A DNP-supported solid-state NMR study of carbon species in fluid catalytic cracking catalysts.
A combination of solid-state NMR techniques supported by EPR and SEM-EDX experiments was used to localize different carbon species (coke) in commercial fluid catalytic cracking catalysts. Aliphatic coke species formed during the catalytic process and aromatic coke species deposited directly from the feedstock respond differently to dynamic nuclear polarization signal enhancement in integral and crushed FCC particles, indicating that aromatic species are mostly concentrated on the outside of the catalyst particles, whereas aliphatic species are also located on the inside of the FCC particles. The comparison of solid-state NMR data with and without the DNP radical at low and ambient temperature suggests the proximity between aromatic carbon deposits and metals (mostly iron) on the catalyst surface. These findings potentially indicate that coke and iron deposit together, or that iron has a role in the formation of aromatic coke.
NMR Spectroscopy, Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands. m.baldus@uu.nl.
Deni
D
Mance
NMR Spectroscopy, Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands. m.baldus@uu.nl.
Johan
J
van der Zwan
Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands. e.t.c.vogt@uu.nl.
Marjolein E Z
ME
Velthoen
Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands. e.t.c.vogt@uu.nl.
Florian
F
Meirer
Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands. e.t.c.vogt@uu.nl.
Bert M
http://orcid.org/0000-0001-5245-1426
BM
Weckhuysen
NMR Spectroscopy, Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands. m.baldus@uu.nl.
Marc
M
Baldus
Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands. e.t.c.vogt@uu.nl and Albemarle Catalysts Company BV, Research Center Amsterdam, PO box 37650, 1030 BE Amsterdam, The Netherlands.
Eelco T C
http://orcid.org/0000-0003-4556-4283
ET
Vogt