Applied Catalysis A: General, Vol.507, 75-81, 2015
Effect of ZrO2, Al2O3 and La2O3 on cobalt-copper catalysts for higher alcohols synthesis
Three cobalt-copper catalysts singly promoted with La, Zr, or Al were studied for catalytic conversion of syngas to higher alcohols. The properties of the promoted catalysts have been characterized by TPR, XRD, XPS and BET. CO hydrogenation was carried out in a plug-flow reactor under 30 bar, GHSV=36000 scc/gcat/h, H-2/CO = 2, and 250 degrees C at differential conversions. The catalyst activity and selectivity to higher alcohols are greatest on CuCoLa2O3: ethanol selectivity 10.5% at a conversion of 0.76%. During 9h of time-on-stream, CO conversion decreased on CuCoLa2O3 while methanol and higher alcohol selectivity increased. The behaviors on CuCoZrO2 and CuCoAl2O3 were different. On these two catalysts, CO conversion and selectivity reached a near-steady state much more quickly than CuCoLa2O3. These results suggest changes on CuCoLa2O3 that increase the selectivity for oxygenates continue with time, at least over the time scale investigated here. (C) 2015 Published by Elsevier B.V.
Keywords:Higher alcohols synthesis;Syngas;Cobalt;Copper;Metal oxide promoters;Modified Fischer-Tropsch catalysts