Majid Sarkari - Young Researchers Club Shiraz Branch, Islamic Azad University, Shiraz Iran
Farhad Fazlollahi - Department of Chemical Engineering, Faculty of Engineering, University of Sistan & Baluchestan,
Mohsen Mansouri - Department of Chemical Engineering, Faculty of Engineering, University of Sistan & Baluchestan,

The effects of K, Ce, Zn, Cs or Rb promoters on the structure and catalytic behavior of precipitated 50%Fe/50%Mn Fischer–Tropsch synthesis (FTS) catalysts were investigated in a fixed-bed reactor. The catalysts are characterized using X-ray diffraction (XRD). It was found that the 50%Fe/50%Mn catalyst that was promoted with K is an optimal catalyst for the conversion of synthesis gas to hydrocarbons especially light olefins. The effect on the 1-alkene selectivity is without doubt due to increased adsorption strength of carbonmonoxide causing an enhanceddisplacement of 1-alkenes while the propensity towards hydrogenation is hardly reduced.The catalysts were assessed in terms of their FTS activity and product selectivity using Anderson– Schulz–Flory (ASF) models. The promoter effect on Fischer-Tropsch iron catalysts caused an increased growth probability of hydrocarbon chains from 0.72 to 0.81 for K to Rb promoter and the olefin/paraffin ratios were increase from Rb to K-promoted catalyst, consequently. Also The effect of pressure on Fe/Mn/K was studied and experiments are presented which show that with pressure increasing, olefin/paraffin ratio decrease from 2.40 to 1.22 while the (α) increase from 0.80 to 0.86.

promoter ,potassium,fe-Mn catalyst,FTS,anderson-schulz-flory