Facile preparation of N-doped porous carbon from chitosan and NaNH2 for CO2 adsorption and conversion

Abstract

• Facile and solvent-free preparation of N-doped porous carbon from chitosan and NaNH 2 . • NaNH 2 serves as both porogen and nitrogen source during carbonization. • Adsorption of CO 2 , SO 2 and H 2 S on N-doped porous carbons are researched. • The adsorption capacity of CO 2 can reach 6.33 mmol·g −1 at 273.15 K and 100 kPa. • Metal-free conversion of CO 2 into formamides by N-doped porous carbon. Although N-doped porous carbon has been widely studied in CO 2 capture and conversion, the preparation process of functionalized porous carbon is usually complicated and costly, which limits the large-scale industrial application of porous carbon. Here, we reported a straightforward method for the preparation of N-doped porous carbon using chitosan (CTS) and NaNH 2 without any solvents. The structure of N-doped porous carbon was characterized by XRD, XPS, SEM, TEM and pore structure analysis, respectively. The developed pore structure and specific surface area of N-doped porous carbon are mainly due to the use of NaNH 2 as both porogen and nitrogen source during carbonization. These prepared porous carbons are used to study the adsorption of CO 2 , SO 2 , H 2 S and CH 4 . The adsorption capacity of CO 2 can reach 6.33 mmol·g −1 at 273.15 K and 100 kPa, which is significantly higher than that of carbon-based adsorbents reported in the literature. The thermodynamics and mechanism of CO 2 adsorption are also discussed. The results suggest that the adsorption of CO 2 by N-doped porous carbon is a physical adsorption process. In addition, a metal-free conversion of CO 2 into formamides is also acquired using N-doped porous carbon as promoter, giving various corresponding formamides in moderate to excellent yields. As a result, the excellent CO 2 uptake, high reactivity, low cost of precursor, and facile synthesis strategy prove that these chitosan-based N-doped porous carbons are a potential candidate for CO 2 capture and conversion.