Development of bimodal cobalt catalysts for Fischer–Tropsch synthesis

Confined small-sized cobalt catalysts stimulate carbon-chain growth reversely by modifying ASF law of Fischer-Tropsch synthesis

Fischer–Tropsch synthesis (FTS) is a promising technology to convert syngas derived from non-petroleum-based resources to valuable chemicals or fuels. Selectively producing target products will bring great economic benefits, but unfortunately it is theoretically limited by Anderson–Schulz–Flory (ASF) law. Herein, we synthesize size-uniformed cobalt nanocrystals embedded into mesoporous SiO₂ supports, which is likely the structure of water-melon seeds inside pulps. We successfully tune the selectivity of products from diesel-range hydrocarbons (66.2%) to gasoline-range hydrocarbons (62.4%) by controlling the crystallite sizes of confined cobalt from 7.2 to 11.4 nm, and modify the ASF law. Generally, larger Co crystallites increase carbon-chain growth, producing heavier hydrocarbons. But here, we interestingly observe a reverse phenomenon: the uniformly small-sized cobalt crystallites can strongly adsorb active C* species, and the confined structure will inhibit aggregation of cobalt crystallites and escape of reaction intermediates in FTS, inducing the higher selectivity towards heavier hydrocarbons.

Fischer–Tropsch synthesis (FTS) is theoretically limited by Anderson–Schulz–Flory (ASF) law. Here, the authors successfully tune the selectivity of products from diesel-range hydrocarbons to gasoline-range hydrocarbons in FTS by controlling the crystallite sizes of confined cobalt, and modify the ASF law.

Effects of CO2 on the deactivation behaviors of Co/Al2O3 and Co/SiO2 in CO hydrogenation to hydrocarbons

Different deactivation behaviors of the prototype Co/γ-Al₂O₃ (CoAl) and Co/SiO₂ (CoSi) catalysts under an excess CO₂ environment were investigated in terms of the surface oxidation and aggregation of cobalt crystallites for the Fischer–Tropsch Synthesis (FTS) reaction.

Effect of cobalt supported on meso–macro porous hydrotalcite in Fischer–Tropsch synthesis

Hydrotalcite based cobalt catalysts were prepared by a slurry precipitation method, followed by a slurry impregnation method.

Effect of the ordered meso–macroporous structure of Co/SiO2 on the enhanced activity of hydrogenation of CO to hydrocarbons

Ordered meso–macroporous silica (MMS) was applied for the cobalt-based FTS reaction, and the enhanced activity on the Co/MMS was mainly due to the larger macropore cavity by enhancing the mass transfer rate which can be easily regenerated by in situ feeding of liquid hydrocarbons.

Influence of the bimodal pore structure on the CO hydrogenation activity and selectivity of cobalt catalysts

The bimodal catalysts with larger second pore showed higher activity, methane selectivity and lower heavy hydrocarbon selectivity than that with smaller ones, under condition of the same first pore size.

Fischer–Tropsch synthesis on Co/AlSBA-15: effects of hydrophilicity of supports on cobalt dispersion and product distributions

The increased C₂–C₄selectivity on the Co/AlSBA-15 was mainly attributed to the formation of small cobalt particles with a stronger metal–support interaction on the outer surface acid sites of the AlSBA-15 due to a higher hydrophilicity of the Al-incorporated SBA-15.