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.
journal_name
Sci Advjournal_title
Science advancesauthors
Meirer F,Kalirai S,Morris D,Soparawalla S,Liu Y,Mesu G,Andrews JC,Weckhuysen BMdoi
10.1126/sciadv.1400199subject
Has Abstractpub_date
2015-04-03 00:00:00pages
e1400199issue
3issn
2375-2548pii
1400199journal_volume
1pub_type
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