(605e) Carbonate-Catalyzed CO2 Hydrogenation

CO₂ hydrogenation is a potentially valuable strategy for upgrading waste CO₂ to fuels and chemicals, but industrially practiced CO₂ hydrogenation is currently limited to the production of low-value C₁ products. To address this gap, new CO₂ hydrogenation chemistry must be developed which is capable of selective C–C bond formation to yield higher value, multi-carbon products. We have recently reported a novel CO₂ hydrogenation process promoted and/or catalyzed by alkali carbonate (M₂CO₃) salts^[1]. It was found that under elevated pressures and temperatures, and in the presence of small amounts of water, M₂CO₃ hydrates can promote CO₂ hydrogenation to formate, oxalate, and other C₂₊ carboxylate salts in the absence of solvents and transition metal catalysts. Notably, small amounts of M₂CO₃-catalyzed ethylene production are also observed.

Herein, we discuss recent developments in the carbonate-promoted CO₂ hydrogenation process. Emphasis is placed on maximizing catalytic production of ethylene, a high-volume precursor in polymer manufacturing. Impacts of both catalyst and reactor design are considered, and the resulting mechanistic insights are discussed. Dispersion of the M₂CO₃ catalyst onto high surface area metal oxide support improves catalyst performance and enables the use of more traditional packed-bed reactor configurations. Switching from a batch reactor to a packed-bed flow reactor design allows for the hydrogenation reaction to be studied under more practically relevant conditions and with finer process control and minimized background reactivity. Supported M₂CO₃ catalysts are characterized using electron microscopy, gas sorption, powder X-ray diffraction, and thermal analysis techniques, and the resulting insights into their physical and chemical properties are related back to observed CO₂ hydrogenation reactivity trends.

[1] Aanindeeta Banerjee and Matthew Kanan. Carbonate-promoted hydrogenation of carbon dioxide to multi-carbon carboxylates. Submitted.