Importance of the surface exchange kinetics as rate limiting step in oxygen permeation through mixed-conducting oxides

Bouwmeester, Henny J.M.; Kruidhof, H.; Burggraaf, A.J.

doi:10.1016/0167-2738(94)90145-7

Cited by 448 publications

(275 citation statements)

References 28 publications

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“…As a result, the backward reaction of surface exchange, expressed in (1), becomes pseudo-zero order at steady state under isothermal operations [45]. Then, based on the global reaction (1) and the reaction rate expression (2), the oxygen permeation rate by the surface exchange reaction on each side of the membrane can be expressed as, Depending on how the expressions in (3) and (4) are simplified or the reaction rate (2) is approximated, different empirical correlations for the surface exchange processes have been proposed [41,43,44,46].…”

Section: Surface Exchangementioning

confidence: 99%

Numerical simulation of ion transport membrane reactors: Oxygen permeation and transport and fuel conversion

Hong

Kirchen

Ghoniem

2012

Journal of Membrane Science

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Ion transport membrane (ITM) based reactors have been suggested as a novel technology for several applications including fuel reforming and oxy-fuel combustion, which integrates air separation and fuel conversion while reducing complexity and the associated energy penalty. To utilize this technology more effectively, it is necessary to develop a better understanding of the fundamental processes of oxygen transport and fuel conversion in the immediate vicinity of the membrane. In this paper, a numerical model that spatially resolves the gas flow, transport and reactions is presented. The model incorporates detailed gas phase chemistry and transport. The model is used to express the oxygen permeation flux in terms of the oxygen concentrations at the membrane surface given data on the bulk concentration, which is necessary for cases when mass transfer limitations on the permeate side are important and for reactive flow modeling. The simulation results show the dependence of oxygen transport and fuel conversion on the geometry and flow parameters including the membrane temperature, feed and sweep gas flow, oxygen concentration in the feed and fuel concentration in the sweep gas.

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Section: Surface Exchangementioning

confidence: 99%

Numerical simulation of ion transport membrane reactors: Oxygen permeation and transport and fuel conversion

Hong

Kirchen

Ghoniem

2012

Journal of Membrane Science

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“…(1) is related to the so called characteristic thickness L, (cm), at which the surface oxygen exchange and the bulk diffusion through the material are equally important during oxygen permeation [4,19]. The relation between h and L, is given by: with f the correlation cubic perovskite lattice factor, which is 0.69 for a [6].…”

Section: Theorymentioning

confidence: 99%

Surface oxygen exchange of LaSrCoO

et al. 1997

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The surface oxygen exchange of Lao.3Sro,, Co0,_6 has been studied by 'SO/'hO exchange followed by dynamic SIMS analysis in the temperature region 700-900°C at a po, of 2.1 X lo4 Pa. The activation energy for the surface exchange rate (k) is 283 kJ mol -' and for the oxygen tracer diffusion coefficient (D *) 56t4 kJ mol-' The absolute values for both k and D * are among the highest known in the literature. The characteristic thickness at a po, of 2.1 X lo4 Pa is calculated to lie in the range 0.70 to 1.3 mm and is a function of temperature. The latter reflects the different activation energies for k and D*. The surface oxygen exchange coefficient is proportional to p& with n =0.41 to.02 at WYC, which has been explained by a rate determining step involving an adsorbed oxygen species and an oxygen vacancy. No oxygen pressure dependence for the tracer diffusion coefficient was observed at this temperature.

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“…Bouwmeester et al [10] defined a characteristic thickness, L C , for membranes where surface kinetics and bulk kinetics are equally important to the flux. Decreasing a membrane's thickness below L C gives essentially no increase in the flux.…”

Section: Surface Kinetics Of Hydrogen Permeation In Mixed Proton-elecmentioning

confidence: 99%

Dense Ceramic Membranes for Hydrogen Separation

Norby

Haugsrud

2007

Membranes for Energy Conversion

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Importance of the surface exchange kinetics as rate limiting step in oxygen permeation through mixed-conducting oxides

Cited by 448 publications

References 28 publications

Numerical simulation of ion transport membrane reactors: Oxygen permeation and transport and fuel conversion

Numerical simulation of ion transport membrane reactors: Oxygen permeation and transport and fuel conversion

Surface oxygen exchange of LaSrCoO

Dense Ceramic Membranes for Hydrogen Separation

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