Influence of zeolite confinement effects on cation-π interactions in methanol-to-hydrocarbon conversion.

By using 2D 13C-13C correlation MAS NMR spectroscopy and DFT calculations, the nature of cation-π interactions between cyclopentenyl cations and benzene was clarified over H-ZSM-5, H-β and H-SSZ-13 zeolites. The cation-π interactions are favored over H-β and H-SSZ-13 with large channels or cages. The zeolite structure is identified to affect the arrangements of cyclopentenyl cations and benzene in the confined environment, leading to different extents of overlapping of positive-negative charge centers and cation-π interaction strength. The stronger cation-π interactions facilitate the bimolecular reactions between cyclopentenyl cations and benzene and the formation of coke species.