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The artificiality of the actual amount adsorbed (AAA) estimated from the experimentally measured Gibbsian surface excess (GSE) of a gas is discussed. The use of AAA for calculation of isosteric heat of adsorption or mixed gas adsorption isotherms using ideal adsorbed solution theory can be misleading and incorrect. The GSE, on the other hand, can be unambiguously used to describe all practical aspects of adsorption science and technology. [ABSTRACT FROM AUTHOR]

The uncertainty in the evaluation of the separation performance of a rapid pressure swing adsorption (RPSA) process for production of a high-purity product gas by using a numerical process model can be impractically high as a result of the theoretical or experimental uncertainty in the estimation of the high adsorbate mass transfer coefficient required by such a process. Actual experimental process performance data are required in order to judge the real value of the process. [ABSTRACT FROM AUTHOR]

A concept of creating an ideal multicomponent-gas adsorbed phase by mixing pure gas adsorbed phases of the components at constant surface potential and temperature using the Gibbsian Surface Excess (GSE) framework of adsorption is proposed. The GSE provides the only unambiguously measured experimental quantity to describe the extent of adsorption. The actual amounts adsorbed can be estimated from the GSE only by making extraordinary assumptions about the volume and structure of the adsorbed phase. The correlations between the multicomponent and pure gas GSE isotherms generated by the proposed concept closely resemble those for the classic Ideal Adsorbed Solution Theory (IAST), which was developed by using the actual amounts adsorbed as the primary variables. The proposed correlations can be obtained by simply substituting the actual amount adsorbed of components in the corresponding IAST correlations by the GSE of the components. All pure and multicomponent gas adsorption data published in the literature are GSE, and they are directly used in the IAST by loosely assuming that they are actual amounts adsorbed. Thus, it appears that the proposed concept of this work has been inadvertently used in all past works which use IAST to estimate multicomponent adsorption isotherms from pure component isotherm data. [ABSTRACT FROM AUTHOR]

The effects of gas-phase axial thermal dispersion andsolid-phasethermal conduction on gas–solid heat transfer in a packed bedof solid particles was numerically studied using a simplified conduction–dispersionmodel for heat transfer in conjunction with a realistic set of boundaryconditions. It is reconfirmed that the exclusion of gas-phase thermalaxial dispersion in the model analysis of gas–solid heat transfercoefficients can result in misleading interpretation of heat transferin packed beds, particularly in the low Reynolds number gas flow region. [ABSTRACT FROM AUTHOR]

It was experimentally demonstrated that the performance of a medical oxygen concentrator based on rapid pressure swing adsorption (RPSA) process using a LiLSX zeolite was improved [lower bed size factor (BSF) and higher oxygen recovery (RO)] when the adsorbent exhibited higher selectivity of adsorption of N2 over O2. The effects of N2 selectivity on BSF and RO as functions of the RPSA process cycle times were found to be complex and nonintuitive. The key properties of a LiLSX zeolite sample for adsorption of N2 and O2 (pure and binary gas isotherms, binary selectivity, pure gas isosteric heats, pure gas mass-transfer characteristics, and degrees of adsorbent heterogeneity), which exhibited a relatively higher selectivity of adsorption for N2 over O2 compared to a previously reported sample, were measured and used in this study. [ABSTRACT FROM AUTHOR]