ZnCl2 and Pd/C catalyzed synthesis of 2-substituted indoles

A facile, mild, efficient, and copper-free method has been developed for the synthesis of 2-substituted indoles via domino Sonogashira coupling/cyclization reaction catalyzed by ZnCl₂ and palladium on carbon with simultaneous formations of C–C and C–N bonds.     

IR, XRD and SEM studies on the mechanism of adsorption of dyes and phenols by coir pith carbon from aqueous phase

Adsorption interactions of dye, phenol and chlorophenol onto coir pith carbon from aqueous solution were investigated using FT-IR Spectroscopy, Scanning Electron Microscopy (SEM), and X-ray diffraction techniques. IR studies revealed the participation of some of the surface functional groups in the adsorption mechanism, SEM revealed the morphological observations of the unloaded adsorbent and thereby changes in the adsorbed carbon. X-ray diffraction studies exhibited a decrease in crystalline nature of the loaded adsorbent compared with unloaded adsorbent.     

Selective fast pyrolysis of biomass impregnated with ZnCl2: Furfural production together with acetic acid and activated carbon as by-products

Fast pyrolysis of biomass materials impregnated with ZnCl₂ offered a promising way to obtain a liquid product rich in furfural (FF) and acetic acid (AA), and the pyrolytic solids could be used as the precursors to prepare activated carbons (ACs). In this study, a lab-scale fast pyrolysis set was designed and used for the quantitative production of the three chemicals. The maximum FF was produced from the corncob impregnated with at least 15 wt% ZnCl₂ and at the pyrolysis temperature around 340 °C, with the yield of more than 8 wt% compared with only 0.49 wt% from the raw corncob. Meanwhile, AA of around 4 wt% could be obtained. The content of the FF and AA was over 50 wt% and 25 wt% on the water-free basis of the pyrolytic liquids. In addition, ACs were prepared from the pyrolytic solids, and they exhibited similar properties as those prepared from direct activation of ZnCl₂-impregnated biomass materials.     

氯化锌活化对炭气凝胶微球的结构与电化学性能的影响

对炭气凝胶微球在高温下进行氯化锌活化改性,并用于制作超级电容器的电极。采用扫描电镜、N2物理吸附-脱附等对炭气凝胶微球的形貌结构进行表征,采用循环伏安、恒流充放电等测定了材料的电化学性能。结果表明,氯化锌活化有效地改善了炭气凝胶微球的孔结构,通过增加炭气凝胶微球的微孔面积和体积,提高了材料的比表面积和孔隙率。经过氯化锌活化,炭气凝胶微球的电化学性能也随之得到提高,电阻明显减小,比电容提高了2倍以上。     

Removal and recovery of vanadium(V) by adsorption onto ZnCl2 activated carbon: Kinetics and isotherms

Adsorption of vanadium(V) from aqueous solution onto ZnCl₂ activated carbon developed from coconut coir pith was investigated to assess the possible use of this adsorbent. The influence of various parameters such as agitation time, vanadium concentration, adsorbent dose, pH and temperature has been studied. First, second order, Elovich and Bangham’s models were used to study the adsorption kinetics. The adsorption system follows second order and Bangham’s kinetic models. Langmuir, Freundlich, Dubinin-Radushkevich and Temkin isotherms have been employed to analyze the adsorption equilibrium data. Equilibrium adsorption data followed all the four isotherms—Langmuir, Freundlich, D-R and Temkin. The Langmuir adsorption capacity (Q ₀) was found to be 24.9 mg g^{− 1} of the adsorbent. The per cent adsorption was maximum in the pH range 4.0–9.0. The pH effect and desorption studies showed that ion exchange mechanism might be involved in the adsorption process. Thermodynamic parameters such as ΔG ⁰, ΔH ⁰ and ΔS ⁰ for the adsorption were evaluated. Effect of competitive anions in the aqueous solution such as PO₄ ^{3 −}, SO₄ ²⁻, ClO₄ ⁻, MoO₄ ²⁻, SeO₃ ²⁻, NO₃ ⁻ and Cl⁻ was examined. SEM and FTIR were used to study the surface of vanadium(V) loaded ZnCl₂ activated carbon. Removal of vanadium(V) from synthetic ground water was also tested. Results show that ZnCl₂ activated coir pith carbon is effective for the removal of vanadium(V) from water.     

Chemical fixation of CO2 with highly efficient ZnCl2/[BMIm]Br catalyst system

The chemical fixation of CO₂ with mono-substituted terminal epoxides or cyclohexene oxide to form cyclic carbonates under the ZnCl₂/[BMIm]Br catalyst system without using additional organic solvents was achieved in excellent selectivity (>98%) and TOF (5410 h⁻¹) and the catalyst could be used six times almost without losing its catalytic activity and selectivity. Besides, the pure cis-cyclic carbonate of cyclohexene oxide was obtained in this catalyst system.     

Crystal structure and vibrational properies of Rb2MgWO2(PO4)2—A new framework phosphate

The new compound Rb₂MgWO₂(PO₄)₂ has been synthesized and characterized by a single-crystal X-structure determination, and IR and Raman spectroscopic studies. The crystal structure is orthorhombic, space group Pbca, with the unit cell dimensions a=9.891(2), b=12.641(2), , Z=8. Compared to the K₂M^IIWO₂(PO₄)₂ series, where M^II=Mg, Mn, Fe, Co, Ni, and Cd, the volume of the unit cell in the present compound is nearly doubled. The MgO₆ and WO₆ octahedra are arranged into polyhedral groups consisting of two edge sharing MgO₆ joined by corners with two WO₆ octahedra. These groups are interconnected through the PO₄ tetrahedra into layers in a×b plane. The Rb⁺ ions perform thermally activated displacements within the cavities formed between the polyhedral layers. The origin of various Raman and IR modes is discussed. These results indicate that a clear energy gap exists between the stretching and remaining modes. The most intense modes are shown to be due to vibrations of the W-O bonds.     

Preparation of activated carbons and their adsorption properties for greenhouse gases: CH4 and CO2

Three kinds of activated carbons were prepared using coconut-shells as carbon precursors and characterized by XRD, FT-IR and texture property test. The results indicate that the prepared activated carbons were mainly amorphous and only a few impurity groups were adsorbed on their surfaces. The texture property test reveals that the activated carbons displayed different texture properties, especially the micropore size distribution. The adsorption capacities of the activated carbons were investigated by adsorbing CH4, CO2, N2 and O2 at 25 ?C in the pressure range of 0-200 kPa. The results reveal that all the activated carbons had high CO2 adsorption capacity, one of which had the highest CO2 adsorption value of 2.55 mmol/g at 200 kPa. And the highest adsorption capacity for CH4 of the activated carbons can reach 1.93 mmol/g at 200 kPa. In the pressure range of 0-200 kPa, the adsorption capacities for N2 and O2 were increased linearly with the change of pressure and K-AC is an excellent adsorbent towards the adsorption separation of greenhouse gases.     

Selective fast pyrolysis of biomass impregnated with ZnCl2 to produce furfural: Analytical Py-GC/MS study

For 20 years ending in the 1990s the city of Barcelona discharged the products from a large primary sewage treatment plant directly into the Mediterranean Sea via underwater conduits. About ca. 3 million m³ of relict sewage sludge, rich in organic matter and heavy metals, has spread over an elongated area offshore, due to successive ruptures of the conduits. The use of the discharge pipes ceased, but the sludge deposit remains in place for the time being.To understand the history and present state of the sludge deposit in advance of future remediation, a program of geophysical mapping, sampling, and analytical work was undertaken. Rock Eval pyrolysis, although created for use in petroleum prospecting, can also be applied to environmental contamination studies. It offers a simple means to effectively delineate the sludge deposit, with the S₂ parameter and the hydrogen and oxygen indices particularly useful. On the molecular level, the sludge flash pyrolysis products notably include relatively abundant C₂₇ and C₂₉ sterenes and steranes, likely produced from the pyrolysis of fecal and other steroids, including coprostanol, in the sewage sludge. Linear alkylbenzenes and trialkylamines, derived from surfactant residues in the sludge, are also detected. The indoles detected are likely the pyrolysis products of proteins, while the alkylnitriles and alkylamides in the pyrolyzate likely derive from bacterial biomass. Principal components analysis aided the interpretation of the large geochemical dataset and a geographic information system enabled the three-dimensional visualization of the results in their geospatial context. The distinctive pyrolysis products and the trace elements would be geochemical markers useful in planning and assessing a future remediation program. The recognition of a distinctive sewage pyrolysis–GC/MS signature in this deposit would facilitate the use of this method in the detection of sewage-contaminated sediments in urban waterways worldwide.     

AlCl3(ZnCl2,MgCl2)对Sm2O3的氯化效果及电化学行为

研究了AlCl₃(ZnCl₂、MgCl₂)对Sm₂O₃的氯化效果以及Sm₂O₃在LiCl-KCl-AlCl₃(ZnCl₂、MgCl₂)熔盐体系中的电化学行为。在LiCl-KCl-Sm₂O₃熔盐中加入AlCl₃(ZnCl₂、MgCl₂)后,ICP测量结果表明,AlCl₃体系中Sm(Ⅲ)离子的浓度最高,并且在923 K时达到最大值;固相反应表明,AlCl₃氯化Sm₂O₃生成SmCl₃,而Sm₂O₃和ZnCl₂(MgCl₂)反应生成SmOCl。电化学行为表明,AlCl₃体系中观察到了两种Al-Sm的合金峰,而ZnCl₂体系中只观察到Zn-Sm金属间化合物的形成峰,MgCl₂体系中没有形成合金。在-6.25 A·cm^-2下,W电极上恒电流电解2 h获得了Al-Li-Sm合金,经XRD分析,合金为Al₂Sm相。     

AlCl3(ZnCl2,MgCl2)对Sm2O3的氯化效果及电化学行为

研究了AlCl_3(ZnCl_2、MgCl_2)对Sm_2O_3的氯化效果以及Sm_2O_3在Li Cl-KCl-AlCl_3(ZnCl_2、MgCl_2)熔盐体系中的电化学行为。在Li Cl-KCl-Sm_2O_3熔盐中加入AlCl_3(ZnCl_2、MgCl_2)后,ICP测量结果表明,AlCl_3体系中Sm(Ⅲ)离子的浓度最高,并且在923 K时达到最大值;固相反应表明,AlCl_3氯化Sm_2O_3生成SmCl_3,而Sm_2O_3和ZnCl_2(MgCl_2)反应生成Sm OCl。电化学行为表明,AlCl_3体系中观察到了两种Al-Sm的合金峰,而ZnCl_2体系中只观察到Zn-Sm金属间化合物的形成峰,MgCl_2体系中没有形成合金。在-6.25 A·cm~(-2)下,W电极上恒电流电解2 h获得了Al-Li-Sm合金,经XRD分析,合金为Al_2Sm相。     

Synthesis of 1,2-dihydro-4H-3,1-benzoxazine derivatives via ZnCl2 catalyzed cyclocondensation reaction

A short and facile synthesis of a series of 1,2-dihydro-4H-3,1-benzoxazine derivatives was accomplished in moderate to good yields via the novel cyclocondensation of substituted o-aminobenzonitrile with aldehydes or ketones catalyzed by ZnCl₂.     

树脂基球状活性炭的制备及对二氧化碳吸附性能的研究

以四种离子交换树脂（两种强碱性树脂D201和D280、两种弱碱性树脂D301G和D301R）为原料,经过磺化、炭化、活化处理制备了树脂基球状活性炭。采用TG、SEM、N₂吸附等对球状活性炭的收率、表面形貌、比表面积进行了表征,研究了所制球状活性炭对CO₂的吸附性能。结果表明,磺化处理有助提高树脂球的炭化收率;得到的四种球状活性炭对CO₂吸附性能良好,强碱性树脂球原料比弱碱性树脂球更具有优势,其中,由强碱性树脂球D201制得的树脂球状活性炭在30 ℃下对CO₂的吸附量可达2.57 mmol/g;十次循环吸附之后,树脂球仍能保持很好的CO₂吸附性能。     

CO2在Na2Cr2O7溶液中的平衡溶解度模型

为研究重铬酸钠(Na₂Cr₂O₇)对CO₂溶解的影响, 本文在带有搅拌的气液相高压平衡釜内, 采用静态法测定了温度在313.2-333.2 K, 压力在0.1-1.9 MPa 范围内, 重铬酸钠浓度分别为0、0.361、0.650、0.901 mol·kg^-1 时, CO₂ 在Na₂Cr₂O₇溶液中的溶解度. 结果表明: (1) Na₂Cr₂O₇对CO₂ 的溶解有盐析效应; (2) CO₂ 在Na₂Cr₂O₇溶液中的溶解符合亨利定律, 并且CO₂溶解度是温度和Na₂Cr₂O₇浓度的函数, 且用改进的Setschenow方程和Peng-Robinson-Pitzer (PR-Pitzer)方程拟合了在此温度、压力及重铬酸钠浓度范围内的实验数据, 拟合效果较好, 并且其平均相对误差分别为4.24%和3.32%.     

Novel ZnCl2-catalyzed one-pot multicomponent synthesis of 2-amino-3,5-dicarbonitrile-6-thio-pyridines

ZnCl₂-catalyzed one-pot multicomponent synthesis of 2-amino-3,5-dicarbonitrile-6-thio-pyridines under microwave heating and conventional heating is described.     

TiO2/SnO2复合光催化剂的耦合效应

采用改进的sol gel技术制备TiO2/SnO2耦合型半导体光催化剂,利用XRD、气相色谱 仪、粒度仪和表面光电压装置等研究了耦合型半导体光催化机理和光催化效率的影响因素, 并通过降解甲醛探讨其在空气污染治理中的作用.实验结果表明,添加20 ％(mol) SnO2的复 合半导体光催化剂,其光催化效率比纯TiO2高一倍以上.据实验结果和粒子紧密堆积原理,提 出强耦合效应和弱耦合效应的光催化反应模型,并用此模型较好地解释了TiO2/SnO2复合型半 导体光催化剂的光催化效率随SnO2含量变化规律.     

Tandem isomerization-lactonization of olefinic fatty acids using the Lewis acidic ionic liquid, choline chloride·2ZnCl2

The tandem isomerization-lactonization of unsaturated fatty acids to their corresponding γ-lactones was carried out for the first time in the presence of a Lewis acidic ionic liquid, choline chloride·2ZnCl₂. The ionic liquid initially catalyzes the stepwise migration of the double bond along the carbon chain toward the carboxyl group at the Δ4 position, which subsequently undergoes lactonization resulting in the formation of γ-lactones. This one step process allows the formation of γ-lactone in good yield with little or no formation of δ-lactones. The studied ionic liquid plays the dual role of solvent as well as catalyst.     

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.     

Cu-Ni/La2O3热解C2H2制备碳纳米管的研究

Nano-sized and well-dispersed Cu-Ni/La₂O₃ can be obtained by reduction of LaCu_0.2Ni_0.8O₃ with the structure of perovskite. Using Cu-Ni/La₂O₃ as catalyst and C₂H₂ as carbon source, carbon nanotubes with a high yield and narrow diameter distribution can be obtained in the reaction temperature range of 650～700℃. Outer diameter of carbon nanotubes rangs from 9nm to 14nm. TG, Raman and XPS analysis indicate that carbon nanotubes prepared by Cu-Ni/La₂O₃ are relatively higher in graphitic degree.     

Change in mechanistic pathway of hydroboration: A detailed kinetic study of H2BBr·SMe2 and HBBr2·SMe2

Hydroboration reactions of 1-octene and 1-hexyne with H₂BBr·SMe₂ in CH₂Cl₂ were studied as a function of concentration and temperature, using ¹¹B NMR spectroscopy. The reactions exhibited saturation kinetics. The rate of dissociation of dimethyl sulfide from boron at 25 °C was found to be (7.36 ± 0.59 and 7.32 ± 0.90) × 10⁻³ s⁻¹ for 1-octene and 1-hexyne, respectively. The second order rate constants, k₂, for hydroboration worked out to be 7.00 ± 0.81 M s⁻¹ and 7.03 ± 0.70 M s⁻¹, while the overall composite second order rate constants, k K, were (3.30 ± 0.43 and 3.10 ± 0.37) × 10⁻² M s⁻¹, respectively at 25 °C. The entropy and enthalpy values were found to be large and positive for k₁, whilst for k₂ these were large and negative, with small values for enthalpies. This is indicative of a limiting dissociative (D) for the dissociation of Me₂S and associative mechanism (A) for the hydroboration process. The overall activation parameters, ΔH^≠ and ΔS^≠, were found to be 98 ± 2 kJ mol⁻¹ and +56 ± 7 J K⁻¹ mol⁻¹ for 1-octene whilst, in the case of 1-hexyne these were found out to be 117 ± 7 kJ mol⁻¹ and +119 ± 24 J K⁻¹ mol⁻¹, respectively. When comparing the kinetic data between H₂BBr·SMe₂ and HBBr₂·SMe₂, the results showed that the rate of dissociation of Me₂S from H₂BBr·SMe₂ is on average 34 times faster than it is in the case of HBBr₂·SMe₂. Similarly, the rate of hydroboration with H₂BBr·SMe₂ was found to be on average 11 times faster than it is with HBBr₂·SMe₂. It is also clear that by replacing a hydrogen substituent with a bromine atom in the case of H₂BBr·SMe₂ the mechanism for the overall process changes from limiting dissociative (D) to interchange associative (I_a).