On the path to sustainable fuels – hydrocarbons having a lower carbon intensity than legacy fossil hydrocarbons – one flow of interest is direct-air capture (DAC) of CO2 followed either by solid oxide electrolysis cell (SOEC), or by reverse water-gas shift (RWGS), to syngas, readily further processed to long-chain hydrocarbons. Unfortunately, the high energy intensity of each step – both of CO2 capture-and-release, and of CO2 upgrade – leads to an energy cost of 55-65 GJ/tonsyngas. Here we pursue reactive capture, which uses alkali carbonate post-direct-air-capture liquid as feedstock, converting the captured CO2 to value-added products while regenerating the capture liquid. Prior reactive capture to syngas has been limited to 32% efficiency at 200 mA/cm2 – the result of the catalyst becoming CO2-starved. We develop hierarchical carbon supports featuring interconnected mesopores and micropores, and this increases interaction between in situ generated CO2, i-CO2 – the limiting reagent – and the catalyst, heterogenized cobalt phthalocyanine. We report as a result carbonate electrolysis at 200 mA/cm2 having energy efficiency to 2:1 syngas of 50%. Life cycle assessment shows that – when energy is supplied using electricity having the carbon intensity of wind –CO2 emissions are reduced from today’s coal-syngas of 2.3 t CO2e/t syngas to a negative emission of –1.5 t CO2e/t syngas, each cradle-to-gate. The minimum selling price (MSP) of syngas produced via the reactive capture is estimated at US$770/t, below that for DAC-SOEC (US$1270/t) and DAC-RWGS (US$1020/t).
