Fe doping Pd/AC sorbent efficiently improving the Hg0 removal from the coal-derived fuel gas

Fe doped Pd/AC (where AC is activated carbon) sorbents (1Pd5Fe/AC) were prepared and tested for removal of elemental mercury (Hg-0) from coal-derived fuel gas at medium range temperatures (150250 degrees C). It is found that the Hg-0 removal efficiency of 1Pd5Fe/AC sorbent was much higher than that of 1Pd/AC sorbent, which has previously been shown to suffer from H2S poisoning. 1Pd5Fe/AC sorbent can maintain its Hg-0 removal efficiency above 92% for 6 h at 200 degrees C. The fresh and used sorbents were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). The results indicated that the Hg-0 removal active components of the 1Pd5Fe/AC sorbent were elemental Pd and Fe2O3. The elemental Pd could react with mercury vapor to form Pd-Hg amalgam. Fe2O3 could react with H2S to produce elemental sulfur which can combine with Hg-0 to form HgS. It is worth noting that PdO existed in both 1Pd5Fe/AC and 1Pd/AC sorbents and could react with H2S to form PdS, which results in the deactivation of sorbents. But Fe2O3 on the surface of 1Pd5Fe/AC sorbent can compete with PdO to react with H2S to produce elemental sulfur, thus inhibiting the deactivation of 1Pd5Fe/AC sorbent. In addition, H-2 and CO were found to promote the Hg-0 removal efficiency. The used 1Pd5Fe/AC sorbent could successfully be regenerated and reused for Hg-0 removal. (C) 2016 Published by Elsevier Ltd.