LOW-TEMPERATURE FISCHER-TROPSCH SYNTHESIS WITH CARBON-SUPPORTED NANOMETRIC IRON-COBALT CATALYSTS

Marketable fuel production from biomass through Fischer-Tropsch synthesis (FTS) process is the main objective of this work. Today, there is need for higher performance FTS catalysts that will lead to sustainable production of biofuels because of the global escalating energy prices, developing environmental concerns and more stringent legislation, particularly the push towards sulphur-free diesel. By developing efficient non-porous catalysts in the nanometric range, operating in the diffusion-controlled 3-phase FTS regime is avoided; this is a must in this direction and constitutes an experimentally proven choice. Potential carbon-supported bimetallic formulations based on iron and cobalt, synthesised by plasma-spray method were produced and tested as FTS nanocatalysts in a continuously-stirred slurry tank reactor (CSSTR) at 260 degrees C, 20-bar pressure and gas hourly specific velocity (GHSV) of 3,600 ml. g(-1). h(-1) for 24 h. Three catalytic formulations tested were: 30% Co-70% Fe, 50% Co-50% Fe, and 80% Co-20% Fe. Their analysis by Transmission Electron Microscopy (TEM) indicated an average particle size of 9.1, 14.4 and 8.9 nm, and BET specific surface areas of 89, 89 and 65 m(2).g(-1) respectively. Overall, the materials showed comparable selectivity of similar to 76% towards the production of C-5-C-22 (petrol + diesel fractions), but catalyst activity decreased in the order of 30% Co-70% Fe >> 80% Co-20% Fe > 50% Co-50% Fe, with carbon monoxide (CO) conversions of 50, 42 and 35% respectively after 24 h on stream.