Formation of Methanol via Fischer‐Tropsch Catalysis by Cosmic Iron Sulphide

• Published in: Chemphyschem 2024-09, Vol.25 (17), p.e202400272-n/a
• Main Authors: Martinez‐Bachs, Berta, Anguera‐Gonzalez, Alexia, Pareras, Gerard, Rimola, Albert
• Format: Article
• Language: English
• Subjects: Astrochemistry; Astronomical models; Catalysis; Catalysts; Chemical reactions; Chemical synthesis; Density functional calculations; Exothermic reactions; Grains; Heterogeneous catalysis; Interstellar chemistry; Interstellar gas; Interstellar matter; Iron; Iron sulfides; Methanol; Potential energy; Quantum chemistry; Reactions kinetics; Surface modelling; Temperature dependence; Vapor phases
• ISSN: 1439-4235; 1439-7641; 1439-7641
• DOI: 10.1002/cphc.202400272

Chemical reactions in the gas phase of the interstellar medium face significant challenges due to its extreme conditions (i. e., low gas densities and temperatures), necessitating the presence of dust grains to facilitate the synthesis of molecules inaccessible in the gas phase. While interstellar grains are known to enhance encounter rates and dissipate energy from exothermic reactions, their potential as chemical catalysts remain less explored. Here, we present mechanistic insights into the Fischer‐Tropsch‐type methanol (FTT‐CH3OH) synthesis by reactivity of CO with H2 and using cosmic FeS surfaces as heterogeneous catalysts. Periodic quantum chemical calculations were employed to characterize the potential energy surface of the reactions on the (011) and (001) FeS surfaces, considering different Fe coordination environments and S vacancies. Kinetic calculations were also conducted to assess catalytic capacity and allocate reaction processes within the astrochemical framework. Our findings demonstrate the feasibility of FeS‐based astrocatalysis in the FTT‐CH3OH synthesis. The reactions and their energetics were elucidated from a mechanistic standpoint. Kinetic analysis demonstrates the temperature dependency of the simulated processes, underscoring the compulsory need of energy sources considering the astrophysical scenario. Our results provide insights into the presence of CH3OH in diverse regions where current models struggle to explain its observational quantity. Periodic quantum mechanical simulations evidence the potentiality to synthesise methanol through a Fischer‐Tropsch mechanism in different astrophysical environments facilitated by the catalytic properties of cosmic FeS grains, which are enhanced by the presence of naturally‐occurring point surface defects.