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Catalyst Deactivation by Carbon Deposition: The Remarkable Case of Nickel Confined by Atomic Layer Deposition
Author(s) -
Afzal Shaik,
Prakash Anuj,
Littlewood Patrick,
Choudhury Hanif,
Khan Ghouri Zafar,
Mansour Said,
Wang Dingdi,
Marks Tobin,
Weitz Eric,
Stair Peter,
Elbashir Nimir
Publication year - 2021
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.202100109
Subject(s) - catalysis , atomic layer deposition , nickel , carbon fibers , chemical engineering , amorphous carbon , raman spectroscopy , deposition (geology) , materials science , coke , hydrocarbon , crystallization , layer (electronics) , chemistry , inorganic chemistry , amorphous solid , nanotechnology , organic chemistry , metallurgy , composite material , composite number , optics , sediment , engineering , biology , paleontology , physics
In hydrocarbon reforming processes, coke formation on the catalyst usually reduces reaction rates. We show that when subjected to thermal treatment, a commercial nickel catalyst, overcoated with alumina, ALD exhibited both higher activity per g Ni and higher carbon formation rates than an uncoated catalyst. During the temperature‐programmed reaction in a CH 4 +CO 2 atmosphere, the uncoated catalyst deactivated rapidly from carbon buildup, but the overcoated catalyst displayed an increase in catalytic activity per g Ni, despite generating two times the surface carbon. The unexpected phenomenon was investigated via TEM/EDS, TGA/DSC, SEM, XRD and Raman spectroscopy. We hypothesize that this may be due to (a) formation of a thicker than expected ‘quasi‐ALD’ overcoat of amorphous alumina, (b) crystallization of ALD overcoat into nanofibers that act as secondary supports for migrating Ni, and (c) the ability of ALD overcoat to isolate carbon as carbon nano‐onions (CNOs).