Pervaporation separation of IPA‐water mixtures through 4A zeolite‐filled sodium alginate membranes

Incorporation of zeolites into natural polymers has been shown experimentally to enhance both the flux and selectivity in pervaporative dehydration separation of organic compounds. Pervaporation is a promising membrane technique for separation of volatile organic compounds (VOCs)/water mixtures. In this study, hydrophilic sodium alginate (SA) mixed membranes were prepared using solution casting technique by incorporating zeolites into the polymer matrix. The prepared membranes were characterized by ATR‐Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), scanning electron microscopy (SEM), Thermal Gravimetric Analysis (TGA), and differential scanning calorimetry (DSC) were tested in a laboratory scale pervaporation experimental set‐up. The effect of experimental parameters such as the type and composition of zeolites on permeation flux and selectivity was investigated. When tested on IPA‐water mixtures, the zeolite‐filled membrane was found to give much higher selectivity. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Enhanced compactness of oriented MFI zeolite films by heat treatment of seed layer

The achievement of compact and defect-free film structure is crucial for the application of b-oriented MFI zeolite film. In this work, a novel heat treatment technique was used to treat zeolite seeded substrates prior to secondary growth. The influence of the heat treatment parameters such as treat temperature and time on the final film morphology were systematically investigated. The relationship between film compactness and the parameters was established. Under the optimized treat temperature of 120?°C and treat time of 1?h, compact and uniform b-oriented MFI zeolite film was achieved. The applicability of the optimum heat treatment condition was validated by employing various film substrates.     

碱激发剂对钢渣胶凝材料抗压强度的影响

以Na2SiO3, NaOH和Ca(OH)2制备碱性溶液,对钢渣进行活化处理得到碱钢渣胶凝材料,考察了Na2SiO3, NaOH和Ca(OH)2用量对材料的抗压强度影响,并对最优抗压强度的碱钢渣胶凝材料进行了表征. 结果表明,Na2SiO3对碱钢渣胶凝材料的7 d抗压强度影响显著,NaOH对材料的3 d抗压强度影响显著,Ca(OH)2对材料的28 d抗压强度影响显著. 当Na2SiO3, NaOH和Ca(OH)2用量分别为11.25, 4.50和6.75 g时,材料的抗压强度最优. 加入碱性溶液有利于胶凝体系中形成沸石类水化产物.     

以低温固相碱熔活化高岭土为原料合成ZSM-5分子筛

以天然矿物高岭土为主要硅铝原料,经低温固相碱熔活化后,在常规水热条件下合成ZSM-5分子筛,考察m(高岭土)∶m(氢氧化钠)、碱熔温度及碱熔时间等因素对高岭土活化效果的影响。采用XRF、XRD、FT-IR和N2-吸脱附等对不同样品进行表征。结果表明,在m(高岭土)∶m(氢氧化钠)=1∶1.5、碱熔温度250℃和碱熔时间30 min条件下,可以实现高岭土完全活化。该活化方式不仅降低了活化温度,且能在极短时间内提高高岭土活性。以最适宜低温固相碱熔活化条件下所得活性硅铝物质为主要原料,硅溶胶为外加硅源,采用水热法合成高相对结晶度的纯相ZSM-5分子筛。与工业ZSM-5分子筛相比,合成ZSM-5分子筛具有更大的比表面积和孔容。     

Optimization of the separation of sulfur hexafluoride and nitrogen by selective adsorption using monte carlo simulations

We present molecular simulations to find the optimal conditions for the separation by adsorption of SF₆ from a gaseous mixture with N₂, a mixture of key interest in electrical applications. The effect of pore size, pressure, and mixture compositions on the selective adsorption of SF₆ was investigated by using Grand Canonical Monte Carlo simulations with simple fluid models and a simplified model of MCM‐41. Simulations performed with multisite fluid models confirm that general trends are predicted using simple models, including a maximum in SF₆ selectivity for pore diameters around 1.1 nm. Simulations were also performed using two atomistic models of zeolite‐templated carbon (ZTC), FAU‐ZTC, and EMT‐ZTC, materials with average pore sizes close to 1.1 nm, obtaining high selectivities for both materials. Selectivities for FAU‐ZTC are approximately four times higher than the best materials published for this mixture separation, opening excellent opportunities to use it for recovering SF₆ from SF₆/N₂ mixtures. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

V_2O_5-沸石-活性炭-凹土脱硝催化剂的研制及脱硝性能

稻壳炭化后添加碱液和铝源分别合成了A型、A+X型和X型沸石-活性炭复合材料,加入凹凸棒石黏土成型,采用浸渍法负载V2O5制备V2O5-沸石-活性炭-凹土复合脱硝催化剂。采用XRD、SEM、N2吸附和EDX对样品进行表征,考察载体类型、V2O5含量和反应温度对催化剂低温脱硝活性的影响。结果表明,二元载体和V2O5协同催化脱硝,其脱硝率高于纯凹土制备的脱硝催化剂。催化剂脱硝活性随V2O5含量的增加而降低。反应温度越高,催化剂脱硝活性越高,最佳的反应温度为250℃,温度大于280℃后活性炭被氧化。     

程序控温吸附法对分子筛扩散性能的研究

提出了研究气体分子在沸石分子筛晶内孔中活化扩散的抛物线降温吸附法,经理论推导得到了计算晶内活化扩散动力学参数的基本公式,同时解决了降温过程中吸附动力学参数的计算问题。在前人工作的基础上,对研究多孔物质扩散性能的 TPD 公式加以改进,使其能够适于沸石分子筛的晶内活化扩散研究。对实际体系的研究结果表明:当采用抛物线降温吸附法对沸石分子筛进行研究时,可根据一次实验的数据,经一次回归计算得到气体分子在沸石分子筛晶内孔中的活化扩散动力学参数及吸附动力学参数,能够方便地进行活化扩散及吸附的研究,并可结合 TPD 数据进一步说明扩散和吸附所具有的特性。     

用“沸石转轮浓缩吸附+氧化燃烧”处理涂装废气的设计

从法规要求、废气初始浓度、设备、安全措施、电气控制等方面详细介绍了涂装车间采用沸石转轮浓缩吸附和氧化燃烧技术处理废气时在规划及设计过程中需注意的要点。