(129c) Core-Shell Bulk BEA-Lamellar MFI Composite Prepared in One-Step: Integration of 3D and 2D Zeolites into Hierarchical Structures for Efficient Alkylation Reactions
The synthesis of hierarchical meso-/microporous zeolite materials with spatially controlled morphology, meso-/microporosity, and acidity is an expanding area of research interest for a wide range of applications. Here, we report a one-step dual template synthesis method for integration of 3-dimensional (3D) bulk BEA and 2D lamellar MFI into a new type of core-shell hierarchical meso-/microporous zeolite composite structures. Specifically, the 2D layered MFI nanosheets were laid over the surface of or interdigitated into the 3D microporous BEA particles in the core-shell bulk BEA-lamellar MFI (BBLM) zeolite structure, which generated a unique morphology of interconnected micropores and mesopores underneath the â??skinningâ?? shell (~3-10 nm) of MFI nanosheets. The structure and morphology of the BBLM zeolites were elucidated by a combination of XRD, SEM, TEM, and Ar physisorption techniques. The composition and acidity were identified using ICP, XPS, solid state NMR, organic base titration, and NH3-TPD measurements. The catalysis tests using conversion of benzyl alcohol in mesitylene showed that BBLM zeolites had an excellent activity and durability, which was resulted from the synergistic integration of the hierarchical structures in the BBLM composite. The core-shell BBLM zeolite provides a good model catalyst with integrated 2D-3D structures and meso-/microporosity for studying a series of important catalytic reactions in hierarchical zeolites. The one-step dual template synthesis method described herein is versatile and facile, which may prove to be a general platform for coreâ??shell hierarchical zeolite design with potentially broader applicability to other porous materials.