Study on the preparation of bimetallic oxide sorbent for mercury removal

Series of adsorbents based on Al2O3 supported Cu and Mn have been prepared and tested for mercury removal from gas streams under various conditions. The metal content, impregnating sequence and the gas composition have significant effect on the performance of the adsorbents. Co-impregnation of Cu and Mn solutions is simple but also of help to improve the Hg pickup capacity, due to the synergic effect of the CuMn oxide, the sorbent prepared using incipient wetness method containing 20% CuO and 20% wt MnO2 has Hg pick capacity of 12.0% wt. It is showed that the oxide form the adsorbent can reduce Hg from more than 11,600 ppb to 0.1 ppb in a single pass. The presence of H2S in the gas stream changes the Hg sorption mechanism and increase Hg pickup capacity. XRD and electron microscope characterization results of the fresh and spent sorbent show that the active phases of the sorbent are CuMn(OH)3Cl and the presence of Mn2O3 catalyses the metallic Hg to convert into HgCl2 or HgCl. There are no elemental Hg present in the spent sorbent, but in the chemical states.