271670 Combined DFT and Microkinetic Modeling Study of Ethanol Steam Reforming On Close-Packed Transition Metals
The catalytic conversion of biomass to fuels and chemicals is an increasingly important research topic. Ethanol, produced from fermentation of biomass, has been considered as a source of hydrogen for fuel cells via steam reforming. Ethanol steam reforming has been carried out over Co, Ni, Pt, Rh, and Ru based catalysts, among others, and on a variety of supports.
It is expected that the nature of the transition metal catalyst will play a key role in the selectivity and activity of the steam reforming process. In order to better understand the role of the metal in this process, a combined density functional theory and microkinetic modeling study was performed. DFT calculations were performed for the close-packed facets of Co, Ni, Pt, Rh, and Ru to identify possible key steps in the mechanism. The impact of these steps on the overall rate is then investigated via detailed microkinetic modeling. We find that the early dehydrogenation steps tend to be rate controlling, while later C‑C and C‑O cracking steps control the selectivity to C1 and C2 hydrocarbons, respectively. In general agreement with the literature, Pt is predicted to be most selective to C-C cracking, while Ru is predicted to show the highest selectivity to C‑O cleavage.