AbstractThe kinetics of physical adsorption of propane from helium on fixed beds of activated alumina at 30°C. and at atmospheric pressure was studied. Two grades of activated alumina with the same average pore size distribution but different pore size distributions were used. Gas concentration, flow rate, and adsorbent particle size were also varied. The rate of internal diffusion controlled the adsorption process and was best described by Ficks' equation for unsteady state diffusion into a sphere. The internal diffusion appeared to be by a pore diffusion rather than by a surface diffusion mechanism