Role of Acetaldehyde in the Roadmap from Initial Carbon-Carbon Bonds to Hydrocarbons during Methanol Conversion

The formation of the initial carbon-carbon (C-C) bonds in the methanol-to-hydrocarbon (MTH) conversion on acidic zeolite has been hotly debated for decades. Recently, the formation of surface-bound acetyl groups involving C-C bonds during the initial period of the MTH conversion has been disclosed. Understanding the exact C-C bond-containing intermediates triggering the MTH conversion and the critical roadmap of the MTH conversion is essential for the further development of this important reaction. Herein, acetaldehyde from the hydrogenation of surface-bound acetyl species was identified to be responsible for triggering the MTH conversion on H-ZSM-5 zeolite. By combining kinetic studies, spectroscopic analyses, and theoretical calculations, the mechanism and roadmap of zeolite-catalyzed MTH conversion from the initial C-C bonds to the hydrocarbon pool compounds were clearly depicted.