Seed-induced and additive-free synthesis of oriented nanorod-assembled meso/macroporous zeolites: toward efficient and cost-effective catalysts for the MTA reaction

摘要

We reported a general seed-induced strategy for the synthesis of both meso/macroporous ZSM-5 and ZSM-11 (denoted as N-ZSM-5 and N-ZSM-11, respectively) under additive-free, low template/SiO2 ratio (from 0.011 to 0.0014) and seed-assisted hydrothermal conditions. It was found that both N-ZSM-5 and N-ZSM-11 were primarily composed of 20-50 nm oriented nanorods, which showed excellent physicochemical properties, such as high crystallinity, large surface area, auxiliary meso/macroporous structures, and uniform size. When being used in the methanol-to-aromatics reaction (MTA), both Zn/N-ZSM-5 and Zn/N-ZSM-11 exhibited high catalytic efficiencies, as reflected by their far longer lifetimes and higher selectivities for total aromatics than conventional Zn/ZSM-5 and Zn/ZSM-11, due to their unique meso/macroporous structure and ultra-small crystal size that resulted in substantial improvements in the mass-transport properties. This seed-induced strategy inspires new ideas for the design and fabrication of oriented nanorod-assembled hierarchical zeolites with lower cost and good catalytic performance.