Impact of the BEA zeolite morphology on isobutane adsorption followed by Reversed-Flow Inverse Gas Chromatography

The mass transfer phenomena of isobutane (i-C4) were investigated at 343 K on three protonic BEA zeolites. Defined by their crystallites sizes and degrees of aggregation, these samples were characterized by Reversed-Flow Inverse Gas Chromatography (RF-GC). This simple technique, used in conjunction with numerical computation, allowed the determination of physicochemical quantities like local monolayer capacities, probability density functions and diffusion coefficients in a time-resolved way. This study enabled to conclude that the effective diffusion coefficient was affected by the size of the zeolite agglomerate whereas the surface diffusion depended on the zeolite crystallite size.