Relumped single-event microkinetic model for alkane hydrocracking on shape-selective catalysts: catalysis on ZSM-22 pore mouths, bridge acid sites and micropores

Abstract

A relumped single-event microkinetic (SEMK) model is developed to describe alkane hydroconversion on shape-selective Pt-H/ZSM-22. The model, considers n -alkane, mono-, di- and tri-branched alkanes for each carbon number and is developed according to the reaction rules formulated for the molecular SEMK model on ZSM-22. Differences in physisorption and protonation behaviour among the carbenium ions on ZSM-22 are accounted for. Reactions can occur at the pore mouth, bridge and micropore acid sites. Lumping coefficients depend on the type of sites. The calculation of the lumping coefficients is performed using a structural class based method, not requiring the generation of the detailed reaction network. The internal composition of a lump is determined by the physisorption properties of the alkanes belonging to the lump. The hydrocracking of n -C6 to n -C18 alkanes is described adequately over a wide range of conversions.