Selective Low-Energy Carbon Dioxide Adsorption Using Monodisperse Nitrogen-Rich Hollow Carbon Submicron Spheres

Monodisperse, nitrogen-doped hollow carbon spheres of submicron size were synthesized using hexamethoxymethylmelamine as both a carbon and nitrogen source in a short (1 h) microwave-assisted synthesis. After carbonization at 550 °C, porous carbon spheres with a remarkably high nitrogen content of 37.1% were obtained, which consisting mainly of highly basic pyridinic moieties. The synthesized hollow spheres exhibited high selectivity for carbon dioxide (CO2) over nitrogen and oxygen gases, with a capture capacity up to 1.56 mmol CO2 g–1. The low adsorption enthalpy of the synthesized hollow carbon spheres permits good adsorbent regeneration. Evaluation of the feasibility of scaling up shows their potential for large-scale applications.