BiMo基复合氧化物催化剂丙烷直接氧化至丙烯醛研究

The effects of the available zoon above the catalyst bed on the performance of the catalyst were investigated. It has been suggested that propylene is an intermediate species in the reaction of propane to acrolein， and a two-step reaction scheme is proposed， the first step is oxidative dehydrogenation of propane to propylene in the gas phase then followed by the second step， the selective oxidation of propylene to acrolein on the surface of the catalyst. The performance of the catalyst depends on both the oxidative dehydrogenation of propane to propylene in the gas phase and the selective oxidation of propylene to acrolein on the catalyst surface. The thermal cracking， homogeneous oxidative dehydrogenation and heterogeneous catalytic dehydrogenation of propane as well as the selective catalytic oxidation of propane to acrolein over BiMoO based mixed oxides catalysts were studied. Under the optimum reaction conditions of propane dehydrogenation and selective oxidation of propylene， the selectivity and the yield of acrolein approached to 45mol% and 14mol%， respectively under about 30mol% propane conversion.     

Aminophosphine oxides in a pyridine series. Studies on the cleavage of pyridine-2- and pyridine-4-yl-(N-benzylamino)-methyldiphenylphosphine oxides in acidic solutions

The synthesis and reactions of 1-(N-benzylamino)-1-(2-pyridyl)- and 1-(N-benzylamino)-1-(4-pyridyl)-methyldiphenylphosphine oxides are described. It was found that these compounds were exceptionally easy to cleave in aqueous sulfuric acid solutions to form diphenylphosphinic acid and the corresponding N-(pyridylmethyl)-benzylamines. The structure of a single diastereoisomer, that is, the (R)-(+)-1-[N-(α-methylbenzylamino)]-1-(4-pyridyl)-(S)-methyldiphenylphosphine oxide was determined by X-ray crystallography. The acidic alcoholysis of the selected model chiral pyridine aminophosphine oxides was investigated by means of ³¹P NMR spectroscopy. The cleavage kinetics were also studied. On the basis of the obtained results, a mechanism of the cleavage was formulated.     

Speciation of vanadium in water with quinine modified resin micro-column separation/preconcentration and their determination by fluorination assisted electrothermal vaporization (FETV)-inductively coupled plasma optical emission spectrometry (ICP-OES)

A simple and selective method of flow injection (FI) using a micro-column packed with quinine modified resin as solid phase extractant has been developed for preconcentration and separation of trace amount of vanadium(V) and vanadium(IV) in water samples, followed by determination with fluorination assisted electrothermal vaporization (FETV)-inductively coupled plasma optical emission spectrometry (ICP-OES). At pH 3 ∼ 3.8, the modified resin is selective towards V(V) and almost not towards V(IV), while, V(IV) could be quantitatively adsorbed by the modified resin at pH 5 ∼ 7. The two vanadium species adsorbed by modified resin could be readily desorbed quantitatively with 0.3 ml of 0.5 mol l⁻¹ HCl. Both vanadium species in elution were then determined by ETV-ICP-OES with the use of polytetrafluoroethylene (PTFE) as chemical modifier. Effects of acidity, sample flow rate, concentration of elution solution and interfering ions on the recovery of the analytes have been systematically investigated. Under the optimal conditions, the adsorption capacities of the quinine modified resin for V(V) and V(IV) are 7.6 and 8.0 mg g⁻¹, respectively. The detection limit (3σ) of V is 0.072 ng ml⁻¹ for FETV-ICP-OES and 0.56 pg ml⁻¹ for FETV-ICP-MS with enrichment factor of 62.5, and the relative standard deviation (R.S.D.) is 4.9% (n = 9, C = 0.2 μg ml⁻¹) and 3.8% (n = 9, C = 1.0 ng ml⁻¹), respectively. The proposed method has been applied to the determination of trace V(V) and V(IV) in different water samples, and the recoveries of V(V) and V(IV) are 100 ± 10%. In order to further verify the accuracy of the developed method, FETV-ICP-MS was employed to analyze the vanadium species in water samples after separation/preconcentration, and analytical results are in good agreement with that obtained by the proposed method. The developed method was also applied to the analysis of the total V in GBW07401 soil certified reference material and in GBW07605 tea leaves certified reference material, and the determined values coincided with the certified values very well.     

同时测定合成样中铜钴镍钒含量的分光光度法--主成分回归法和偏最小二乘法比较

研究了主成分回归和偏最小二乘方法在多组分分光光度法分析中的应用,以５－Ｂｒ－ＰＡＤＡＰ（２〔５－溴－２－吡啶）－偶氮〕５－二乙氨基苯酚）为显色剂,ＯＰ（聚乙二醇辛基苯基醚）作为增溶增稳剂,在ｐＨ＝３．６的条件下,用主成分回归及偏最小二乘分光光度法同时测定了合成样中的铜、钴、镍、钒４组分含量,测定相对误差在－６．００％～４．００％之间。实验证明,对于加和性不好的体系偏最小二乘分光光度法要优于主成分回     

GC-MS characterization and quantification of sterols and cholesterol oxidation products

Summary A GC-MS method has been studied for characterization and quantification of phytosterols, cholesterol and cholesterol oxidation products. Baseline separations have been achieved between cholesterol, cholesterol 5-6-epoxide, 5-cholestene-3-ol-7one (7-keto-cholesterol), cholestene-3-5-6-triol, 5-cholestene-3-25-diol (25-hydroxycholesterol), 5-cholestene-3-20-diol (20-hydroxycholesterol), 5-cholestene-3-7-diol (7-hydroxycholesterol) and 5-cholestene-3-19-diol (19-hydroxycholesterol) as well as between -cholestane, cholesterol, stigmasterol, campesterol and -sitosterol. Excellent linearity of response has been obtained permitting reliable quantification. The characterization of each derivatized sterol has been performed by mass-spectrometry. The results confirm the utility of combined gas chromatography-mass spectrometry in the analysis and characterization of sterols and cholesterol oxidation products.     

金属氧化物电化学电容器

电化学电容器是一类利用电化学双电层或电极材料在电极表面及体相发生的氧化还原反应而存储能量的装置，具有高比能量、良好的可逆性和长循环寿命。金属氧化物电极目前主要有贵金属氧化物和过渡金属氧化物。本文简要介绍了金属氧化物电化学电容器的储能机理、特点及应用，总结了电极材料的制备及改性方法；并简要评述了电极材料的研究进展。     

二维层状磷酸亚磷酸钒(Ⅳ)化合物[V2O2(OH)(HPO3)(HPO3)0.7(PO3OH)0.3].(C6N2H16)0.5的水热合成与结构表征

迄今, 在中温水热条件下已合成了大量具有空旷骨架结构的过渡金属磷酸盐微孔材料[1], 这类材料在非线性光学材料、磁性材料、超导材料及催化等诸多方面具有潜在的应用前景[2～5].     

复合氧化物LaMn1-xFexO3(x=0-1)的XPS研究

用XPS方法研究了具有ABO3结构的LaMn1-xFexO3（x＝0－1）氧化物的氧化还原性能、表面组成和吸附氧种．样品经还原和再氧化处理后，Mn2p和Fe2p结合能的变化对Fe和Mn之间发生的氧化还原提供了明显的证据．可表示如下：Me4＋＋Fe（3－δ）→Mn（4－δ）＋＋Fe3＋通过计算机用三种氧物种（OⅠ，OⅡ和OⅢ）对O1s峰进行拟合，确定了每种氧物种的状态．同时，以氧物种含量随还原、再氧化的变化，确定了发生在表面上的氧化还原反应同OⅠ和OⅡ吸附氧物种有关．在此基础上，对吸附位与氧之间的电子转移过程进行了讨论．     

Spectrophotometric method for determination of vanadium and its application to industrial, environmental, biological and soil samples

The very sensitive, fairly selective direct spectrophotometric method for the determination of trace amount of vanadium (V) with 1,5-diphenylcarbohydrazide (1,5-diphenylcarbazide) has been developed. 1,5-diphenylcarbohydrazide (DPCH) reacts in slightly acidic (0.0001–0.001 M H₂SO₄ or pH 4.0–5.5) 50% acetonic media with vanadium (V) to give a red–violet chelate which has an absorption maximum at 531 nm. The average molar absorption coefficient and Sandell’s sensitivity were found to be 4.23×10⁴ l mol⁻¹ cm⁻¹ and 10 ng cm⁻² of V^v, respectively. Linear calibration graph were obtained for 0.1–30 μg ml⁻¹ of V^v: the stoichiometric composition of the chelate is 1:3 (V: DPCH). The reaction is instantaneous and absorbance remain stable for 48 h. The interference from over 50 cations, anions and complexing agents has been studied at 1 μg ml⁻¹ of V^v. The method was successfully used in the determination of vanadium in several standard reference materials (alloys and steels), environmental waters (potable and polluted), biological samples (human blood and urine), soil samples, solution containing both vanadium (V) and vanadium (IV) and complex synthetic mixtures. The method has high precision and accuracy (s=±0.01 for 0.5 μg ml⁻¹).     

Alkyl Monolayer Passivated Metal–Semiconductor Diodes: 2: Comparison with Native Silicon Oxide

To understand the electrical properties at passivated metal–semiconductor interfaces, two types of mercury–insulator–silicon (n‐type) junctions, Hg|C₁₀H₂₁? Si and Hg|SiO₂? Si, were fabricated and their current–voltage and capacitance–voltage characteristics compared. Both of them exhibited near‐ideal rectifying characteristics with an excellent saturation current at reverse bias, which is in contrast to the previously reported ohmic behavior of an unmodified mercury–silicon junction. The experimental results also indicated that the n‐decyl monolayer passivated junction possesses a higher effective barrier height, a lower ideality factor (that is, closer to unity), and better reproducibility than that of native silicon oxide. In addition, the dopant density and build‐in potential, extracted from capacitance–voltage measurements of these passivated mercury–silicon junctions, revealed that alkyl monolayer derivatization does not alter the intrinsic properties of the silicon substrate. The calculated surface state density at the alkyl monolayer|silicon interface is lower than that of the silicon oxide|silicon interface. The present study increases the possibility of using advanced organic materials as ultrathin insulator layers for miniaturized, silicon‐based microelectronic devices.