Pd-SiO2复合膜的氢气选择渗透特性

Palladium membranes were prepared on an a-alumina support by metal-organic compound chemical vapor deposition (MOCVD) method from palladium(Ⅲ) acetate precursor. Permeation properties of hydrogen and helium gas were studied as a function of the number of times of deposition of palladium on the peeling off phenomenon of palladium, which is common in electroless plated membrane, was observed. Silica was introduced into the pores to prevent the palladium grain from peeling off. The palladium-silica conjugated membrane does not show the peeling off phenomenon and can withstand the high temperature up to 800℃ which is the upper limit of our apparatus.The separation factor for hydrogen gas over carbon dioxide gas was improved with the increase of number of times of silica coating by sacrificing the H2 permeation and finally increased to four times. The improvement on the separation of hydrogen gas over carbon dioxide for pulladium-silica conjugated membrane was evaluated and a model of permeation pattern (palladium and silica) was proposed. This model suggests that the separation factor for hydrogen over carbon dioxide could be improved by introducing silica layer because the silica layer fills the pores and reduces the gas permeation without sacrificing the hydrogen permeation through the palladium region. These results indicate that the introduction of silica into the palladium grain is a promising means to improve the hydrogen separation performance of palladium based composite membranes.     

溶胶修饰陶瓷膜的气体渗透

本文用纯氮气、氢气及氮氢混合气以静态法和流动法分别研究了自研制的复合不对称陶瓷膜的气体渗透性能，并获得了较适宜的涂膜次数及尖透工条件（温度、压差）对膜渗透性能的变化规律。作者对氮氢混俣气流动体系中混合气流速、组成及吹扫气量对渗透性能的影响也进行了详细研究。     

高聚物/陶瓷复合膜的气体渗透及分离行为

以实验室制备成功的SR／Ceramic和PPESK／Ceramic复合膜为基础,对O2、N2、H2、CO、CO2、CH4等气体在高聚物／陶瓷复合膜上的渗透性能进行研究;在较宽的温度范围内考察了复合膜的使用效果,并获得各种气体的渗透活化能及其与气体临界温度的关系;渗透活化能随临界温度的增大而增低。同时,以空气分离体系为对象,考察了膜分离器的操作参数q和pr对膜分离系统过程行为的影响;实验结果和理论分析一致。     

膜分离技术在回收炼厂气中氢气的应用

介绍了膜分离技术在中石化上海高桥分公司回收炼厂气中氢气的应用。重点介绍了气体膜分离的原理,工艺流程以及标定情况。针对生产运行中出现的问题做了分析,并提出处理措施。通过对生产过程的优化调整,提高了炼厂氢气资源的利用效率和经济效益。     

膜技术在氢气分离中的应用

与传统分离方法相比,膜分离技术在气体分离中的应用具有许多优势。氢气既是重要的工业原料又是清洁的燃料,近年来需求量剧增。简述了膜分离净化氢气的机理、使用的膜材料,并对其应用前景进行展望。     

Pd/TiAl膜的制备研究

采用无电镀技术在多孔TiAl金属问化合物支撑体上制备了Pd膜.用SEM测定Pd膜的表面和断面的形貌,EDS测定从膜层到支撑层元素的组成,结果表明,支撑体表面形成了均匀致密的Pd膜,膜层的主要成分是单质Pd,所制钯膜的厚度为2～3μm.在350℃～500℃的温度范围内考察Pd膜透氢性能,当500℃,0.1 MPa时,H2的渗透系数为4.0×10-6mol·m-2·s-1·Pa-1,H2/N2的分离系数为30.测得本文所制备Pd膜的活化能为10.8 kJ/mol.     

合成氨弛放气膜分离氢回收与氨蒸馏的集成应用

合成氨弛放气中含有价值较高的氢气与氨气,传统的处理方法是将弛放气回收氨气后送燃烧系统,造成了氢气的极大浪费.将膜分离氢回收与氨蒸馏集成一个系统,在回收氢气的同时回收氨,使膜分离技术具有更强的兼容性和灵活性,从投资与回报方面分析也能体现出此集成方法的经济性与合理性.     

合成氨贮罐气膜法氢回收的设计和操作

采用膜分离技术回收合成氨贮罐气中的氢组分,返回合成氨系统作为加氢脱硫单元的氢源。设计膜分离器时,膜面积增加使渗透气氢浓度降低而经济效益上升。当贮罐气流量1300Nm3/h、渗透气绝压为0.8MPa,氢产品浓度为85%-90%时,可以获得约287.7×104Yuan/a以上的经济效益,投资回收期在17个月内。在膜分离器操作时,氢氮选择性系数降低以及贮罐气压力降低都会引起氢回收率降低,导致经济效益下降,二者对氢浓度的影响不明显。     

分子筛膜制备技术

综述了近十余年来分子筛膜制备技术的进展，详细介绍了评述了分子筛膜的制备方法如原位水热合成法，二次生长法，汽相法等合成方法及其优缺点，此外还介绍了膜上缺陷的形成及其去除方法。     

高选择性聚吡咙气体分离膜的合成及气体分离

基于国内外最新研究文献，系统论述了一类新型含氮芳杂环聚合物膜材料——聚吡咙的合成、制膜及气体分离性能，讨论了单体结构与聚吡咙膜的气体透过行为的关系。指出链刚性是影响聚吡咙膜气体分离性能的重要因素之一，它决定了聚吡咙大分子链的链间距和自由体积分数。室温下聚吡咙膜对氦气、氢气、二氧化碳和氧气的渗透系数最高分别可达166、74．4、63．6和16．4Barrer，对He／CH4，H2／N2，CO2／CH4和O2/N2的分离系数最高分别可达3214，389，150和12．5。由4，4’—(六氟异丙基)—苯二甲酸酐合成的半阶梯聚吡咙膜显示了极好的气体透过性。有些聚吡咙膜的气体选择透过性甚至超越了常规聚合物膜的上限。符合具有商业吸引力的气体分离膜的指标要求，尤其在氧氮分离、二氧化碳和甲烷的分离领域具有很大的应用潜力。     

钯膜制备新技术

介绍了钯膜的制备方法及在载体上制备越薄钯膜的改进技术，由无电子电镀过程制备的钯膜对氢渗透速率高，对氢有良好的选择性，由金属有机气相沉积法（MOCVD）在载体孔内沉积钯膜有助于防止氢的脆化作用，利用渗透压的新技术可控制膜的微观结构和孔隙率。将多孔不锈钢作为载体时，利用不同的技术能克服氢的脆化作用，减少钯膜厚度以及防止钯－银层与不锈钢间金属原子的相互扩散，由光催化沉积可在半导体载体上制备越薄钯膜。     

无机分离膜

本文综述了无机膜的结构及特性,无机膜的分离机理、无机膜的制备方法。介绍了常见的几种无机膜及其在气体、液体以及生化产品的分离、废水处理、啤酒、饮料的滤菌、海水淡化等领域中的应用。展望了无机膜在硫化氢分解制氢、丙烷、环己烷和乙苯脱氢等反应中实现反应分离一体化的前景。     

气体分离膜材料研究进展

介绍了高分子材料、无机材料、有机－无机杂化材料三类气体分离膜材料，主要包括聚酰亚胺、聚砜、聚二甲基硅氧烷、聚[1-(三甲基硅氧烷）－1－丙炔]等高分子材料，以及致密无机膜和多孔无机膜材料，并且对有机－无机杂化材料作了简要概述。在评价了各种膜材料性能的基础上，展望了气体分离膜材料的发展前景。     

Pervaporation and Vapor Permeation Tutorial: Membrane Processes for the Selective Separation of Liquid and Vapor Mixtures

Pervaporation and vapor permeation are membrane-based processes proposed as alternatives to conventional separation technologies. Applications range from organic solvent removal from water, ethanol, or butanol recovery from fermentation broths, solvent/biofuel dehydration to meet dryness specifications, and organic-organic separations such as the removal of sulfur compounds from gasoline. Unlike membrane filtration processes, which rely on an applied liquid pressure gradient and size sieving to accomplish a separation, pervaporation and vapor permeation separate compounds based on a chemical activity driving force and the sorption and diffusion of the compounds through the membrane. These properties enable the separation of even miscible liquid mixtures.     

超薄Pd～Cu／Al2O3合金膜的透氢性能

以多孔Al2O3陶瓷管为基体,采用化学镀法分步沉积Pd和Cu金属层,再经高温合金化处理,制备组分不同的Pd-Cu合金膜,膜厚均约为4μm.研究合金膜在100~650℃范围内的透氢性能,考察温度和膜组成对透氢性能的影响.结果表明:H2在膜表面的扩散过程是H2渗透速率的主要控制步骤;温度对膜透氢性能的影响规律因膜组成而异,这可能与合金膜在不同组成、不同温度条件下所呈现的晶相结构有关.     

Pore Network Modeling of Nanoporous Ceramic Membrane for Hydrogen Separation

Pore network modeling of porous media has this advantage that can consider the pore structure incorporating any desired details, but it has not been studied sufficiently. In addition, most studies are limited to mathematical modeling only which need validation. In the present study, this approach was applied to hydrogen separation from syngas by nanoporous ceramic membrane to predict the membrane permeance theoretically based on its pore structure. Gas transport through nanoporous membrane was modeled with the aim of a 2D network model. A dusty gas model was used for gas transport in the individual pores. Model validation showed that the model predictions are in good agreement with the experimental data with the coordination number of 2.5 and the pore length of about 20 nm. A parametric study indicated that hydrogen permeance through the membrane increases with the average and minimum pore size and decreases with temperature and pressure. Also, hydrogen selectivity increases slightly with temperature and decreases with pressure and average pore size.     

Water Gas Shift Reaction in a Membrane Reactor Using a High Hydrogen Permselective Silica Membrane

A membrane reactor (MR) for the water gas shift (WGS) reaction was developed by integrating a highly hydrogen permselective silica membrane. The membrane was prepared using an extended counter-diffusion chemical vapor deposition (CVD) method. A tetramethylorthosilicate (TMOS) silica source was fed from one side of the membrane support and oxygen gas fed from the other. The dense silica film was deposited on a porous support by pressurizing the side that TMOS is supplied. A high hydrogen permselective silica membrane was obtained by this method. A commercial Pt catalyst was used in the WGS reaction. Efficacy of the silica membrane toward the WGS reaction was investigated as a function of temperature (523-623 K), steam/carbon monoxide (S/C) ratio (1-3), differential pressure (0-100 kPa), and gas hourly space velocity (GHSV; 1800-5400 h^?1). The CO conversion in the MR was higher than that for a fixed bed reactor (FBR) under all experimental conditions, and was also higher than the thermodynamic equilibrium conversion under almost all experimental conditions. This was due to the selective abstraction of hydrogen from the product stream by the silica membrane. At an S/C of 1.0, the CO conversion in the MR was superior to that in a FBR by 16.8%.     

钯银合金膜反应器中二甲醚水蒸汽重整体系的透氢性能研究

二甲醚(DME)由于其清洁环保特性成为燃料电池电动汽车的理想氢源之一。在200~300℃温度范围,1.0×105~4.0×105Pa的压力范围内,Pd-Ag-Au-Ni合金膜对H2与Ar和N2的分离系数接近无穷大,同时,膜具有较好的透氢稳定性。通过实验研究了膜反应器中Ar、N2、CO、CO2、H2O和DME等气体存在时对钯银合金膜透氢性能的影响。实验结果表明,Ar、N2、DME基本对透氢性能无影响,CO2、CO、H2O存在时,会影响氢气的渗透性。三者当中,CO2的影响最小,混合气中H2O比CO对透氢性能的影响大,这是由于H2O在钯膜表面有更大的竞争吸附作用。本研究结果为更详细地研究二甲醚水蒸气重整制氢过程提供了重要参考依据。     

膜分技术在甲醇弛放气中的应用

介绍了用膜分离方法从合成甲醇弛放气中回收氢气的情况.     

无机透氧膜的发展与应用

阐述了无机膜的优缺点及其透氧技术的研究与应用进展,并对无机膜透氧技术发展中存在和尚待解决的问题作了简要评述.