Stabilizing Supported Ni Catalysts for Dry Reforming of Methane by Combined La Doping and Al Overcoating Using Atomic Layer Deposition

Sol Ahn, Patrick Littlewood, Yiqi Liu, Tobin J. Marks, Peter C. Stair

Research output: Contribution to journalArticlepeer-review

Abstract

Deposition of La2O3and Al2O3on Al2O3-supported Ni catalysts was performed to study their effects on heterogeneous catalysts for the dry reforming of methane (DRM) reaction. An alumina-supported Ni catalyst (Ni/Al2O3, 2 wt % of Ni), synthesized via incipient wetness impregnation, loses ∼87% of its initial activity within 45 h under DRM conditions. While overcoating of Al2O3on this catalyst via atomic layer deposition (ALD) helps stabilize the catalytic activity in long time-on-stream (TOS) tests, this overcoated catalyst is ca. 40 times less active than the uncoated catalyst at peak activity. This Al2O3-overcoated Ni/Al2O3catalyst also exhibits a long induction period (∼20 h) due to the slow reduction of Ni2+within the catalytically inactive nickel aluminate (NiAl2O4) phase, formed by the interaction of metallic Ni with the Al2O3overcoat during pre-DRM treatment at the 700 °C reaction temperature. Here, we report that, while doping small amounts of La (∼0.03 wt %) into the Ni/Al2O3catalyst does not significantly affect the catalytic activity or stability by itself, the addition of ALD-Al2O3on top of the La2O3-promoted Ni catalysts significantly suppresses the long TOS deactivation, helps recover the peak activity of uncoated Ni/Al2O3, and eliminates the DRM induction period. This strategy obtains the stabilization benefits of Al2O3overcoating on Ni/Al2O3while, at the same time, avoiding the formation of undesirable NiAl2O4species.

Original languageEnglish (US)
Pages (from-to)10522-10530
Number of pages9
JournalACS Catalysis
Volume12
Issue number17
DOIs
StatePublished - Sep 2 2022

Keywords

  • COconversion
  • atomic layer deposition
  • bimetallic catalysis
  • catalyst design
  • catalyst stability
  • methane reforming
  • sintering
  • supported catalyst

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)

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