Unravelling the metal-support interactions in χ-Fe5C2/MgO catalysts for olefin synthesis directly from syngas

We reported a chi-Fe5C2/MgO catalyst for olefin synthesis directly from syngas (STO), showing high selectivity to C-2-C-4 olefins and catalytic stability. With characterization of the morphology, electronic structures, and adsorption/desorption properties using in/ex situ techniques (XPS, TEM, XRD, MES, PHTA and TPD), we revealed that MgO could act not only as a structural promoter to disperse the active iron phase and prevent particle agglomeration during the reaction, but also as an electronic modifier to transfer electrons to iron. In particular, by combination of spectroscopy and theory calculations, we have proved that the close intimacy between chi-Fe5C2 and MgO (similar to 0.3 electrons transfer from MgO to chi-Fe5C2) enhanced CO dissociative adsorption whilst weakening the secondary hydrogenation of olefins, leading to the enhancement of selectivity. The dual roles of MgO in chi-Fe5C2/MgO may shed light upon rational design of practical STO catalysts by taking advantage of the exceptional strong metal-support interactions (SMSIs).

Automated summary

The study reports a chi-Fe5C2/MgO catalyst for olefin synthesis from syngas, with MgO playing dual roles as a structural promoter and electronic modifier. Characterization techniques revealed the mechanism behind the catalyst's high selectivity and stability, shedding light on the rational design of practical STO catalysts utilizing strong metal-support interactions.