Identifying a bi-molecular synergetic adsorption mechanism for catalytic transformation of ethanol/acetaldehyde into 1,3-butadiene

The catalytic synthesis of 1,3-butadiene (1,3-BD) from bio-based ethanol offers an alternative and sustainable process beyond petroleum. However, the intrinsic active sites and corresponding mechanism of 1,3-BD formation have not been fully elucidated yet. By correlating systematic characterization results with catalytic performance, the open Zr species, i.e., Zr(OH)(OSi)₃ moieties, were identified as the active site over the Zr/MFI-BM catalysts for the catalytic transformation of ethanol-acetaldehyde into 1,3-BD. In conjunction with controlled experiments and theory calculations, ethanol and acetaldehyde are proposed to synergistically co-adsorb on the Zr(OH)(OSi)₃ species in a bi-molecular mode, which assists the acetaldehyde condensation and accelerates the critical Meerwein-Ponndorf-Verley-Oppenauer reduction, and accordingly promotes 1,3-BD formation. These findings will stimulate the search towards new metal-zeolite combinations for efficient production of value-added 1,3-BD via biomass-derived ethanol and beyond.