Controllable synthesis of ZSM-11/ZSM-5 intergrowth zeolite using 1,3-cyclohexanedimethanamine as organic template

Abstract

A new organic template, 1,3-cyclohexanedimethanamine (1,3-CDA), is found to be effective in directing the crystallization of ZSM-11 zeolite. Phase transformation from ZSM-11 to ZSM-5 was observed when varying the molar ratios of OH−/SiO2, Na+/SiO2 and SiO2/Al2O3. ZSM-11/ZSM-5 intergrowth zeolites with ZSM-5 contents from 10 to 100% were synthesized. The structural intergrowth was evidenced by TEM, and its formation may be ascribed to the competition between ZSM-11 and ZSM-5 zeolite in the system. The morphology of zeolite varies with the change of composition of the starting gel. The particle sizes of the products decrease with the increase of 1,3-CDA/SiO2 and Na+/SiO2 ratios. With the increase the OH−/SiO2 ratio, the sizes decrease at first and then increase. Meanwhile, the morphologies change from cross-like aggregates of orthotropic rods to aggregates of nano-rods, and then to irregular bulk crystals. With the decrease of SiO2/Al2O3 ratios from 100 to 40, the particle sizes decrease from 200 to about 50 nm, resulting in the formation of nanosized ZSM-11/ZSM-5 intergrowth zeolite.