Iron-silica nanocomposites as a catalyst for the selective conversion of syngas to light olefins

A series of Fe/SiO₂ catalysts were prepared by one-pot synthesis and conventional co-precipitation methods; they were characterized by N₂ physisorption, X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, and temperature-programmed reduction. The performances of the Fe/SiO₂ catalysts in Fischer-Tropsch synthesis (FTS) were evaluated in a fixed-bed reactor for the production of light olefins from syngas. The results showed that in the Fe/SiO₂ catalyst prepared by one-pot synthesis method, the iron oxide is present as iron-silica nanocomposite in the form of Fe₃O₄ (magnetite). Compared with the catalyst prepared by conventional co-precipitation method, the magnetite-silica nanocomposite by one-pot synthesis exhibits a more uniform spherical-like morphology, narrower size distribution (30 nm in average) and better reducibility. In FTS, the Fe/SiO₂ catalyst prepared by one-pot synthesis method exhibits higher activity and selectivity to light olefin as well as lower selectivity to methane and better stability.