EXPERIMENTAL INVESTIGATION OF THE AEROSOL-CATALYZED OXIDATION OF SO2 UNDER ATMOSPHERIC CONDITIONS

Abstract

One of the most important processes affecting the chemical and physical form of atmospheric sulfur dioxide is the interaction of gaseous SO2 with solid or liquid aerosol particles. The investigation of the catalytic activity of some synthetic aerosols and dust particles of different industrial origin under real atmospheric conditions (i.e. a wide range of relative humidity and temperature) have been investigated in the course of an experimental research program at Karlsruhe Nuclear Research Center, Germany. The experiments were carried out in a 4.5 m3 climate-controlled reaction chamber especially designed for SO2-experiments in the ppm-concentration range. Starting with SO2-concentrations of 3–5 mg m–3 the removal of SO2 from gas phase in the presence of moist aerosol-free air and moist aerosol-polluted air was investigated as was the change of chemical composition of aerosols due to SO2-adsorption and catalytic oxidation. The results of these experiments with synthetic MnSO4 aerosols and fly-ash particles of a hard coal fired power plant are presented. They indicate a strong dependence of the catalytic oxidation rate on the relative humidity but no disappearance of the catalytic activity at low relative humidities.