Nanocatalysts from Ionic Liquid Precursors for the Direct Conversion of CO2 to Hydrocarbons

The direct conversion of carbon dioxide (CO2) into lower olefins (C2-C4) is a highly desirable process as a sustainable production route. Lower olefins, i.e., ethylene, propylene and butenes (C2-C4), are key building blocks in the current chemical industry. The reaction proceeds via two main consecutive reactions: Reverse Water Gas Shift (RWGS) to produce CO followed by the further conversion of CO to hydrocarbons via the Fischer−Tropsch reaction2. This process is achieved by a multifunctional iron-based catalyst supported on zeolites providing three types of active sites (Fe3O4, Fe5C2 and acid sites), which cooperatively catalyse a tandem reaction1.
To date, attempts at synthesising a suitable catalyst for the direct hydrogenation reaction follow a conventional precipitation procedure, whereby Iron Oxide Nanoparticles (IONs) are produced and then embedded within a zeolite structure by granule mixing. This method provides no control over the size and shape of the IONs formed; a characteristic of imperative importance due to its significant effect on the hydrocarbon product distribution obtained. In our novel approach, ionic liquids are utilised for the synthesis of the IONs resulting in better control over size and morphology of the nanostructured material, and as a consequence, better conversion and selectivity towards the olefins.