Comparison of catalytic consequences of ionic liquid-templated ZSM-22 and ZSM-5 zeolites in propene dimerization

The ionic liquid-templated TON- and MFI-type zeolites having 10-membered rings were synthesized and their catalytic performances on propene dimerization were studied. The comparable acid site strength among TON- or MFI-type zeolites accounted for the nearly identical propene dimerization turnover rates despite their different Si/Al ratios. At the low propene conversion (<5%), the TON- and MFI-type zeolites (with a Si/Al ratio of 30-120) obtained a dimer selectivity of over 70% and less than 42%, respectively. The different channel structures and acid properties of zeolite were responsible for the different catalytic selectivity in TON- and MFI-type zeolites. Compared to MFI zeolite, TON with a smaller void size was much more suitable for stabilizing the transition states and intermediates for dimers under the reaction conditions. In addition, a three-stage and a three-in-one dimerization reaction pathways were proposed for the ZSM-22 and ZSM-5 zeolites, respectively.

Automated summary

In this study, TON- and MFI-type zeolites with 10-membered rings were synthesized using ionic liquid-templating method. Their catalytic performances in propene dimerization were investigated. Despite different Si/Al ratios, the TON- and MFI-type zeolites showed comparable propene dimerization turnover rates due to their similar acid site strength. The different channel structures and acid properties of zeolite were responsible for the variation in catalytic selectivity between TON- and MFI-type zeolites.