导电性聚呋喃的氧化合成及应用

总结了芳香族聚呋喃的氧化聚合方法,系统论述了聚合过程中影响聚呋喃性质的各种因素,推测了聚呋喃的链结构,介绍了聚呋喃的各种改进方法和效果。指出聚呋喃及其共聚物是一种电导率在10-11到10-1S.cm-1范围内有机半导体材料,其电聚合沉积膜具有奇特的电活性、优良的热加工性和特殊的表面形貌,可望在金属离子和有机物质的吸附与富集、传感探测等领域发挥作用。     

CO2 adsorption on zeolite X/activated carbon composites

Two series of zeolite X/activated carbon composites with different ratios of zeolite and activated carbon were prepared through a combination process of CO₂ activation of the mixtures of elutrilithe and pitch and subsequent hydrothermal crystallization in alkaline solution. An additional surface modification was achieved in diluted NH₄Cl solution. CO₂ and N₂ uptakes on the composites before and after modification were determined for pressures up to 101?kPa at 273 and 298?K, respectively. Langmuir-Freundlich and Toth adsorption models were used to describe the adsorption isotherms of CO₂ and the corresponding heats of adsorption were estimated with the Clausius-Clapeyron equation. Both before and after modification, all composites exhibited a remarkable preferential adsorption of CO₂ compared to N₂, with the modified composites showing a higher adsorption selectivity to CO₂ over N₂ than the unmodified composites. With an increasing ratio of zeolite in the composites, adsorption capacity and adsorption heat of CO₂ on the composites increased simultaneously. Lower adsorption heat was observed both before and after modification especially at the low-loading region and when there was less energetic heterogeneity on the surface of the modified composites. The results may be attributed to the elimination of strong basic sites on the modified composites, which is favorable for desorption of CO₂ on the adsorbents and application in pressure swing adsorption processes.     

IMPEDANCE CHARACTERISTICS OF POLYFURAN FILMS

Electrochemical impedance spectroscopy (EIS) was first used for the characterization of polyfuran (PFu) films thathad been formed electrochemically on an Au electrode. The polyfuran was measured in high oxidation state, intermediateoxidation state and reduction state, respectively. As the oxidation level is increased, the ionic conductivity of PFu/BF_4~-increases. And impedance studies on PFu show that the anion BF_4~- appears to be mobile with a high diffusion coefficient ofapproximately 10~(-8)cm~2· s~(-1).     

The synthesis and properties of zeolite CF-3

The novel zeolite CF-3, with a high ratio of SiO₂/Al₂O₃ and a characteristic X-ray powder diffraction pattern, has been synthesized hydrothermally from a TMEDA-Na₂O–SiO₂–Al₂O₃–H₂O system at 200°C. The molar composition of CF-3 is (0.4–0.6)Na₂O·(1.5–6.3)TMEDA·Al₂O₃·(80–400)SiO₂·(0–17)H₂O·CF-3 is similar to ZSM-39 and melanophlogite, which have a clathrate-type structure.     

Synthesis of Na-A and/or Na-X zeolite/porous carbon composites from carbonized rice husk

Na-A and/or Na-X zeolite/porous carbon composites were prepared under hydrothermal conditions by NaOH dissolution of silica first from carbonized rice husk followed by addition of NaAlO₂ and in situ crystallization of zeolites i.e., using a two-step process. When a one-step process was used, both Na-A and Na-X zeolites crystallized on the surface of carbon. Na-A or Na-X zeolite crystals were prepared on the porous carbonized rice husk at 90 °C for 2-6 h by changing the SiO₂/Al₂O₃, H₂O/Na₂O and Na₂O/SiO₂ molar ratios of precursors in the two-step process. The surface area and NH₄⁺-cation exchange capacity (CEC) of Na-A zeolite/porous carbon were found to be 171 m²/g and 506 meq/100 g, respectively, while those of Na-X zeolite/porous carbon composites were 676 m²/g and 317 meq/100 g, respectively. Na-A and Na-X zeolites are well-known microporous and hydrophilic materials while carbonized rice husk was found to be mesoporous (pores of ∼3.9 nm) and hydrophobic. These hybrid microporous-mesoporous and hydrophilic-hydrophobic composites are expected to be useful for decontamination of metal cations as well as organic contaminants simultaneously.     

Preparation of graphene/zeolite composites and the adsorption of pollutants in water

Russian Journal of Applied Chemistry - Based on the advantages of graphene and zeolite, respectively, the graphene/zeolite composites with core-shell structure were synthesized. The features of the...     

聚氨酯/分子筛复合材料的制备及性能

以聚对苯二甲酸乙二醇酯（PEA）、甲苯二异氰酸酯（TDI-80）、扩链剂（MOCA）、分子筛为原料,采用预聚体法制备了聚氨酯／分子筛复合材料．考察了分子筛的种类及加入量对聚氨酯／分子筛复合材料的耐溶剂性能、力学性能及热分解温度的影响．结果表明：在相同加入量的前提下,采用4A和13X分子筛制备的复合材料,前者的耐溶剂性能及力学性能要优于后者,当加入量为5％时,性能达到最佳．两者的加入均能提高复合材料的热分解温度,但影响相差不大．     

The effect of triethyl citrate on the dispersibility and water vapor sorption behavior of polylactic acid/zeolite composites

The aim of this study was to investigate the water vapor adsorption behavior and mechanical properties of poly (lactic acid) (PLA)/zeolite (5, 10, or 15 phr) composites prepared with triethyl citrate (TEC; 20 phr) via a melting process. TEC was used to improve the flexibility of the PLA and the dispersibility of the zeolite in TEC-zeolite suspensions that were ultra-sonicated. It was found that zeolite was uniformly dispersed in the PLA matrix, and the interfacial adhesion between the PLA matrix and zeolite was enhanced by TEC. In addition, the tensile strengths and Young's modulus of the composites improved with increasing zeolite content. The PLA/zeolite composites prepared with TEC had increased water vapor permeability and contact angles compared to neat PLA and standard PLA/zeolite due to the presence of TEC. In particular, TEC accelerated the hydrolysis of the PLA surface in a high humidity environment, resulting in an improvement in water vapor sorption capacity. At the same zeolite content of 15 phr, the equilibrium moisture content (EMC) values of PLA/zeolite films prepared with TEC increased by up to 39.25 mg/g whereas those prepared without TEC only increased by up to 24.33 mg/g. The results suggest the possibility of applying PLA/zeolite films prepared with TEC as a flexible active packaging material.     

High-resolution physical adsorption on supported borosilicate MFI zeolite membranes: comparison with powdered samples

We have performed physical adsorption measurements to analyze the structure of intact MFI membranes with a nominal Si:B ratio of 12.5:1. Argon adsorption isotherms of membranes at 77 K are nearly identical to isotherms of corresponding zeolite powders throughout most of the domain of relative pressures, the exception being the micropore-filling region (between 10⁻⁵ and 10⁻⁴ relative pressure). The isotherm in the micropore-filling region is steeper by a factor of 4–5 for the borosilicate membranes than it is for a powder made under the same conditions, while the saturation loadings are found to be similar. This implies a difference in how the zeolite pores fill with argon – either thermodynamic or kinetic in origin – and that fluxes for argon permeation through such powder and membrane samples may differ. Our membrane adsorption measurements reveal no hysteresis and hence no mesoporsity in the zeolite membranes. This finding, from adsorption measurements, stands in contrast to recent alkane permeation measurements on these membranes, which suggest the presence of mesopores. We reaffirm the conclusion, found in previous work, that zeolite membranes can be approximated as a zeolite powder plus a support for the purposes of adsorption characterization.     

Nanocomposite fuel cell membranes based on Nafion and acid functionalized zeolite beta nanocrystals

We have prepared nanocomposite proton exchange membranes (PEMs) based on Nafion with sulfonic acid functionalized zeolite beta (AFB) as an additive. 2.5 and 5 wt% AFB composite membranes possess proton conductivity/methanol permeability (selectivity) ratios as much as 93% higher than commercial Nafion 117 at 21 °C, and 63% higher at 80 °C. These 2.5 and 5 wt% AFB composite membranes also outperform commercial Nafion 117 in direct methanol fuel cell performance evaluations. The composite membranes are characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, four-electrode impedance for proton conductivity, two-compartment permeation for methanol crossover, and direct methanol fuel cell performance.     

Green synthesis of graphene nanosheets/ZnO composites and electrochemical properties

A green and facile approach was demonstrated to prepare graphene nanosheets/ZnO (GNS/ZnO) composites for supercapacitor materials. Glucose, as a reducing agent, and exfoliated graphite oxide (GO), as precursor, were used to synthesize GNS, then ZnO directly grew onto conducting graphene nanosheets as electrode materials. The small ZnO particles successfully anchored onto graphene sheets as spacers to keep the neighboring sheets separate. The electrochemical performances of these electrodes were analyzed by cyclic voltammetry, electrochemical impedance spectrometry and chronopotentiometry. Results showed that the GNS/ZnO composites displayed superior capacitive performance with large capacitance (62.2 F/g), excellent cyclic performance, and maximum power density (8.1 kW/kg) as compared with pure graphene electrodes. Our investigation highlight the importance of anchoring of small ZnO particles on graphene sheets for maximum utilization of electrochemically active ZnO and graphene for energy storage application in supercapacitors.     

Application of FTIR spectra for evaluating interfacial reactions in metal matrix composites

Manufacturing of Saffil/MgLi metal matrix composites by the melt infiltration process is accompanied by extensive interfacial redox reaction between δ-Al₂O₃ fibers (Saffil) and lithium. The present paper deals with the Fourier transform infrared spectroscopy examination of Saffil fibers isolated from Mg–8 wt% Li alloy by the bromine/methylacetate agent focusing on the insertion of Li⁺ ions into δ-Al₂O₃ and their influence on water adsorption. Insertion of Li⁺ into δ-Al₂O₃ is monitored by gradual change of Al–O stretching bands (400–900 cm⁻¹) towards more simple patterns of a spinel-like product assigned as δ(Li) which transforms to LiAl₅O₈ during subsequent annealing. Rapid increase in the water adsorption with increase in Li content, indicated by the changes in H–O–H bending (about 1,650 cm⁻¹) and O–H stretching (about 3,500 cm⁻¹), is connected with the ionicity of the δ(Li) phase, which attracts polar water molecules.     

国际互联网与沸石相关的化学化工信息资源

介绍了Internet上与沸石和天然沸石有关的化学化工信息资源,并初步讨论国际互联网和国内互联网上沸石信息量。     

A study of PP/PET composites: Factorial design,mechanical and thermal properties

Due to the economic importance of polypropylene (PP) and polyethylene terephthalate (PET), and the large amount of composites made with PP matrix and recycled PET as reinforcing material; an investigation was performed regarding the mechanical and thermal behavior of PP composites containing recycled polyethylene terephthalate fibers (rPET). Interfacial adhesion between the two materials was achieved by adding a compatibilizer, maleic anhydride grafted polypropylene, PP-g-MA. Mechanical behavior was assessed by tensile, flexural, impact and fatigue tests, and thermal behavior by HDT (Heat Deflection Temperature). Fractured surfaces and fiber were investigated by scanning electron microscopy. Multiple regression statistical analysis was performed to interpret interaction effects of the variables. Tensile strength, tensile modulus, flexural strength, flexural modulus and HDT increased after rPET fiber incorporation while strain at break, impact strength and fatigue life decreased. Addition of compatibilizer increased tensile strength, flexural strength and flexural modulus, fatigue life and HDT while tensile modulus, strain at break and impact strength decreased. However, at low fiber content, the impact strength increased, probably due to nucleation effects on PP.     

Intercalation of xylenol orange, morin and calmagite into NaY zeolite and their application in dye/zeolite modified electrode

The intercalation of xylenol orange, morin and Calmaigite into NiaY zeolite were studied by XRD, TGA, and BET and diffuse reflectance. These dye incorporated into NaY zeolite by ion exchange in aqueous phase. Results show that xylenol orange can be intercalating better into zeolite. The dye molecules are strongly retained in the channels of zeolites. The prepared intercalated dye/zeolite, for the first time, was used as the modifier for carbon past electrode. The dye/zeolite modified carbon paste electrode was developed for the voltammetric determination of Cu(II). Copper(II) was selectively preconcentrated. Results shows the peak current intensity increased in order of calmagite > xylenol orange > morin dyes intercalated in zeolite. The results agree with complex formation of those dyes as chelating agents with Copper(II).     

Hollow mesoporous zeolite microspheres: hierarchical macro-/meso-/microporous structure and exceptionally enhanced adsorption properties

We report the synthesis of a new kind of uniform hollow zeolite microspheres with hierarchical macro-/meso-/microporosity by an efficient strategy combining bi-templating, steam-assisted crystallization and then a mild alkaline etching method. This novel product has a hollow architecture, highly crystallized zeolite shells and more importantly, high dye adsorption capabilities.     

Ab initio quantum chemical study on the zeolite catalyzed transformations of para-xylene

Unimolecular 1,2-methyl shift reaction and disproportionation of para-xylene is investigated by means of ab initio quantum chemical calculations. Isolated gas-phase models are used to estimate the optimum volume of the reaction complex. Space filling of the computed models is examined in zeolite Y, Beta and ZSM-5. It is suggested that the shape selectivity effect of zeolite molecular sieves on the disporportionation reaction can be associated with the steric conditions of the intrinsic rearrangement of the reaction complex in the course of the chemical transformation.     

Transport properties of alkanes through ceramic thin zeolite MFI membranes

Polycrystalline randomly oriented defect free zeolite layers on porous α-Al₂O₃ supports are prepared with a thickness of less than 5 μm by in situ crystallisation of silicalite-1. The flux of alkanes is a function of the sorption and intracrystalline diffusion. In mixtures of strongly and weakly adsorbing gases and a high loadings of the strongly adsorbing molecule in the zeolite poze, the flux of the weakly adsorbing molecule is suppressed by the sorption and the mobility of the strongly adsorbing molecule resulting in pore-blocking effects. The separation of these mixtures is mainly based on the sorption and completely different from the permselectivity. At low loadings of the strongly adsorbing molecules the separation is based on the sorption and the diffusion and is the same as the permselectivity. Separation factors for the isomers of butane (n-butane/isobutane) and hexane (hexane/2,2-dimethylbutane) are respectively high (10) and very high (> 2000) at 200°C. These high separation factors are a strong evidence that the membrane shows selectivity by size-exclusion and that transport in pores larger than the zeolite MFI pores (possible defects, etc) can be neglected.     

Polyaniline composites: improving the electrochemical properties by template synthesis

We have been exploring the idea of using the heterogeneous porosity of inorganic (sol-gel silica) and organic (poly(vinylidene fluoride)) films as a template for the preparation of polyaniline composites. The large size pore distribution (~2.5–800 nm) in both template matrices results in a part of the polyaniline growing more ordered than in films synthesized without spatial restriction. Small-angle X-ray scattering and scanning electron microscopy experiments were done to determine the extreme values of the pore diameters. Using other experimental techniques, including cyclic voltammetry, UV-Vis-NIR spectroscopy, electrochemical impedance and chronopotentiometry, we concluded that the electrochemical properties of polyaniline, such as oxidation and reduction charges, diffusion coefficient and charge-discharge capacity, are improved in these composites. Electronic Publication     

Phonon spectra and phonon-dependent properties of AgSO4, an unusual sulfate of divalent silver

Phonon spectra of recently synthesized Ag(II)SO₄ have been measured using infrared absorption and Raman scattering spectroscopy, and theoretically predicted using density functional theory calculations. Excellent agreement between experimental and theoretical results with correlation coefficient of 1.05 allowed for full assignment of the experimentally observed vibrational bands, as well as calculation of standard vibrational entropy of AgSO₄ (118.2 J mol⁻¹ K⁻¹), vibrational heat capacity at constant volume (99.1 J mol⁻¹ K⁻¹), zero-point energy (48.3 kJ mol⁻¹). The experimental cut-off frequency of the phonon spectrum equals 1116 cm⁻¹ which translates to the Debye temperature of 1606 K. High frequencies of S–O stretching modes render sulfate connections of Ag(II) attractive precursors of high-T_C superconductors.