Synthesis of mechanically robust porous carbon monoliths for CO2 adsorption and separation

Porous carbon materials with developed porosity,high surface area and good thermal-and chemicalresistance are advantageous for gas adsorption and separation.However,most carbon adsorbents are in powder form which exhibit high pressure drop when deployed in practical separation bed.While monolithic carbons have largely addressed the pulverization problem and preserved kinetics and usually suffer from abrasion during multiple adsorption-desorption cycles.Herein,we proposed the designed synthesis of mechanically robust carbon monoliths with hierarchical pores,solid nitrogen-containing framework.The synthesis started with the polymerization of resorcinol and formaldehyde under weakly acidic conditions generated from cyanuric acid,and then an appropriate amount of hexamethylenetetramine（HMTA）was added as a crosslinker to prompt the formation of three dimensional frameworks.After carbonization process,the as-obtained porous carbon monoliths have a high radial compressive strength of 886 N/cm as well as a BET specific surface area of up to 683 m/g.At approximately 1 bar,the COequilibrium capacities of the monoliths are in the range of 3.1–4.0 mmol/g at 273 K and of 2.3–3.0 mmol/g at 298 K,exhibiting high selectivity for the capture of COover Nfrom a stream which consists of 16.7%（v%）COin N.Meanwhile,they undergo a facile COrelease in an argon stream at 298 K,indicating a good regeneration capacity.After cycle testing,sieving and regeneration,the adsorbent has no mass loss,compared to that of its fresh counterpart.