Optimization of preparation and process conditions for production of lightolefins via FTS on the Fe-Co catalysts

Catalysts have many applications in various industries, so their production is very important.Among catalysts, various types of iron and cobalt base catalysts with different catalyst supportare widely used in Fischer–Tropsch synthesis. The Fischer–Tropsch process is designed andimplemented based on the two main methods of fixed bed and slurry [۱, ۲].In this project, the basis of the work is based on the fixed bed method of Fischer–Tropschsynthesis, during which iron-cobalt catalysts have been prepared by three methods of solidphase, hydrothermal and wetness impregnation synthesis. Catalyst synthesis was performed in allthree methods with ۵ different ratios of iron to cobalt. The syntheses have been done byobserving all the relevant points and details. A total of ۱۵ catalysts were synthesized andevaluated under the reaction condition in order to produce light olefins by the Fischer–Tropschmethod. The physical and chemical properties of the catalysts were investigated by SEM, BET,XRD and ICP/MS. Reactor test conditions were performed at a pressure of ۱ atmosphere andtemperatures of ۲۷۰, ۳۰۰, ۳۳۰, ۳۶۰ and ۳۹۰°C with a GHSV of ۳۳۰۰ hr-۱ and a ratio of H۲ toCO equal to ۲. Catalysts synthesized by wetness impregnation method with the iron to cobaltratio of ۰.۲۵ to ۰.۷۵ had the best performance. For the production of these catalysts, gammaalumina was used as the catalyst support and iron and cobalt nitrate salts were used as iron andcobalt precursor respectively. The best CO conversion is about ۴۶% and the best selectivity isabout ۲۸% based on ethylene selectivity. It is noteworthy that other olefins, including propylene,have been produced with ethylene.

Keywords:

Fischer-Tropsch Synthesis , Light Olefin , Solid Phase Synthesis