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Abstract Hierarchical lamellar zeolites, comprised of both micro- and mesoporosity, afford high active site accessibility and mass transport in processing of bulky molecules. Here, we report the synthesis of hierarchical lamellar MFI zeolites with sequential intergrowth that is induced by composition variation in the standard recipe of 100SiO 2 /0.5Al 2 O 3 /3C 22-6-6 /18.5Na 2 O/4000H 2 O, where C 22-6-6 stands for the diquaternary ammonium surfactant ([C 22 H 45 N+(CH 3) 2 C 6 H 12 N+(CH 3) 2 C 6 H 13 ]Br− 2) template. The influences of C 22-6-6 concentration, alkalinity, and aluminum amount on the intergrowth of hierarchical lamellar MFI zeolites were investigated. The consequences of intergrowth on mesoporosity were analyzed. In all studied synthesis conditions except for very low alkalinity, hierarchical lamellar MFI zeolites were successfully crystallized. The increasing template concentration in the synthesis gel resulted in an increase in intergrowth and thus mesoporsotiy in the hierarchical MFI products. The increasing alkalinity led to an increase and then a decrease in mesoporosity in the hierarchical MFI products, which reflects the same trend in intergrowth in the hydrothermal synthesis process. The aluminum concentration, however, did not significantly affect the intergrowth and mesoporosity of the resultant hierarchical MFI zeolites. The sequential intergrowth achieved by simple variation in the synthesis composition for lamellar MFI zeolites resulted in higher structure hierarchy, mesoporosity, and acid site accessibility in one-step. Graphical abstract Image 1 Highlights • Hierarchical lamellar MFI zeolites were synthesized in one-step. • Intergrowth enhanced mesoporosity in hierarchical lamellar MFI zeolites. • Intergrowth increased with increasing surfactant template content in synthetic gel. • Intergrowth increased and then decreased with alkalinity in synthetic gel. • Aluminum content in synthetic gel did not influence intergrowth noticeably. [ABSTRACT FROM AUTHOR]

The combination of two compositionally and/or structurally different zeolites into one single zeolite composite particle is a potential approach to integrate advantages of different zeolite structures for desirable properties and applications. In the present study, we report the overgrowth of lamellar mesoporous silicalite-1 on the commercial microporous MFI and BEA zeolites, respectively, to render hierarchical meso-/microporous lamellar silicalite-1/MFI (L-Si/MFI) and lamellar silicalite-1/BEA (L-Si/BEA) zeolite composites via hydrothermal crystallization of lamellar silicalite-1 with the assistance of a diquaternary ammonium template. Epitaxial growth of lamellar silicalite-1 on commercial bulk MFI was observed, resulting in the L-Si/MFI zeolite composite as porcupine sensory message ball with nerve-stimulating silicalite-1 bumps extended from the MFI particle. In the L-Si/BEA zeolite composite, the lamellar silicalite-1 was laid over the surface of or partially interdigitated into the commercial bulk BEA particle, forming a BEA nanosponge structure connected to lamellar silicalite-1 nanosheets. The resultant interconnected micro- and mesoporosity in the L-Si/MFI and L-Si/BEA composite zeolites allowed facile mass transport of bulky molecules. The acid sites sitting on the external surface of commercial MFI and BEA zeolites were partially passivated by the lamellar silicalite-1. The consequences of improved mass transport and passivation of external acid sites on the catalytic performance of these zeolite composites were tested in 2 wt% molybdenum (Mo) loaded L-Si/MFI and L-Si/BEA for direct non-oxidative methane aromatization reaction, which showed higher methane conversion and hydrocarbon product formation as well as higher selectivity to naphthalene and coke in comparison with 2 wt% Mo-loaded commercial MFI and BEA catalysts. [ABSTRACT FROM AUTHOR]