Role of SO2 for Elemental Mercury Removal from Coal Combustion Flue Gas by Activated Carbon

• Published in: Energy & fuels Vol. 22; no. 4; pp. 2284 - 2289
• Main Authors: Uddin, Md. Azhar, Yamada, Toru, Ochiai, Ryota, Sasaoka, Eiji, Wu, Shengji
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 16.07.2008
• Subjects: Air pollution caused by fuel industries; Applied sciences; Energy; Energy. Thermal use of fuels; Environmental; Exact sciences and technology; Pollution reduction; Air pollution control; Reaction order; Activated carbon; Coal; Combustion; Flue gas purification; Mercury; Sulfur dioxide
• ISSN: 0887-0624; 1520-5029
• DOI: 10.1021/ef800134t

In order to clarify the role of SO2 in the removal of mercury from coal combustion flue gas by activated carbon, the removal of Hg0 vapor from simulated coal combustion flue gas containing SO2 by a commercial activated carbon (AC) was studied. The Hg0 removal experiments were carried out in a conventional flow type packed bed reactor system with simulated flue gases having a composition of Hg0 (4.9 ppb), SO2 (0 or 500 ppm), CO2 (10%), H2O (0 or 15%), O2 (0 or 5%), and N2 (balance gas) at a space velocity (SV) of 6.0 × 104 h−1 in a temperature rang 60−100 °C. It was found that, for SO2 containing flue gas, the presence of both O2 and H2O was necessary for the removal of Hg0 and the Hg0 removal was favored by lowering the reaction temperature in the order of 60 > 80 > 100 °C. The presence of SO2 in the flue was essential for the removal of Hg0 by untreated activated carbon. The activated carbons pretreated with SO2 or H2SO4 prior to the Hg0 removal also showed Hg0 removal activities even in the absence of SO2; however, the presence of SO2 also suppressed the Hg0 removal of the SO2-pretreated AC or H2SO4 preadded AC.