Assessment of high performance SAPO-34/S-PEEK composite coatings for adsorption heat pumps

In this work, a new composite adsorbent coating on aluminum support, based on SAPO34 zeolite filler embedded into sulfonate polyether ether ketone matrix is investigated for adsorption heat pumps (AHP) applications. Composite zeolite/polymer mixtures, with 80–95 wt% content of SAPO-34 zeolite filler have been prepared and coated on aluminum substrates. The as prepared coatings showed a pull-off adhesion strength up to 2.0 MPa, significantly higher than conventional values of composite zeolite coatings reported in the literature. Scanning electron microscopy analysis demonstrated that the coating has a homogeneous morphology with zeolite filler well interconnected in the composite coating structure. Water adsorption isobars were carried out at equilibrium in the temperature range 30–120°C. The best adsorption performances for AHPs applications were observed for the PZ-95 batch, where a maximum water uptake of ∼29.0 wt% was reached, highlighting that the polymer matrix presence does not alter the zeolite adsorption capability (31.3 wt%).     

Desorption kinetics of thick zeolite coatings prepared by induction heating for adsorption heat pump applications

Journal of Porous Materials - Zeolite coatings were directly crystallized on stainless steel substrates, which included double layer wire mesh cylinders and tubes, by induction heating. X-ray...     

Breakthrough analysis of carbon dioxide adsorption on zeolite synthesized from fly ash

Zeolite (FAZ) was synthesized by the fusion method using coal fly ash to adsorb carbon dioxide. The experimental adsorption was operated batchwise in a laboratory-scale packed-bed adsorber to obtain the breakthrough curves of CO₂ under conditions such as adsorption temperatures (20–80 °C), flow rates of gaseous mixture of carbon dioxide and nitrogen (40–100 cm³/min), and concentration of CO₂ (3000–10000 ppmv) at atmospheric pressure of 101.3 kPa. The influence of the experimental conditions, such as the gas flow rate, concentration of CO₂ and adsorption temperature on adsorption behavior, was discussed. The deactivation model, combined the adsorption with the deactivation of adsorbent, was used to analyze the physicochemical properties, such as the adsorption kinetics, capacity and heat of adsorption, by fitting the experimental data of the breakthrough curves to this model. The adsorptive activity and capacity of FAZ were as almost same as those of the commercial zeolite of Wako 4A.     

Tailoring the reaction mixture composition for preparing zeolite coatings on aluminum supports in alkaline environments

Various alkaline reaction mixture compositions were tested for determining their suitability to be used in the direct crystallization of zeolites on aluminum supports. No organic materials, such as templates, complexing agents, and corrosion inhibitors were included in the reaction mixtures. It was observed that aluminum supports remained quite stable in alkaline synthesis mixtures when suitable reaction mixture compositions with relatively high silica content were used. These favorable compositions might be recognized from their sodium silicate/(sodium hydroxide?+?sodium aluminate) mass ratios, as depicted in this study. Coatings were prepared on aluminum by using some of these compositions. It was determined that aluminum hydroxide phases commonly forming on the support could be eliminated to a great extent and consequently, crystalline coatings of zeolites P and Y were obtained on aluminum surfaces. The coatings exhibited trivial mass loss in the mechanical stability tests applied.     

Synthesis of structured filamentous zeolite materials via ZSM-5 coatings of glass fibrous supports

Structured filamentous zeolitic materials were synthesized by ZSM-5 coatings deposited on the glass fibrous supports. A homogeneous coverage of the support filaments was obtained via the synthesis of MFI crystals in fluoride-containing media at neutral pH 7. These materials combine the open macrostructure of woven filamentous fabrics with well-defined microstructure of ZSM-5 crystals. The samples were characterized by BET, XRD and SEM methods. The gas-phase partial oxidation of benzene by N₂O to phenol was investigated as a function of the chemical composition of the support and the ZSM-5 synthesis procedure. The fluorinated zeolitic materials demonstrated the highest activity (above 20% of benzene conversion) with a 97% selectivity towards phenol formation.     

Comparison of adsorption isotherms on Cu-BTC metal organic frameworks synthesized from different routes

Due to the differences in synthesis procedures used in preparation of metal organic frameworks, surface area and pore volume of the samples usually vary from one laboratory to another. The adsorption characteristics of the frameworks are also affected. In such cases, usually a scaling factor is employed to match isotherms obtained in different laboratories (or those from experiments and simulations). In an attempt to validate the use of a scaling factor, in this work we compare adsorption properties of N₂, O₂, Ar, CO₂, C₃H₈ and SF₆ on Cu-BTC (HKUST-1) framework synthesized using two different procedures. It was observed that Cu-BTC sample with higher surface area and pore volume has greater adsorption capacity for all gases at the two temperatures considered (298.25 and 318.15 K). For all gases, the ratio of specific adsorption capacities of the two samples can be broadly classified into two regions. In the low loading region this ratio was about 2.03 with in a 10% uncertainty envelope. However, in the high loading region, it increases to about 2.58. Thus, the scaling factor needed to compare adsorption isotherms of Cu-BTC having different surface areas may not be unique. This value seems to be strongly affected by loading, whereas it is relatively insensitive to the type of gas used, temperature or pressure.     

等温或非等温颗粒吸附动力学模型:应用于吸附热泵(英文)

Understanding the interaction between a fluid and a solid phase is of fundamental importance to the design of an adsorption process.Because the heat effects associated with adsorption are comparatively large,the as-sumption of isothermal behavior is a valid approximation only when uptake rates are relatively slow.In this article,we propose to determine when it is needed to choose the isothermal or non-isothermal assumption according to two physical parametersα(ratio convection/capacity) andβ(quantity of energy/capacity) .The proposed problem is solved by a mathematical method in the Laplace domain.Whenα→∞(infinitely high heat transfer coefficient) or β→0(infinitely large heat capacity) ,the limiting case is isothermal.When the diffusion is rapid(α10) the kinetics of sorption is controlled entirely by heat transfer.If the adsorption process is to be used as a heat pump,it shall be represented by an isotherm model withαandβas high as possible.     

Thermodynamics of hydrogen adsorption on the zeolite Ca-Y

Variable-temperature infrared spectroscopy was used for a thermodynamic study on hydrogen adsorption on the zeolite Ca-Y. Adsorption renders the H–H stretching mode infrared active, at 4078 cm⁻¹; and simultaneous measurement of IR absorbance and hydrogen equilibrium pressure, over a range of temperature, allowed standard adsorption enthalpy and entropy to be determined. They resulted to be ΔH°= −15.0(±1.0) kJ mol⁻¹ and ΔS° = −127(±10) J mol⁻¹ K⁻¹, respectively. These relatively high values of adsorption enthalpy and entropy are discussed in the broader context of corresponding data for other hydrogen adsorbents.     

沸石改性及其吸附性能研究

对沸石进行降低硅铝比改性，改性沸石对H2O，H2S，NH3的饱和吸附量分别为16.8％，18．2mg/g，71．1mg/g，而只进行过焙烧的沸石为9．3％，11．7mg/g,38.4mg/g，表明沸石经降低硅铝比改性后，对H2O，H2S，NH3的吸附量大大提高。     

红辉沸石两步水热法合成A型分子筛机理研究

以红辉沸石为原料,采用两步水热法将其转化为A型分子筛,系统地探讨A型分子筛的转化机理。对不同晶化时间的样品进行系统表征,深入解析天然红辉沸石转化A型分子筛的成核机制、生长控制、晶型稳定转化等结构基础问题。研究表明,A型分子筛的生长可分为3个阶段：在成核诱导期（晶化时间≤0.5 h）,凝胶中的β笼通过双四元环构筑成α笼,生成较多晶核及少量1μm小晶体;此后为快速生长期（晶化时间1～4 h）,大量晶核通过聚集生长形成2μm大晶体;在生长稳定期（晶化时间5～8 h）,通过二次成核凝胶将会转化为更多的分子筛晶体。A型分子筛的形成遵循：铝硅酸盐凝胶→四元环、六元环→双四元环、β笼→α笼的晶化过程,因而其转化过程符合液相转化机理。     

水热法合成β沸石结晶度的研究

以四乙基氢氧化铵为模板剂 ,采用水热法合成 β沸石。考察水热法合成 β沸石时体系中有机模板剂用量、水硅比、钠硅比及晶化时间等对合成的 β沸石相对结晶度的作用。样品的相对结晶度用X射线衍射仪分析。得出各种因素对合成 β沸石相对结晶度的影响     

换热器的管束支撑结构发展概况

综述了管壳式换热器壳程内换热管束支撑结构的发展概况.管束支撑由传统的弓形折流板发展为多种结构形式的折流杆、整圆形孔板和螺旋折流板等,不但提高了换热器整体传热性能,而且还大大降低了壳程流动阻力.可为换热器的结构优化和性能完善提供参考.     

沸石的改性处理及吸附性能研究

介绍了沸石改性的方法,讨论了影响沸石吸附性能的因素.实验表明,在废水温度为25℃,pH为6,Cd2 的初始质量浓度为50 mg/L,吸附剂的用量为20g/L,吸附时间为120 min的条件下,改性沸石对镉离子的去除率达到99.12%.     

疏水硅沸石吸附1,3-丙二醇的研究

FX-Ⅱ型沸石对1,3-丙二醇单组分溶液中1,3-丙二醇的静态饱和吸附量达到121.1 mg/g;在1,3-丙二醇和甘油的混合溶液中,研究了甘油质量浓度、吸附时间、吸附温度和盐离子质量浓度对1,3-丙二醇吸附的影响,实验结果表明高的甘油质量浓度对1,3-丙二醇吸附影响较大,吸附时间为14 h时1,3-丙二醇吸附达到平衡,低温及低盐离子质量浓度有利于1,3-丙二醇吸附;对实际发酵液的静态吸附结果表明,增大发酵液pH值可以减少有机酸对1,3-丙二醇的竞争吸附;pH值为7时,1,3-丙二醇吸附量达到102.5 mg/g;筛选了与吸附剂相关的脱附剂,用体积分数50%的乙醇解吸,解吸率达到86%。在此基础上初步研究了沸石对发酵液中1,3-丙二醇的动态吸附,1,3-丙二醇解吸率为82%。与传统的蒸馏法相比,沸石吸附法工艺简单,具有较大的研究和应用前景。     

Equilibrium studies on the adsorption of reactive azo dyes into zeolite

Zeolite was used as a low-cost adsorbent to evaluate its ability to remove color from textile effluents. The zeolit (clinoptilolite) used in this study is a natural clay mineral from the Gbrdes region of Turkey. The adsorption of reactive dyes into zeolite was investigated by a series of batch adsorption experiments. Three reactive dyes (Everzol Black, Everzol Red, Everzol Yellow) were used in laboratory studies. Adsorption test were carried out as a function of solids concentration, conditioning time and dye concentration. The degree of hydrophilicity was found to play an important role in the uptake of reactive dyes. The adsorption results indicated that natural zeolite has a limited adsorption capacity for reactive dyes but can be distinctly improved by modifying its surfaces with quaternary amines. A comparison of natural and modified zeolites at 5% solids concentration indicated that, while the adsorption densities of dyes with natural zeolite yielded negative or slightly positive values, those with modified zeolite gave adsorption densities in the range of 2.9 to 7.6 mg/g.     

Enhanced adsorption of heavy metal ions onto simultaneous interpenetrating polymer network hydrogels synthesized by UV irradiation

Simultaneous interpenetrating polymer network (IPN) hydrogels have been prepared by UV-initiated polymerization of a mixture of 2-acrylamido-2-methyl-1-propansulfonic acid (AMPS) and triethylene glycol divinyl ether (DVE-3) with enhanced adsorption properties for heavy metal ion removal. The swelling ratio of the IPN hydrogels determined by gravimetric method increased with the AMPS content in the formulation. The IPN hydrogels were used to remove heavy metal ions from aqueous solution. The effects of pH value of the feed solution and AMPS content in the formulation on the adsorption capacity were investigated. The results indicated that the adsorption capacity increased with the pH values and AMPS content in the formulation. Furthermore, the synergistic complexation of metal ions with two polymer networks in the IPN was found in the adsorption studies. The adsorption isotherm of the IPN hydrogels can be well fitted to the Freundlich model. The adsorption kinetics on IPN hydrogels clearly followed an initial transport-controlled adsorption process, but transited to an attachment-controlled adsorption kinetics in the later stage. Thermodynamic parameters such as the Gibbs free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) for the adsorption were estimated. Results suggested that the adsorption process was a spontaneous, exothermic process that had positive entropy.     

ZSM-5沸石分子筛吸附模拟废水中对苯二酚的研究

以正硅酸乙酯为硅源、偏铝酸钠为铝源、四丙基氢氧化铵为模板剂,利用水热合成法制备ZSM-5沸石分子筛并将其应用到吸附水中对苯二酚的研究,考察了吸附时间、对苯二酚溶液pH值、吸附温度、吸附剂用量对吸附效果的影响。结果表明,最佳吸附条件是:吸附温度为35℃,吸附时间为60 min,对苯二酚溶液pH值为6,吸附剂用量为0.4 g。此时,对苯二酚的去除率最高,达到了68.28%。     

金属氟碳外墙涂料的研究

介绍了金属氟碳涂料的基本生产配方、制备工艺及涂膜性能指标。分析讨论了氟含量、分散剂、CAB树脂、蜡浆、固化剂和其他助剂的选择及对产品性能的影响。     

Removal of methylene blue from aqueous solution by adsorption onto zeolite synthesized from coal fly ash and its thermal regeneration

BACKGROUND: The removal of cationic dyes from wastewater is of great importance. Three zeolites synthesized from coal fly ashes (ZFAs) were investigated as adsorbents to remove methylene blue (MB), a cationic dye, from aqueous solutions. Experiments were conducted using the batch adsorption technique under different conditions of initial dye concentration, adsorbent dose, solution pH, and salt concentration. RESULTS: The adsorption isotherm data of MB on ZFAs were fitted well to the Langmuir model. The maximum adsorption capacities of MB by the three ZFAs, calculated using the Langmuir equation, ranged from 23.70 to 50.51 mg g^?1. The adsorption of MB by ZFA was essentially due to electrostatic forces. The measurement of zeta potential indicated that ZFA had a lower surface charge at alkaline pH, resulting in enhanced removal of MB with increasing pH. MB was highly competitive compared with Na⁺, leading to only a < 6% reduction in adsorption in the presence of NaCl up to 1.0 mol L^?1. Regeneration of used ZFA was achieved by thermal treatment. In this study, 90–105% adsorption capacity of fresh ZFA was recovered by heating at 450 °C for 2 h. CONCLUSION: The experimental results suggest that ZFA could be employed as an adsorbent in the removal of cationic dyes from wastewater, and the adsorptive ability of used ZFA can be recovered by thermal treatment. Copyright © 2010 Society of Chemical Industry     

粉煤灰微波合成沸石在水处理中的应用

以粉煤灰为原料采用微波水热合成法制备沸石,将其用于废水处理中,考察了粉煤灰合成沸石对氨氮、磷、Fe2+、Mn2+、Cu2+的去除效果.实验结果表明,与粉煤灰相比,粉煤灰合成沸石具有更高的氨氮、磷去除率;在吸附去除废水中的Fe2+、Mn2+、Cu2+时,合成沸石比天然沸石更有效.