Pt/H-ZSM-22 hydroisomerization catalysts optimization guided by Single-Event MicroKinetic modeling

A Single-Event MicroKinetic (SEMK) model for hydroconversion of decane over bifunctional Pt/H-ZSM-22 zeolite catalysts is constructed. A distinction is made between acid sites at micropore mouths, inside micropores, and at bridges between micropore mouths. The catalyst descriptors used for the SEMK model are as follows: the concentrations of the acid sites and the corresponding physisorption and protonation enthalpies of the reacting molecules. The SEMK model indicates that the hydroisomerization yield can be enhanced by elimination of strong acid sites from the micropores. The acid strength of the investigated catalyst was found to be dependent on the way the 1,6-diaminohexane template used in the crystallization is removed. ZSM-22 samples with strongest acidity were obtained via calcination at 823 K followed by ammonium exchange. Weaker acidity was obtained according to the SEMK model when the template was removed via cation exchange against ammonium. The resulting Pt/H-ZSM-22 catalyst exhibited a 10% higher maximum isomerization yield.