Promoter Effects on Iron-Silica Fischer-Tropsch Nanocatalysts: Conversion of Carbon Dioxide to Lower Olefins and Hydrocarbons at Atmospheric Pressure

If CO2 hydrogenation is to become a viable process for the utilisation of CO2, improved catalysts are urgently needed. We report the promotional effects of Group11 and 13 metals on the performance of iron-silica catalyst systems under atmospheric pressure. The addition of low loadings of gold resulted in a significant improvement in catalyst performance both in terms of conversion and selectivity to lower (C-2-C-4) olefins. Small loadings of indium proved highly effective for increasing CO2 conversion, whereas at higher loadings the selectivity to lower olefins could be dramatically increased. Catalysis tests involving palladium-promoted systems also proved successful with large increases in selectivity towards C5+ hydrocarbons observed. The catalysts were characterised by X-ray photoelectron spectroscopy, TEM and SEM, which confirmed the nanostructured nature of the catalytic species involved.