Sulfur dioxide (SO2) is one of the major pollutants emitted by coal-burning power stations and metallurgical plants because it is the major cause for acid rain. A unique desulfurization method capable of SO2 removal from dilute sulfurous flue gases down to the atmospheric level was developed. The method is based on absorbing SO2 with a Li-Na-K carbonate eutectic melt and subsequent regeneration of the melt with CO or CH4. The regeneration with CO produces a 3:1 CO2:COS mixture.
Carbonyl sulfide (COS) is a poisonous, polluting gas that has to be converted to elemental sulfur, which is an environmentally benign and, potentially, commercially useful product. We have studied thermal decomposition of COS to elemental sulfur and various temperatures and CO2:COS ratio. The decomposition can be almost complete, and a reduction of the activation energy for the reaction using a catalyst has also been observed.
We have measured the decomposition rates at different temperatures within the range 500-800 degrees Celsius and at three different flow rates (i.e. residence times). We have monitored concentrations of COS and its decomposition products using gas chromatographer. The quartz tube inside the furnace has some catalytic activity towards COS decomposition and, therefore, lowered considerably the activation energy. The effect of CO2 on the decomposition process was also measured and found to be promoting decomposition below 600 °C. At the optimal conditions COS decomposition rate of 93% was achieved.