CO₂ to chemicals: evaluating the potential of Fischer-Tropsch naphthas as a circular source of light olefins

Rising industrial CO₂ emissions and the limited capacity of current abatement technologies highlight the need for scalable carbon utilization pathways. Fischer-Tropsch synthesis provides a route to convert captured CO₂ into hydrocarbon feedstocks compatible with existing petrochemical processes, such as steam cracking. However, their suitability as steam cracker feedstocks has not yet been fully demonstrated. Three Fischer-Tropsch (FT)-derived feedstocks were generated from captured CO₂ via Reverse Water-Gas Shift followed by Fischer-Tropsch synthesis. The crude FT oil (i) was hydrotreated to produce hydrotreated FT oil (ii), and subsequent distillation yielded a hydrotreated FT naphtha (iii). The feedstocks were characterized using comprehensive two-dimensional gas chromatography, benchmarked against fossil naphtha in a bench-scale steam cracker, and evaluated for their impact on the carbon intensity of ethylene production. FT-derived feedstocks were highly paraffinic and contained negligible sulfur, nitrogen, halogens, and metals. Crude FT oil contained 11.7 wt% oxygenates and 11.3 wt% olefins, which were removed by hydrotreatment, yielding more stable steam cracker feedstocks. When steam-cracking the respective oils at 880 °C, the crude FT oil produced 38% more ethylene than fossil naphtha, while the yield of pyrolysis fuel oil (C₁₀₊) was halved. Further upgrading to hydrotreated FT naphtha increased the ethylene advantage to 48% and reduced pyrolysis fuel oil formation to one-third of that with fossil naphtha. The higher ethylene selectivity led to a 27% reduction in cracker-level CO₂ intensity compared with fossil naphtha. These results demonstrate that CO₂-derived FT feedstocks can serve as clean, high-yield alternatives for light olefin production within existing petrochemical infrastructure.