Permeation of linear and branched alkanes in ZSM-5 supported membranes

Nanocomposite MFI-alumina and FAU-alumina Membranes: Synthesis, Characterization and Application to Paraffin Separation and CO2Capture

“…A more realistic evaluation of the membrane performance is obtained however by assessing the temperature behaviour of the flux of a target species across the membranes in the temperature range 398-523 K. Figure 6 shows the evolution of the n-butane flux across membranes M7 and M10 and i-butane flux across membrane M7 as a function of temperature. As expected for a membrane with a 752 3800 3600 3400 3200 3000 2800 2600 Kubelka Munk (a. low amount of defects [34], the pure n-butane permeance reaches a maximum at about 448 K. The pure i-butane flux is about 50 times lower than the value obtained for n-butane and increases steadily with temperature up to 523 K. Since the diffusivity of i-butane is much lower than that of nbutane, its maximum temperature is expected to lie beyond the temperature range surveyed in this study.…”

Positron Emission Profiling Study of the Diffusion of 3-Methylpentane in Silicalite-1

“…The activation energy obtained from the corrected diffusivities by Millot et al using the Membrane permeation technique [33] is equal to 50 kJ/ mol, which is quite close to the value of the activation energy measured here. Deviation from the linear dependence was observed for the logarithm of the diffusivity versus reciprocal temperature, which was attributed by the authors to the strong variation of diffusion coefficient with the coverage.…”

“…As the pressure increases from 0 to 4.5 kPa (figure 7), an unusual effect of the partial pressure of 3-methyl- Significantly lower activation energies (50 kJ/mol), compared to the values reported here for similar conditions, were measured at 0.1 bar and at 0.06 bar of feed pressure with the Membrane permeation technique [33]. Corrected diffusivities from [33] were almost equal at these partial pressures, which means that there was no concentration effect observed.…”

“…Corrected diffusivities from [33] were almost equal at these partial pressures, which means that there was no concentration effect observed. Probably, this is due to the partial pressure conditions that were high enough so that the diffusivity did not change much anymore.…”

Positron Emission Profiling: a Study of Hydrocarbon Diffusivity in MFI Zeolites

“…The value of the apparent activation energy for silicalite-1 is also reproduced by other methods such as the ZLC and the square wave methods [73][74][75]. Discrepancies, however, occur with techniques such as membrane permeation and TEOM, that provided somewhat higher values of the activation energy for n-hexane, i.e., 34.7 kJ mol -1 [76] and 38 kJ mol -1 [45], respectively. In the membrane permeation technique very high loadings up to eight molecules per unit cell were used, which may explain the discrepancy.…”