Optimizing the accessibility of zeolite Y on FCC catalyst to improve heavy oil conversion capacity

Optimizing the accessibility of zeolite Y, the main active component in fluid catalytic cracking (FCC) catalyst, is a crucial strategy to improve the heavy oil cracking performance of FCC catalysts. Four FCC catalysts with different Y zeolite content were prepared via in-situ crystallization method by adjusting the crystallization time. The distribution characteristics of the Y zeolite in in-situ crystallized catalysts have been characterized by scanning electron microscopy (SEM), laser confocal fluorescence microscopy and high-resolution field emission scanning electron microscopy (HR-FESEM). A unique structural feature of the FCC catalysts has been achieved, with the Y zeolite component mainly distributing in the outer layer of microspheres. The results of adsorption rate of macromolecule probes reveal that the appropriate zeolite layer thickness and topology were beneficial to the mass transfer performance and acid accessibility of FCC catalyst. The effective utilization ratios of zeolite in the novel FCC catalysts for heavy oil cracking on advanced catalyst equipment (ACE) is in good correspondence with the mass transfer performance of macromolecules and the accessibility of acid sites. It could be confirmed that the excellent heavy oil conversion performance of a FCC catalyst does not depend on the content of zeolite, but rather on the distribution characteristics are in favor of the accessibility of zeolite components.