Stability of mercury compounds at high temperatures

Combustion of fossil fuels is the main anthropogenic source of mercury. The efficiency of methods for removing mercury from coal syngas or flue gases mainly depends on the chemical forms of mercury. Despite the fact that temperature fractionation is a common approach to defining mercury species in solid samples, the accuracy of known results is still questionable. For developing the method of temperature fractionation, a home-made apparatus was used, in which known mercury compounds, pure or mixed with SiO2, were heated by a slow increase of temperature (approximately 2.2 °C min-1) to 800 °C in a flow of either nitrogen or air. Released elemental mercury was detected by an atomic absorption spectrometry technique. The results showed that not only the type of carrier gas, but also the substrate affected the number and size of the peaks and the temperature at which elemental mercury was released.