Direct synthesis of hierarchical zeolites through mesoporous 3D wormhole framework using single-head quaternary ammonium salt as structure-directing agent

Abstract Hierarchical aluminosilicate zeolites with uniform mesoporosity were successfully synthesized by one-stage crystallization under constant temperature with a novel single-head quaternary ammonium salt ([C 18 H 37 –N + (CH 3 ) 2 –C 6 H 12 –N(CH 3 ) 2 ]Br − ) as mesoporogen and structure-directing agent (SDA). Through precisely controlling the molar ratio of Si/Al and synthetic time, the mesoporous 3D wormhole framework (MCM-48) and crystalline microporous MFI structure were simultaneously constructed, revealed by a series of in-depth characteristic studies. Combining the advantages of the significantly improved diffusion from the mesoporous MCM-48 and the strong framework acidity of the crystalline microporous MFI zeolite, the hierarchical aluminosilicate zeolites exhibited outstanding catalytic activity with good reusability towards bulky aldol condensation compared with the conventional meso- or microporous zeolites. Graphical abstract