Sustainable production of green feed from carbon dioxide and hydrogen

Carbon dioxide hydrogenation to form hydrocarbons was conducted on two iron-based catalysts, prepared according to procedures described in the literature, and on a new iron spinel catalyst. The CO₂ conversion measured in a packed-bed reactor was limited to about 60 % because of excessive amounts of water produced in this process. Switching to a system of three packed-bed reactors in series with interim removal of water and condensed hydrocarbons increased CO₂ conversion to as much as 89 %. The pure spinel catalyst displayed a significantly higher activity and selectivity than those of the other iron catalysts. This process produces a product called green feed, which is similar in composition to the product of a high-temperature, iron-based Fischer-Tropsch process from syngas. The green feed can be readily converted into renewable fuels by well-established technologies. Drying out: A new iron-based spinel catalyst tested in a new configuration of fixed-bed reactors in series displays a dramatic increase in activity and productivity of C₅+ hydrocarbons from CO₂ in comparison with other published catalysts (see picture). The results can be considered as a breakthrough in one of the key steps required for the conversion of CO ₂ and water to liquid fuels and represents a feasible process.