Oxygen permeation flux

Table 1. Reforming properties and oxygen permeation flux of the single-stack MPOX reformer.

Figure 5. Oxygen permeation flux, conversion, and selectivity of CSO-15MFO at 800 °C as a function of time. The oxygen permeation flux of 1 p.mol/cm s corresponds to 1.34 sccm/cm. ...

Figure 5 Oxygen permeation flux through membranes of uncoated LaggSr0 gCoO g at 1173 K and LogjSrgjCoO g coated with SrCoggFeg 20j g at 1183 K. The coating was deposited on the feed side. Data were taken from ref. 28...

Finally, we briefly describe the observations recently made in the present authors laboratory in an attempt to increase the oxygen permeation flux through stabilized bismuth oxide by substitution of the 5-Bi203 host with 40 mol% terbium on the bismuth sites (BT40). Measurements using the concentration cell method and ac impedance confirmed that BT40 exhibits good p-type... 

B.A. Van Hassel, J.E. ten Elshof and H.J.M. Bouwmeester, Oxygen permeation flux through Lai-ySryFeOs-e limited by carbon monoxide oxidation rate. Appl. Catal. A General, 119 (1994) 279-291. 

T. Kawada, T. Horita, N. Sakai, H. Yokokawa and M. Dokiya, Experimental determination of oxygen permeation flux through bulk and grain boundary of Lao.TCao.sCrOa. Solid State Ionics, 79 (1995) 201-207. 

Figure 9.12 Temperature dependence of the oxygen permeation fluxes through various mixed-conducting membranes, made of perovskite-related compounds with predominant electronic conductivity, under fixed oxygen chemical potential gradients...

The zirconia-based pump-sensor device can be used for controlling the oxygen partial pressure in closed systems typical applications include the oxygen permeation flux measurements, oxygen monitoring in molten metals, and coulometric titration. 

It has been reported [22] that micro/nano surface reactive layers introduced on the surface of oxygen ion transport membranes enhanced the oxygen permeability of dense oxygen-permeable perovskite-type ceramic membranes, Lao.7Sro.3Gao.6Feo.403 6. The results also showed that the oxygen permeation flux is influenced by the surface area of the surface-reactive layer. 

Table 3.1 Oxygen permeation fluxes of some MIEC membrane materials...

Lao.sSrijGao.eFei.aOs+s [24] and SrFeCoo.sOx [65] were also successfully used as MIECM for POM more than 1,000 h. A membrane reactor based on a brown-millerite structure materials could be continuously operated for over one year under syngas atmosphere at 900°C [66]. The syngas production rate was 60ml/cm. min, and equivalent oxygen permeation flux was 10-12 ml/cm. min. The composition of the membrane was not specified in the literature. 

When oxygen-ionic diffusion is purely the limiting step, the one dimensional oxygen permeation flux can be expressed by Eq. 6.1 according to the Wagner theory ... 

Oxygen permeation fluxes oxygen exchange and transport models suffer from not considering that the membrane is a polycrystal material in which grain boundaries have different properties than bulk grain. 

Fig. 6.4 Arrhenius plots of oxygen permeation fluxes through LSFG, LSFG/2M and LSFG/5M membranes (thickness=l mm). Numbers in kJ/mol refer to the activation energies of oxygen permeation...

Fig. 6.5 Oxygen permeation flux through LSFG/5M membrane versus oxygen partial pressure on air side for different temperatures lep) and corresponding values of the surface exchange coefficient calculated with Eq. 6.3 (right)...

NOTE k values were estimated from oxygen permeation fluxes versus... 

Fig. 6.8 SEM micrograph of a multilayer perovskite reactor (left) and its oxygen permeation flux with temperature compared with a thick dense membrane right)...

The applicability of oxygen membrane materials depends essentially on their oxygen permeation fluxes. The dependence of the flux density j02 on the oxygen pressure difference across the membrane of thickness L can be calculated by the using of the measured total conductivity o and calculated values Oi for the ion conductivity. 

Figure 3. The estimated oxygen permeation fluxes through 0.1 cm thick membranes of the LaSr2Fe yCryOs+sas functions of the permeate-side oxygen partial pressure at 950X1.

Material Temperature rc) Oxygen permeation flux (mL nvn cnT ) Stability in the POM (h) Reference ... 

Whereas most perovskite material have operation temperatures above 800 °C, our BCFZ perovskite hollow fiber membrane could be successfully used for oxygen separation from air between 400 and 500 °C (Figure 16.6). As Figure 16.6 shows, the oxygen permeation flux increases from 0.03 to 0.45 mL cm min as the temperature rises from 400 to 500 °C. However, in... 

Figure 16.7 Low temperature oxygen separation from air Oxygen permeation flux through a BCFZ hollow fiber membrane as a function of time at 500 °C. At this temperature a continuous decrease of the oxygen flux is observed. For regeneration, the fiber was heated to 925 °C, kept at this temperature for 1 h in air, then cooled down to 500 °C for the next run. Experimental details Air flow rate on the shell side= 150 mL min He flow rate on the core side = 30 mL min 0.43 cm effective membrane area.

Therefore, the membrane surface areas for exchange reactions are increased noticeably while the effective membrane thickness for bulk diffusion is also decreased (only limited to the central dense layer). As a consequence, the oxygen permeation flux can be improved greatly, e.g. a maximum improvement factor of 18.6 can be obtained at 800 °C for the H2S04-modified membranes. ... 

Length variable of hollow fiber membrane Length of hollow fiber membrane Number of hollow fiber membranes Oxygen permeation flux Atmosphere pressure Pressure in fiber lumen and shell side Oxygen partial pressure in the upstream and downstream side... 

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