Ordered mesoporous carbons: citric acid-catalyzed synthesis, nitrogen doping and CO2 capture

Abstract

Ordered mesoporous carbon materials (OMCs) were synthesized with the use of citric acid as an environmentally friendly catalyst to catalyze the polymerization of resorcinol/formaldehyde resin. The obtained carbon materials with high thermal stability have a 2D hexagonal mesopore system with uniform pore size of ∼5.2 nm and high surface area of 612∼851 m² g⁻¹, which were available under a wide composition range of reaction systems at the reaction temperature of 50–80 °C and the molar ratio of formaldehyde to citric acid of ≥3. The presence of citric acid in the synthesis system can enhance the hydrogen bonding between the triblock copolymer and resol and further introduce more micropores to the final carbon material, which is favorable for CO₂ adsorption. The nitridation of the OMCs in ammonia flow at the temperature of 650–1000 °C is demonstrated to be effective in introducing basic functionalities that enhances the specific interaction of CO₂ and adsorbent. The N-doped OMCs exhibit enhanced CO₂ uptake with a CO₂ capture capacity of 3.46 mmol g⁻¹ for the 1000 °C-nitrided sample. Both textural and surface chemistry influenced the CO₂ capture performance of the resultant mesoporous carbon adsorbents.