Investigation of Kölbel—Engelhardt Synthesis over Iron-Based Catalysts

The catalytic behaviour of iron-based mono-and bimetallic systems on different supports was studied in the Kölbel—Engelhardt (KE) synthesis at 498–598 K and atmospheric pressure with a fixed bed flow reactor (CO/H2O=3). In the case of monometallic catalysts the activity was found to be dependent on the nature of the support, the pretreatment condition, the contact time and the reaction temperature. The most active catalyst were those supported on low surface area supports (e.g. SiO2, TiO2, ZrO2). Such catalysts were easily reducible and showed good crystalline structure, unlike those supported on high surface area samples (SiO240Å, γ-Al2O3, MgO). Alloying iron with cobalt noticeably enhanced activity, selectivity and stability of all catalysts independent of the supports. The product distribution was shifted to higher hydrocarbons and selectivity to olefin formation increased. It is proposed that the major portion of hydrocarbons produced in the KE reaction was via a sequential reaction pathway involving the water-gas shift reaction followed by the Fischer-Tropsch reaction.