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71.
Di Li Naoki Ohashi Shunichi Hishita Taras Kolodiazhnyi Hajime Haneda 《Journal of solid state chemistry》2005,178(11):3293-3302
An overall comparative study was carried out on N-doped, F-doped, and N-F-codoped TiO2 powders (NTO, FTO, NFTO) synthesized by spray pyrolysis in order to elucidate the origin of their visible-light-driven photocatalysis. The comparisons in their experimentally obtained characteristics were based on the analysis of XPS, UV-Vis, PL, NH3-TPD and ESR spectra. The comparisons in their theoretically predicted properties were based on the analysis of the calculated electronic structures. As the results, N-doping into TiO2 resulted in not only the improvement in visible-light absorption but also the creation of surface oxygen vacancies. F-doping produced several beneficial effects including the creation of surface oxygen vacancies, the enhancement of surface acidity and the increase of Ti3+ ions. Doped N atoms formed a localized energy state above the valence band of TiO2, whereas doped F atoms themselves had no influence on the band structure. The photocatalytic tests indicated that the NFTO demonstrated the highest visible-light activity for decompositions of both acetaldehyde and trichloroethylene. This high activity was ascribed to a synergetic consequence of several beneficial effects induced by the N-F-codoping. 相似文献
72.
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
73.
XRF分析铁矿粉的标准选择判据研究和应用 总被引:2,自引:0,他引:2
本文对XRF法分析铁矿的基体校正元素进行了研究,并建立了标准选择判据,编制的计算软件可以自动地从大量标样中选择适合该样品分析的标准。该法可用于粉末压片制样的分析,方法快速,准确度和精密度均符合生产要求。 相似文献
74.
Promotion of Ionic Liquid to Dimethyl Carbonate Synthesis from Methanol and Carbcn Dioxide 总被引:2,自引:0,他引:2
Promotion of ionic liquid, 1-ethyl-3-methylimidazolium bromide (emimBr), to the synthesis of dimethyl carbonate (DMC) from methanol and carbon dioxide in the presence of potassium carbonate and less amount of methyl iodide under mild conditions was investigated. The results showed that the high selectivity and raised yield of DMC was achieved due to the addition of emimBr in the reaction system. And effect of several reaction conditions such as temperature, pressure and amount of emimBr was discussed. 相似文献
75.
Arno Behr 《Angewandte Chemie (International ed. in English)》1988,27(5):661-678
The carbon dioxide molecule has been of limited importance as a synthetic unit in organic chemistry. When it is coordinated to transition metals, however, completely new possibilities arise; CO2 can bond to metal complexes in a variety of ways and can enter into insertion and coupling reactions, or become catalytically attached to other substrates. The formation of C? C bonds between carbon dioxide and unsaturated hydrocarbons under conditions of homogeneous catalysis makes available new synthetic routes to industrially interesting organic compounds. 相似文献
76.
Octavio Surez-Iglesias Ignacio Medina Consuelo Pizarro Julio L. Bueno 《Fluid Phase Equilibria》2007,260(2):279-286
The Taylor–Aris chromatographic technique was employed for the determination of diffusion coefficients of 2-fluoroanisole, 2-bromoanisole, allylbenzene and 1,3-divinylbenzene at infinite dilution in supercritical carbon dioxide from 313.16 to 333.16 K and pressures between 15 and 35 MPa. As expected, the diffusivities rise when temperature increases and pressure decreases. Numerous predictive equations are compared with experimental data: Lai–Tan, Liu–Ruckenstein cluster formula, Woerlee, Hippler–Schubert–Troe, Catchpole–King, Eaton–Akgerman, He, He–Yu, Liu–Silva–Macedo, Funazukuri and coworkers, Dariva–Coelho–Oliveira, Zhu–Lu–Zhou–Wang–Shi and the Liu–Ruckenstein RHS formula. The equations of He, He–Yu and Catchpole–King are the best of all, but cannot be used in the whole range of temperatures and solvent densities. 相似文献
77.
PRODUCTION OF LIGHTOLEFINS FROM CO_2 HYDROGENATION OVER Fe/SILICALITE-2 CATALYST Ⅱ. PROMOTION EFFECT OF MnO PROMOTER 下载免费PDF全文
IntroductionItilasbeenshot'-nthattileadditionofMnOpromotertoFocatal}stcanresultinaremarkableimprovementinthesclectivit}'to11ghtalkenesforCOh}!drogenationll'l.Ho-c'cvcr.thecadetofMnOonCH4formationandCOconversionisvery'ambigUouslltolMoreover.MnOpromotergrca… 相似文献
78.
Sulfur Dioxide as Ligand and Synthon. XIII. Reactions of Isocyanide-tris(triphenylphosphane)nickel(0) Complexes with Sulfur Dioxide and N-p-tolylsulfinylamine Reactions of the isocyanide-tris(triphenylphosphane)-nickel(0) complexes [(RNC)Ni(PPh3)3] (R = tBu, Cy, PhCH2, p-TosCH2) with SO2 and p-TolNSO are described. The sulfur dioxide and N-p-tolylsulfinylamine complexes obtained by PPh3 ligand substitution have been characterized by means of i.r. and 31P n.m.r. spectra. The X-ray crystal structure of [(Ph3P)2(CyNC)Ni(SO2)] · 0.5 PhMe and (Ph3P)(tBuNC)Ni(η2-p-TolNSO) have been determined. 相似文献
79.
Sulfonylation of alkenes through photoredox‐catalyzed functionalization of alkenes with thiourea dioxide under visible‐light irradiation is achieved. The reaction of alkenes, thiourea dioxide and electrophiles provides a green and efficient access to alkyl sulfones and sulfonamides. A broad reaction scope is presented with good functional group compatibility and excellent regioselectivity. A plausible mechanism involving a radical addition process with sulfur dioxide radical anion (SO2‐) derived from the oxidation of sulfur dioxide anion (SO22–) is proposed, which is supported by fluorescence quenching experiments. 相似文献
80.
Virgil Percec Anatoliy V. Popov Ernesto Ramirez‐Castillo 《Journal of polymer science. Part A, Polymer chemistry》2005,43(2):287-295
The single‐electron‐transfer/degenerative‐chain‐transfer mediated living radical polymerization (SET–DTLRP) of vinyl chloride (VC) in H2O/tetrahydrofuran at 25 °C catalyzed by thiourea dioxide [(NH2)2C?SO2] is reported. This polymerization occurs only in the presence of a basic sodium bicarbonate (NaHCO3) buffer and the electron‐transfer cocatalyst octyl viologen. The resulting poly(vinyl chloride) (PVC) has a number‐average molecular weight of 1500–7000 and a weight‐average molecular weight/number‐average molecular weight ratio of 1.5. This PVC does not contain detectable amounts of structural defects and has both active chloroiodomethyl and inactive chloromethyl chain ends. Because of possible side reactions caused by the primary sulfoxylate anion (SO), the catalytic activity of (NH2)2C?SO2 in the SET–DTLRP of VC is lower than that of the single‐electron‐transfer agent sodium dithionite. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 287–295, 2005 相似文献