Hydrothermal synthesis of nitrogen-doped ordered mesoporous carbon via lysine-assisted self-assembly for efficient CO2 capture.

Abstract

Nitrogen-doped ordered mesoporous carbons (NOMCs) were synthesized by single-step hydrothermal self-assembly using F127 as a soft template, hexamine as a formaldehyde source, l-lysine as a polymerization catalyst, and 3-aminophenol as both carbon and nitrogen sources. The microstructure of the NOMCs was characterized by XRD, N2 adsorption/desorption, TEM, FTIR, and XPS. The results indicated that the obtained NOMCs exhibited a large specific surface area, uniform pore size distribution and highly ordered 2-D hexagonal mesostructure (P6mm). Besides, the nitrogen was uniformly doped into the carbon framework in the form of various nitrogen species. The adsorption isotherms of CO2 and N2 were also determined and could be well fitted by a DSL model. The capture capacity of CO2 was affected by both the nitrogen content and mesostructure of the adsorbents. Overall, NOMC-L-0.5 displayed excellent CO2 capture capacity (0 °C, 3.32 mmol g−1; 25 °C, 2.50 mmol g−1), and still demonstrated great regenerability with only 2% loss after several CO2 adsorption/desorption cycles. Moreover, the CO2/N2 selectivity calculated by IAST was as high as 43.2 at 25 °C in a typical composition of flue gas (binary mixtures with 15% CO2). The superior adsorption performance enables NOMCs to be a promising CO2 adsorbent in practical applications.