Investigation of mixtures of a Co-based catalyst and a Cu-based catalyst for the fischer-tropsch synthesis with Bio-Syngas: The importance of indigenous water

A series of different mechanical mixtures of a narrow-pore Co/γ-AlO catalyst and a Cu-based WGScatalyst has been investigated in the low-temperature Fischer-Tropsch synthesis (483 K, 20 bar) with a model bio-syngas (H/CO = 1.0) in a fixed-bed reactor. The higher the fraction of WGS-catalyst in the mixture, the lower is the Co-catalyst-time yield to hydrocarbons. This is ascribed to a strong positive kinetic effect of water on the Fischer-Tropsch rate of the Co-catalyst, showing the importance of the indigenously produced water, especially in fixed-bed reactors where the partial pressure of water is zero at the reactor inlet. A preliminary kinetic modeling suggests that the reaction order in PHO is 0.3 for the Co/γ-AlO catalyst in the range of the studied reactor-average partial pressures of water (i.e., 0.04-1.2 bar). © 2011 Springer Science+Business Media, LLC.