Effect of calcium addition on catalytic ethanol steam reforming of Ni/Al2O3: I. Catalytic stability, electronic properties and coking mechanism

Catherine K.S. Choong, Ziyi Zhong, Lin Huang, Zhan Wang, Thiam Peng Ang, Armando Borgna, Jianyi Lin, Liang Hong*, Luwei Chen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

91 Scopus citations

Abstract

Ca-modified Ni/Al2O3 catalysts with various Ca loadings of 0, 3, 5 and 7 wt% were studied for low temperature catalytic ethanol steam reforming (ESR). Catalyst with 3 wt% of Ca remains stable at 673 K for at least 24 h, while 0 wt%, 5 wt% and 7 wt% Ca modified catalysts deactivate easily. The addition of Ca increases the particle size of active Ni which promotes the formation of un-reactive and encapsulating carbons, undermining the stability of highly loaded (7 wt%) Ca-modified Ni catalyst. XPS valence band shows that the presence of Ca increases the density of Ni 3d band valence electrons which helps in dissociation of methane and deactivates the catalysts, as in the case of nickel catalysts supported on 7 wt% of Ca on Al 2O3. Excellent catalytic performance of 10Ni/3Ca-Al 2O3 is due to the effective coke removal and the amorphous nature of coke deposition. Optimized Ca loading was found to play a critical role in coke removal, through its effect on Ni particle size, valence band of catalyst and steam gasification of coke.

Original languageEnglish
Pages (from-to)145-154
Number of pages10
JournalApplied Catalysis A: General
Volume407
Issue number1-2
DOIs
StatePublished - 4 Nov 2011
Externally publishedYes

Keywords

  • Calcium oxide
  • Coke mechanism
  • Ethanol
  • Nickel catalyst
  • Stability
  • Steam reforming
  • Surface OH groups
  • Water adsorption

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