Nitrogen-containing high surface area carbon cryogel from co-condensed phenol–urea–formaldehyde resin for CO₂ capture

A cost-effective nitrogen-doped super high surface area carbon cryogel has been successfully synthesized from phenol–urea–formaldehyde (PUF) resin. Pore structure and chemical characteristics were investigated using scanning electron microscopy, Fourier transform infrared spectroscopy, element analysis, X-ray photoelectron spectrometry, mercury porosimetry and N₂ adsorption–desorption. It was found that the organic cryogel with mesopores and macropores from PUF resin having a N content of 9.03 wt%, which is an ideal precursor for preparing N-doped carbon cryogels. The carbon cryogel obtained having a high apparent surface area of up to 1710 m²/g, large micropore volumes up to 0.64 cm³/g, a small average micropore width of 1.04 nm and a moderate nitrogen content of 2.08 wt%. The lab-made carbon cryogel showed good CO₂/N₂ sorption selectivity, 15.8:1 at 273 K and 16.4:1 at 298 K. The CO₂ capture capacities as high as 5.5 mmol/g at 273 K and 4.5 mmol/g at 298 K up to 1 bar were obtained, which were among the highest compared to other commercial carbon materials.