Functionalized Carbon Spheres for Energy-Efficient CO2 Capture: Synthesis, Application, and Reaction Mechanism

Catalyst-facilitated amine regeneration provides exciting new opportunities to fulfill the Paris Climate Accord by developing an energy-efficient and economically feasible CO2 capture process. However, finding inexpensive and easy-to-synthesize catalysts, along with understanding the catalytic desorption mechanism, is imperative. Herein, we develop an environmentally friendly glucose-derived carbon sphere nanocatalyst with isethionic acid functionalization which can optimize the CO2 desorption rate of CO2-loaded aqueous monoethanolamine (MEA) solutions at ∼86 °C. The desired physicochemical properties of the developed materials can be readily tuned by varying the amount of isethionic acid used for functionalization. The synthesized catalysts accelerated the CO2 desorption rate by up to 108% and reduced the heat duty by ∼10.8% compared to the traditional uncatalyzed MEA regeneration. NMR analysis unveils that unlike conventional regeneration where carbamate stability hinders the low-temperature CO2 desorption, the prepared catalysts can decompose carbamate at much lower temperatures and thereby reduce the energy consumption of amine regeneration. These catalysts can be readily separated and are stable in cyclic uses, making them suitable for industrial-scale applications. Catalyst-facilitated solvent regeneration at 86 °C can allow the regenerator to use low-grade industrial waste heat, which may enable efficient CO2 capture facilities to be installed at a wide range of industrial sites to achieve net zero emissions by 2050.