(418ba) Design and Synthesis of Nitrogen-Doped Mesoporous Carbon for Selective CO2 Capture

Solid-state post-combustion CO₂ sorbents have certain advantages over traditional aqueous amine systems, including reduced regeneration energy since vaporization of liquid water is avoided, tunable pore morphology, and greater chemical variability.

Mesoporous carbons are promising for CO₂ capture due to their chemical inertness, low cost, high surface area, and tunable pore structures. Their porous structure and high surface area allow addition of chemical functionality by grafting or impregnation. Nitrogen functionalization plays an important role in surface chemistry to achieve enhanced CO₂ adsorption capacity. We report here an ordered mesoporous nitrogen-doped carbon made using the co-assembly of modified-pyrrole and triblock copolymer through a soft-templating method, which is facile, economical, and fast compared to the hard-template approach.  In the synthesis process, the pyrrole precursor acts as both the carbon and nitrogen source.  Carbonization of the resultant polymeric assembly generates a graphitic carbon structure and porous network through the removal of the block copolymer template.  A high surface area mesoporous carbon was achieved that is comparable to the silica counterpart. The resulting material shows promising CO₂ capture performance, reaching equilibrium adsorption of 1.0 mmol CO₂/g of material at 25 °C and 0.1 bar. Furthermore, the hierarchical macro-meso-microporous structure of this N-doped carbon allows for fast diffusion of CO₂ gas into the adsorption sites and controlled pore condensation within the microporous structure. Another potential benefit is that the thermal conductivity of the mesoporous carbon is higher than its silica counterpart, resulting in faster regeneration with enhanced stability using a temperature swing adsorption process. These properties of mesoporous carbons made from a conducting polymer render these as desirable materials for CO₂ capture.