Catalyst Design of CO2 hydrogenation and Off-gas Upgrading

Abstract

The steady increase of CO2 in the atmosphere owing to the excessive use of fossil fuels is seriously threatening the future of humankind by accelerating climate change. Among the proposed a carbon capture and utilization options, catalytic CO2 hydrogenation is attractive because the process is very similar to the well-established CO hydrogenation. The CO2 hydrogenation process usually involves two consecutive steps: the reverse water−gas shift (RWGS) and subsequent CO hydrogenation reactions. In CO2 hydrogenation over Fe-based catalysts, the Fe3O4 phase catalyzes the RWGS reaction, and its reduced form, the Hägg iron carbide (χ-Fe5C2) phase, provides active sites for CO hydrogenation and chain growth. CO2 hydrogenation can produce a wide variety of products, including methane, light olefins, and heavier (C5+) hydrocarbons. Gaseous by-products produced by CO2 hydrogenation reaction contain large amounts of light olefins and paraffins (C2‒C4). Hydroformylation not only simplifies the separation process by converting only olefins to liquid aldehydes and alcohols but also produces high-value-added chemicals with high commercial value. The newly developed Rh/CeO2-Al2O3 single atom catalyst was applied to upgrade the off-gas generated from CO2 hydrogenation by performing hydroformylation using a olefin/paraffin mixed gas.