First molecule with carbon–carbon bond in methanol-to-olefins process

[Display omitted] •A detailed resolution for framework O site about CHA type zeolite H-SAPO-34 is made.•A new first CC bond formation manner generating ketene for MTO process is proposed.•Barrier of ketene formation is much lower than other CC coupling mechanisms. We report a theoretical investigation of the initiation reactions of methanol to olefins (MTO) process, where we study the detailed reaction mechanism from methanol to ketene. These reactions catalyzed by zeolite H-SAPO-34 are investigated by periodic density functional theory method. Our results demonstrate that carbon monoxide interacts with surface methoxy species to form ketene containing the first carbon–carbon bond is more favorable than other reported carbon–carbon coupling mechanisms. This study gives a new insight into the type of reaction intermediate—ketene, as well as the first carbon–carbon bond formation during the MTO process.