MASS-TRANSFER OF ALKANES IN ZEOLITE PACKED-BED REACTORS STUDIED WITH POSITRON EMISSION PROFILING - 2 - MODELING

A model for mass transport in biporous packed beds was used to simulat e axial concentration profiles of n-hexane measured with positron emis sion profiling (PEP). Axial dispersion dominated the mass transport be havior 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 con tributes significantly to the peak width of the PEP profiles. As a res ult, new micropore diffusion constants for H-ZSM-22 and H-ferrierite a re reported. The prospects for studying the reaction kinetics of the h ydroisomerization reaction of alkanes is discussed.