A regenerable N-rich hierarchical porous carbon synthesized from waste biomass for H2S removal at room temperature

In this study, N-rich hierarchical porous carbons (NPCs) were synthesized via one step strategy from cypress saw-dust with carbon nitride (CN) loading and K2CO3 activation. NPCs exhibited excellent performance for H2S removal with the sulfur capacity up to 4262 mg/g at room temperature. It was much higher than 12.5 mg/g of porous carbon (PC) which was only activated by K2CO3. The NPCs with CN loading showed hierarchical porous structure with micropores and mesopores volume up to 0.434 and 0.597 cm(3)/g, respectively. Moreover, NPCs had high N contents (up to 12.37 wt%) and high relative contents of pyridinic N and pyrrolic N within 76.61-84.37%, which were identified as active sites for H2S adsorption by density functional theory calculation, enhancing H2S removal. The formation mechanism of NPCs was investigated by TG-FTIR, suggesting that CN pyrolysis result in hierarchical porous structure and rich N-containing functional groups by gradually releasing H2O, CO2 and NH3. Moreover, the NPCs showed high regeneration ability, remaining 86.6% of the initial sulfur capacity after five regeneration cycles, and sulfur (S) was the main desulfurization product (H2S + O-2 -> S + H2O). The results demonstrate that NPCs are promising catalysts to remove H2S efficiently with low cost and high reusability. (C) 2021 Elsevier B.V. All rights reserved.