Frequency response for nonisothermal adsorption in biporous pellets

Sun, Lianming; Meunier, F.; Grenier, P.; Ruthven, Douglas M.

doi:10.1016/0009-2509(94)87008-x

Cited by 62 publications

(47 citation statements)

References 11 publications

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“…The frequency response (FR) method in kinetic studies, which consists of sinusoidal modulation of the volume of an experimental chamber and recording of the pressure, was first developed in the 1960s (Polinski and Naphtali, 1963) and 1970s (Evnochides and Hznley, 1970;BCtemps et al, 1977). It has attracted more attention in recent years to determine the mass-transfer kinetics in adsorbents ( Van-Den-Begin and Rees, 1989;Jordi and Do, 1992;Yasuda, 1994;Sun et al, 1994). This development is due to the following advantages.…”

Section: Introductionmentioning

confidence: 99%

Thermal frequency response method for the study of mass‐transfer kinetics in adsorbents

et al. 1996

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Section: Introductionmentioning

confidence: 99%

Thermal frequency response method for the study of mass‐transfer kinetics in adsorbents

et al. 1996

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“…It has been shown that the difference between non-isothermal and isothermal uptakes for a constant pressure differential adsorption test can be significant due to a very small change in the adsorbent temperature (Sircar, 1981). The same behavior is encountered by all differential adsorption tests mentioned earlier (Ruthven, 1984;Haul andStremming, Sircar, 1983, 1984;Sircar and Kumar, 1984;Sun et al, 1994;Sun and Meunier, 1993). Figure 2 also shows that the non-isothermal effect is amplified when the mass transfer coefficient is high, the gas circulation rate is low, and the isosteric heat of adsorption is high (not studied in this work), as expected.…”

Section: Non-isothermal Sorption Uptake By Closed-loop Recycle Methodmentioning

confidence: 53%

“…Consequently, analytical solutions of non-isothermal ad(de)sorption kinetic models using different sorption mechanisms can be obtained to facilitate data analysis. Examples include (i) differential constant pressure gravimetric tests for a pure adsorbate involving mass transfer by Fickian Diffusion models (neglecting or including the thermal resistance within the adsorbent particle) (Ruthven, 1984;Haul and Stremming, 1984) or Linear Driving Force (LDF) models (neglecting or including the thermal resistance within the adsorbent particle) (Sircar, 1983;Sircar and Kumar, 1984), (ii) differential constant pressure gravimetric tests for binary adsorbates with mass transfer by LDF model (Sircar, 1994), and (iii) differential frequency response test for a pure adsorbate using a bi-porous adsorbent (combined micropore and macropore diffusion) (Sun et al, 1994) or an adsorbent with combined micropore and surface barrier resistances (Sun and Meunier, 1993).…”

Section: Introductionmentioning

confidence: 99%

Gas sorption kinetics by differential closed-loop recycle method: Effect of heat of adsorption

Sircar

2006

Adsorption

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An analytical mathematical model is used to investigate the influence of minute adsorbent temperature changes on the kinetics of sorption of a gaseous adsorbate from mixture with a carrier gas using a differential closed loop recycle method. Isothermal operation may not be achieved even when a very high gas circulation rate is used. Very small changes in the adsorbent temperature during the process can cause substantial departure from isothermal uptake behavior. It is shown that the kinetic process can be assumed to be isothermal only for trace adsorbate concentrations. A criterion for validity of isothermal data analysis is proposed.

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“…Expressions for G n,i can be derived for a variety of mass transfer mechanisms 39,40 including multicomponent models with cross coefficients. 33 Adsorbed-phase transfer functions are given here only for simple systems with no cross-coefficients.…”

Section: Theorymentioning

confidence: 99%

Mass Transfer of Binary Mixtures of Oxygen and Argon in a Carbon Molecular Sieve

Giesy

Mitchell

LeVan

2014

Ind. Eng. Chem. Res.

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Transport of binary O 2 /Ar gas mixtures in a carbon molecular sieve (CMS) has been studied using concentrationswing frequency response. The rate data for this binary gas system are described well by the transport models (surface barrier for Ar and surface barrier plus micropore diffusion for O 2 ) and parameters that were found to govern transport of the respective pure gases on the same CMS. These results suggest that transport of O 2 is not impeded by the presence of Ar. However, the experimental data do not rule out the possibility of some enhancement of the O 2 transport rate. Furthermore, O 2 and Ar isotherms on this CMS were observed to be linear in the region over which frequency response experiments were performed, suggesting that the micropore diffusion component of O 2 transport behavior is unaffected by the presence of Ar. Because transport of Ar in this CMS is much slower than O 2 , the dynamic response of this system owes the majority of its character to O 2 adsorption, and the effect of O 2 on Ar transport remains hidden. INTRODUCTIONCarbon molecular sieve (CMS) materials have received attention as potential adsorbents for the production of high-purity (>99%) O 2 from air by pressure swing adsorption (PSA). 1−14 In traditional zeolite-based PSA processes, the O 2 product is often limited to 94−95% purity, as the similar adsorption behavior of O 2 and Ar on many zeolites results in a substantial Ar impurity in the product. 1,2 In CMS, however, O 2 adsorbs much more rapidly than Ar, allowing separation of these two gases to be effected by the difference in their adsorption rates.To rigorously design a PSA process utilizing CMS or any other adsorbent, accurate knowledge of the adsorption rate behavior of the relevant adsorbent/gas system is desirable. Adsorption rates are generally limited by mass transfer, which can occur by one or more of a variety of possible mechanisms including micropore diffusion, macropore diffusion (ordinary diffusion, Knudsen diffusion, or Poiseuille flow), transport across a surface barrier, and external mass transfer. The existence of cross-coefficients introduced by multicomponent transport models can further complicate adsorption rate behavior. As a result, adsorption rates are an important and nontrivial subject worthy of thorough investigation.As CMS has long been recognized for its ability to produce purified N 2 from air, many of the studies of adsorption rates of atmospheric gases on CMS have been focused on O 2 and N 2 . 15−28 However, with the exception of a few studies, 24,25,29 adsorption rates of Ar have been largely ignored. Moreover, though adsorption rates of pure gases are generally presumed to differ from those of gases in multicomponent mixtures, studies of adsorption rates in such mixtures have been infrequent. 26 We thus conclude that there remains a need for further study, especially regarding adsorption rates of mixtures of O 2 and Ar.In a recent work, 30 we studied pure component adsorption rates of O 2 , N 2 , and Ar on two varieties of CMS using pr...

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Frequency response for nonisothermal adsorption in biporous pellets

Cited by 62 publications

References 11 publications

Thermal frequency response method for the study of mass‐transfer kinetics in adsorbents

Thermal frequency response method for the study of mass‐transfer kinetics in adsorbents

Gas sorption kinetics by differential closed-loop recycle method: Effect of heat of adsorption

Mass Transfer of Binary Mixtures of Oxygen and Argon in a Carbon Molecular Sieve

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