Steam Reforming of Ethanol Over Supported Co and Ni Catalysts

The ethanol steam reforming has been investigated over supported cobalt catalysts at atmospheric pressure. About 12% cobalt was supported on Al₂O₃, SiO₂ and TiO₂, and a commercial Ni/Al₂O₃ catalyst (G90B) was included for comparative purposes. The selectivity was found to depend strongly on the support, especially at low and medium temperatures. The initial activity of the cobalt catalysts correlated well with the metal dispersion. Acetaldehyde was an important C-containing product at low temperatures, whereas at high temperatures CO, CO₂ and CH₄ dominated the product spectrum. A significant production of ethene was observed, especially on the alumina-supported catalysts. The results are in agreement with a mechanism involving acetaldehyde as an intermediate in the steam reforming. At high temperatures (>550 °C) the conversion was complete and the product distribution approaches the equilibrium. The H₂ yield approached 5 moles H₂/mole ethanol converted, which is close to the maximum according to thermodynamic calculations. The alumina-supported catalysts (both Co and Ni) showed acceptable deactivation rates, but high carbon formation.