Research ArticleSURFACE CHEMISTRY

Life and death of a single catalytic cracking particle

Science Advances  03 Apr 2015:
Vol. 1, no. 3, e1400199
DOI: 10.1126/sciadv.1400199

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Abstract

Fluid catalytic cracking (FCC) particles account for 40 to 45% of worldwide gasoline production. The hierarchical complex particle pore structure allows access of long-chain feedstock molecules into active catalyst domains where they are cracked into smaller, more valuable hydrocarbon products (for example, gasoline). In this process, metal deposition and intrusion is a major cause for irreversible catalyst deactivation and shifts in product distribution. We used x-ray nanotomography of industrial FCC particles at differing degrees of deactivation to quantify changes in single-particle macroporosity and pore connectivity, correlated to iron and nickel deposition. Our study reveals that these metals are incorporated almost exclusively in near-surface regions, severely limiting macropore accessibility as metal concentrations increase. Because macropore channels are “highways” of the pore network, blocking them prevents feedstock molecules from reaching the catalytically active domains. Consequently, metal deposition reduces conversion with time on stream because the internal pore volume, although itself unobstructed, becomes largely inaccessible.

Keywords
  • Chemistry
  • Catalysis
  • Catalyst deactivation
  • Fluid Catalytic Cracking
  • Crude Oil Processing
  • X-ray Microscopy
  • Chemical Imaging
  • Metal Poisons
  • Zeolite

This is an open-access article distributed under the terms of the Creative Commons Attribution license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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