Fischer–Tropsch synthesis in slurry-phase reactors over Mn- and Zr-modified Co/SiO 2 catalysts

Abstract

Fischer–Tropsch (F–T) synthesis was carried out in a gas-flowed slurry-phase reaction system over Mn- and Zr-modified Co/SiO 2 catalysts. A 0.5 L stirred tank slurry reactor (STSR) was used for catalyst screening and a 12.5 L slurry bubble column reactor (SBCR) was used for trial pilot operation. While using the 0.5 L reactor for catalyst screening, Co supported on the SiO 2 with an average pore size of 10 nm showed a high catalytic performance for the F–T synthesis due to the suitable Co particle size in the catalyst. Zr promoter improved the activity and Mn promoter improved the stability of Co/SiO 2 catalyst for the F–T synthesis. H 2-TPR profiles indicated that Zr and Mn promoters improved the reduction degree of Co 3O 4 particles (on SiO 2 surface) to Co 0 active species in H 2 flow at low temperature. While using the 12.5 L reactor for trial pilot operation over Mn–Zr–Co/SiO 2 catalyst, the space-time yield (STY) of C 5+ hydrocarbons (liquid fuel) showed almost the same values when various solvents ( n-C 16H 34, n-C 14H 30, diesel from petrol station, F–T crude oil) were used. Diesel and F–T crude oil are suitable for using in a large-scaled F–T synthesis plant owing to the low prices. Mn–Zr–Co/SiO 2 catalyst achieved a STY of C 5+ hydrocarbons larger than 1000 g-C 5+ kg-cat − 1 h − 1 in the 12.5 L reactor. The production capacity of liquid fuel from the 12.5 L reactor reached to 15.6 L per day (assumed for 24 h continuous operation). The stirring was very important for the F–T synthesis both reaction in the 0.5 L reactor and reaction in the 12.5 L reactor. The shape of slurry reactor also influenced the CO conversion for the F–T synthesis: reaction in the 12.5 L SBCR gave a higher CO conversion than that of reaction in the 0.5 L STSR (at the same W/F value under the same stirring speed) because the slender column reactor (SBCR) extended the residue time of reaction gas in the slurry-phase containing catalyst.