The integration of direct air capture (DAC) of CO2 and its hydrogenation to methanol is highly promising in the context of transforming this greenhouse gas into value-added carbon feedstocks. Until now, such processes relied on amines, which are prone to oxidative degradation and suffer from notable toxicity and volatility. In the present study, we have established the first example of an alkali hydroxide-based system for the integrated process. In a one-pot system, CO2 was efficiently captured by an ethylene glycol solution of the base and subsequently hydrogenated to methanol at relatively mild temperatures (100−140 °C) using homogeneous ruthenium catalysts. The produced methanol can be easily separated by distillation. Additionally, low temperature regeneration of the hydroxide base was observed for the first time. Finally, CO2 was captured from ambient air and further hydrogenated to methanol quantitatively. We postulate that the high capture efficiency and stability of hydroxide bases make them superior to existing amine-based routes for direct air capture and conversion to methanol in a scalable process. This system offers easy integration of existing hydroxide-based CO2 scrubbing industries to utilize the captured CO2 to produce methanol, paving a way for a sustainable and carbon neutral future.

Integrative CO2 capture and conversion to methanol: Shifting from amines to alkali hydroxides

ACS Fall 2020 Virtual Meeting

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