Polyaniline-supported iron catalyst for selective synthesis of lower olefins from syngas

Uniform iron nanoparticles dispersed on polyaniline have been used as catalysts for the direct conversion of synthesis gas into lower olefins. As compared to active carbon and N-doped active carbon, polyaniline as a support of Fe catalysts showed higher selectivity of lower olefins (C_2–4). The C_2–4 selectivity reached ～50% at a CO conversion of 79% over a 10 wt% Fe/polyaniline catalyst without any promoters. The XRD, H₂-TPR, TEM and HRTEM studies revealed that the presence of nitrogen-containing groups in polyaniline structure could promote the dispersion and reduction of iron oxides, forming higher fraction of iron carbides with smaller mean sizes and narrower size distributions. The propylene-TPD result indicates that the use of polyaniline support facilitates the desorption of lower olefins, thus suppressing the consecutive hydrogenation to form undesirable lower paraffins.