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Keywords:

  • cracking;
  • zeolites;
  • nanostructures;
  • hydrothermal synthesis;
  • mesoporous materials

Abstract

A hierarchical ZSM-5 zeolite with a bimodal meso-microporous system, high crystallinity, and a large surface area and meso-micropore volume was successfully synthesized from a natural layered aluminosilicate mineral rectorite without using a secondary mesoscale template. The physicochemical and catalytic properties of the hierarchical ZSM-5 zeolite were extensively characterized. The results showed that the mesopores of the synthesized hierarchical ZSM-5, which are almost slitlike intercrystal pores, originate from the construction of primary nanorods of the ZSM-5 zeolite. Analysis of the crystallization process revealed that the undissolved rectorite debris acted as seed crystals and played a structure-directing role, which is the key factor that influences the formation of the hierarchical structure. Such a hierarchical ZSM-5 zeolite, as a result of its unique structural characteristics and increased accessibility of acid sites, possessed a remarkably enhanced activity for the cracking of 1,3,5-triisopropylbenzene, a dramatically higher anti-deactivation ability for cumene conversion, and a significantly improved propylene-boosting performance for heavy oil cracking than the other catalysts tested.