Mass transfer of alkanes in zeolite packed-bed reactors studied with positron emision profiling. 2. Modeling

A model for mass transport in biporous packed beds was used to simulate axial concentration profiles of n-hexane measured with positron emission profiling (PEP). Axial dispersion dominated the mass transport behavior in the medium-pore zeolites H-mordenite and H-ZSM-5. Comparison of simulations of experiments using the small-pore zeolites (i.e., H-ZSM-22 and H-ferrierite) shows that micropore diffusion limitation contributes significantly to the peak width of the PEP profiles. As a result, new micropore diffusion constants for H-ZSM-22 and H-ferrierite are reported. The prospects for studying the reaction kinetics of the hydroisomerization reaction of alkanes is discussed