UiO-66 and its Br-modified derivates for elemental mercury removal

Phenyl bromine-appended metal-organic frameworks (Br-MOFs) were synthesized and applied in elemental mercury (Hg-0) removal from simulated flue gas, considering the stability of bromine on the materials at the same time. The techniques of PXRD, nitrogen adsorption, TGA and XPS were used to characterize the materials. Phenyl bromide on the MOFs was the main active site for Hg-0 capture. The optimal Br-MOF showed high Hg-0 removal efficiency of more than 99% for 48 h at 200 degrees C, whereas the efficiency of un-functionalized MOF and conventional bromine impregnated active carbon dropped to 59.8% and 91.2% within 5 h, respectively. The crystalline integrity of the Br-MOF was maintained after Hg-0 adsorption. Br-MOF exhibited enhanced Hg-0 removal efficiency when SO2 was introduced to the flue gas. However, exposure Br-MOF to flue gas with steam resulted in low Hg-0 removal efficiency. Bromine leaching experiments proved that Br-MOFs have high bromine stability over the Hg-0 adsorption process, avoiding the possible bromine pollution caused by the conventional bromine impregnated adsorbents. All of these results demonstrated the phenyl bromine-appended MOFs to be potential Hg-0 adsorbent regarding its high Hg-0 capture efficiency and low environmental risk. (C) 2016 Published by Elsevier B.V.