The transient time-lag method was applied to the determination and modeling of global coefficients for CO2 and C2H6 diffusion through a composite MFI cylindrical membrane. The results were described by:

CO2:     D(m2/s) = 1.68 x 10-8exp[-13.6(kJ/mol)/RT]

C2H6:     D(m2/s) = 2.26 x 10-8exp[-13.8(kJ/mol)/RT]

The developed equations were used for the estimation of global apparent diffusion coefficients, including the Knudsen-like diffusion through intercrystalline holes and intracrystalline microporous diffusion.

The Application of Transient Time-Lag Method for the Diffusion Coefficient Estimation on Zeolite Composite Membranes. J.Sanchez, C.L.Gı̂jiu, V.Hynek, O.Muntean, A.Julbe: Separation and Purification Technology, 2001, 25[1–3], 467–74

Figure 11

Diffusivity in MFI Zeolite at 500C as a Function

of the Kinetic Diameter of the Diffusant