Fe-MOF-derived highly active catalysts for carbon dioxide hydrogenation to valuable hydrocarbons

Fe-based catalysts were acquired by one-step Fe-MIL-88B pyrolyzation and it showed high catalytic performance on hydrogenated conversion of carbon dioxide to valuable hydrocarbons. The iron compositions and catalytic performance of the catalysts were determined by pyrolysis temperatures according to XRD, SEM, TEM, N₂-physisorption, Raman and evaluation results. Magnetite was obtained at 773 K while metallic iron was the main phase when the pyrolysis temperature increased to 973 K. Different catalytic performances over these catalysts were attributed to the transformation of iron species under the reaction conditions. Olefin-to-paraffin ratio (O/P) over pyrolyzed and K-doped catalysts was 1.3 and 5.5, respectively, and the two samples exhibited CO₂ conversion with 46.0% and 43.1%, respectively. Higher catalytic performance was achieved when certain amount of Fe₃O₄ and χ-Fe₅C₂ existed in catalysts whereas metallic iron and/or θ-Fe₃C had detrimental effects on lower conversion of CO₂ and selectivity of valuable hydrocarbons.