Reduction of sulphur gas emissions using activated carbon

Sulphur dioxide, as one of the gases responsible for acid rain, is produced mainly by coal-fired power stations. Shifting to fuels with a lower carbon-to-hydrogen ratio, such as natural gas, is generally considered as an effective method to reduce greenhouse gas emissions and to drop the concentration of sulphur dioxide in the atmosphere. Elimination of hydrogen sulphide from natural gas is necessary for its corrosive effects and production of sulphur dioxide in combustion process. Activated carbon can convert this compound to elemental sulphur and water in an oxidation reaction. In this study, activated carbon produced from luscar char was used for this reaction. The effects of porous characteristics and surface chemistry on the performance of catalyst were studied using diffuse reflectance infrared Fourier transform spectroscopy, nitrogen adsorption and temperature programmed desorption methods. It is shown that oxidation of activated carbon by nitric acid increased surface oxygen groups on activated carbon, which can be thermally desorbed at the next step. This product has more active sites in comparison to original activated carbon and shows a better performance in oxidation reaction. Applying impregnating agents, especially potassium iodide reduces the production of sulphur dioxide in the reaction as an undesirable product.