Net reduction of CO2 via its thermocatalytic and electrocatalytic transformation reactions in standard and hybrid processes

Abstract

Many research efforts into CO2 reduction to valuable products are motivated by a desire to reduce the atmospheric CO2 concentration. However, it is unclear how laboratory-scale catalytic performance translates to the goal of reducing CO2. In this Perspective, we analyse recently reported thermocatalytic and electrocatalytic performances for reduction of CO2 to methanol in terms of net CO2 reduction, on a mole basis. Our calculations indicate that even an ideal catalytic process needs to be powered by electricity emitting less than 0.2 kg of CO2 per kWh to achieve a net reduction in CO2. We conclude that hybrid processes combining thermocatalysis and electrocatalysis are promising opportunities to reduce CO2 to methanol, as long as practical electrocatalysts achieve reaction rates two orders of magnitude larger than those observed in current laboratory tests. In such a scenario, an increase in the global methanol market could benefit the overall reduction of atmospheric CO2 via conversion of CO2 to methanol. CO2 hydrogenation is frequently acclaimed as a strategy for greenhouse gases mitigation, although the carbon footprint of the corresponding electrocatalytic or thermocatalytic process is often neglected. This Perspective analyses the amount of CO2 generated during methanol production for different catalytic processes and hybrid thereof.