Effects of seeding on the fast crystallization of ZSM-11 microspheres with intergrowth morphology and small particle size

摘要

A facile and efficient route toward the synthesis of submicron ZSM-11 with intergrowth morphology and controllable particle size is developed, which is characterized by adding micron ZSM-11 microspheres into a little spot of TBA-contained [(TBA)(2)O/SiO2 = 0.005] gel precursors. By tuning the seed contents and aging period duration at ambient temperature, well crystallized ZSM-11 zeolites with adjustable particle size from 0.2 to 1.0 mu m were obtained. Compared with the micron seed particles, the prepared submicron ZSM-11 exhibited both enhanced external surface area and mesopore volumes. The existence of seed particles was found to provide surface area for the formation of new nuclei, while the aging period benefits the occurrence of nucleation behavior, both of which are responsible for the fast crystallization rate as well as the small particle size of products. Besides homogeneous seeds, heterogeneous seeds, such as ZSM-5 and Y can also do a contribution to accelerate the crystallization rate. It was found that the common building units between ZSM-5 seed and ZSM-11 product are favorable for both the nucleation and crystal growth process, while the locally arranged structure of fragments from Y seed are mainly responsible for the crystal growth.