ZSM-5@MCM-41 composite porous materials with a core-shell structure: Adjustment of mesoporous orientation basing on interfacial electrostatic interactions and their application in selective aromatics transport

A series of hierarchically porous materials with core-shell structures have been successfully fabricated through a modified Stöber method. The interfacial growth of mesoporous silica with adjustable mesochannel orientation on the surface of ZSM-5 nanocrystal results in the formation of a core-shell structure. The zeta potentials of ZSM-5 nanocrystals have been carefully adjusted through interfacial assembly with a certain amount of anionic surfactants, thus inducing different electrostatic interactions with positively charged cetyltrimethylammonium bromide micelles. The alignment of the outer silicate mesopores around the ZSM-5 nanocrystals transforms from parallel into vertical relative to the zeolite surface, so that the orientation effect of interfacial interactions is experimentally confirmed to be effective in the epitaxial growth of mesoporous shell on the surface of nano-zeolite. The adsorption capacities of the composite porous materials have been dramatically improved after the epitaxial growth of mesoporous shells. Moreover, the materials demonstrate different diffusion efficiencies for organic molecules on the basis of their mesochannel alignments.