Influence of operating conditions on the performance of biomass-based Fischer-Tropsch synthesis

The environmental concerns and the European liquid (bio) fuel regulations have determined a growing demand on biofuels. Fischer-Tropsch synthesis can provide clean synthetic fuels containing low concentrations of sulfur, nitrogen, and aromatics. While Fischer-Tropsch synthesis using natural gas and coal is a well established and commercialized process for more than 70 years, the new technology of Fischer-Tropsch synthesis using biomass as feedstock is gaining more and more attention due to the possibilities of using renewable raw materials. In this work, in order to optimize the Fischer-Tropsch synthesis, the influence of operating conditions has been studied in a slurry reactor using a Co-based catalyst. Experiments were performed at different syngas composition (variation of H-2/CO ratio) and pressure (24, 20, and 16 bar), keeping the other parameters (temperature, 230 degrees C; gas flow, 5 Nm(3)/h) constant. The effects of pressure on CO conversion, product distribution, C5+ selectivity, Par/Ole ratio, and alpha value were investigated, and the results were compared with data from literature. It was found that-increasing the reaction pressure-heavier hydrocarbons were formed, and CO conversion increased from 44.2 to 63.7 %. A slight change has been observed in the case of an a value between 0.89 and 0.9, C5+ selectivity between 90.6 and 91.7 %, and Par/Ole ratio between 11.4 and 14.1. An important role for the results obtained was attributed to H-2/CO ratio variation during the experiments.