Development of low-temperature desulfurization performance of a MnO2/AC composite for a combined SO2 trap for diesel exhaust

Abstract

Growing concern about the removal of sulfur dioxide (SO₂) from combustion exhaust has resulted in the development of desulfurization materials for a SO₂ trap. In this study, a manganese dioxide/activated carbon (MnO₂/AC) composite was proposed as a low temperature desulfurization material for a combined SO₂ trap. The MnO₂/AC composite was synthesized using a redox deposition method and characterized using scanning electron microscopy (SEM), nitrogen adsorption, X-ray fluorescence spectrometry (XRF) and Fourier transform infrared (FTIR) spectroscopy. The SO₂ adsorption capacity of the composites was measured using thermogravimetry and the SO₂ adsorption characteristics were also investigated. In the low temperature region (50–200 °C), the MnO₂/AC composite exhibits good SO₂ trap performance and the MnO₂ conversion of the composite is significantly improved. It was found that the SO₂ adsorption on the MnO₂/AC composite is a chemisorption process. The experimental data for SO₂ adsorption on the MnO₂/AC composite could fit the Freundlich model well. Changes in the thermodynamic parameters were determined. The calculated values of ΔG⁰ and ΔH⁰ indicate that the SO₂ adsorption on the MnO₂/AC composite is spontaneous and thermodynamically favorable.