HYDROCARBON SELECTIVITY FROM COBALT FISCHER-TROPSCH CATALYSTS

A cobalt Fischer-Tropsch catalyst was studied in a continuous-flow, well-stirred slurry reactor at 220-240-degrees-C, 0.5-1.5 MPa, H2/CO feed ratios between 1.5 and 3.5, H-2 conversions between 6 and 68%, and CO conversions between 11 and 73%. Increasing space velocity (decreasing conversion) or decreasing reactor H2/CO ratio decreased the yield of (undesired) C1 products and increased the yield of (desired) C10+ products. Reactor temperature and pressure had little effect on the carbon number distribution. The extent of the readsorption of 1-alkenes, formed by the primary synthesis, into growing chains on the catalyst surface in contrast to hydrogenation to the corresponding alkane or isomerization to the 2-alkene reflects an intricate interplay among many variables.