Cu-MOFs的生长调控及其催化水解羰基硫的性能

羰基硫(COS)广泛存在于以煤、焦炭、渣油和天然气等为原料生产的化工原料气中,不仅腐蚀管道设备,使下游催化剂发生硫中毒,而且还会造成环境污染.因此,COS脱除具有重要意义.在各种方法中,催化水解COS(COS+H2O→CO2+H2S)由于具有反应条件温和、转化率高和副反应少等优点越来越受重视.其关键在于发展高效的催化剂.近年来,金属-有机骨架材料(metal-organic frameworks,MOFs)由于其独特的物理化学性质引起人们广泛关注.与传统材料相比,MOFs不仅拥有超高的比表面积和规则的孔道结构,而且其结构具有可设计性强和易调变等特点,是一类非常有潜力的多相催化剂.然而,目前MOFs在催化水解COS方面的研究应用未见报道.此外,MOFs的合成方法主要有水/溶剂热法、扩散法和微波辅助加热法等.近年来新发展的电化学法具有合成效率高、操作方便和环境友好等优点,在材料合成中显示出巨大的优越性,但利用电化学法合成MOFs相关研究还较少. 本文采用快速温和的电化学方法制备了典型的Cu-MOFs(HKUST-1).该方法可以有效缩短反应时间,通过调节反应电压(15–30 V),在室温下电解3 h,可得到一系列HKUST-1样品.根据合成中设置的电压值,样品分别命名为HKUST-1-E15,HKUST-1-E20,HKUST-1-E25和HKUST-1-E30.XRD表征结果显示,不同电压下合成样品的XRD谱图与通过晶体数据拟合的HKUST-1图出峰位置基本一致.SEM结果表明,合成电压对样品形貌的影响很大.HKUST-1-E15主要呈长棒状结构,长约为15μm.随着电压的增大,HKUST-1-E20的形貌逐渐转变为较短的四棱柱体.当电压为25 V时,所得HKUST-1-E25呈八面体状.进一步提高合成电压,HKUST-1-E30颗粒变小,没有特殊形貌,并出现明显的团聚.COS水解测试结果显示,不同电压下合成样品的活性差异大,这主要是由于样品的形貌及比表面积差异引起的.其中,HKUST-1-E25样品的活性较好.在150°C下,该样品对COS的转化率接近100%,比水热法合成的HKUST-1-Hy的活性更高.在此基础上,进一步对活性测试过程的条件进行优化,发现当原料气流速为30 mL/min,水温为40°C时,催化剂的COS水解性能最优.此外,样品的活性稳定性测试结果显示,相比传统的氧化铜材料,HKUST-1是一类较稳定的COS水解催化剂.     

A new convenient procedure for the thionation of carbonyl compounds utilizing tetrachlorosilane-sodium sulfide

A combination of tetrachlorosilane (TCS) and sodium sulfide in acetonitrile is found to be an efficient thionating reagent for aromatic aldehydes in the absence of catalysis to give the corresponding thioaldehydes as trimers in good yields. Under cobalt(II) chloride catalysis, α,β-unsaturated ketones react with TCS-Na₂S to give the respective disulfides in good yields via the intermediacy of β-mercaptoketones at ambient temperature.     

Simultaneous catalytic hydrolysis of carbonyl sulfide and carbon disulfide over Al2O3-K/CAC catalyst at low temperature

In this work, a series of coal-based active carbon(CAC) catalysts loaded by Al2O3were prepared by sol-gel method and used for the simultaneous catalytic hydrolysis of carbonyl sulfide(COS) and carbon disulfide(CS2) at relatively low temperatures of 30-70 ℃. The influences of calcinations temperatures and operation conditions such as: reaction temperature, O2concentration, gas hourly space velocity(GHSV) and relative humidity(RH) were also discussed respectively. The results showed that catalysts with 5.0 wt% Al2O3calcined at 300 ℃ had superior activity for the simultaneous catalytic hydrolysis of COS and CS2. When the reaction temperature was above 50 ℃, catalytic hydrolysis activity of COS could be enhanced but that of CS2was inhibited. Too high RH could make the catalytic hydrolysis activities of COS and CS2decrease. A small amount of O2introduction could enhance the simultaneous catalytic hydrolysis activities of COS and CS2.     

Simultaneous catalytic hydrolysis of carbonyl sulfide and carbon disulfide over AlzO3-K/CAC catalyst at low temperature

In this work, a series of coal-based active carbon(CAC) catalysts loaded by Al2O3were prepared by sol-gel method and used for the simultaneous catalytic hydrolysis of carbonyl sulfide(COS) and carbon disulfide(CS2) at relatively low temperatures of 30-70 ℃. The influences of calcinations temperatures and operation conditions such as: reaction temperature, O2concentration, gas hourly space velocity(GHSV) and relative humidity(RH) were also discussed respectively. The results showed that catalysts with 5.0 wt% Al2O3calcined at 300 ℃ had superior activity for the simultaneous catalytic hydrolysis of COS and CS2. When the reaction temperature was above 50 ℃, catalytic hydrolysis activity of COS could be enhanced but that of CS2was inhibited. Too high RH could make the catalytic hydrolysis activities of COS and CS2decrease. A small amount of O2introduction could enhance the simultaneous catalytic hydrolysis activities of COS and CS2.     

Absolute absorption measurements of polymer films for optical waveguide applications by photothermal deflection spectroscopy

A self‐contained experimental technique is proposed for measuring the absolute optical absorption spectra, thermal diffusivity, and thermal conductivity of polymer thin films. The technique is based on photothermal deflection spectroscopy and provides sensitivity that is high enough to quantify the very small optical absorption losses in polymer films used for optical waveguide applications. The capabilities of the technique are demonstrated with measurements performed on thin films of poly(methyl methacrylate) and a fluorinated polymer (CYTOP). An error analysis is presented, and the factors are discussed that influence the accuracy of the technique. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2717–2726, 2001     

On the line intensity ratios of prominent Si II,Si III,and Si IV multiplets

Line intensities of singly, doubly and triply ionized silicon (Si II, Si III, and Si IV, respectively) belonging to the prominent higher multiplets, are of interest in laboratory and astrophysical plasma diagnostics. We measured these line intensities in the emission spectra of pulsed helium discharge. The Si II line intensity ratios in the 3s3p²²D–3s²4p²P^o, 3s²3d²D–3s²4f²F^o, and 3s²4p²P^o–3s²4d²D transitions, the Si III line intensity ratios in the 3s3d³D–3s4p³P^o, 3s4p³P^o–3s4d³D, 3s4p³P^o–3s5s³S, 3s4s³S–3s4p³P^o, and 3s4f³F^o–3s5g³G transitions, and the Si IV line intensity ratios in the 4p²P^o–4d²D and 4p²P^o–5s²S transitions were obtained in a helium plasma at an electron temperature of about 17,000 ± 2000 K. Line shapes were recorded using a spectrograph and an ICCD camera as a highly-sensitive detection system. The silicon atoms were evaporated from a Pyrex discharge tube designed for the purpose. They represent impurities in the optically thin helium plasma at the silicon ionic wavelengths investigated. The line intensity ratios obtained were compared with those available in the literature, and with values calculated on the basis of available transition probabilities. The experimental data corresponded well with line intensity ratios calculated using the transition probabilities obtained from a Multi Configuration Hartree–Fock approximation for Si III and Si IV spectra. We recommend corrections of some Si II transition probabilities.     

原位Raman光谱揭示中性条件下硫化钼结构变化对其电催化析氢反应的促进作用

硫化钼是析氢反应(HER)有前途的电催化剂. S-或Mo物种均被认为是形成吸附氢触发HER反应的活性位, 但Mo中心和S配体间相互作用的本质仍不清楚. 另外, 采用中性的水作为质子源用于产氢, 来开发低成本的水裂解催化剂体系为研究者高度关注, 但人们很少研究中性水条件下HER反应的机理. 本文采用原位电化学Raman光谱对所合成的硫化钼中Mo-Mo和S-S物种在中性条件下的结构变化进行了监测. 结果显示, 归属于端位S-S物种的谱带随着Mo-Mo, Mo3-μ3S和Mo-S振动谱带频率而同步变化, 表明Mo-Mo键与端位S-S键起着协同作用, 从而有利于氢气的生成. 这可能是通过三核Mo3-μ3S物种的内部重组而确认的. 本文所揭示的HER反应中金属-配体相互作用的本质与作用表明了一个不同的反应机理, 而以往的机理认为, S或Mo活性位独立起作用而促进HER反应的进行.     

[Hmim]_3PW_(12)O_(40):A high-efficient and green catalyst for the acetalization of carbonyl compounds

<正>[Hmim]_3PW_(12)O_(40) was developed and used in the acetalization of carbonyl compounds in excellent yields.The ionic liquidheteropoly acid hybrid compound and reaction medium formed temperature-dependent phase-separation system with the ease of product as well as catalyst separation.The catalyst was recycled more than 10 times without any apparent loss of catalytic activity.     

Systematic line selection for online coating thickness measurements of galvanised sheet steel using LIBS

LIBS can be used as an online method of characterizing galvanized coatings on sheet steel moving through a production line. The traversing sheet steel is irradiated with a series of single laser bursts, each at a different position on the sheet steel. An ablation depth in the same range as the coating thickness (about 10 μm) is achieved by using a Nd:YAG laser at 1064 nm in collinear double-pulse mode. The coating thickness is determined from the ratio of the intensities of an iron line and a zinc line measured at a burst energy high enough to penetrate the coating with a single burst. Experiments at different burst energies were carried out to optimize the thickness resolution, and a method of systematically selecting iron and zinc lines was deduced, which is based on multivariate data analysis (MVDA) of the intensity ratios calculated for a set of 6 zinc lines and 21 iron lines. A temperature correction was applied, because the parameters of the plasma change with burst energy, and the influence of this on the thickness resolution is discussed. The ambient atmosphere present (air, Ar, N₂) as well as self-absorption of spectral lines both have an influence on the thickness resolution. At optimum conditions, a thickness measurement accuracy of better than 150 nm was obtained for a set of electrolytic galvanized sheet steels with coating thicknesses in the range 4.1–11.2 μm.     

SiCl4-Zn induced reductive coupling of carbonyl compounds: novel and efficient routes for one-pot syntheses of 1,2,3-triaryl-2-propen-1-ones and pinacolones at room temperature

An unprecedented one-pot reductive trimerization of aromatic aldehydes to 1,2,3-triaryl-2-propen-1-ones as well as tandem reductive coupling-rearrangements of aryl ketones to pinacolone analogues was efficiently achieved using tetrachlorosilane-zinc at room temperature.     

Quantitative millimetre wavelength spectrometry at pressures approaching atmospheric: Part I. Absolute determination of transition line strengths and sample concentrations with a confocal Fabry-Perot cavity spectrometer

The absolute determination of the millimetre wave power absorption coefficient of gas samples in a Fabry-Perot cavity whose resonant frequency is synchronised to a millimetre wavelength source is described. A theoretical treatment valid for pressures >200 Pa is developed. Absolute absorption coefficient measurements have been made on lines of SO₂ in the 50-60 GHz region that compared favourably with literature values. A calibration curve for SO₂ using the 59224.84 MHz line at 667 Pa over the concentration range 1-100% in N₂ has been produced. This technique could be especially useful for remote monitoring and process control applications because it is not necessary to scan the spectral line in order to determine the concentration of a species. The source runs at a single frequency coinciding with the peak of a millimetre wavelength (MMW) absorption line. This means that the technique could operate effectively at pressures up to and above atmospheric without the need for sophisticated MMW sources that can sweep across a wide frequency band.     

Absolute quantum yield measurements for the formation of oxygen atoms after UV laser excitation of SO2 at 222-4 nm

The dynamics of formation of oxygen atoms after UV photoexcitation of SO₂ in the gas-phase was studied by pulsed laser photolysis-laser-inducedfluorescence ‘pump-and-probe’ technique in a flow reactor. SO₂ at room-temperature was excited at the KrCl excimer laser wavelength (222.4 nm) and O(³P_j) photofragments were detected under collision-free conditions by vacuum ultraviolet laser-induced fluorescence. The use of narrow-band probe laser radiation, generated viaresonant third-order sum-difference frequency conversion of dye laser radiation in Krypton, allowed the measurement of the nascent O(³P_j=2,1,0) fine-structure state distribution:n _j=2/n_j=1/n_j=0 = (0.88 ± 0.02)/(0.10 ± 0.01)/(0.02 ± 0.01). Employing NO₂photolysis as a reference, a value of Φ₀(³P) = 0.13 ± 0.05 for the absolute O(³P) atom quantum yield was determined. The measured O(³P) quantum yield is compared with the results of earlier fluorescence quantum yield measurements. A suitable mechanism is suggested in which the dissociation proceeds via internal conversion from high rotational states of the initially excited SO₂(~C¹B₂ (1, 2, 2) vibronic level to nearby continuum states of the electronic ground state.