One-step synthesis of MgO-MnO loaded N-doped carbon aerogel for ultrahigh low-temperature H2S desulfurization

Abstract

Hydrogen sulfide (H₂S) is a hazardous and malodorous pollutant with severe environmental and health impacts. A promising approach for H₂S removal involves coupling adsorption with low-temperature catalytic oxidation using alkaline metal oxide-loaded carbon-based materials. However, the effectiveness of these materials is often limited by pore blockage caused by metal oxides and desulfurization byproducts. N-doped carbon aerogels offer a solution to this issue due to their large specific surface area and well-developed pore structure. In this study, a novel MgO-MnO-loaded N-doped carbon aerogel (MgO-MnO/NC) was synthesized by one-step high-temperature pyrolysis of cellulose-based aerogel precursor for highly efficient low-temperature H₂S desulfurization. The effects of pyrolysis temperature and metal oxide loading on H₂S removal efficiency was systematically investigated. The optimized MgO-MnO/NC-600–0.3 (where 600 represents the pyrolysis temperature and 0.3 denotes the mass ratio of metal salts to cellulose) exhibited outstanding H₂S removal performance, achieving an ultrahigh desulfurization capacity of 1696 mg/g. The desulfurization conditions, such as O₂ content and relative humidity, were found to play a crucial role in the H₂S removal process. In situ DRIFTS and XPS analyses revealed a synergistic mechanism of reactive adsorption and catalytic oxidation on the MgO-MnO/NC surface. The desulfurization products were identified as sulfur, sulfate and metal sulfide (MgS and MnS). This study not only proposes a feasible strategy for fabricating biomass-derived aerogel carbon, but also offers valuable insights into the catalytic oxidation of H₂S for enhancing the desulfurization performance of N-doped carbons.