Directly transforming as-synthesized MCM-41 to mesoporous MFI zeolite

Abstract

Mesoporous MFI zeolite is fabricated through impregnating a structure-directing agent into as-synthesized MCM-41 followed by dry-gel conversion to transform amorphous silica to zeolite crystal. The original surfactant in the as-synthesized MCM-41 is used as the necessary mesoporogen to direct the mesopore genesis of zeolites, using the process of streaming to spur the transformation and tailoring the texture of mesoporous ZSM-5 by adjusting the Si : Al ratio in the MCM-41 source. The resulting sample is characterized by X-ray diffraction, IR spectroscopy, TEM and N₂ adsorption to evaluate the textural properties of the mesoporous zeolite. Two kinds of nitrosamines with different structures are used as probe molecules to survey the adsorption function of the resulting mesoporous zeolite. Mesoporous zeolites exhibit good adsorption capacities and exceed either microporous zeolite or mesoporous silica. This synthesis strategy omits the fabrication and removal of the carbon template and simplifies the synthesis process of mesoporous zeolites, saving energy and time.