The molecular sieve 4‐A water vapor sorption therm

Jury, Stanley H.; Horng, Jiin S.

doi:10.1002/aic.690190226

Cited by 7 publications

(9 citation statements)

References 10 publications

(6 reference statements)

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“…Two heats of adsorption are clearly evident in Table 1. Excluding the values of Ulku et al (2005), [inconsistent with all the other data], the heat of adsorption below a fractional loading θ of ∼ 0.2 varies from 100 to 125.5 kJ/mol (Dubinin et al 1969;Vergnaud et al 1965;Zhdanov et al 1981;Breck 1974) and above a θ of ∼0.2, decreases from 74.06 to 50.63 (Breck 1974;Dubinin et al 1969;Avgul et al 1968;Jury and Horng 1973;Cointot et al 1968;Zhdanov et al 1981). The break point of θ ≈ 0.2 is consistent with transition from the β cage to the α cage.…”

Section: Introductionmentioning

confidence: 72%

“…The Morris (1968) subject to the restriction that K i p ≤ 1 (a) models were calculated using solver in the EXCEL package. Also the 5 parameter equation of Gorbach et al (2004) and the model of Jury and Horng (1973) is compared to one of the models derived. In executing the calculation, a relative form of the residual was employed for each isotherm, e.g.,…”

Section: Modeling Results and Application To Datamentioning

confidence: 99%

“…Therefore the 3 parameter Toth-Langmuir model is probably the optimum model for the Gorbach et al data. 4.1 Literature models similar to the above Two models that of Gorbach et al (2004) and Jury and Horng (1973) have many similarities with the dual site Langmuir model. The optimized Gorbach et al (2004) model is which may be rearranged as…”

Section: -Parameter Modelsmentioning

confidence: 86%

“…The saturation loading of water on the 4A zeolite crystals is given by Breck as 0.28 or 0.285 g/g Z and by Ulku et al (Breck 1974;Morris 1968;Gorbach et al 2004) and 0.2058 g/g pellet (Jury and Horng 1973). Allowing for the 80% crystals the latter are equivalent to a saturation loading of 0.25 to 0.257 g/g Z.…”

Section: Introductionmentioning

confidence: 99%

“…Other theories employed are the Polanyi Potentail theory (Cointot et al 1968;Qin et al 1980), Dubinin isotherm (Cointot et al 1968, and 18 models by Gorbach et al (2004) such as (Henry-Langmuir, Toth, Sips, BET and Aranovich). Jury and Horng (1973) employ a two site Langmuir theory, consisting of a zeolite site and a clay binder site and they attributed approximately 16% of the adsorption to being on the clay binder site.…”

Section: Introductionmentioning

confidence: 99%

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Water isotherm models for 4A (NaA) zeolite

Loughlin

2009

Adsorption

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The adsorption data of Gorbach et al. (Adsorption 10(1): 29-46, 2004) and Morris (J. Colloid Interface Sci. 28: 149-155, 1968) for the adsorption of water on 4A zeolite pellets is re-analyzed. Model isotherms are derived considering a two site hypothesis, one for the α cage and one for the β cage. Four simple model isotherms are fitted to the data. Both a dual site Toth or dual site Langmuir isotherm model fit the data adequately.The optimized standard enthalpy and entropy of adsorption parameters derived from the data are surprising for the β cage. The optimized standard enthalpy of the β cage is 1/3rd of that observed calorimetrically, and the standard entropy of adsorption is positive, a physical impossibility. Substituting the calorimetric enthalpy of adsorption corrected the standard differential entropy of sorption values resulting in the standard entropy of sorption values varying significantly with temperature. This variation is postulated to be due to either water of hydration formation, or clathrate formation, or the formation of clusters of water such as dimers, trimers, etc.Keywords Adsorption · Water · 4A (NaA) zeolite · Langmuir isotherm · Toth isotherm · Ruthven isotherm · Dual site isotherm · Standard enthalpy of adsorption · Standard entropy of adsorption Nomenclature f i fractional size of site i K ci dimensionless equilibrium constant ci, cβ for cage β and cα for cage α respectively

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Section: Introductionmentioning

confidence: 72%

Section: Modeling Results and Application To Datamentioning

confidence: 99%

Section: -Parameter Modelsmentioning

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Water isotherm models for 4A (NaA) zeolite

Loughlin

2009

Adsorption

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Solute condensation in adsorption beds during thermal regeneration

Friday

LeVan

1982

AIChE Journal

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This theoretical study shows that a liquid phase can be developed in and passed through a fixed-bed adsorber during thermal regeneration. The liquid results from passing hot gas from the inlet end of the bed, where the adsorbate is desorbed, towards the cool outlet end, where condensation of the solute occurs. The stage model of an adsorption bed is applied to two examples, the regeneration of an activated carbon bed with adsorbed benzene using hot nitrogen and the regeneration of a 4A molecular sieve bed with adsorbed water using hot methane. DAVID K. FRIDAY andM. DOUGLAS LEVAN Department of Chemical EngineeringUniversity of Virginia Charloitesville, VA 22901 SCOPE Displacement of adsorbed compounds from a fixed-bed adsorber often results from the passage of a hot gas into the column. This process, called thermal regeneration, finds wide application in solvent recovery, dehydration, and liquid treating operations. Following the heating step, the bed is cooled and is then ready for reuse.This work considers theoretically the thermal regeneration of an adiabatic adsorption column with the development of a liquid phase in the bed. The objectives of this paper are, first, to show that the liquid condensate phase can be formed during thermal regeneration and, second, to present a simple yet versatile model that can be used to predict regeneration behavior for various systems and operating conditions. Thorough treatment will lead to improved methods for the design of adsorption systems and to a better fundamental understanding of coupled heat and mass transfer in adsorptive media.The phenomenon of solute condensation has not been investigated previously although a basis for it has been described by Basmadjian et al. (1975). In their study of thermal regeneration of 5A molecular sieve with adsorbed carbon dioxide using nitrogen, a plateau of readsorbed carbon dioxide was predicted for which the adsorbed-phase concentration exceeded the initial loading. Basmadjian et al. referred to this phenomenon as roll-up.Several methods are available that can be applied to this problem. Many recent theoretical analyses of adiabatic processes in fixed-bed adsorbers have been based on the method of characteristics 1965;Rhee et al., 1970;Pan and Basmadjian, 1971;Banks, 1972;Basmadjian et al., 1975 Ikeda, 1979), the packed bed is modeled as a number of stages, plates, mixing cells, or tanks in series. Our model is obtained by discretizing in the axial direction the partial differential equations for conservation of mass and energy in a fixed bed to obtain ordinary differential equations for each stage. As in the method of characteristics approach, the effects of heat and mass transfer resistances are neglected. Since the model used here is based on finite differences, as the number of stages is increased the results for concentration and temperature profiles in the bed approach those given by the method of characteristics.Two systems are examined: the passage of hot nitrogen into a fixed bed of activated carbon with adsorbed benzene, a...

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Maximum temperature in fixed-bed sorption columns and isosteric heats of adsorption

Pollock

Jury

1976

Journal of the Franklin Institute

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The molecular sieve 4‐A water vapor sorption therm

Cited by 7 publications

References 10 publications

Water isotherm models for 4A (NaA) zeolite

Water isotherm models for 4A (NaA) zeolite

Solute condensation in adsorption beds during thermal regeneration

Maximum temperature in fixed-bed sorption columns and isosteric heats of adsorption

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