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Evidence of Intracrystalline Mesostructured Porosity in Zeolites by Advanced Gas Sorption, Electron Tomography and Rotation Electron Diffraction
Author(s) -
GarciaMartinez Javier,
Xiao Changhong,
Cychosz Katie A.,
Li Kunhao,
Wan Wei,
Zou Xiaodong,
Thommes Matthias
Publication year - 2014
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201402499
Subject(s) - mesoporous material , zeolite , selectivity , fluid catalytic cracking , chemical engineering , materials science , catalysis , sorption , porosity , scanning electron microscope , adsorption , coke , chemistry , organic chemistry , composite material , metallurgy , engineering
The small size of micropores (typically <1 nm) in zeolites causes slow diffusion of reactant and product molecules in and out of the pores and negatively impacts the product selectivity of zeolite based catalysts, for example, fluid catalytic cracking (FCC) catalysts. Size‐tailored mesoporosity was introduced into commercial zeolite Y crystals by a simple surfactant‐templating post‐synthetic mesostructuring process. The resulting mesoporous zeolite Y showed significantly improved product selectivity in both laboratory testing and refinery trials. Advanced characterization techniques such as electron tomography, three‐dimensional rotation electron diffraction, and high resolution gas adsorption coupled with hysteresis scanning and density functional theory, unambiguously revealed the intracystalline nature and connectivity of the introduced mesopores. They can be considered as molecular highways that help reactant and product molecules diffuse quickly to and away from the catalytically active sites within the zeolite crystals and, thus, shift the selectivity to favor the production of more of the valuable liquid fuels at reduced yields of coke and unconverted feed.