Hierarchically porous, N-defect enriched C-nanosheets boost the H2S selective oxidation to elemental sulfur

Abstract

H2S selective oxidation to elemental sulfur (S8) is a typical reaction where the mass product diffusion (e.g., S8) through the catalytic bed is crucial as well as the reagents accessibility (e.g., H2S, O2) to the active sites. The NaNO3-assisted pyrolysis of polyacrylamide was applied to synthesize defect-enriched N-doped carbon nanosheets with thickness up to c.a. 2 nm, featured by fully accessible and highly interconnected pores, for boosting the H2S selective oxidation process. The PAM-0.3-700 sample has revealed an unprecedented desulfurization activity with sulfur formation rate of 1165 gsulfur kgcat.−1 h−1, other than a remarkable stability (>80 h). Experimental and theoretical studies have unveiled the critical role of edge sites containing unpaired electrons and nitrogen species with respect to the material aptitude towards O2 dissociation and HS- activation. The material in presence of a highly interconnected porous network facilitates the reactants/product diffusion especially for catalysis operated under harsh experimental conditions.