No abstract

Fischer-Tropsch Synthesis (FTS) is a process which converts synthesized gas (a mixture of H2 and CO) to synthetic liquid fuels and valuable chemicals with the existence of metal catalysts and suitable operational conditions. Less costly and plentiful biomass from agricultural waste can be converted into synthesized gas by thermal gasification. FTS derived Biofuel is a high quality, clean fuel and have a very low sulfur content in comparison to conventional fuel. In this study, FTS reaction was investigated in a tubular fixed bed reactor on prepared Co-Ni bimetallic catalysts supported by walnut shells derived activated carbon (AC) to study the synergistic effect of the active metals on the catalyst's physical properties as well as hydrocarbon liquid product distribution. Employed catalysts were synthesized by wet impregnation method and were characterized afterwards by XRD, TPR-H2, BET surface area and FESEM-EDX techniques to identify the morphology and physical properties of the catalysts. Maximum gasoline selectivity of 69% was achieved on the 7Co7Ni/AC bimetallic catalyst, which was considered as the best bimetallic catalyst among others. Temperature increase from 220°C to 300°C enhanced gasoline selectivity from 69% to 92%. In addition, carbon monoxide (CO) conversion increased as well from 43% to 65% on the 7Co7Ni/AC bimetallic catalyst. On the contrary, increased reaction pressure from 1 bar to 9 bar decreased gasoline selectivity from 92% to 36% but increased CO conversion is from 65% to 84% on the 7Co7Ni/AC bimetallic catalyst. The optimum reaction conditions were considered based on the maximum selectivity of gasoline which was 300°C reaction temperature and 1 bar reaction pressure. In conclusion, the employing of bimetallic Co-Ni catalysts supported by AC in Fischer-Tropsch reaction has significantly enhanced the catalytic activity and improved gasoline selectivity due to the achieved high metal dispersion, better reduction degree and large surface area. Higher reaction temperatures increased gasoline selectivity whereas, higher reaction pressures decreased gasoline selectivity.