Direct observation of olefin homologations on zeolite ZSM-22 and its implications to methanol to olefin conversion

In this paper, we studied olefin homologation reactions on zeolite ZSM-22, whose one dimensional pore structure inhibited the hydrocarbon pool mechanism and secondary reactions of the methanol to olefin (MTO) conversion. Homologation of ethylene, propylene and styrene were directly observed between ¹³C labeled methanol and olefins. Isotopic tracking shows high selectivity for homologation reaction, e.g. from ethylene, propene has one ¹³C atom, butene has two ¹³C atoms, and pentene has three ¹³C atoms. Homologation of styrene's side chain also showed very specific isotopic pattern. The role of olefin homologation is speculated as a key reaction during the induction time of MTO process.