Pyridinic and pyrrolic nitrogen-doped porous carbon improves control of N2 and H2 adsorption thermodynamic for N2/H2 separation

Abstract

Hydrogen, a clean and efficient energy source, faces challenges in enrichment and purification. This study addresses the issue by introducing pyridinic and pyrrolic nitrogen functionalities into phenolic resin-based porous carbon (PC) through melamine pyrolysis, significantly enhancing N₂/H₂ selectivity. The nitrogen-containing groups exhibit a stronger inhibitory effect on hydrogen adsorption than on nitrogen adsorption. Meanwhile, the high specific surface area of the original porous carbon is maintained. At 298 K and 2 bar, the selectivity of N₂ over H₂ reached 14.47 in this work. Density functional theory (DFT) reveals that the inductive effect and direct interaction of edge pyrrolic nitrogen groups contribute to substantial electrostatic effects, with the disparity in adsorption energy being the fundamental reason for enhanced selectivity. This work provides new insights into efficient hydrogen purification, demonstrating the potential of nitrogen-functionalized PCs for N₂/H₂ separation.