Polyethyleneimine-functionalized mesoporous carbon nanosheets as metal-free catalysts for the selective oxidation of H2S at room temperature

Abstract

Nitrogen-functionalized mesoporous carbon nanosheets are designed and constructed by supporting polyethyleneimine (PEI) on mesoporous carbon nanosheets. The carbon nanosheets possess a two-dimensional lamellar structure, interconnected mesoporous framework and highly dispersed PEI with considerable basic sites which work cooperatively to improve the desulfurization capability at room temperature. The appropriate residual pores after PEI loading provide a fast H2S diffusion channel, accessible interfacial area and storeroom for the product. Moreover, the nanosheet structure could shorten the diffusion pathway to promote the reaction kinetics. The nitrogen functional group of PEI as base sites is effective to enhance the interaction with H2S and facilitate its dissociation into HS−, resulting in a high breakthrough sulfur capacity of 13.68 mmol/g. A reaction mechanism by the combination of amine group promoted H2S dissociation and carbon induced O2 activation is proposed. This work raises the possibility of employing nitrogen-functionalized porous carbons as efficient catalyst for H2S selective oxidation.