Branched growth of ZSM-12 zeolite on seeds

In this work, two ZSM-12 zeolites with stellar morphology and dendritic morphology were synthesized from the synthesis system containing nanorod-aggregated hexagonal prism seed and microrod seed, respectively, in the presence of CTAB. The stellar ZSM-12 zeolite was composed of core and branches, while the dendritic ZSM-12 zeolite consisted of stem and branches. For the two zeolites, the branches grew on {310} planes of seed and were in twin relation with the seed. The c-axes of branch and seed were parallel to each other, while the b-axes of them exhibited the angular relation of 65°. The crystallization process of the two zeolites were investigated by using XRD, SEM, and TEM characterizations. It was demonstrated that the branched growth on seeds was controlled by two factors: diffusion of reactive species and adsorption of CTAB. The Mullins-Sekerka instability occurred under the diffusion-limited condition, resulting in the formation of branches on seed. The adsorption of CTAB on side facets of branches inhibited the occurrence of secondary branching.