Catalyst Deactivation by Carbon Deposition: The Remarkable Case of Nickel Confined by Atomic Layer Deposition

Shaik Afzal, Anuj Prakash, Patrick Littlewood, Hanif Choudhury, Zafar Khan Ghouri, Said Mansour, Dingdi Wang, Tobin Marks, Eric Weitz, Peter Stair, Nimir Elbashir*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

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).

Original languageEnglish (US)
Pages (from-to)2988-3000
Number of pages13
JournalChemCatChem
Volume13
Issue number13
DOIs
StatePublished - Jul 7 2021

Keywords

  • Atomic layer deposition
  • DRM
  • alumina nanofibers
  • carbon nano onions
  • deactivation

ASJC Scopus subject areas

  • Catalysis
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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