Si3N4 induced Fe-Si interaction in iron-based Fischer-Tropsch synthesis catalysts for suppressing CO2 formation

Si 3 N 4 is proposed as a precursor to construct Fe-Si interactions in FTS catalysts. • Fe/Si 3 N 4 catalyst exhibits stronger Fe-Si interaction and higher Fe 2 SiO 4 content than Fe/SiO 2 . • The formation of Fe 2 SiO 4 stabilizes Fe species and suppresses the formation of Fe 3 O 4 . • Preventing the formation of Fe 3 O 4 makes for decreasing CO 2 selectivity and WGS activity. Precise control over the metal-support interfacial structure plays a critical role in enhancing the activity and selectivity of iron-based catalysts for syngas conversion. Using silicon nitride as the starting precursor of silicon support, a series of SiN x O y supports with different oxidation degree were constructed via controlled oxidation under air, enabling modulation of the Fe-Si interfacial environment. A systematic comparison between silicon nitride-derived supports and conventional silica support revealed significant differences in structural evolution and catalytic behavior of iron catalysts. Spectroscopic characterizations including FTIR, solid-state NMR, XPS, XRD, and Mössbauer spectroscopy demonstrated that the unique interfacial structure formed during the oxidation of Si 3 N 4 stabilizes the active iron species (carbides) and suppresses the formation of undesired phases (Fe 3 O 4 ), thereby reducing CO 2 selectivity. These findings underscore the critical influence of support precursors on interfacial chemistry and reaction pathways, providing new insights and strategies for the rational design of Fe-based catalysts. Download: Download high-res image (76KB) Download: Download full-size image