4A沸石从水溶液中吸附氯化十四烷基吡啶

4A沸石可部分或全部代替三聚磷酸钠,以减少合成洗涤剂对水质富营养化的影响,在硬水中使用也不致降低洗涤效力.本文研究了4A沸石在不同pH水溶液中和无机盐存在下对氯化十四烷基吡啶(TPC)的吸附作用,初步探讨了吸附机制.     

氢在A、X及ZSM-5型沸石上的高压物理吸附

The hydrogen adsorption properties and uptake capacities of the A, X and ZSM-5 types of zeolites were investigated at temperatures of 77, 195 and 293 K and pressures up to 7MPa, using a conventional volumetric adsorption apparatus. All hydrogen adsorption isotherms were basically type I, but the maximum in isotherm,a unique feature of supercritical adsorption, was observed at high pressures of 2-5 MPa at 77 K. The isosteric heats of adsorption were determined from the isotherms and the factors that influence their variations were discussed. Different types of zeolites exhibited remarkably different hydrogen uptake, based on both the framework structure and the nature of the cations present. The highest gravimetric storage capacity of 2.55wt% was obtained for NaX-type zeolite at 4 MPa and 77 K. In CaA, NaX and ZSM-5 types of zeolites,hydrogen uptakes were proportional to the specific surface areas, which were associated with the available void volumes of the zeolites. A threshold in hydrogen adsorption observed in NaA and KA was attributed to a pore blocking effect by large cations in KA. A ratio of the kinetic diameter of adsorbate to the effective opening diameter of zeolite was used to judge the blocking effect for physisorption.     

ZSM-5沸石膜的吸附表征

The framework and thickness of synthesized ZSM-5 membranes were characterized using static and dynamic adsorption methods. It is shown that the adsorptive properties of the membranes are the same as ZSM-5 zeolite, the average thickness of the membranes was 13 μm calculated from the adsorptive ability, which matched very well with the result measured by scanning electron micrograph. The results also shown that zeolite membranes have greated adsorptive ability than zeolite powders. The high Si/Al rate zeolite membranes have selective ability on ethanol/water, and this interpreted the separation of ethanol-water mixtures with the membranes.     

沸石吸附储氢研究进展

沸石类微孔材料作为储氢介质的研究已成为近年来储氢领域中备受关注的热点问题,但对于其储氢机理、储氢容量及其影响因素的文献报道不尽一致。本文从吸附实验测定和理论计算模拟方面综述了各种结构类型沸石的吸附储氢的研究结果。重点分析了沸石的结构类型、硅铝比、阳离子类型及吸附实验条件差异对储氢量的影响,并讨论了超临界吸附理论模型的发展状况,最后探讨了沸石作为储氢材料的可行性和发展方向。     

壳聚糖-沸石复合膜对茶汤中茶多酚的选择性吸附

将壳聚糖和沸石物理共混制成膜,以壳聚糖-沸石复合膜作为吸附剂,对茶汤中茶多酚进行吸附研究,考察了吸附剂用量、时间、温度、浓度、pH值等因素对吸附效果的影响,就壳聚糖-沸石复合膜对荼多酚的吸附动力学进行初步探讨,并用HPLC分析其对荼多酚和咖啡因的选择性吸附.结果 表明,将4.0mL 4％壳聚糖和0.2％沸石的混合液制成...     

氢在沸石上的吸附行为

应用基于Ono-Kondo格子理论得到的通用吸附等温方程, 通过分析氢在不同温度下, 在沸石NaX、CaA、NaA和ZSM-5上的吸附数据, 确定了氢的最大单层吸附容量. 并引入维里吸附方程, 由第二维里吸附系数和圆柱孔的Lennard-Jones(12-6)势模型计算了氢与沸石微孔壁面的作用势. 结果表明, 通用吸附等温方程可较好地描述氢在沸石上的超临界吸附行为, 拟合所得的氢在沸石上的最大单层吸附容量与吸附剂相关, 而与吸附温度无关. 圆柱孔作用势模型计算所得的氢分子在沸石上的吸附作用势与吸附热相近. 氢分子间的作用力表现为吸引力.     

吡啶在H-MOR分子筛孔道中吸附的量子化学研究

 用24T模型和两种ONIOM2方法(QM/QM和QM/MM)研究了杂原子H-AlMOR和H-BMOR分子筛的结构、酸性及其对吡啶的吸附性能. 吸附热以及分子筛的几何结构和电子结构数据表明, H-BMOR的B酸性远远弱于H-AlMOR, 因此二者可分别应用于对酸性要求不同的催化反应. 采用QM/QM计算得到的吡啶在H-AlMOR上的吸附热(219.3 kJ/mol)与实验结果(200 kJ/mol)比较接近. QM/QM方法尽管耗时较多,但能得到更精确的结果,而QM/MM方法可用于定性研究及对模型结构的初步预测. 吸附复合物的结构参数及红外振动频率等数据表明,吡啶在两种分子筛上吸附时均发生了质子转移,生成PyH+…ZeO-离子对. 此外,吸附复合物中还存在多重氢键作用.     

红外光谱研究CO在NiY沸石上的吸附

1.前言 关于负载过渡金属的沸石体系,其CO吸附态的研究较少。就已报导的几篇论文看,载镍沸石上CO的行为与载镍氧化物上大不相同。如在NiY沸石上,吸附CO时不仅在2170和2120cm~(-1)附近有吸收带,而且在更高的频率约2200cm~(-1)也呈现吸收峰;但在载镍氧化物体系上就观察不到。对上述3个峰的归属目前仍无定论。已经报导的也互相矛盾。为此,本文藉原位红外光谱探讨了CO在NiY沸石上的吸附,并通过与不载镍沸石和非晶形SiO_2 -A1_2O_3体系比较,对上述3个峰的归属提出初步看法。     

An isotherm equation for adsorption from binary liquid mixtures on solids involving surface heterogeneity and differences in molecular sizes of components and its numerical verification

An equation derived previously¹⁴ for adsorption from binary liquid mixtures composed of molecules of different sizes on heterogeneous solids has been reexamined. Verification of this equation by means of numerical simulation showed its applicability for describing the liquid adsorption onto weakly and strongly heterogeneous surfaces.

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Eine Isothermen-Gleichung für die Adsorption aus binären flüssigen Gemischen an heterogenen Oberflächen fester Körper unter Berücksichtigung der Differenzen in den Molekülgröen der Komponenten und ihre numerische Verifikation

Zusammenfassung Es wurde die früher¹⁴ abgeleitete Isothermen-Gleichung der Adsorption aus binären flüssigen Gemischen an heterogenen Oberflächen fester Körper abermals untersucht. Durch Computersimulation wurde gezeigt, daß diese Gleichung den obengenannten Prozeß, der sich sowohl an schwach wie auch an stark heterogenen Oberflächen vollzieht, gut beschreibt.

     

Theoretical studies on the adsorption from non-ideal binary liquid mixtures on heterogeneous surfaces involving difference in molecular sizes of components

An equation for the phenomenon of competetive adsorption from binary liquid mixtures onto solids has been derived using the kinetic approach. In this equation the difference of the molecular sizes, the non-ideality of both bulk surface phases, and the energetic heterogeneity of the solid surface have been taken into account.

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Theoretische Untersuchungen zur Adsorption aus nichtidealen binären Lösungsmittelgemischen an heterogene Oberflächen fester Körper unter Berücksichtigung der Unterschiede in den molekularen Größen der Komponenten

Zusammenfassung Auf Grund kinetischer Erwägungen wurde eine Gleichung, die die Konkurrenzadsorption aus binären Lösungsmittelgemischen an den Oberflächen fester Körper beschreibt, aufgestellt. In der Gleichung wurde der Größenunterschied der Teilchen, die Nichtidealität der Lösung in der Volumen- und Oberflächenphase, sowie die energetische Heterogenität der Oberfläche des festen Körpers berücksichtigt.

     

A model of adsorption at liquid-solid interface involving association in the bulk phase

A model of monolayer adsorption of binary liquid mixtures on homogeneous and heterogeneous solid surfaces involving association of one component in the bulk phase is discussed. Suitable model calculations, illustrating association and heterogeneity effects, have been performed according to an equation derived for adsorption excess. This equation has been examined by using the experimental data of adsorption of alcohols from benzene andn-heptane on silica gel.

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Adsorptionsmodell für die Grenzfläche Feststoff-Flüssigkeit unter Berücksichtigung der Assoziation in der Flüssigkeitsphase

Zusammenfassung Es wird ein Adsorptionsmodell binärer, flüssiger Mischungen an homogenen und heterogenen Oberflächen von Feststoffen unter Beachtung der Assoziation eines der Bestandteile in der Flüssigkeitsphase diskutiert. Mit der aus dem Oberflächenüberschuß abgeleiteten Gleichung wurden entsprechende Modellberechnungen durchgeführt, die die mit Assoziation und Heterogenität verbundenen Effekte illustrieren. Die Gleichung wurde für die experimentellen Daten der Alkoholadsorption aus Benzol undn-Heptan an Kieselgel überprüft.

     

Multilayer effects in adsorption of alcohols from benzene andn-heptane on silica gel

Experimental data for the title systems are compared with calculations based on theoretical adsorption parameters.

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Mehrschichteffekte bei der Adsorption von Alkoholen aus Benzol undn-Heptan auf Silicagel (Kurze Mitteilung)

Zusammenfassung Für die im Titel genannten Systeme werden experimentelle Daten mit Berechnungen verglichen, die auf theoretischen Parametern basieren.

     

Study of adsorption from solutions by frontal chromatography

Summary The automatic frontal chromatography installation was described. By this chromatographic method the adsorption isotherm of benzene from n-heptane solutions on hydroxylated surface of silica with various porosity has been determined. This investigation was performed at different flow rates of eluent and in a wide range of concentrations. The isotherm of adsorption obtained by this chromatographic method has been compared with the results of the static measurements. The coincidence of adsorption isotherms measured at the various flow rates are shown to be a criterion of proximity the chromatographic process to the equilibrium.     

Physico-chemical applications of liquid chromatography I. Investigation of the adsorption of cardiac glycosides from water-ethanol solutions on silanized silica

Summary Using the cardiac glycoside cymarin as the example the application of liquid chromatography for the study of adsorption from solutions and the determination of the corresponding thermodynamic characteristics was investigated. The adsorption isotherm of cymarin at small concentrations from a water-ethanol solvent on silica gel modified by dimethyldichlorosilane was measured under static conditions using analytical LC to determine the concentrations of solutions after adsorption. The values of the Henry constants were obtained by extrapolating the slope of the adsorption isotherm down to zero concentration. The specific retention volumes for different but small sample sizes of cymarin in the chromatographic column were measured, the adsorbent and the water-ethanol eluent being the same as in the static conditions. The specific retention volume for a small (zero) sample size determined by liquid chromatography experiment coincides with the Henry constant of cymarin adsorption determined in static conditions. In favourable cases liquid chromatography can be used to determine the equilibrium constants for adsorption from solution. The dependence of the Henry constants on temperature was investigated for several cardiac glycosides. The influence of the modification of the adsorbent surface on the separation of the cardiac glycosides was also studied.     

Adsorption of polypropylene from dilute solutions on a zeolite column packing

Faujasite type zeolite CBV-780 was tested as adsorbent for isotactic polypropylene by liquid chromatography. When cyclohexane, cyclohexanol, n-decanol, n-dodecanol, diphenylmethane, or methylcyclohexane was used as mobile phase, polypropylene was fully or partially retained within the column packing. This is the first series of sorbent-solvent systems to show a pronounced retention of isotactic polypropylene. According to the hydrodynamic volumes of polypropylene in solution, macromolecules of polypropylene should be fully excluded from the pore volume of the sorbent. Sizes of polypropylene macromolecules in linear conformations, however, correlate with the pore size of the column packing used. It is presumed that the polypropylene chains partially penetrate into the pores and are retained due to the high adsorption potential in the narrow pores.     

分子筛材料在小分子吸附分离中的应用

吸附分离技术与工艺在工业上具有重要意义. 常见的吸附剂包括沸石分子筛、 金属有机框架材料、 活性炭等材料. 分子筛具有比表面积大、 稳定性高、 生产成本低等优势, 可以满足吸附分离技术中高效、 节能和环保的需求, 是一种非常有应用前景的小分子混合物分离吸附剂. 本文综合评述了吸附分离领域中常用的吸附剂材料的特点和吸附分离机理与评价方法, 总结了分子筛在空气分离、 烃类分离、 二氧化碳吸附、 芳香硫化物脱除、 一氧化碳吸附、 氮氧化物吸附、 氢气储存吸附及氢同位素分离等领域的应用, 并对基于分子筛膜的小分子混合物分离现状进行了介绍. 此外, 本文还系统分析了分子筛对不同混合物的吸附分离性能与其拓扑结构、 骨架组成及改性方法之间的关系, 并对未来的研究前景进行了展望.     

A new isotherm equation for single-solute adsorption from dilute solutions on energetically heterogeneous solids

A new isotherm equation is proposed for describing single-solute adsorption from dilute solution on energetically heterogeneous solids. This equation comprises all isotherm equations being an extension of simpleLangmuir isotherm to single-solute adsorption on heterogeneous solids. The phenol adsorption data from dilute aqueous solutions on activated carbon are studied by using this new equation.

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Eine neue Isothermengleichung für die Adsorption aus verdünnten Einzelkomponentenlösungen auf energetisch heterogenen Festkörpern (Kurze Mitteilung)

Zusammenfassung Es wurde eine neue Isothermengleichung für die Adsorption aus verdünnten Einzelkomponentenlösungen auf energetisch heterogenen Festkörpern vorgeschlagen. Diese Gleichung schließt alle bisherigen Isothermengleichungen in sich ein, die Verallgemeinerungen der einfachenLangmuir-Isotherme für Adsorption auf heterogenen Festkörpern sind. Es wurden Daten der Adsorption von Phenol aus verdünnten Wasserlösungen auf aktivierte Kohle unter Verwendung der neuen Gleichung untersucht.