Direct Conversion of Metal Carbonates and Bicarbonates to Methanol Over a Cu/ZnO/Al2O3 Catalyst.

The utilization of metal carbonates to produce directly valuable carbon feedstocks remains a major challenge, particularly under mild operating conditions. Herein, we report the elusive conversion of inorganic metal carbonates, such as sodium and potassium carbonates, to methanol in a one-step process with molecular hydrogen over a heterogeneous Cu/ZnO/Al2O3 catalyst. The hydrogenation occurs effectively at a relatively mild temperature of 200°C and proceeds in presence of ethylene glycol in the liquid phase with methanol yields of up to 95%. Alkali carbonates/bicarbonate salts obtained by capturing CO2 from ambient air (Direct Air Capture, DAC) and flue gas CO2 with aqueous alkali media also undergo facile hydrogenation to methanol.