nan Huhetaoli

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

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.

Development of a compact MnO2 filter for removal of SO2 from diesel vehicle emissions

Increasing concern about sulfur dioxide (SO2) from diesel vehicle exhausts causing detrimental effects on NOx removal catalysts has resulted in the development of dry desulfurization filters for complete removal of SO2. In this study, a compact MnO2 filter was developed for diesel emission control. The SO2-capture behavior of the compact MnO2 filter was investigated by using a volumetric device in a low temperature range (200–400 °C) and low SO2 pressure conditions. The maximal capacity of the MnO2 filter was 304.1 mgSO2 per gMnO2 at 400 °C. Based on the experimental results, the required volume of the MnO2 filter was estimated as only 0.6 L for a diesel car with 30 000 km distance traveled per year. The thickness of the MnO2 filter had significant influence on its SO2-capture performance. The sulfate reaction mechanism was also discussed by using a grain model under four reaction temperature conditions for improving the efficiency of the design of the desulfurization filter. The sulfate process can be divided into two control stages (the chemical reaction control stage and the solid diffusion control stage) and the prediction models fit the experimental data well for both control stages, indicating that the two-stage grain model is suitable for the sulfate reaction between the MnO2 filter and SO2. The calculated apparent activation energy of 18.8 kJ mol−1 indicates that the MnO2 filter exhibits high activity for SO2 adsorption in a pure SO2 atmosphere.