炭分子筛上氧、氮吸附特性的实验测定

针对BF型炭分子筛孔结构的特点,利用双分散孔结构吸附模型,采用色谱扰动-应答方法,对微孔扩散控制传质机理进行了实验认定,测定了O2的吸附平衡常数K、扩散时间常数Dc/rc2以及O2、N2两组分常温下的吸附等温线.     

高比表面积炭分子筛的制备及其吸附特性

本文以沥青中间相为原料,采用KOH化学活化法,获得了比表面高达2363m~2/g的炭分子筛(CMS);用2400吸附仪N_2吸附测定了其孔结构,并研究了其对六价铬(Cr_(VI))及Au(CN)~-_2离于的吸附性能。结果表明。其平均孔径为24.7(?),微孔及总孔容积大大高于活性炭,其吸附容量和吸附速度也大大优于活性炭。     

炭分子筛的变压吸附制氮

PVC生产装置属甲级爆单位，其安全保护气体——氮气的生产方法和成本对PVC的生产和成本影响很大。采用炭分子筛的变压吸附制氮，其效率高、低成本、低危险性、工艺简单、寿命长，无论现在还是将来都将是PVC行业生产的第一选择。     

CH_4/N_2在炭分子筛上的吸附平衡与扩散模型

使用高精密质量吸附仪(IGA-100,HIDEN)测定了CH4和N2纯组分在炭分子筛上于298、313和328 K温度下的吸附等温线及吸附动力学曲线,研究了CH4和N2在炭分子上的吸附热力学及动力学性质。选择Double Langmuir模型(DL)对吸附等温线数据进行了模拟;选择Fick扩散模型进行了吸附动力学的模拟。结果表明,DL模型可以准确地描述CH4和N2在炭分子筛上的吸附,拟合相关系数都非常接近1,N2在该炭分子筛上的吸附量大于CH4的吸附量;通过Fick扩算模型计算得:2 4N CHD/D=7.26,N2在该炭分子筛上的扩散速率大于CH4,所以该炭分子筛可以实现固定床出口直接富集CH4的目的。     

变压吸附制氮技术

介绍了变压吸附制氮原理及其工业生产过程，推荐使用炭分子筛吸附工艺。     

炭分子筛的表征

炭分子筛是浓缩煤层气变压吸附机组的关键材料,性能的好坏直接影响变压吸附机组的性能。通过在77 K下N2的吸脱附等温线对炭分子筛的比表面积、孔径分布进行测定,通过吸附试验对炭分子筛吸附N2,O2,CO2,CH4,H2的能力及N2和CH4在炭分子筛上的吸附速度进行比较,以确定不同炭分子筛分离气体的能力。     

均三甲苯在MCM-22和MCM-56分子筛上的吸附和扩散

以MCM-22和MCM-56分子筛为研究对象,考察烃类均三甲苯在MWW型分子筛上的吸附和扩散,同时对分子筛进行XRD、N2吸附和TEM等表征,探究分子筛的结构特性与吸附和扩散之间的关系。研究表明,均三甲苯在MWW型分子筛中的吸附和扩散位置为外表面半超笼。单层和错层结构使MCM-56较MCM-22分子筛拥有更多的外表面酸性位,有利于均三甲苯的吸附。与MCM-22相比,MCM-56分子筛片层结构较薄,焙烧导致晶体外部结构的卷曲使烃类大分子均三甲苯在MCM-56分子筛中的扩散受阻。     

碳沉积法制富氮用炭分子筛的研究

本文提出的碳沉积法是用煤焦油馏分油的有机溶液浸渍煤炭化物,然后热解以进行“孔调变”。确定了最佳工艺条件,制得富氮性能良好的炭分子筛。并用D-A方程求取了各种样品的微孔结构参数。     

由活性炭制备富氧用炭分子筛的初步研究

本文初步研究了由商品活性炭直接制备富Ｏ２用炭分子筛的可能性，考察了工艺条件对炭分子筛空分性能的影响。批出可以通过调变商品活性炭的孔隙分布直接获得有一定空分能力的炭分子筛。     

CH4／O2在炭分子筛上的吸附动力学

为消除低浓度煤层气对煤层开采存在的安全隐患,提出了利用甲烷和氧气在炭分子筛上的动力学差异进行脱氧的工艺。采用容积法测定了纯CH4和O2在炭分子筛颗粒上的吸附动力学数据,并利用单床变压吸附装置测定了混合气体在298．15K,各压力下的穿透曲线。研究结果显示：吸附初期,O2在CMS上的扩散速率明显大于CH4;在混合体系穿透曲线上,O2的穿透时间远大于CH4,炭分子筛固定床表现出对O。的优先吸附选择性,可以实现出口直接富集甲烷的目的。0．4MPa时,当产品气中CH4含量为92．44％时,CH4回收率为73．27％。     

Separation of Methane and Nitrogen by Adsorption on Carbon Molecular Sieve

Abstract

Adsorption equilibrium of methane and nitrogen on CMS 3K from Takeda Corp. were gravimetrically measured at 298, 308, and 323 K and at pressures up to 2000 kPa. The most adsorbed gas is methane followed by nitrogen. The adsorption loading at 550 kPa and 308 K is 1.73 mol/kg for methane and 0.91 mol/kg for nitrogen. Experimental data were fitted with the multisite Langmuir model. Single component uptake of these gases at low pressures was used to determine the adsorption kinetics. Adsorption of nitrogen is much faster than methane, although this gas is preferentially adsorbed. The adsorption rate of both gases was controlled by a surface barrier resistance at the mouth of the micropore combined with micropore diffusion. Breakthrough curves of pure gases and their binary mixtures were measured at ambient temperature. A bi‐LDF (Linear Driving Force) model was used to predict the fixed‐bed behavior. Large differences in the adsorption kinetics were observed: at 308 K the LDF constant ratio was K_μ,N2 /K_μ,CH4 =133, although because of much higher adsorption of methane, the overall kinetic selectivity was 1.9 at 308 K. The data obtained in this work can be used for adsorption separation processes modeling for methane purification from nitrogen‐contaminated streams.     

Kinetics of Isothermal Ethanol Adsorption onto a Carbon Molecular Sieve under Conventional and Microwave Heating

The isothermal kinetics of ethanol adsorption from aqueous solution onto a zeolite type carbon molecular sieve (CMS‐3A) under conventional heating (CH) and microwave heating (MWH) was investigated. The adsorption kinetics is described by the model of a phase‐boundary controlled reaction for both heating modes. The activation energy (E_a) for the adsorption process under MWH is lower than under CH while the preexponential factor (lnA) is higher. Ethanol adsorption is a kinetically complex process whose complexity changes with the mode of heating. The established decrease in E_a and increase in lnA under MWH compared to CH is explained with the increase in the ground vibrational level of the – OH twisting vibrations in the ethanol molecule and with the decrease in its anharmonicity factor which is caused by the selective resonant transfer of energy from CMS‐3A to the OH oscillators.     

Separation of Argon and Oxygen by Adsorption on a Titanosilicate Molecular Sieve

Abstract

A titanosilicate molecular sieve adsorbent, Ba-RPZ-3, was synthesized and tested for its use in the separation of O₂+Ar mixtures at room temperature. A clean resolution of both gases was achieved in pulse chromatographic experiments using a standard column (0.25″ OD, 3.5 grams of adsorbent). In another experiment, using a column containing 30 grams of adsorbent and a continuous O₂+Ar feed at 10 cm³/min, argon breakthrough was detected more than 5 minutes before the oxygen breakthrough, and the separation was sufficiently sensitive to achieve quantitative separation of mixtures with low argon content (5% Ar). Equilibrium adsorption isotherms and isosteric heats of adsorption for oxygen and argon were found to be almost identical at room temperature. The thermodynamic selectivity was found to be mildly in favor of oxygen (～1.1–1.2). However, the adsorption of oxygen was observed to be much faster than argon, indicating that the separation of the O₂+Ar mixtures was based on the sieving properties of the adsorbent and the difference in sizes of O₂ molecules and Ar atoms. This indicates that a suitably-oriented oxygen is physically smaller than argon, despite the fact that many references assume that oxygen is larger than argon.     

Breakthrough Analysis for Adsorption of Phosphine on 5A Molecular Sieve

Adsorption experiments were carried out under dynamic conditions for the removal of phosphine (PH₃) in nitrogen on a fixed bed of 5A molecular sieve. The experiments were conducted to characterize the breakthrough characteristics of PH₃ in the fixed bed under different operating conditions, including bed temperature, bed mass, and initial PH₃ concentration. A mathematical model was developed to predict the breakthrough profiles of PH₃ during adsorption on the 5A molecular sieve. The model was successfully validated with the observed experimental breakthrough data, showing that the adsorption capacity increases with decreasing temperature and with rising phosphine concentration in the gas mixture. The study showed the potential application of 5A molecular sieve in controlling PH₃ emission.     

炭分子筛膜的发展现状及应用

结合炭分子筛膜的发展状况,叙述了炭分子筛膜的制备方法。概括了炭分子筛膜在气体分离领域中的应用,展望了炭分子筛膜未来的发展方向。认为今后研究的重点应是如何得到气体分离选择性好且分离产率高的炭分子筛膜。     

甲烷沉积法对甲烷/氮气分离炭分子筛性能的研究

高性能甲烷/氮气分离用炭分子筛是保证低浓度煤层气变压吸附分离的前提.以椰壳炭化料为原料在一定条件下活化制备了炭前驱体,以甲烷为沉积剂通过气相炭沉积调孔制备炭分子筛,考察沉积时间、沉积温度、沉积剂浓度和沉积剂量对变压吸附分离甲烷/氮气效果的影响,采用N2吸附法分析了炭前驱体的比表面积和孔径分布.结果表明:炭化时间40 m...     

中空玻璃用分子筛氮气吸附测定

针对现行的国家标准CB／T10504—2008《3A分子筛》的使用,着重讨论了中空玻璃用干燥剂的氮气吸附对中空玻璃的质量的影响及其测试方法,以及在测试中需要注意的浮力校正问题。     

几种分子筛对甲醛气体吸附性能的研究

对3A,5A,13X,MCM-41型4种分子筛进行了甲醛分子静态吸附实验,发现5A和13X分子筛静态吸附平衡时吸附量接近.用低温氮气吸附法测定了各样品的BET-比表面积和吸附脱附等温曲线,用密度函数理论法计算各样品的孔容孔径分布.重点探究比表面积,孔径,阳离子,骨架结构对5A和13X分子筛甲醛吸附性能的影响,结果证明阳离子和骨架结构对5A和13X分子筛吸附甲醛的性能有重大影响.活化再生后,两种分子筛的吸附性能具有良好的重现性.     

氮气和氧气在碳分子筛上的吸附相平衡研究

用双柱定容容量法测定了氮气和氧气在碳分子筛上温度分别为25、30、35、40及45℃时的吸附等温线,平衡压力最高达到1 Mp,等温线用Langmuir方程拟合能得到良好的实验结果,并求出了氮气和氧气在这两种吸附剂上的吸附热。     

炭分子筛的孔径分布研究

采用容积法测定了CO2在两种炭分子筛（CMS-200A、CMS-200B）上的吸附等温线,温度为273K、相对压力为0.000001～0.9。通过HK模型和D-R方程对吸附平衡数据进行分析,计算得到了两种炭分子筛的孔径分布。结果表明：两者的孔径分布主要在0.35～0.8nm之间,CMS-200B的平均孔径略大于CMS-200A。HK模型和D-R方程两种方法均可以反映出两种炭分子筛孔径分布的差异,且计算得到的结论是一致的。