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Understanding Support Effects of ZnO‐Promoted Co Catalysts for Syngas Conversion to Alcohols Using Atomic Layer Deposition
Author(s) -
Nathan Sindhu S.,
Asundi Arun S.,
Singh Joseph A.,
Hoffman Adam S.,
Boubnov Alexey,
Hong Jiyun,
Bare Simon R.,
Bent Stacey F.
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.202001630
Subject(s) - catalysis , syngas , oxygenate , chemical engineering , cobalt , fischer–tropsch process , carbon fibers , atomic layer deposition , chemistry , heterogeneous catalysis , selectivity , inorganic chemistry , xanes , carbon monoxide , catalyst support , deposition (geology) , layer (electronics) , materials science , organic chemistry , composite number , engineering , composite material , paleontology , physics , quantum mechanics , sediment , spectroscopy , biology
Co 2 C, an emerging catalyst for the conversion of syngas to oxygenates, shows support‐sensitive behavior that has not yet been fully explained. Here, we characterize Co catalysts modified with ZnO atomic layer deposition on SiO 2 , carbon, CeO 2 , and Al 2 O 3 supports. We find that under syngas conditions, ZnO‐promoted Co transforms into Co 2 C on SiO 2 , carbon, and CeO 2 , but not on Al 2 O 3 . Moreover, the support affects the extent of carburization: while the SiO 2 ‐supported catalyst carburizes completely, carbon‐ and CeO 2 ‐supported catalysts show incomplete conversion of Co to Co 2 C. These three catalysts also exhibit different oxygenate selectivities. In contrast, the modified Al 2 O 3 ‐supported catalyst retains the Fischer‐Tropsch catalytic properties of metallic Co. By depositing increasing amounts of Al 2 O 3 by ALD on the SiO 2 support, decreasing Co 2 C formation and oxygenate selectivity occurs. In‐situ XANES reveals that Al 2 O 3 prevents Co 2 C formation by enabling the ZnO to restructure into ZnAl 2 O 4 during reduction. Thus, in addition to modifying the active catalyst phase, the promoter can also strongly interact with the support, significantly impacting catalyst performance.