Fischer–Tropsch synthesis: induction and steady-state activity of high-alpha potassium promoted iron catalysts Original Research Article

Iron Fischer–Tropsch synthesis (FTS) catalysts with different potassium loadings showed different induction periods during which the conversion increased from a low initial level to a peak value before declining to attain a lower stable activity at the same reaction conditions. A lower K loading produced a slightly higher peak conversion and a shorter induction period. Although, the induction period and the peak conversion were slightly dependent on the K loading for the iron catalyst, the stabilized conversions and the stabilization periods were independent of potassium content. The C2C4 olefin to paraffin ratio of the gaseous products and the CO2 selectivity did not change significantly as the potassium content increased from 5 to 10%. An increase in reaction temperature produced a new induction period and a higher conversion than was obtained before the reaction temperature was increased. The H2/CO ratio also had an important influence on FTS conversions. Increasing the H2/CO ratio in the feed gas lowered the H2 utilization. A higher H2/CO ratio feedstock gas produced lower FTS catalyst activity compared to a low H2/CO ratio gas.