Synthesis of a hierarchically macro-/mesoporous zeolite based on a micro-emulsion mechanism

A new type of hierarchically porous ZSM-5-type zeolite, Hp-ZSM, with well defined macro-/meso-/microporous structures was facilely synthesized via a simple steam-assisted conversion route in the presence of ethanol. This novel material exhibits a tri-modal porous structure: a macroporous network with macropore sizes of 50-200 nm; a well defined mesoporous structure of pore size around 2.5 nm in the macroporous framework and a typical microporous ZSM-5 structure in the mesoporous framework. A micro-emulsion mechanism was proposed for the formation of the macroporosity where ethanol is assumed to form 'oil' droplets in the water phase in the presence of surfactants.