Highlights and challenges in the selective reduction of carbon dioxide to methanol

Carbon dioxide (CO2) is the iconic greenhouse gas and the major factor driving present global climate change, incentivizing its capture and recycling into valuable products and fuels. The 6H+/6e− reduction of CO2 affords CH3OH, a key compound that is a fuel and a platform molecule. In this Review, we compare different routes for CO2 reduction to CH3OH, namely, heterogeneous and homogeneous catalytic hydrogenation, as well as enzymatic catalysis, photocatalysis and electrocatalysis. We describe the leading catalysts and the conditions under which they operate, and then consider their advantages and drawbacks in terms of selectivity, productivity, stability, operating conditions, cost and technical readiness. At present, heterogeneous hydrogenation catalysis and electrocatalysis have the greatest promise for large-scale CO2 reduction to CH3OH. The availability and price of sustainable electricity appear to be essential prerequisites for efficient CH3OH synthesis. This Review identifies competitive advantages and drawbacks of heterogeneous and homogeneous catalytic hydrogenation, as well as enzymatic catalysis, photocatalysis and electrocatalysis, for CO2 reduction to methanol.