Density of O-atoms in an Afterglow Reactor During Treatment of Wool

Density of neutral oxygen atoms in the ground state has been measured during treatment of wool fabric samples. Samples were placed in an afterglow reactor with a volume of about 5 l, which was pumped with a two stage rotary pump with the nominal pumping speed of 28 m³/h. The source of the oxygen atoms was a microwave discharge operating in the surfatron mode at 2.45 GHz and adjustable output power up to 300 W. The density of O-atoms in the afterglow chamber was measured with a fiber-optics catalytic probe. For the empty reactor, the O density depended on discharge parameters and was between 0.8 and 2.8 × 10²¹ m⁻³ at 40 and 50 Pa respectively. During the treatment of wool, the O density depended largely on the exposure time. For untreated samples, the O density was below the detection limit of the probe, while prolonged treatment allowed for recovering the O density. The recovery always occurred after having submitted wool samples to the dose of the order of 10²³ atoms/m². The results were explained by oxidation of the thin lipid layer on the surface of the wool fibres.     

Neutral oxygen atom density in the MESOX air plasma solar furnace facility

The density of neutral oxygen atoms in the MESOX set-up, one device of the PROMES-CNRS solar facilities, was determined by a fiber-optics catalytic probe (FOCP). Plasma was created in a flowing air within a quartz tube with the outer diameter of 5 cm by a 2.45 GHz microwave generator with the output power up to 1000 W. The flow of air was varied between 4 and 20 l/h. The O-atom density was found to increase monotonously with the increasing discharge power, and it decreased with the increasing flow rate. The degree of dissociation of oxygen molecules in the plasma column depended largely on the flow rate. At the air flow of 4 l/h it was about 80% but it decreased to about 20% at the flow of 20 l/h.     

Au/CeO2/Y和Au-MFe2O4催化剂用于有氧条件下CH4还原NOx的研究

以CeO2／Y分子筛和MFe2O4(M=Ni,Co，Zn)为载体，制备Au／CeO2／Y和Au-MFe2O4负载型金催化剂．用CH4做还原剂，考察了它们在有氧条件下催化还原NOχ的活性．结果表明：在Au-Y中引人助剂Ce，使得Au／CeO2／Y的催化活性高于Au／Y；Au-CoFe2O4的催化活性高于Au-Fe2O3，反应温度为300℃时，NOχ在Au-CoFe2O4上的转化率达到39．70%．     

TiO2(110)面的弛豫结构及吸附O2的密度泛函研究

采用DFT/B3LYP方法研究了TiO2 ( 110 )的完整和氧缺陷表面的弛豫构型 ,并对O2 在氧缺陷表面的三种可能吸附构型进行了优化 ,计算了它们的吸附能、振动频率和重叠布居 .分析并预测了吸附后可能产生的物种 .本文的计算结果与XPS ,TPD和ELS等实验吻合     

CeO2/TiO2 Monolith Catalyst for the Selective Catalytic Reduction of NOx with NH3: Influence of H2O and SO2

The influences of H₂O and SO₂ on CeO₂/TiO₂ monolith catalyst for the selective catalytic reduction(SCR) of NO_x with NH₃ were investigated. In the absence of SO₂, H₂O inhibited the SCR activity, which might be ascribed to the competitive adsorption of H₂O and reactants such as NH₃ and/or NO_x. SO₂ could promote the SCR activity of CeO₂/TiO₂ monolith catalyst in the absence of H₂O, while in the presence of H₂O it speeded the deactivation. During the SCR reaction in SO₂-containing gases, Ce(III) sulfate species formed on the catalyst surface, resulting in the enhancement of Brønsted acidity. This played a significant role in the enhanced SCR activity. However, in the presence of both H₂O and SO₂, a large amount of ammonium-sulfate salts formed on the catalyst surface, which resulted in the blocking of catalyst pores and deactivated the catalyst. In addition, the NO_x conversion was more sensitive to gas hourly space velocity in the presence of H₂O than in the absence of H₂O. The relatively high space velocity would result in a higher formation rate of ammonium-sulfate salts on per unit catalyst in the presence of H₂O and SO₂, which caused obvious deactivation of Ce/TiO₂ monolith catalyst.     

An Efficient Catalytic Procedure for the Selective Oxidation of Sulfides to Sulfoxides by Citric Acid/Al(NO3)3.9H2O/MBr Under Mild and Heterogeneous Conditions

A wide range of aliphatic or aromatic sulfides are selectively oxidized to the corresponding sulfoxides using Al(NO₃)₃.9H₂O, citric acid and a catalytic amount of KBr or NaBr in the presence of wet SiO₂ (50% w/w)in CH₂Cl₂ under mild and heterogeneous conditions in good to high yields.     

First-principles study of O2 adsorption and dissociation on the CuCr2O4 (100) surface

The adsorption and dissociation of molecular oxygen on spinel CuCr₂O₄ (100) surface were carried out by first-principles calculations based on density functional theory (DFT). The calculated results indicate that the Cr site is most favorable for atomic oxygen adsorption, with an adsorption energy of 402.8 kJ/mol. For molecular oxygen adsorption, there are three types of favorable interaction modes: O₂ forms bonds with the Cu site or O₂ binds to two Cr sites or O₂ interacts with both Cu and Cr sites simultaneously. The lowest activation energy (E_a = 35.4 kJ/mol) was found through exploring possible reaction pathways for O₂ dissociation. The relationship between E_a and reaction enthalpy (ΔH) for O₂ dissociation adsorption reactions fits Brønsted-Evans-Polanyi (BEP) behavior.     

纳米V2O5／ZnO光催化剂对壬基酚聚氧乙烯醚降解的催化活性

采用氨浸法制备了不同V2O5含量的纳米V2O5/ZnO光催化剂,并用X射线衍射、比表面积测定、透射电镜、X射线光电子能谱和漫反射紫外-可见光谱测定了催化剂的晶型、比表面积、形貌尺寸、表面组成和光谱特征.以壬基酚聚氧乙烯醚(NPE-10)为模型污染物,分别在紫外光和可见光照射下考察了光催化剂的催化活性.结果表明,随着V2O5含量的增加,V2O5/ZnO的粒径逐渐减小,比表面积逐渐增大.与纳米ZnO样品相比,V2O5/ZnO中V2p的结合能减小,而Zn2p和O1s的结合能增大,V2O5/ZnO表面的羟基氧和吸附氧含量增加.n(V)/n(Zn)=2·5%的V2O5/ZnO光催化剂样品的催化活性最高(在紫外光和可见光照射3h后,NPE-10降解率分别约为79%和62%).     

Kinetic Spectrophotometric Determination of Nanogram Levels of Manganese (II) Based on its Catalytic Effect on the Oxidation of an Azo Compound with Potassium Periodate in the Presence of 1, 10-Phenanthroline

ABSTRACT

The catalytic effect of manganese (II) on the oxidation of Diphenylamine-4-azo-benzen-4'-sulfonic acid potassium salt with potassium periodate in the presence of 1, 10-phenanthroline in weakly acidic media was studied. A catalytic kinetic spectrophotometric method for determination of manganese (II) in the range 0.05 – 2.5 ng ml-^?1 can be determined by the fixed-time method with a detection limit of 0.017 ng ml-^?1. The method was applied successfully to the determination of manganese (II) in tap water and human urine.     

基于氟硼二吡咯染料的汞离子荧光分子探针的合成与光谱性质

合成了一种中位-苯甲酸基取代的氟硼二吡咯类染料衍生物(1)并研究了它的金属离子传感性能。在甲醇溶液中,染料1显示出显著的对汞离子具有选择性的"开-关"型亲离子荧光团响应,而对其他一些代表性碱金属、碱土金属、过渡金属及重金属离子等都没有明显的荧光响应;同时染料1在对所检测的金属离子中,通过其溶液颜色的改变对汞离子显示出明显的选择性显色行为,以便实现对汞离子的"裸眼检测"。     

丁醇醛和丁醇酸热解形成CO和CO2机理的密度泛函理论研究

采用密度泛函理论方法B3LYP/cc-pVTZ,对模型化合物2,3,4-羟基丁醛的脱羰基和2,3,4-羟基丁酸的脱羧基反应机理进行了量子化学理论研究。对两种模型化合物分别设计了三种热解反应途径,计算了不同温度下各热解反应途径的标准热力学及动力学参数。计算结果表明,纤维素热解过程中CO₂和CO的逸出分别与脱羧基和脱羰基反应相对应,脱羧基和脱羰基反应均为分子内氢原子转移的协同过程。脱羰基反应是吸热反应,而脱羧基反应是放热反应。饱和丁醇醛的脱羰基反应反应能垒为288.8 kJ/mol,脱水后的不饱和烯醇醛的脱羰基反应能垒增大;饱和丁醇酸的脱羧基反应能垒较高,为303.4 kJ/mol,脱水后的不饱和烯醇酸的脱羧基反应能垒明显减小,这说明脱水有利于CO₂的生成。     

Construction of Two Stable Co(II)-Based Hydrogen-Bonded Organic Frameworks as a Luminescent Probe for Recognition of Fe3+ and Cr2O72− in H2O

A pair of cobalt(II)-based hydrogen-bonded organic frameworks (HOFs), [Co(pca)₂(bmimb)]_n (1) and [Co₂(pca)₄(bimb)₂] (2), where Hpca = p-chlorobenzoic acid, bmimb = 1,3-bis((2-methylimidazol-1-yl)methyl)benzene, and bimb = 1,4-bis(imidazol-1-ylmethyl)benzene were hydrothermally synthesized and characterized through infrared spectroscopy (IR), elemental and thermal analysis (EA), power X-ray diffraction (PXRD), and single-crystal X-ray diffraction (SCXRD) analyses. X-ray diffraction structural analysis revealed that 1 has a one-dimensional (1D) infinite chain network through the deprotonated pca⁻ monodentate chelation and with a μ₂-bmimb bridge Co(II) atom, and 2 is a binuclear Co(II) complex construction with a pair of symmetry-related pca⁻ and bimb ligands. For both 1 and 2, each cobalt atom has four coordinated twisted tetrahedral configurations with a N₂O₂ donor set. Then, 1 and 2 are further extended into three-dimensional (3D) or two-dimensional (2D) hydrogen-bonded organic frameworks through C–H···Cl interactions. Topologically, HOFs 1 and 2 can be simplified as a 4-connected qtz topology with a Schläfli symbol {6⁴·8²} and a 4-connected sql topology with a Schläfli symbol {4⁴·6²}, respectively. The fluorescent sensing application of 1 was investigated; 1 exhibits high sensitivity recognition for Fe³⁺ (K_sv: 10970 M⁻¹ and detection limit: 19 μM) and Cr₂O₇²⁻ (K_sv: 12960 M⁻¹ and detection limit: 20 μM). This work provides a feasible detection platform of HOFs for highly sensitive discrimination of Fe³⁺ and Cr₂O₇²⁻ in aqueous media.     

An anthracene based fluorescent probe for the selective and sensitive detection of Chromium (III) ions in an aqueous medium and its practical application

An anthracene based fluorescent probe, integrated with thiophene moiety, exhibited selective and sensitive detection of chromium (III) ions over other metal ions. Its synthesis was achieved by simple mixing of two commercially available compounds, 2-aminoanthracene, and 2-thiophenecarboxaldehyde, in onestep without the needed complex purification process. The probe molecule ( ANT-Th ) offered exceptional features such as “turn-on” fluorescence response, low detection limit (0.4 μM), and fast response time (<1 min) via C=N bond hydrolysis. Also, a simple test paper system was developed for the rapid detection of chromium (III) ions with the naked eye.     

Fe(NO3)3·9H2O/Fe(HSO4)3: An efficient reagent system for the oxidation of alcohols, thiols and sulfides in the absence of solvent

Fe(NO3)3·9H3O/Fe(HSO4)3 was used as an efficient reagent system for the oxidation of alcohols to their corresponding carbonylcompounds. All reactions were performed in the absence of solvent in good to high yields. Under the same reaction conditions,thiols and sulfides were also converted to their corresponding disulfides and sulfoxides, respectively.     

不同硅铝比Al-ITQ-13分子筛的甲醇制丙烯反应催化性能

采用晶种法直接合成了硅铝比(SiO_2/Al_2O_3物质的量比)为137、224和309的三种Al-ITQ-13分子筛,并采用粉末X射线衍射(XRD)、扫描电镜(SEM)、N_2吸附-脱附、固体核磁共振(MAS NMR)和NH_3-程序升温脱附(NH_3-TPD)等分析方法对不同硅铝比分子筛进行了表征,并在固定床微型反应评价装置上,考察了硅铝比对甲醇转化制丙烯反应性能的影响。结果表明,不同硅铝比Al-ITQ-13分子筛呈现出相似的织构性质,酸量及酸强度随着硅铝比的升高逐渐下降。硅铝比对甲醇转化反应的产物分布存在较大的影响;随着硅铝比的升高,氢转移反应和芳构化反应活性降低,使得乙烯选择性下降,而丙烯和丁烯的选择性升高。硅铝比由137提高到309,丙烯的选择性(质量分数)由46.04%增加到55.52%,而丙烯/乙烯比由3.39提高到6.57。     

涂丝Ag-Ag2S电极测定水体中微量氰化物的研究

本文报道了涂丝Ag-Ag2S电极测定水体中微量氰化物(CN-)的分析方法。该方法对现用的Ag(CN)2-指示剂配制方法以及使用浓度作了新的改进,加之成功地在ISAB中引入有机溶剂等,较大程度地提高了测定CN-的灵敏度。该方法测定CN-的线性范围为1.0×10-3～1.0×10-7mol/L,检出限可达4.0×10-8mol/L,标准偏差小于0.015,回收率为99%～104%。本方法与比色法对照,相对误差≤1.3%,结果令人满意。     

Effect of O2/CH4 ratio on the optimal specific-energy-input (SEI) for oxidative reforming of biogas in a plasma-shade reactor

In a novel plasma-shade reactor for oxidative reforming of biogas (CH₄/CO₂ = 3/2), the effects of specific-energy-input (SEI) on CH₄ and CO₂ conversions and energy cost of syngas were investigated at O₂/CH₄ ratios ranged from 0.42 to 0.67. At each of O₂/CH₄ ratios, V-shape profiles of energy cost of syngas increasing with SEI were observed, reaching the lowest value at the optimal SEI (Opt-SEI). With the increase of O₂/CH₄ ratio, the Opt-SEI decreased significantly. Moreover, at the Opt-SEI, O₂ and CH₄ conversions and dry-basis concentration of syngas increased and energy cost of syngas decreased greatly with the increase of O₂/CH₄ ratio.     

A thallium(I) tetranuclear cubic cage unit in an interpenetrated supramolecular polymer: A new precursor for the preparation of Tl2O3 nanostructures

A new thallium(I) supramolecular polymer, [Tl₄(μ₃-4-BN)₄]_n (1) [9-HBN = 4-hydroxy benzonitrile], with a disordered cubic cage structural unit has been synthesized and characterized. The single-crystal X-ray data of compound 1 shows one type of Tl^I ion in the tetranuclear cubic cage structure with a coordination number of three. In addition to two intra cage thallophilic interactions in 1, each thallium(I) atom has a weak Tl?N secondary interaction with the nitrile group of the 4-BN⁻ ligand. Finally the Tl-ions attain the O₃Tl?NTl₂ coordination sphere with a stereo-chemically ‘active’ electron lone pair on the metal. The self assembly between the benzonitrile groups of one cubic cage structure with an adjacent one with a Tl?N short contact, by π-π stacking and weak hydrogen bonding interactions, results in the formation of a new interpenetrating thallium(I) supramolecular polymer. The thermal stability of 1 was studied by thermo gravimetric (TG) and differential thermal analyses (DTA). Nanostructures of thallium(III) oxide were prepared from a calcination process of compound 1 fine powder at 743 K. These nanostructures were characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM).     

InCl3-CH3CN-H2O: an efficient catalyst-solvent combination for the synthesis of Perlin aldehydes and related compounds. Application in the synthesis of unnatural l-azasugars

InCl₃-CH₃CN-H₂O has been found to be an efficient catalyst-solvent combination for the synthesis of Perlin aldehydes and related compounds. While acetylated glycals afforded the Perlin aldehydes directly with InCl₃ and water, benzylated glycals on the other hand provided the hemiacetals under identical condition. The methodology reports a non-mercurial approach to Perlin aldehydes. Noteworthy is that this reaction is more facile as well as highly selective with glycals possessing a hydroxyl as a leaving group than with a benzyloxy group. Extension of this reaction to 2-C-hydroxymethyl glycals resulted in the formation of the corresponding hemiacetals, which were further transformed in to unsaturated azasugars with an exo-methylene group at C-2 position. Glycosidase inhibition studies reveal that these compounds display selectivity in inhibiting glucosidases rather than galactosidases.