A Mechanistic Basis for the Effects of Crystallite Size on Light Olefin Selectivity in Methanol to Hydrocarbons Conversion on MFI

Light olefin selectivity in methanol-to-hydrocarbons conversion on MFI increases with an increase in the crystallite size of MFI because intra-crystalline residence time of methylbenzenes increases as a consequence of increased transport restrictions, which enables these methylbenzenes to undergo multiple methylation/dealkylation reaction cycles before exiting the crystal.