Three-dimensional 10-ring zeolites: The activities in toluene alkylation and disproportionation

• Series of 10-ring zeolites was synthesized and deeply characterized.
• Selectivity into para-isomers in toluene alkylation and disproportionation was related to diffusion of 2,2-dimethylbutane.
• Presence of 12-rings in zeolite *SFV was found decisive for low para-selectivity of this zeolite.

Three-dimensional 10-ring zeolites TUN, IMF, –SVR, MFI and MEL were investigated as for their acid properties, adsorption of 2,2-dimethylbutane and in toluene disproportionation and its alkylation with isopropyl alcohol. The results were compared against zeolite *SFV, the structure of which consists mainly of MEL zeolite with some additional 12-ring channel system. With exception of –SVR synthesized with high Si/Al ratio, all other zeolites provided Si/Al ratios in a narrow region. Novel zeolites TUN, IMF, and –SVR exhibited higher conversions than MFI and MEL in toluene alkylation. TUN and IMF were substantially more active in toluene disproportionation indicating less diffusion restrictions of channel structure on the disproportionation reaction. *SFV showed a similar catalytic behavior to MEL with much lower selectivity to p-xylene and p-cymene. This could indicate that both toluene disproportionation and alkylation proceed in reaction space of *SFV being similar to those of MFI and MEL. *SFV and TUN exhibited much faster adsorption of 2,2-dimethylbutane than MFI, MEL, IMF, and –SVR. It was concluded that the presence of some larger transport pores in *SFV than in other zeolites is responsible for fast adsorption of 2,2-dimethylbutane and transport of products resulting in a low selectivity to p-xylene and p-cymene.

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