Fe2O3上AsH3催化氧化反应机理的理论研究

本文采用密度泛函理论方法研究了Fe₂O₃上AsH₃的催化氧化反应机理.该反应以Fe₂O₃中的两个Fe原子为不同的活性中心进行研究,每个活性中心均设计了3个步骤. AsH₃分子依次与3个O₂分子在催化剂上相互作用分别形成中间体H₃AsO₂、H₃AsO₄及最终产物H₃AsO₆.研究发现,当氧化反应发生在1号铁原子(Fe1)附近,其速度控制步骤活化自由能垒为49.99 kcal/mol;当氧化反应发生在2号铁原子(Fe2)附近,其活化自由能垒为21.20 kcal/mol,与直接氧化(50.14 kcal/mol)相比大大降低.可见AsH₃在Fe₂O₃上的催化氧化反应更易发生在Fe2附近.     

在N2中[VnCr3—n（μ3—O）（μ—O2CCH3）6（THF）3]X[n=0—3,X=Cl^—1,ClO4^—,（VO5）0.5^—]及[VnFe3—n（μ3—O）（μ—O2CCH3）6（THF）3]X（n=0—3,X=Cl^—1）

The reaction behavior of the title complexes have been investigated by means of in situ IR in nitrogen atmosphere. It has been found that they enabled the acetic acid to convert to acetone and methane in different temperatures. The results indicate that the sequence of the ketonization reaction activity for the clusters was [V3OAT] > [VFe2OAT], [V2CrOAT] > [Fe3OAT], [VCr2OAT] > [Cr3OAT] [OAT = (mu 3-O) (mu-O2CCH3)6 (THF)3], and the sequence of the methanation reaction activity for the clusters was [Cr3OAT] > [VCr2OAT], [V2CrOAT] > [V3OAT] > [VFe2OAT], [Fe2OAH]. The ketonization reaction activity of [Fe3OAT] were obviously lower than that of [Fe3OAH] [OAH = (mu 3-O) (mu-O2CCH3)6 (H2O)3] and the methanation reaction activity of [Cr3OAT] were also much lower than that of [Cr3OAH]. The difference between [Fe3OAH], [Cr3OAT] and [Fe3OAH], [Cr3OAH] mentioned above were discussed.     

Large enhancement of radiative strength for soft transitions in the quasicontinuum

Radiative strength functions (RSFs) for the (56,57)Fe nuclei below the separation energy are obtained from the 57Fe(3He,alphagamma)56Fe and 57Fe(3He,3He'gamma)57Fe reactions, respectively. An enhancement of more than a factor of 10 over common theoretical models of the soft (E(gamma) less than or approximately equal 2 MeV) RSF for transitions in the quasicontinuum (several MeV above the yrast line) is observed. Two-step cascade intensities with soft primary transitions from the 56Fe(n,2gamma)57Fe reaction confirm the enhancement.     

Ultrasonically initiated emulsion polymerization of styrene in the presence of Fe2+

Ultrasonically initiated emulsion polymerization of styrene was carried out in the presence of Fe(2+). The addition of a small amount of Fe(2+) markedly enhanced the polymerization rate of styrene. In the presence of 50 microM Fe(2+), the conversion of monomer in the reaction time of 60 min was 2.4 times as high as that in the absence of Fe(2+). The increase in the polymerization rate was due to higher concentration of hydroxyl (*OH) radicals generated via Fenton reaction of Fe(2+) with hydrogen peroxide (H(2)O(2)), which was proved by a lower amount of H(2)O(2) in Fe(2+) aqueous solution compared with that in pure water during ultrasonic irradiation. However, the addition of excessive Fe(2+) had no further accelerating effect on the polymerization rate due to the reduction of *OH radicals by Fe(2+). So it is an effective way to add an appropriate amount of Fe(2+) to accelerate ultrasonically initiated emulsion polymerization of styrene.     

利用原位红外光谱研究若干过渡金属氧化物-丙酸体系，Fe2Cr（μ3-O）（μ-O2CC2H5）6（H2O）3Cl*xH2O及Cr3（μ3-O）（μ-O2CC2H5）6（H2O）3NO3*xH2O的反应行为

利用原位红外光谱法研究标题化合作在N2 中的反应行为。发现它们在不同温度下能使丙酸分别转化为乙醛和戊酮。金属氧化物对丙酸的戊酮化反应活性顺序是 :Fe3O4 >MnO2 >Cr2 O3>Co2 O3>Ni2 O3,这顺序与下列簇合物对该反应的活性顺序类似 :[Fe2 MnOPH]>[Fe3OPH]>[Fe2 CrOPH]>[Fe2 CoOPH]>[Fe2 NiOPH]>[Cr3OPH][OPH =(μ3 O) (μ O2 CC2 H5) 6(H2 O) 3]。对于戊酮化反应 ,过渡金属氧化物的反应温度明显高于相应的 [Fe2 MOPH]的反应温度 ,这旁证了 [Fe2 MOPH]的活性组分不是其金属氧化物。还讨论了Fe3O4 ,Fe2 O3 对丙酸分别转化为乙醛和戊酮反应活性的明显差异。     

3d~5金属离子共掺杂NaYF_4:Yb,Er纳米晶的上转换发光

采用水热法制备了Mn~(2+)/Fe~(3+)共掺杂的NaYF_4上转换纳米晶,通过改变掺杂浓度来调控晶相、晶粒尺寸以及上转换荧光发射强度。以Fe~(3+)共掺杂的上转换纳米晶为晶核,通过改变反应时间来调控SiO_2壳厚度,观察到上转换荧光发射强度在反应4 h的条件下出现最大值。Mn~(2+)/Fe~(3+)共掺杂的上转换纳米晶样品整体上转换荧光强度分别提高到3.7倍和4.5倍,同时Fe~(3+)共掺样品的红色上转换荧光增强近7倍。基于近红外980 nm激光激发下的稳态光谱研究,提出Yb~(3+)-过渡族离子和Er~(3+)之间的能量传递以及晶场对称性的改变引起了这种增强效应,随着过渡族离子掺杂浓度的增加,过渡族离子之间的交换相互作用导致上转换荧光的猝灭。     

在N2中［VnCr3－n(μ3-O)（μ-O2CCH3）6（THF）3］X［n＝0－3，X＝Cl－，ClO－4，（VO5）－0.5］及［VnFe3－n（μ3-O）（μ-O2CCH3）6（THF）3］X（n＝0－3，X＝Cl－）反应行为的原位红外光谱研究

利用原位红外光谱研究标题化合物在N2中的反应行为。发现它们在不同温度下能使乙酸分别转化为丙酮和甲烷。它们对乙酸的丙酮化反应活性顺序：［V3OAT］＞［VFe2OAT］，［V2CrOAT］＞［Fe3OAT］，［VCr2OAT］＞［Cr3OAT］［OAT＝（μ3-O）（μ-O2CCH3）6（THF）3］。它们对乙酸的甲烷化反应活性顺序：［Cr3OAT］＞［VCr2OAT］，［V2CrOAT］＞［V3OAT］＞［VFe2OAT］，［FeO3OAT］。对乙酸的丙酮化反应活性［Fe3OAT］明显低于［Fe3OAH］［OAH＝（μ3-O）（μ-O2CCH3）6（H2O）3］。对乙酸的甲烷化反应活性［Cr3OAT］也明显低于［CrOAH］。并对上述［Fe3OAT］，［Cr3OAT］与［Fe3OAH］，［Cr3OAH］之间差异进行了讨论     

Improving the catalytic performance of nickel-iron oxide to oxygen evolution reaction by refining its particles with the assistance of ionic liquid

Ionics - In this work, an electrocatalyst (IL-NiO·Fe2O3) to oxygen reduction reaction (OER) was fabricated by hydrothermal method with the assistance of ionic liquid...     

Low frequency sonocatalytic degradation of Azo dye in water using Fe-doped zeolite Y catalyst

Sonocatalytic degradation of acid red B (ARB) dye was investigated using Fe doped zeolite Y catalysts with the assistance of low frequency (20 kHz) ultrasonic irradiation. Low concentration of Fe ions from different precursors was loaded onto the zeolite using wet impregnation method. Catalytic degradation of ARB dye was found to be accelerated by the reaction between Fe (II) and Fe (III) ions and hydrogen peroxide (H₂O₂) generated in situ by the ultrasound-mediated dissociation of water molecules. Fe (II)/Y exhibited higher degradation efficiency at the beginning of the reaction but achieved almost similar degradation at the end of the process. The increase of pH significantly decreased the degradation efficiency of ARB dye and strongly affected the leaching and catalyst stability. The highest efficiency was achieved at an initial pH of 3 with nearly 100% degradation in less than 60 min. Both catalysts showed no significant changes in terms of their mean particle sizes before and after reaction. Finally, Fe (III)/Y showed better performance evaluated based on leaching of Fe and also catalyst reusability. Only minor physical changes occurred during the degradation process for four consecutive runs of reaction.     

流动注射抑制化学发光法测定异烟肼

以异烟肼与K3 Fe(CN) 6的氧化还原反应对Luminol K3 Fe(CN) 6的化学发光反应的抑制为基础 ,设计出一种简便、快速、灵敏度高的流动注射抑制化学发光测定异烟肼的新方法。测定线性范围为 1 4× 10 -3 ～5 5 μg·mL-1,检出限为 4 8× 10 -4 μg·mL-1(3σ) ,RSD小于 3 5 % (n =9) ,并对 45种物质进行了干扰试验。本法成功地应用于药剂中异烟肼含量测定 ,回收率为 98 2 %～ 10 1%。本法与DSC法进行了对照 ,结果满意。     

Reaction mechanisms between Al and Fe3O4 powders in the formation of an Al-based metal matrix composite

The reaction mechanisms between Al and Fe₃O₄ powders were investigated. Differential thermal analysis revealed that a two-step displacement reaction between Al and Fe₃O₄ took place during sintering. Initially, the Fe₃O₄ was converted to amorphous FeO at ～720°C and some of the Al was oxidized to amorphous Al₂O₃. In the final stage, when the temperature reached ～840°C, crystalline Al₂O₃ particles were produced in the molten Al–Fe liquid. The effects of cooling rate on the microstructures were studied. When the Al–Fe liquid was furnace-cooled to room temperature, proeutectic Al₃Fe plates, plate-like divorced eutectic Al₃Fe and Al₂O₃ particles were in situ formed in the Al(Fe) matrix. While quenching from 700°C, nanometer-sized Al dendrites and Al–Al₆Fe eutectic lamellae were produced in the Al matrix. However, when it was rapidly quenched from 900°C, the size of the proeutectic Al₃Fe phases was further reduced and Al₆Fe nanorods were found in the Al–Al₆Fe eutectics. A model was proposed to describe the transformation of the Al–Fe intermetallics during solidification.     

Fe/ZnO (0001)体系界面相互作用中薄膜厚度效应的光电子能谱研究

利用同步辐射光电子能谱(SRPES)和X射线光电子能谱(XPS)技术,系统研究了室温下Fe/ZnO界面形成过程中Fe薄膜与氧结尾的ZnO(000 1 )衬底之间的相互作用,结果显示初始沉积的Fe明显被表面氧氧化为Fe²⁺离子,在Fe覆盖度为0—3 nm的范围内,分别观察到与界面电荷传输、化学反应以及薄膜磁性相关的三个有意义的临界厚度,这一结果将有助于基于Fe/ZnO界面的相关器件的设计和研发.     

三核铁钌簇配位取代反应的紫外与红外光谱研究

利用紫外光谱和红外光谱研究了十二羰基三铁和十二羰基三钌分别与二苯基乙炔和三苯基膦的配位取代反应。谱图数据揭示出原始物质消失和新物质形成过程，并对结果产物作了压片红外光谱测定，进一步证实了新物质的生成。     

A study of nanostructures formed in the hydrogen reduction of Fe(OH)<Subscript>3</Subscript>

A complex study of the hydrogen reduction of nanosized iron hydroxide Fe(OH)₃ at 400°C was performed. It was shown that, during the reduction of Fe(OH)₃ to iron metal α-Fe, intermediate compounds such as Fe(OH)₂, α-FeOOH, β-FeOOH, γ-FeOOH, δ-FeOOH, and FeO are formed along with stable iron oxides α-Fe₂O₃, γ-Fe₂O₃, and Fe₃O₄. A scheme of chemical and structural transformations that occur in the reduction of nanosized Fe(OH)₃ is presented. The scheme takes into account the possibility of the bifurcation mechanism of reaction development.     

二苯基硫脲的配位取代反应及其红外光谱表征

研究了二苯基硫脲分别与二十羧基三钌和十二羰基二铁的配位取代反应,红外光谱跟踪反应从开始到结束,谱图数据揭示出原始物消失和新物质的形成过程,并对产物Ru3(CO)9CSN2HPh2和Fe3(CO)sS2CNPh作了KBr压片红外光谱表征。     

Determination of polyphenols in tea by a new method spectrophotometry

The authors developed a method for the determination of tea polyphenols. Phenanthroline is a sensitive regent for the determination of Fe2+, it can react with Fe2+ to form an orange complex in acidic solution. A new spectrophotometric method was proposed for the determination of tea polyphenols in tea samples based on that tea polyphenols could react with Fe3+ to produce Fe2+, and the orange complex would be formed by the reaction of Fe2+ with Phenanthroline in acidic solution. In the presence of positive iron surfactant CTMAB, the sensitivity of chromogenic reaction was improved. The work focused on the optimizing of experiment conditions such as wavelength of determination, buffer solution, surfactant, and the react time etc. At the maximum absorption wavelength of 510 nm, the apparent molar absorptivity was 0.88 x 10(5) L x mol(-1) x cm(-1), Beer's law was obeyed in the range of 4.00 to 32.00 microg x mL(-1) Polyphenols. The detection limit was 2.0 microg x mL(-1). This method was applied to the determination of polyphenols in tea samples with satisfactory results. The method has three merits, namely high level of accuracy and sensitivity, simplicity, and simple equipment.     

过渡金属氧化物催化剂上NH3 分解Claus反应机理研究

运用浸渍法制备了七种过渡金属氧化物催化剂 .对于NH3 分解反应均可获得很高的NH3 转化率 ;对于NH3 分解Claus反应则可以获得较高的SO2 转化率和单质硫选择性 .通过比较发现Co3 O4 TiO2 和Fe2 O3 TiO2 催化剂的低温活性比较高 .经过XRD表征发现 ,在NH3 分解Claus反应中 ,催化剂的活性相可能是过渡金属硫化物 .结合活性评价和XRD表征结果提出了NH3 分解Claus反应的机理 .     

气相中Fe+催化CO与N2O循环反应的理论计算研究

采用密度泛函UB3LYP/6–311+G(2d)方法计算研究了Fe+在基态和激发态与CO与N2O反应的反应机理。全参数优化了反应势能面上各驻点的几何构型,用频率分析方法和内禀反应坐标（IRC）方法对过渡态进行了验证,并用UB3LYP/6–311++G(3df,3pd)、单点垂直激发等方法分别进行各驻点单点能校正,四重态和六重态反应势能面交叉点CP确定,计算结果表明,该反应为两步反应,且反应机理都为插入—消去反应,势能面上的两个交叉点能够有效的降低反应的活化能,这在动力学和热力学上都是有利的。     

Insights into the sonochemical decomposition of Fe(CO)5: theoretical and experimental understanding of the role of molar concentration and power density on the reaction yield

The present work analyses, in detail, the optimization of a sonochemical process with respect to concentration of precursor and power supplied in a system. This is due to that even a small change in power dramatically changes the high-energy conditions created with the bubble collapse. A model reaction that has been considered for this purpose involves the decomposition of Fe(CO)₅ in decalin solvent as this reaction is strongly influenced by the cavitation conditions. Sonochemical treatment of this carbonyl results in the formation of amorphous Fe₂O₃, which on heat treatment gives nanocrystalline Fe₂O₃. It has been observed that concentration and power density parameters play an important role to obtain higher decomposition of Fe(CO)₅ and hence higher yield of the amorphous Fe₂O₃ product. Also, using the experimentally observed results, a correlation (polynomial) has been developed.     

金属离子对纳米TiO2悬浊液的光催化性能影响的光谱研究

以钛氧有机物为前驱体,利用微乳液法制备了纳米TiO2微晶。用X射线衍射(XRD)和红外光谱(FTIR)等测试技术对产物进行了表征,并就纳米TiO2悬浊液中加入金属离子后光催化降解甲基橙溶液进行了初步的研究。光谱分析表明,纳米TiO2悬浊液中加入Bi3 离子后对甲基橙溶液的光催化降解有很大的促进作用,Bi3 与TiO2质量比为1∶8及TiO2的浓度为1.6g·L-1时光催化活性最佳。