In-situ template method to synthesize metal/non-metal doped carbon for SO2 adsorption at low concentration: DFT and experimental studies

Abstract

SO2 is one of the most significant air molecular contaminants (AMC). The development of materials for capturing low-concentration SO2 at room temperature is of great importance for industrial production and environmental safety. In this study, hierarchical porous carbon materials with Zn–N–C active structures were synthesized in one step using an in-situ template method. Among them, Zn/AC-2 exhibited a high specific surface area (1143.73 m2/g) and micropore volume (0.42 cm3/g). Dynamic adsorption tests were conducted under the conditions of an inlet concentration of 90 ppm, with a temperature of 23 °C and a humidity of 50%. The results indicated that the material showed an excellent capturing performance for SO2, with a breakthrough adsorption capacity of 3.37 mmol/g. Through characterization techniques including XPS, XRD, and SEM-EDS, it was found that the metal elements were dispersed in atomic form within the carbon framework, demonstrating the effectiveness of the modification method. A comparative study of the new adsorbent and spent adsorbent proved that SO2 reacts with extremely high catalytic efficiency on the material surface to generate SO3, revealing the reaction mechanism on the material surface. Finally, based on density functional theory, the microscopic reaction mechanism of the interaction between SO2 and the prepared material surface was studied at the molecular level. The results showed that the reaction energy barrier on the material surface is only 1.01 eV, and the reaction releases 3.14 eV of energy, indicating that the reaction can spontaneously occur at room temperature.