(66c) Surface Chemistry of Carbon on Ni and Ni-Alloys: Promotion of the Long-Term Stability of Reforming Ni Catalysts by Surface Alloying

Reforming of hydrocarbon fuels is one of the most important heterogeneous catalytic processes. Current reforming catalysts such as Ni, however, suffer from two major problems: (i) carbon-induced deactivation and (ii) sulfur poisoning of the catalyst.

We have utilized Density Functional Theory (DFT) calculations to study the surface chemistry of carbon atoms and carbon fragments on various Ni facets. These studies demonstrated that there is a strong thermodynamic driving force to form extended carbon networks which diminish the long-term activity of Ni. We have further utilized DFT to identify Ni-containing alloys that are more carbon-tolerant than monometallic Ni, i.e., that have a lower propensity to form the carbon networks. Subsequent steady-state reactor studies validated the predictions of the DFT calculations. Aside from the steady-state reactor tests, the catalysts were characterized with multiple spectroscopic and microscopic tools.

We will provide a very general and physically intuitive model that can explain the enhanced performance of the Ni alloys.2

1 E.Nikolla, A. Holewinski, J. Schwank, S. Linic; ?Controlling Carbon Surface Chemistry by Alloying: Carbon Tolerant Reforming Catalyst?, Journal of the American Chemical Society, 2006; 128(35); 11354-11355.

2 E.Nikolla, A. Holewinski, J. Schwank, S. Linic "Promotion of the long-term stability of reforming Ni catalysts by surface alloying", Journal of Catalysis, 250(1), 85-93, 2007