Direct synthesis of e-kerosene from CO2 and H2 on a Fe-Zn-Cu-K catalyst: a promising route?

One-pot CO2 conversion to long chain hydrocarbons is gaining interest for renewable liquid fuels production, such as Sustainable Aviation Fuels (SAF). To maximize the process efficiency, it is necessary to find catalytic formulations and operative conditions that minimize undesired byproducts while maximizing the rate of conversion of the reactants. In this work, the performances of a conventional Fischer-Tropsch Fe-Zn-Cu-K catalyst have been analyzed at process conditions suitable for the one-pot production of long-chain hydrocarbons (e-crude) from stoichiometric H2/CO2 mixtures, at temperatures in the range 220 - 350 °C, pressures of 10 - 30 barg and GHSV values of 2.4 - 6 L/(STP)/h/gcat. In most of the operating conditions, the catalyst exhibited ∼50 % selectivity towards condensable hydrocarbons, liquid at room temperature and atmospheric pressure, with products consistently following a bimodal Anderson-Schulz-Flory distribution. The produced e-crude (∼0.2 g/h/gcat) was fractionated to obtain an e-kerosene fraction, which was then compared to a fossil-derived kerosene in terms of composition and physicochemical properties. The synthesized e-kerosene exhibited a higher content of linear olefins and a lower content of branched and aromatics species, highlighting the need for further upgrading to meet standard SAF specifications.