色谱法测沸石分子筛上的吸附和传递系数

本文用脉冲色谱法研究了氧和氮在沸石分子筛上的吸附和扩散性能,用矩量分析法计算了氧和氮的吸附平衡常数和扩散系数。实验结果表明,沸石分子筛吸附剂优先吸附氮。     

炭分子筛

分子筛有沸石分子筛和高岭土分子筛,它们都具有硅酸铝的晶型结构。以煤为原料,经过特殊处理制得用以分离空气中的氧和氮的炭分子筛,是近年才研制成功的,它是无定型结构。炭分子筛不仅有象活性炭一样的疏水性,而且具有10(?)以下发达的微孔,孔径均     

炭分子筛改性及其对乙烯和氧气的吸附分离性能

用气相碳沉积法对炭分子筛进行了改性,并对吸附阶段温度、裂解温度、堵孔剂分压等改性条件予以详细考察;采用称量法在真空电子天平上评价了改性炭分子筛上乙烯和氧气的吸附扩散性能。结果表明,改性后炭分子筛选择吸附氧气的能力大大提高,可作为直接脱除乙烯中少量氧气的吸附剂。对扩散曲线模拟计算,拟合良好。     

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。     

固相离子交换法制备Li-Ca-LSX分子筛及其氮氧分离性能的研究

以液相离子交换制得Ca-Na-LSX型分子筛,再采用固相离子交换制备不同交换度的Li-Ca-LSX分子筛。在室温(25℃)下测定了样品对氮气、氧气的静态吸附,得到分子筛氮氧分离系数。结果表明:随着Ca2+交换度从12%增加到92%,Ca-Na-LSX分子筛氮、氧吸附量均增加,氮氧分离系数提高;固相锂离子交换后,Li-Ca-LSX分子筛的Li+交换度从43.3%下降到34.2%,氮吸附量的增幅较大,氮氧分离系数显著提高,当Li+、Ca2+交换度分别为34.2%、60.2%时,分子筛样品的氮氧分离系数达到6.1。     

变压吸附空分制氮用炭分子筛制备技术

正产品和技术简介:由煤、坚果壳(核)、酚醛树脂等原料制备变压吸附空分制氮用炭分子筛(CMS)系列成套技术,包括独有的粘结剂配方、高效CMS调孔过程实时控制技术和CMS整粒技术。所制备的变压吸附空分富氮用炭分子筛的性能达到国际先进水平,具有较强的市场竞争力。应用范围:产品炭分子筛(CMS)用作变压吸附空分制氮     

分子筛氮氧分离性能的测定方法

分子筛以其对氮氧具有选择性吸附的特性而成为变压吸附空分制氧领域应用的主体吸附剂。分子筛氮氧分离性能的测定方法对变压吸附用分子筛产品的质量控制具有重要的理论和现实意义。简述了目前常规的分子筛氮氧分离性能测定方法,并介绍了相关测定原理、测定过程,分析了测定过程的优缺点。经比较,容量法更适合作为氮氧分离性能评价的标准方法来进行推广。     

焦粉制备炭分子筛的研究

以鞍钢化工总厂焦粉为原料制备空分制氮用炭分子筛,并对其进行了探讨性研究.实验考察了焦粉与粘结剂的配比(10%～25%)、粘结剂的种类(煤焦油和树脂)、炭化时间(600～800℃)、浸渍时间(0.25～1.5h)等条件对炭分子筛空分性能的影响.实验使用单因素实验法和正交实验法相结合的方法得出制备炭分子筛的最佳条件.实验结果表明:在焦粉与复合粘结剂(煤焦油和环氧树脂)的配比为25%,浸渍时间为1h,炭沉积终温为700cC的最佳条件下制备的炭分子筛具有最佳空分制氮效果.     

改质分子筛的成型体

一、改质目的分子筛的工业应用较为广泛,它可用于净化气体、制取富氧、富氮空气、石油精制、乙烯裂解等等。例如,乙烯干燥工艺使用宜于对含有微量水份效果好的3A型分子筛。本文所述改质分子筛成型体是对A型分子筛而言,工业使用的分子筛一般用粘土为粘合剂成型,这种成球的分子筛在工业装置上使用,特别采用过热水蒸汽再生时、往往因球本身机械强度不够,表面易破碎掉粉,同时吸附质带有不纯杂质在孔经内产生结炭,这种现     

由灵武煤新法干馏半焦制备炭分子筛的研究

以灵武不粘煤的固体热载体新法干馏半焦为原料，综合使用碳化法和碳沉积法进行了空分富氮用炭分子筛的制备研究，考察了碳化和碳沉积工艺条件对产品空分性能的影响，并用ＦＴＩＲ和ＸＲＤ技术对产品炭分子筛进行了表片。结果表明，灵武煤的新法干馏半焦是制备炭分子筛的优良产；在最佳工艺条件下制得的炭分子筛的空分性能可与进口的同类产品相媲美；炭分子筛是典型的无定形炭，其表面含氧官能团主要是Ｃ－Ｏ键和Ｃ＝Ｏ键。     

Modification of pore size in activated carbon by polymer deposition and its effects on molecular sieve selectivity

The separation of air for nitrogen production can be carried out by pressure-swing-adsorption over a carbon molecular sieve. The separation is kinetically controlled, since the equilibrium adsorption of both oxygen and nitrogen is very similar, but the adsorption kinetics for oxygen is faster than for nitrogen. Several methods to prepare carbon molecular sieves are reported. In this work, we synthesized a carbon molecular sieve from a commercial activated carbon. After deposition of polyfurfuryl alcohol, these materials were subjected to carbonization at 800°C under an inert atmosphere. All the microporous materials were characterized by analysis of kinetics and equilibrium adsorption data. The molecular sieve performance was assessed by the O₂/N₂ uptake ratio. The material prepared by two depositions has characteristics similar to those of commercial CMS.     

Air separation by pressure swing adsorption

The original pressure swing air separation process, developed almost simultaneously by Exxon and Air Liquide, uses a nitrogen selective zeolite adsorbent to produce a high purity oxygen product. The same basic process is still widely used in small scale units although, for larger scale units, many modifications to the cycle have been introduced in order to reduce power consumption. Although nitrogen can in principle be recovered from the blowdown stream of such systems, if high purity nitrogen is the required product, it is more economic to use an oxygen selective adsorbent. Most adsorbents show either no selectivity or preferential adsorption of nitrogen. However, in small pore carbon molecular sieves or 4A zeolite there is a substantial difference in diffusion rates so that an efficient kinetic separation is possible. Somewhat different cycles are generally used in such processes. Progress in modelling the dynamic behaviour of both types of PSA system is reviewed and comparisons between experimental performance and the model predictions are shown. A simple linear driving force model provides a good overall prediction of the effects of process variables but the computationally more cumbersome diffusion model gives better quantitative agreement with experiment. Comparisons are drawn between the performance achieved (in nitrogen production) with two different kinetically selective adsorbents; RS-10 (a modified 4A zeolite) and Bergbau Forschung carbon molecular sieve.     

氧气和氮气的吸附动力学行为测定

利用双柱定容容量法实时记录的数据研究了氮气和氧气在碳分子筛及13X分子筛上的吸附动力学行为,重点讨论了吸附时体系内的温度变化情况以及温度变化对于吸附和扩散行为的影响,指出建立数学模型时,温度变化的不可忽略性,同时获得了可用于非等温动力学模型计算的数据.     

Investigation of the mechanism for the separation of nitrogen—oxygen mixtures on carbon molecular sieves

Sorption separation of nitrogen-oxygen mixtures by carbon molecular sieves, e.g. to produce nitrogen using the pressure swing adsorption principle, proceeds under the condition of non-equilibrium. Experimental data based upon measurements of sorption equilibria and kinetics for nitrogen and oxygen on several samples of carbon molecular sieve particles in the temperature range 0–50°C suggest the existence of a surface barrier in the pore mouths of slit-like micropores for these particular samples. The conclusion on this phenomenon is supported by the results of canonical and grand canonical Monte Carlo simulations. Both types of analysis give a deeper insight into the complex non-equilibrium separation process.     

Prediction of breakthrough curves of oxygen—nitrogen coadsorption system on molecular sieves

The coadsorption breakthrough curves of oxygen—nitrogen on 5A zeolite molecular sieve (MSZ-5A) and carbon molecular sieve (MSC) are predicted theoretically and compared with experimental data. According to the binary equilibrium isotherms, the theoretical isothermal model for coadsorption fixed bed has been established under consideration of the effect of the solid phase mass transfer resistance. The breakthrough curves are obtained by solving the above model numerically for oxygen—nitrogen system in fixed beds of MSZ-5A and MSC at 293.15 K and 392 kPa. The data of pure component isotherms are used to obtain the numerical solution. The predicted curves are in good agreement with the experimental data.     

Carbon-based oxygen selective desiccants for use in nitrogen PSA

Techniques for the production of composite oxygen selective adsorbents are disclosed. These adsorbents are comprised of a carbon molecular sieve (CMS) which is kinetically selective for the adsorption of oxygen over nitrogen and an agent for the sorption of water such as LiCl or SiO₂. The adsorption properties of the composite adsorbents and results obtained from pressure swing adsorption (PSA) process testing are presented. The composite adsorbents improve the nitrogen PSA process performance (recovery and productivity) over the use of conventional desiccants which do not exhibit oxygen selectivity. Using a standard nitrogen PSA process cycle, replacement of conventional inorganic desiccants like alumina with the current CMS-based desiccants improved air recovery 2 to 4 percentage points and increased nitrogen productivity 15 to 20% at 70°F and a nitrogen purity of 99.5%.     

变压吸附制纯氧过程阀系数的优化控制

利用电路网络模型,对变压吸附制纯氧阀系数进行优化控制,在碳分子筛为第一级吸附,5A分子筛作为二级吸附工艺中,可得到浓度为99.06%,回收率为28.4%的氧气产品,从而提高了氧气的回收率,增加了单位吸附剂的生产能力,节省了动力消耗.     

Adsorption of very low level carbon dioxide impurities in oxygen on a 13X molecular sieve

An experimental study, of selective adsorption of very low level carbon dioxide impurities (in oxygen) on a Linde type 13X molecular sieve, has been described. The adsorption process was studied dynamically using laboratory scale apparatus. Operating parameters were selected to simulate conditions normally employed during the operation of large scale oxygen purifiers. Carbon dioxide impurity levels were nearly constant throughout each adsorption run, but ranged between 10 and 50 ppm from trial to trial. Therefore, the carbon dioxide adsorption capacity of the 13X molecular sieve could be determined as a function of varying, but very low, carbon dioxide impurity concentrations in oxygen.     

变压吸附制氮机组运行总结

变压吸附空分制氮技术以洁净的压缩空气为原料,利用焦炭分子筛吸附其中的氧气成分,从而制得高纯度的氮气。介绍了变压吸附制氮机组的工作原理、影响氮气纯度的因素以及运行状况。