Pd/Al2O3 Sorbents for Elemental Mercury Capture at High Temperatures in Syngas

Abstract

To capture elemental mercury (Hg0) at high temperatures in simulated syngas, Pd/Al2O3 sorbents were developed using an impregnation method. The Pd/Al2O3 sorbents with a Pd loading value of 8% exhibited high Hg0 capture activity from 200 to 270 °C. Over 90% of the mercury capture by 8Pd/Al2O3 was achieved for operating temperatures up to 270 °C. The superior performance of Pd/Al2O3 sorbents could be primarily ascribed to the formation of a Pd–Hg amalgam. H2 and CO were found to be promotional on Hg0 capture because of the reduction of PdO to Pd metal. H2S significantly inhibited Hg0 capture due to the consumption of the active palladium. HCl promoted Hg0 capture, which could be ascribed to the catalytic oxidation of Hg0 to HgCl2. H2O showed a prohibitive effect on Hg0 removal. The regeneration experiments indicated that the spent Pd/Al2O3 sorbents could be facilely revivified and reused.