RETRACTED: Solar photothermochemical alkane reverse combustion

A one-step, gas-phase photothermocatalytic process for the synthesis of hydrocarbons, including liquid alkanes, aromatics, and oxygenates, with carbon numbers (C n ) up to C 13 , from CO 2 and water is demonstrated in a flow photoreactor operating at elevated temperatures (180–200 °C) and pressures (1–6 bar) using a 5% cobalt on TiO 2 catalyst and under UV irradiation. A parametric study of temperature, pressure, and partial pressure ratio revealed that temperatures in excess of 160 °C are needed to obtain the higher C n products in quantity and that the product distribution shifts toward higher C n products with increasing pressure. In the best run so far, over 13% by mass of the products were C 5 + hydrocarbons and some of these, i.e., octane, are drop-in replacements for existing liquid hydrocarbons fuels. Dioxygen was detected in yields ranging between 64% and 150%. In principle, this tandem photochemical–thermochemical process, fitted with a photocatalyst better matched to the solar spectrum, could provide a cheap and direct method to produce liquid hydrocarbons from CO 2 and water via a solar process which uses concentrated sunlight for both photochemical excitation to generate high-energy intermediates and heat to drive important thermochemical carbon-chain-forming reactions.