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(532an) Stabilizing Supported Ni Catalysts for Dry Reforming of Methane By a Multicomponent Atomic Layer Deposition

Ahn, S. - Presenter, Northwestern University
Marks, T. J., Northwestern University
Stair, P. C., Northwestern University
Deposition of a doping agent and Al2O3 on Al2O3-supported Ni catalysts was performed to study their effects on the stabilization of heterogeneous catalysts for the dry reforming of methane (DRM) reaction. An alumina-supported Ni catalyst (Ni/Al2O3, 2 wt.% of Ni), loses ~50% of its initial activity within 15 h under DRM conditions. While overcoating of Al2O3 on this catalyst via atomic layer deposition (ALD) helps stabilize the catalyst in long time-on-stream (TOS) tests, this overcoated catalyst is ~40 times less active than the uncoated catalyst at peak activity. This Al2O3 overcoated Ni/Al2O3 catalyst also exhibits a long induction period (~20 h) due to slow reduction of the Ni2+ within the catalytically inactive nickel aluminate (NiAl2O4) phase, formed by interaction of metallic Ni with the Al2O3 overcoat at the 700 °C reaction temperature. Previously, it was proposed that the presence of a doping agent in an alumina support might inhibit NiAl2O4 formation. Here we report that the addition of Al2O3 on top of the doping element promoted Ni catalysts reduces long TOS deactivation, helps recover the peak activity of uncoated Ni/Al2O3, and eliminates the induction period. We present a doping strategy via ALD that obtains the stabilization benefits of Al2O3 overcoating on Ni/Al2O3 while, at the same time, avoids the formation of undesirable NiAl2O4 species by doping a new element on the surface prior to Al2O3 overcoating.