Removal Of Elemental Mercury From Simulated Coal Combustion Flue Gas By Mineral Sorbent Modified With MnCl₂

Energy supply of China is mainly relied on coal. Coal consumption of China has accounted for the half of the world's total consumption every year. In recent years, the environmental issues caused by coal combustion has been increasing serious and the mercury emission from coal combustion has become global concern. China is the largest mercury emission country in the world at present, the control of coal-fired mercury emission in China has become an urgent problem. In this paper, natural minerals and industrial waste was chosen as efficient material to prepare a mineral sorbent and its application for mercury removal has been studied.The sorbents were prepared by a mixture of mineral A/B/C modified with MnOx. Experiments were carried out on a laboratory-scale fixed-bed reactor to investigate the mercury removal efficiency. The sorbent was characterized by an X-ray diffraction (XRD), scanning electron microscope (SEM) and other characterization methods.The result showed that different manganese salts precursors affected greatly on HgO removal efficiency. The MnCl2 modified sorbent samples exhibited much better adsorption performance than the ones modified by Mn(NO3)2, the main reason for the huge difference in adsorption performance was that the different presence state of the active component on the sorbents surface. The optimal preparation condition was 10% MnCl2 loading value and 400? calcination temperature according to a series experiment results.The sorbent had a good HgO removal performance at range of 200 to 500 ?, and the HgO removal efficiency reached 90% at temperature between 300 and 400 ?. The main active components of the sorbent were manganese oxides and active chlorine which formed from the MnCl2 decomposition at high calcination temperature. The oxygen in the flue gas played an important role in maintaining the high HgO removal efficiency, trace amount of NO showed a little promoting effect on mercury removal while SO2 and HC1 showed a visible inhibitory effect. H2S had a promoting effect in the oxygen-free atmosphere.The sulfur resistance of Fe-doped modified sorbent had a significant promotion on HgO removal efficiency in the president of SO2 in gas phase. The reason might be that SO2 priority to react with Fe2O3, while protected the active component MnOx from reacting with SO2.