Surface coordinate geometry of iron catalysts: hydrogenation of CO2 over Fe/TiO2 prepared by a novel method
Titania-supported iron oxide catalyst has been designed based on a geometric consideration. The catalyst prepared by reducing the precursor obtained from incipient wetness impregnation in H2 at proper temperature exhibits good activity (CO2 conversion >24%) and selectivity (>60%) in the selective synthesis of hydrocarbons (C2–C5) from CO2 and H2. The catalytic activity has been found to vary with iron weight loadings in a “twin maxima” fashion and, also, to be affected by the reduction temperature. Mössbauer and EXAFS analyses suggest that the active phase is coordinatively unsaturated ferrous cations associated with α-Fe. Alternative arrangement of the two phases in a proper way is beneficial to relax the Fe-O bonds and results in the highest catalytic activity for the catalyst, but the formation of predominantly FeTiO3 phase finally makes the catalyst inactive.
Keywordsiron catalyst titania hydrogenation of CO2 Mössbauer EXAFS Raman
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