FUNDAMENTALS OF THE THEORY OF ADSORPTION IN MICROPORES OF CARBON ADSORBENTS - CHARACTERISTICS OF THEIR ADSORPTION PROPERTIES AND MICROPOROUS STRUCTURES
FUNDAMENTALS OF THE THEORY OF ADSORPTION IN MICROPORES OF CARBON ADSORBENTS - CHARACTERISTICS OF THEIR ADSORPTION PROPERTIES AND MICROPOROUS STRUCTURES
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DOI：
10.1016/0008-6223(89)90078-x
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发表时间：
1989-01-01
期刊：
影响因子：
10.9
通讯作者：
DUBININ, MM
中科院分区：
文献类型：
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作者：
DUBININ, MM
在最可能的狭缝状、有限尺寸类型的碳吸附剂的微孔中的蒸气吸附理论的基础在于被吸附物和吸附剂原子之间以及被吸附物质本身的原子之间的分散相互作用。由于孔尺寸（半宽度）与吸附分子的孔尺寸（半宽度）的可互换性，发生了可用可互换空间的体积填充，即，吸附力场碳活化的早期阶段产生几乎均匀的微孔，其尺寸可以通过小角度X射线和量热法技术适当地估计，所述技术涉及测量吸附剂浸入具有不同分子尺寸的液体中的热。这两种方法给出的结果是一致的。Dubinin和Radushkevich提出了一个具有两个参数的均相吸附结构方程，即吸附体积W_0和吸附特征能。在偏差不超过10%的情况下，半宽度x 0与E0的乘积是常数。对于非均匀微孔，合理的近似是假设正常的体积分布。在这种情况下得到的Dubininin-Stoeckli方程包含三个表征分布范围的参数W 0、E0和色散δ。这些参数是有效的，因为活性炭还含有较大的中孔，其表现出比微孔弱的吸附。由293 K下标准苯蒸气的实验吸附等温线确定的W 00、E0和δ的有效值，允许以合理的精度估计在约100 ℃的温度范围内的其它蒸气的吸附等温线。吸附等温线的真实的参数针对中孔中的吸附进行了校正，即，具有真实的参数W 0 0、E0和δ的等温线可用于计算给定尺寸范围内微孔的几何表面积和它们的体积。因此，有效吸附特性W 00、E0和δ与中孔比表面积Sme一起，是每个活性炭样品的吸附性能和微孔结构的定量特征。苯在293 K和氮气在77 K作为参考蒸汽进行了比较，并讨论了它们的特异性。
At the basis of the theory of vapor adsorption in the micropores of carbon adsorbents of the most probable slit-like, limited-size type lie the dispersion interactions between the adsorbate and adsorbent atoms as well as between the atoms of the adsorbed substance themselves. As a consequence of commensurability of the pore sizes (half-widths) with those of the adsorbed molecules there occurs the volume filling of the available micropore space, i.e., the field of adsorption forces. Early stages of activation of carbons produce practically homogeneous micropores, the size of which may suitably be estimated by small-angle x-ray and calorimetry techniques involving measurements of the heats of immersion of adsorbents into liquids with different molecular size. The two methods give results that are in agreement. Dubinin and Radushkevich proposed an equation for homogeneous micropore structures with two parameters, the micropore volumeW0and the characteristic energy of adsorptiono. With deviations not considerably in excess of 10%, the product of micropore half-widthx0byE0is a constant. For nonhomogeneous micropores the reasonable approximation is to assume the normal micropore volume distribution. The Dubinin-Stoeckli equation obtained for this general situation involves three parametersW0,E0, and dispersion δ characterizing the distribution range. The parameters are effective since active carbons also contain larger mesopores, which exhibit weaker adsorption than micropores. The effective values ofW00,E0and δ, determined from the experimental adsorption isotherm of the standard benzene vapor at 293 K, allow the adsorption isotherms of other vapors within a temperature range of about 100 degrees to be estimated with reasonable accuracy. The real parameters for adsorption isotherms corrected for the adsorption in mesopores, i.e., the isotherms with the real parametersW00,E0, and δ, can be used for calculating the geometric surface area of micropores and their volume within a given size range. Thus, the effective micropore characteristicsW00,E0, and δ are, together with the specific surface area of mesoporesSme, a quantitiative characteristic of the adsorption properties and microporous structure of each active carbon specimen. Benzene at 293 K and nitrogen at 77K are compared as reference vapors and their specificity is discussed.