HYDROGENATION OF CARBON-MONOXIDE ON UNSUPPORTED FE-MN-K CATALYSTS FORTHE SYNTHESIS OF LOWER ALKENES - PROMOTER EFFECT OF MANGANESE

Unsupported Fe-Mn-K catalysts prepared earlier by incorporating potass ium in-situ during coprecipitation of iron- and manganese oxides have been found to exhibit good catalytic activity and high alkene selectiv ity in the C2-C4 range, during syngas conversion. The effect of mangan ese on the alkali promoted iron catalysts towards hydrocarbon synthesi s was studied here. Manganese in moderate amount promotes catalytic ac tivity as well as selectivity of lower alkenes. Using a catalyst conta ining about 20 mol-% Mn and 0.5% K, at 673 K, 3 kg/cm2 pressure, WHSV = 800 h-1 and H-2/CO = 1, it was possible to obtain good carbon monoxi de coversion with 70-80% lower alkenes without formation of excess met hane and carbon dioxide.