Ketenes in the Induction of the Methanol‐to‐Olefins Process

Ketene (CH(2)=C=O) has been postulated as a key intermediate for the first olefin production in the zeolite‐catalyzed chemistry of methanol‐to‐olefins (MTO) and syngas‐to‐olefins (STO) processes. The reaction mechanism remains elusive, because the short‐lived ethenone ketene and its derivatives are difficult to detect, which is further complicated by the low expected ketene concentration. We report on the experimental detection of methylketene (CH(3)−CH=C=O) formed by the methylation of ketene on HZSM‐5 via operando synchrotron photoelectron photoion coincidence (PEPICO) spectroscopy. Ketene is produced in situ from methyl acetate. The observation of methylketene as the ethylene precursor evidences a computationally predicted ketene‐to‐ethylene route proceeding via a methylketene intermediate followed by decarbonylation.