Abstract

The addition of ethanol to synthesis gas and its influence on the production of higher alcohols (HA) was investigated over Cs- and Ru-Cu/ZnO catalysts at 320 degrees C and an initial pressure of 5.0 MPa in a batch reactor. A change in the reaction path from aldol-type condensation of C1-intermediates to homocoupling of ethanol was found upon increase of the ethanol to CO ratio. Furthermore, the productivity toward HA was enhanced for higher ethanol to CO ratios. The production of HA was maximized with the side products in an acceptable range for nEtOH:nCO = 0.5. Excess of ethanol gave lower production rates and leaching of the metals was observed. Cesium (0.3-1.0 mol %) proved to be a better dopant. Excess of Cs (3 mol %) led to a lower catalyst performance, probably due to a blockage of the active sites and a change in the reducibility of the catalyst.