In this work, we reported a nitrogen-doped
porous carbon (NPC)
that was prepared from waste polyurethane (PU) foams through hydrothermal
carbonization and further activation. The possible reactions occurred
during the hydrothermal carbonation and activation process of waste
PU were proposed based on the results of gas chromatography–mass
spectrometry and thermogravimetric Fourier transform infrared. Hydrothermal
carbonization significantly improved the porous structure and surface
N-containing active groups on carbon. The specific surface area and
the total pore volume were obtained at 1419 m2/g and 0.80
cm3/g, respectively, for porous carbon prepared under 200
°C for 6 h, which were much higher than those without hydrothermal
carbonization (1100 m2/g and 0.66 cm3/g). Moreover,
the nitrogen contents on the porous carbon increased from 1.4 to 2.8
wt % with the majority of pyridinic and pyrrolic N species. The saturated
sulfur capacity of NPC reached as high as 205.06 mg/g, which was almost
2.5 times higher than that without hydrothermal carbonization. The
desulfurization performance could be tightly related to the hierarchical
porous structure and active nitrogen species on the carbon induced
by hydrothermal carbonization/catalysis. Thus, our current efforts
provide a facile strategy for the preparation of porous adsorbent
for H2S removal with the low cost and high efficiency.