ZnHZSM-5催化丙烷芳构化的失活动力学研究

在等温积分反应器中实验研究了由丙烷制取轻质芳烃BTX（苯、甲苯及二甲苯）的芳构化过程中，锌改性的HZSM－5催化剂的积炭失活对反应过程的影响，通过对常压、不同反应温度下的实验数据所进行的动力学分析，建立起了失活动力学模型，并通过拟合实验数据对模型做了筛选，最终确定了基于Langumir-Hinshelwood模型的反应速率方程和由独立失活机理推出的2级独立失活速率方程，该模型对深入了解轻烃芳构化反应及指导反应器设计均具有重要的意义。     

A glue method for fabricating membrane electrode assemblies for direct methanol fuel cells

We present a simple glue method for fabricating membrane electrode assemblies (MEA) for direct methanol fuel cells (DMFC). Rather than the conventional “dry” hot-pressing method that relies solely on hot-pressing at a high pressure and temperature to form a MEA, the “wet” method developed in this work introduces a binding agent, consisting of Nafion^® solution, between a polymer electrolyte membrane (PEM) and an anode/cathode. The introduced binding agent can provide a better adhesion and stronger binding force between a membrane and an electrode, thereby facilitating a better interfacial contact between the electrode and the Nafion^® membrane, which has been proved by scanning electron microscopy (SEM) analyses to the cross-sectional morphology of the MEA after long-term operation. The cell performance characterization showed the MEA fabricated by the glue method was more stable in cell performance than that fabricated by the conventional hot-pressing method. Cyclic voltammetry (CV) results also demonstrated the MEA fabricated by the glue method exhibited a higher electrochemical surface area (ESA) as a result of the improved interfacial contact between the Nafion^® membrane and the electrodes. Finally, the DMFC with the MEA fabricated by the glue method was characterized by the electrochemical impedance spectroscopy (EIS).     

Glass Furnace Boost Technology-Series/Parallel Switch

In the paper, the characters and fields were introduced for utilizing the Series/Parallel Switch (SPS). The circuit principle of the SPS technology was analyzed in detailed, explained and illuminated. We understood clearly the difference between SPS and single-phase transformator by the figure and table. Finally, it summarized that the main characters of SPS.     

马来酸酐接枝聚乙烯对无卤阻燃PE-HD护套料的改性研究

研究了马来酸酐接枝聚乙烯对无卤抑烟阻燃PE-HD护套料的改性效果，并进行了增韧机理上的探讨。采用扫描电镜对复合材料进行了断面观察，并测试了材料的力学性能、流变性能、耐热性能和氧指数。结果表明，马来酸酐接枝聚乙烯能够极大地提高复合材料的界面相容性，增强材料的界面相互作用，提高阻燃剂微粒在树脂基体中的分散效果，同时形成了一个可塑性界面层，所以能够提高材料的韧性。     

锌灰制备活性氧化锌新工艺

以炼锌厂废锌灰为原料，经硫酸浸取制备活性氧化锌，考察了工艺条件对锌浸出率的影响。实验结果表明：锌灰在50℃浸取，酸用量40g／L，可使锌的溶出率达92．8％。碱式碳酸锌最佳水解温度为40℃，水解时间为2h，pH为7．5时，溶液中锌质量浓度为10g／L，得到96％以上的水解率。采用该工艺制得的氧化锌符合HG／T2572-1994。     

Ionic elastomer blends of zinc salts of maleated natural rubber and carboxylated nitrile rubber: Effect of grafted maleic anhydride

Zinc neutralized maleated natural rubbers (Zn‐MNR) were prepared by solution grafting and neutralization with zinc acetate in one‐step. It was later used for blending with carboxylated nitrile rubber (XNBR) in the composition of 50/50 parts by weight. The effect of grafted anhydride content (1.2, 1.6, 2.0, and 2.5% wt of NR) on the tensile properties of ionic rubber blends (Zn‐MNR/XNBR) was investigated. The tensile strength of the ionic blends was found to be greater than those of pure rubbers. The modulus, tensile, and tear strength of the blends dramatically increased with increasing levels of grafted anhydride. The ionic rubber blends also possessed superior physical properties compared to those of the corresponding nonionic rubber blends (MNR/XNBR). Dynamic mechanical thermal analysis and scanning electron microscopic studies were performed to verify the process of mixing. Fourier transform infrared spectroscopic studies were carried out to characterize the nature of specific intermolecular interactions between Zn‐MNR and XNBR chain segments. The results indicated that the ion‐ion (Zn⁺ ‐COO^?) interactions between Zn‐MNR and XNBR are formed at the interface, which provides the mean of compatibilization in the ionic rubber blends. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Modification of glassy carbon electrode with multi-walled carbon nanotubes and iron(III)-porphyrin film: Application to chlorate, bromate and iodate detection

In this study, multi-wall carbon nanotubes (MWCTs) is evaluated as a transducer, stabilizer and immobilization matrix for the construction of amperometric sensor based on iron-porphyrin. 5,10,15,20-Tetraphenyl-21H,23H-porphine iron(III) chloride (Fe(III)P) adsorbed on MWCNTs immobilized on the surface of glassy carbon electrode. Cyclic voltammograms of the Fe(III)P-incorporated-MWCNTs indicate a pair of well-defined and nearly reversible redox couple with surface confined characteristics at wide pH range (2-12). The surface coverage (Γ) and charge transfer rate constant (k_s) of Fe(III)P immobilized on MWCNTs were 7.68 × 10⁻⁹ mol cm⁻² and 1.8 s⁻¹, respectively, indicating high loading ability of MWCNTs for Fe(III)P and great facilitation of the electron transfer between Fe(III)P and carbon nanotubes immobilized on the electrode surface. Modified electrodes exhibit excellent electrocatalytic activity toward reduction of ClO₃⁻, IO₃⁻ and BrO₃⁻ in acidic solutions. The catalytic rate constants for catalytic reduction of bromate, chlorate and iodate were 6.8 × 10³, 7.4 × 10³ and 4.8 × 10² M⁻¹ s⁻¹, respectively. The hydrodynamic amperometry of rotating-modified electrode at constant potential versus reference electrode was used for detection of bromate, chlorate and iodate. The detection limit, linear calibration range and sensitivity for chlorate, bromate and iodate detections were 0.5 μM, 2 μM to 1 mM, 8.4 nA/μM, 0.6 μM, 2 μM to 0.15 mM, 11 nA/μM, and 2.5 μM, 10 μM to 4 mM and 1.5 nA/μM, respectively. Excellent electrochemical reversibility of the redox couple, good reproducibility, high stability, low detection limit, long life time, fast amperometric response time, wide linear concentration range, technical simplicity and possibility of rapid preparation are great advantages of this sensor. The obtained results show promising practical application of the Fe(III)P-MWCNTs-modified electrode as an amperometric sensor for chlorate, iodate and bromate detections.     

Characterization of boron-doped diamond electrodes by electrochemical impedance spectroscopy

Charge transfer on boron doped diamond (BDD) electrodes was studied by cyclic voltammetry and electrochemical impedance spectroscopy. The diamond films of 5 μm thickness and boron content between 200 ppm and 3000 ppm were prepared by the hot filament CVD technique on niobium substrate and mounted in a Teflon holder as rotating disk electrodes. The electrochemical measurements were carried out in aqueous electrolyte solutions of 0.5 M Na₂ SO ₄ + 5 mM K₃[Fe(CN)₆]/K₄[Fe(CN)₆]. Significant deviation in the redox behaviour of BDD and active Pt electrodes was indicated by a shift of the peak potentials in the cyclic voltammograms with increasing sweep rate and lower limiting diffusion current densities under rotating disk conditions. In the impedance spectra an additional capacitive element appeared at high frequencies. The potential and rotation dependence of the impedance spectra can be described quantitatively in terms of a model based on diffusion controlled charge transfer on partially blocked electrode surfaces. Direct evidence for the non-homogeneous current distribution on the diamond surface was obtained by SECM measurements.     

Air electrode supported manganese electrocatalysts for neutral electrolyte magnesium air cell

The catalysts of air electrode were prepared by sintering the active carbon loaded with manganese nitrate and potassium permanganate at 360 °C The air electrode was made up of a catalyst layer, a waterproof and gas-permeable layer, a current collecting substrate and a second waterproof and gas-permeable layer. The cell was assembled by the air electrode, pure magnesium anode and 10% NaCl solution used as electrolyte. The microstructures of air electrodes before and after discharging were characterized by SEM. The electrochemical behaviors of the air electrodes were determined by means of polarization curves, volt-ampere curves and constant current discharge curves. The polarization voltage of air electrode is—173 mV (vs SCE) at the current density of 50 mA/cm². The air electrodes exhibits good activity and stability in neutral electrolyte. The magnesium-air cell could work at 5 W for more than 7 h.     

复合白云石表面链状纳米CaCO_3的制备

在Ca(OH)_2-H_2O-CO_2反应体系中,根据非均匀成核原理,通过调整体系反应温度、Ca(OH)_2浓度、ZnSO_4添加量等反应参数,控制在白云石颗粒表面生成具有链状结构的纳米Ca-CO_包覆层.利用SEM,XRD等检测表征手段,分析了不同反应参数对纳米CaCO_3晶形的影响.结果表明:当反应温度为25℃,ZnSO_4加入量为Ca(OH)_2的4%,Ca(OH)_2浓度为0.3mol/L时,在白云石颗粒表面生成了长径比为7:1的链状纳米CaCO_3.提高体系的反应浓度能够减少ZnSO_4的加入量.