Jr. Hufton et Dm. Ruthven, DIFFUSION OF LIGHT ALKANES IN SILICALITE STUDIED BY THE ZERO LENGTH COLUMN METHOD, Industrial & engineering chemistry research, 32(10), 1993, pp. 2379-2386
Micropore diffusion coefficients for propane, n-butane, and isobutane
in three samples of silicalite crystals were measured by the zero leng
th column (ZLC) method. Experiments were analyzed by the traditional l
ong-time approach and by a new short-time method. For isobutane, micro
pore diffusion coefficients obtained from all three samples by both an
alysis methods agreed well with previously reported chromatographic an
d membrane measurements. For the linear alkanes, the rate of micropore
diffusion, even in the largest crystals (350 x 100 mum), was too fast
for reliable measurement and the form of the ZLC response curves was
consistent with equilibrium control. Taken as a lower limit, the appar
ent diffusion coefficients obtained for propane and n-butane are consi
stent with the results of microscopic experiments and recent chromatog
raphic and frequency response studies.