Diffusion of methane, n-butane, n-hexane, isobutane and 3-methylpentane in ZSM-5 supported membranes was studied from ambient to 723K. The Maxwell–Stefan equations were used for the interpretation of the results. From these, micropore diffusion coefficients and apparent diffusion activation energies were obtained. The results (table 63) were described by:

methane:     D(m2/s) = 3.8 x 10-8exp[-4.3(kJ/mol)/RT]

n-butane:     D(m2/s) = 8.7 x 10-9exp[-11.7(kJ/mol)/RT]

n-hexane:     D(m2/s) = 6.0 x 10-7exp[-34.7(kJ/mol)/RT]

isobutane:     D(m2/s) = 3.6 x 10-8exp[-31.2(kJ/mol)/RT]

3-methylpentane:     D(m2/s) = 4.7 x 10-7exp[-50.0(kJ/mol)/RT]

For the light linear and branched alkanes (C1, C4), the literature data obtained using macroscopic or microscopic techniques or molecular dynamics simulations were in close agreement. For n-hexane, however, the literature data exhibited marked discrepancies. The present diffusivities agreed only with reported macroscopic data. In the case of 3-methylpentane, the present diffusivities were in close agreement with macroscopic literature data, but the agreement with microscopic results was limited.

Permeation of Linear and Branched Alkanes in ZSM-5 Supported Membranes. B.Millot, A.Méthivier, H.Jobic, H.Moueddeb, J.A.Dalmon: Microporous and Mesoporous Materials, 2000, 38[1], 85–95

Table 63

Diffusion in ZSM-5 Zeolite

continued

Table 63 (continued)

Diffusion in ZSM-5 Zeolite