxyamide ligands, that could easily be synthesized from ketopinic acid and C2 symmetrical chiral diamines in a small number of steps. 相似文献
37.
N‐Silylaminotitanium trichlorides, Me3S(R)N‐TiCl3 ( 18 ) [R = tBu ( a ), SiMe3 ( b ), 9‐borabicyclo[3.3.1]nonyl (9‐BBN)( c )], and (CH2SiMe2)2N‐TiCl3 ( 18d ) were obtained in high yield and high purity from the reaction of the respective bis(silylamino)plumbylene with an excess of titanium tetrachloride. The crystal structure of 18a was determined by X‐ray analysis. The reactions of the analogous stannylenes with an excess of TiCl4 did not lead to 18 . N‐Lithio‐trimethylsilyl[9‐(9‐borabicyclo[3.3.1]nonyl)]amine ( 8 ) was prepared, structurally characterized and used for the synthesis of a new bis(amino)stannylene 10 and a plumbylene 11 . The compounds 18a—d served as ideal starting materials for the synthesis of bis(silylamino)titanium dichlorides, where the silylamino groups can be identical ( 19 ) or different ( 20 ). This was achieved either by the reaction of 18 again with bis(amino)plumbylenes or with lithium N‐silylamides. In contrast to the direct synthesis starting from titanium tetrachloride and two equivalents of the respective lithium amide, which in general affords 19 with identical amino groups only in low yield, the procedure starting from 18 is much more versatile and gave the pure compounds 19 or 20 in almost quantitative yield. Further treatment of the dichlorides 19 or 20 with lithium amides led to tris(amino)titanium chlorides 21 . The dichlorides 19 or 20 reacted with two equivalents of alkynyllithium reagents to give the first well characterized examples of di(alkyn‐1‐yl)bis(N‐silylamino)titanium compounds 22 — 27 . These compounds reacted with trialkylboranes (triethyl or tripropylborane) by 1, 1‐organoboration. In some cases, the extremely reactive reaction products could be identified as novel 1, 1‐bis(silylamino)titana‐2, 4‐cyclopentadienes 28 — 31 bearing a dialkylboryl group in 3‐position. In solution, the proposed structures of all products were deduced from a consistent set of data derived from multinuclear magnetic resonance spectroscopy (1H, 11B, 13C, 14N, 15N, 29Si, 35Cl NMR). 相似文献
38.
采用简便的方法, 合成了Schiff碱钛配合物Ti(Salen)2Cl2[Salen为N,N-(3,5-di-tert-butylsalicylidene)anilinato]并与Al(i-Bu)3组成二元催化体系用于n-辛基联烯的聚合. 实验结果表明, 在单体与催化剂摩尔比为100, n(Al)/n(Ti)=50, 催化剂于80 ℃陈化时间1 h后, 于80 ℃本体聚合16 h得到聚n-辛基联烯, 转化率100%, 分子量Mw=1.1×105, MWD=1.77, 1,2聚合链节单元质量分数为50%. 相似文献
39.
为了实现快速检测果珍中的二氧化钛含量,提出了应用近红外光谱技术结合化学计量学的快速检测方法。研究采用了320份果珍样本进行光谱特性的检测,其中200个样本用来建模,120个样本进行预测。首先比较了标准正态变量校正(SNV)、变量标准化(Normalize)、多元散射校正(MSC)等6种不同的数据预处理方法对偏最小二乘法(PLS)建模预测效果的影响。然后将PLS模型与应用主成分(PC)建立的主成分-神经网络校正(PC-ANN)模型进行比较。结果表明,MSC预处理的效果最好,PLS模型的最佳主成分数为7,预测值与标准值的相关系数R2达0.900 8,预测标准误差RMSEP为0.05。PC-ANN模型预测值与标准值的R2为0.868 4,RMSEP为0.04。说明PLS模型比PC-ANN模型的预测效果好。同时本研究也说明能够应用可见/近红外技术对二氧化钛进行快速定量测定。 相似文献