Pyrrolic N-enriched carbon fabricated from dopamine-melamine via fast mechanochemical copolymerization for highly selective separation of CO2 from CO2/N2

Abstract

A pyrrolic N-enriched microporous carbon composite was synthesized using mechanochemical strategy via copolymerized melamine/dopamine (PDA/MA) within ultra-short reaction time (30 min) for CO2 capture from gaseous mixture of CO2/N2. Dopamine doping efficiently restrained the sublimation of melamine during calcination, which leaded to higher yield (>70 wt%) in comparison with pure C3N4. The synthesized carbon composite possessed ultra-microporous structure (5.3–5.6 Å) and abundant (pyrrolic N of 13.1 wt%) CO2-philic sites. Results showed that PDA0.3/MA0.7-2 exhibited high CO2 capacity of 16.0 wt% (3.64 mmol/g) at 298 K and 20.3 wt% (4.6 mmol/g) at 273 K and 1.0 bar pressure. The isosteric heat of adsorption (Qst) was 37.4 kJ/mol, indicating a strong interaction of the composite with CO2 molecules. Ideal adsorption solution theory demonstrated that PDA0.3/MA0.7-2 possessed a super high CO2 selectivity (108) in CO2/N2 (10:90) mixture at 273 K. High CO2 capacity and selectivity, green and fast fabrication strategy and cost effective raw materials make the proposed novel PDA/MA carbons as promising candidates for CO2 capture from post-combustion flue gases.