The effect of NH
3 addition on SO
2 adsorption properties of steam activated semicoke (activated carbon) has been investigated . When activated carbon was used by repeating SO
2 adsorption at 130°C and regeneration in N
2 at 450°C, the amounts of surface oxide which were not decomposed at regeneration temperature increased. It was, however, found out that these surface oxides were removed easily by heating the activated carbon in the presence of NH
3 at regeneration temperature .With the decrease of amounts of surface oxide, there was an increase in the specific surface area of activated carbon. In addition to the removal of surface oxide with NH
3, some surface oxides were found to form basic nitrogen compounds . These compounds are estimated to be active sites for SO
2 adsorption.
When NH
3 was added in a flue gas, both sulfuric acid and its ammonium saltswere adsorbed on activated carbon. These ammonium salts decomposed to form NH
3during regeneration process at 450°C. It is concluded that the NH
3 reacts with surface oxide to form H
2O and N
2 and this effectively decrease the carbon loss during regeneration. With adding NH
3 in a flue gas, it is found out that the rate of decrease of SO
2 adsorption capacity during repetition of adsorption-regeneration process can be suppressed. However, the strength of a activated carbon was found out to decrease much faster than a activated carbon used without adding NH
3 in a flue gas.
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