The role of methoxy groups in methanol to olefin conversion

In a methanol-to-olefin conversion mechanism (MTO) study, by using zeolite ZSM-22's one-dimensional channels to exclude the hydrocarbon pool mechanism as well as secondary reactions, we found very low olefin yield during an extended reaction time under normal MTO conditions. More significantly, no H/D exchange between the acidic proton and the hydrogen atoms on methoxy groups was observed, even at elevated temperatures as high as 500 °C, suggesting no C - H activation for methoxy groups under normal MTO reaction conditions. In comparison, substantial H/D exchange was found on ethoxy groups. These results confirmed that methoxy groups are energetically not favored to form C - C bonds directly.