Determination of Azeotropic Behavior in Adsorbed Mixtures

Siperstein, Flor R.

doi:10.1007/s10450-005-5898-3

Cited by 11 publications

(19 citation statements)

References 16 publications

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“…The resulting threeparameter expression for the excess Gibbs energy is asymmetrical in composition and has an exponential dependency upon the reduced grand potential, thus being thermodynamically consistent [4,7]. Another contribution of the current investigation is to discuss the behaviour of adsorption azeotropes in relation to the infinite dilution activity coefficients and their visualization on the reduced grand potentialcomposition diagram at constant temperature and pressure, therefore confirming and extending the conditions for azeotrope existence defined by Siperstein [12].…”

Section: Introductionsupporting

confidence: 78%

“…With the aim of determining the conditions where azeotropic behaviour is observed, Siperstein [12] showed that the existence of an adsorption azeotrope can be defined from relations between the infinite dilution activity coefficients and the surface pressure of the pure components at the same temperature and reduced grand potential of the mixture. In particular, these relationships can be obtained from the slope of the bubble point pressure curve while it approaches the pure component.…”

Section: Implications Of Azeotropic Behaviourmentioning

confidence: 99%

“…Several works in the literature have shown experimental data of adsorption azeotropes for mixtures of polar and non-polar components adsorbed into heterogeneous adsorbents including 13X, H-modernite, ZSM-5 and silicalite [6,[8][9][10][11]. Among the causes of non-ideal and azeotropic behaviour energetic heterogeneity of adsorption sites, steric exclusion effects and interactions between molecules in the adsorbed phase have been proposed [6,12]. Whatever the cause of non-idealities, engineers require accurate thermodynamic models to correlate and predict multicomponent adsorption equilibria in support of rigorous process simulation tools.…”

Section: Introductionmentioning

confidence: 99%

“…Parameter of the 1-parameter Margules equation (-) A 12 First parameter of the van Laar equation (-) A 21 Second parameter of the van Laar equation (-) B…”

mentioning

confidence: 99%

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Activity coefficient models for accurate prediction of adsorption azeotropes

et al. 2021

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In this study seven adsorption azeotropes involving binary systems and zeolite-based adsorbents were systematically investigated. Pure component isotherms and mixed-gas adsorption data were taken from published literature except for the benzene–propene system on silicalite, which is newly presented in this work using molecular simulations. Experimental adsorbed phase composition and total amount adsorbed of the azeotropic systems were compared with the predictions of several models including: the ideal adsorbed solution theory (IAST), the heterogeneous ideal adsorbed solution theory (HIAST) and the real adsorbed solution theory (RAST) coupled with the 1-parameter Margules (1-Margules) and the van Laar equations. In the latter two models an additional loading parameter was incorporated in the expression of the excess Gibbs energy to account for the reduced grand potential dependency of the activity coefficients in the adsorbed phase. It was found that the HIAST and RAST–1-Margules models were able to predict the azeotropic behaviour of some systems with good accuracy. However, only the RAST–van Laar model consistently showed an average relative deviation below 3% compared to experimental data for both the adsorbed phase composition and the total amount adsorbed across the systems. This modified van Laar equation is therefore preferable in those engineering applications when the location of adsorption azeotropes is required with great accuracy and when there is lack of detailed characterization of the adsorbent that is needed to carry out molecular simulations.

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Section: Introductionsupporting

confidence: 78%

Section: Implications Of Azeotropic Behaviourmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Parameter of the 1-parameter Margules equation (-) A 12 First parameter of the van Laar equation (-) A 21 Second parameter of the van Laar equation (-) B…”

mentioning

confidence: 99%

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Activity coefficient models for accurate prediction of adsorption azeotropes

et al. 2021

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“…Adsorption of the carbon dioxide(1)/propane(2) binary system on zeolite 13X exhibits an azeotrope and it has been studied extensively introducing a model for the excess Gibbs energy [14]. Isotherms parameters are reported in Table 1.…”

Section: Common Tangent Approach For Non-ideal Adsorption At Low Presmentioning

confidence: 99%

Common tangent plane in mixed-gas adsorption

Santori

Luberti

Brandani

2015

Fluid Phase Equilibria

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A B S T R A C TThe minimisation of the distance function between the Gibbs energy of mixing and its common tangent plane (or line) is applied to adsorbed solutions. A specific algorithm to deal with the associated bilevel programming problem is presented and discussed. This approach is validated with experimental data and ideal adsorbed solution theory calculations for an ideal case and with experimental data for two nonideal cases at low and high pressure. While the presently adopted non-ideal formulation provides solutions fulfilling only the necessary condition for equilibrium, the common tangent plane approach proposed in this paper enables the direct evaluation of the necessary and sufficient solution.

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Polyhydroxy glucose functionalized silica for the dehydration of bio-ethanol distillate

Tang

Row

2013

Bioprocess Biosyst Eng

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Although most of the water in a bio-ethanol fermentation broth can be removed by distillation, a small amount of water remains in the bio-ethanol distillate as the water-ethanol azeotrope. To improve the use of ethanol as a fuel, glucose-modified silica, as an adsorbent, was prepared using a facile method and applied to the dehydration of bio-ethanol distillate. The factors affecting the adsorption capacity of the adsorbent, such as the particle size, initial concentration of water in the samples, adsorption temperature and adsorbent dose, were examined by measuring the adsorption kinetics and equilibrium. The Langmuir, Freundlich and Temkin isotherms were used to evaluate the adsorption efficiency. Of these, the Freundlich and Temkin isotherms showed a good correlation with the experimental data. The Langmuir isotherm showed some deviation from the experimental results, and indicated that adsorption in this case was not a simple monolayer adsorption. The property of the adsorbent was attributed to functionalized silica with many hydroxyl groups on its surface. An examination of the separation factors of water/ethanol revealed the modified silica to have preferential selectivity for water. Compared to activated carbon and silica, glucose-modified silica exhibited higher adsorption capacity for water under the same adsorption conditions. In addition, the glucose-modified silica adsorbent exhibited a relatively constant adsorption capacity for five adsorption/desorption cycles.

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Determination of Azeotropic Behavior in Adsorbed Mixtures

Cited by 11 publications

References 16 publications

Activity coefficient models for accurate prediction of adsorption azeotropes

Activity coefficient models for accurate prediction of adsorption azeotropes

Common tangent plane in mixed-gas adsorption

Polyhydroxy glucose functionalized silica for the dehydration of bio-ethanol distillate

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