Synthesis of Wool-Ball-Like ZSM-5 with Enlarged External Surfaces and Improved Diffusion: A Potential Highly-Efficient FCC Catalyst Component for Elevating Pre-cracking of Large Molecules and Catalytic Longevity

A hierarchical ZSM-5 zeolite composed of nano-sized MFI zeolite crystals was synthesized without using secondary template by a traditional hydrothermal procedure. The as-synthesized hierarchical ZSM-5 and a reference catalyst were both characterized by XRD, SEM, FT-IR, in situ infrared (IR) spectrometry of pyridine, NH3-TPD, N2 adsorption–desorption, intelligent gravimetric analyzer, and by thermogravimetry analyses. After examining and comparing the results, it is discovered that the hierarchical ZSM-5 catalyst displays excellent catalytic performance with an improved conversion of isopropylbenzene and a longer catalytic life because of its dramatically enlarged external surfaces. The results also display that the shortened diffusion path length contributes to enhancing the stability of the hierarchical catalyst by depressing the coking deposit during the catalytic cracking of n-octane. A wool-ball-like zeolite composed of nano-sized MFI crystals was synthesized without a secondary template by the traditional hydrothermal procedure. Nanocrystallization of crystal particles in the hierarchical ZSM-5 zeolite gives the catalyst an improved diffusion and a dramatically enhanced external surface which contributes to elevating pre-cracking of large molecules and catalytic longevity, and to offering a potential and high-efficiency FCC catalyst component.