TY - JOUR
T1 - Catalyst Deactivation by Carbon Deposition
T2 - The Remarkable Case of Nickel Confined by Atomic Layer Deposition
AU - Afzal, Shaik
AU - Prakash, Anuj
AU - Littlewood, Patrick
AU - Choudhury, Hanif
AU - Khan Ghouri, Zafar
AU - Mansour, Said
AU - Wang, Dingdi
AU - Marks, Tobin
AU - Weitz, Eric
AU - Stair, Peter
AU - Elbashir, Nimir
N1 - Publisher Copyright:
© 2021 Wiley-VCH GmbH.
PY - 2021/7/7
Y1 - 2021/7/7
N2 - 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 CH4+CO2 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).
AB - 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 CH4+CO2 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).
KW - Atomic layer deposition
KW - DRM
KW - alumina nanofibers
KW - carbon nano onions
KW - deactivation
UR - http://www.scopus.com/inward/record.url?scp=85103380475&partnerID=8YFLogxK
U2 - 10.1002/cctc.202100109
DO - 10.1002/cctc.202100109
M3 - Article
AN - SCOPUS:85103380475
SN - 1867-3880
VL - 13
SP - 2988
EP - 3000
JO - ChemCatChem
JF - ChemCatChem
IS - 13
ER -