H2O2-assisted self-template synthesis of N-doped biochar with interconnected mesopore for efficient H2S removal

Abstract

N-doped mesoporous carbon has been used as an efficient metal-free catalyst for hydrogen sulfide (H2S) removal. Traditional synthesis methods for mesopore usually are expensive, corrosive, not eco-friendly, and less N-functional groups remained, leading to the poor removal efficiency for H2S. This study provides a facile and green synthesis of N-doped interconnected mesoporous biochars (HNBCs) designed from waste biomass with the cross-linked lignin self-template removed by H2O2. Compared with those without H2O2 (NPC), HNBCs exhibited higher mesopores volume and more basic sites, i.e., pyridinic N (PdN), pyrrolic N (PyN), -CO, and π-π*, which worked as the main active sites. As a result, adding H2O2 increased the breakthrough sulfur capacity to 181 mg/g for HNBC prepared from cypress sawdust, which was about 5 times that without H2O2 (37 mg/g). The desulfurization and regeneration performance were highly related to the cross-linked mesoporous structure and basic sites on the HNBC. This self-template removing method could easily extend to other waste biomass containing lignin and provide an insight into the advantages of efficient biomass self-structure utilization in the biochar designed properly.