(750g) Ni-Based Catalysts Synthesized By Atomic Layer Deposition for Dry Reforming of Methane

Gould, T. D., University of Colorado at Boulder
Lubers, A. M., University of Colorado at Boulder
Medlin, J., University of Colorado
Weimer, A. W., University of Colorado Boulder
Falconer, J. L., University of Colorado Boulder

Supported Ni catalysts with particle diameters of approximately 2.5 nm were synthesized by atomic layer deposition (ALD).  These catalysts were evaluated for dry reforming of methane activity and stability.  The Ni ALD catalysts exhibited a higher activity per gram of metal than catalysts prepared by incipient wetness, and performed slightly better than Ni catalysts in the literature that were promoted with Mg or Pt.  Additionally, the Ni ALD catalysts exhibited higher long-term activity than other catalysts for up to 72 h at 600°C. When the Ni ALD catalysts were modified with Pt ALD, their activity increased, sintering decreased, and resistance to coking was enhanced.  Modifying the incipient wetness Ni catalysts with 1 cycle of Pt ALD increased their activity per gram of metal by more than a factor of 2.  Adding 1 cycle of Pt ALD to the Ni ALD catalysts doubled the activity per gram of metal of the Ni ALD catalyst, resulting in the highest activity per gram of metal of all the samples investigated.  Additionally, modifying the Ni ALD catalyst with Pt ALD decreased the loss of activity due to sintering. The Ni ALD catalysts deactivated by ~50% of their initial activity due to sintering within the first 6 h, but the Pt ALD-modified catalysts only deactivated by 2% over 6 h at 600°C.  The nature of bimetallic interaction was probed via CO-TPD and temperature-programmed reduction.  Additionally, the structure of the as-prepared samples and heat treated samples were analyzed by HRTEM.