AMnO (A=Cu, Ni and Zn) sorbents coupling high adsorption and regeneration performance for elemental mercury removal from syngas.

AMnO (A= Cu, Ni and Zn) spinel sorbents synthesized by a low-temperature sol-gel auto-combustion method were for the first time used to eliminate elemental mercury (Hg) from syngas. CuMnO sorbent exhibits the highest Hg adsorption performance under simulated syngas, higher than 95 % Hg capture efficiency is obtained at 200 °C. Adsorption-regeneration experiments demonstrate that the regenerability of CuMnO is excellent. The influences of syngas compositions on Hg elimination over CuMnO were examined. HS plays the most important role in Hg removal from syngas, which can be adsorbed on CuMnO surface and transformed into active sulfur species to react with Hg to form surface-bonded HgS. X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption (TPD) experiments prove that HgS is formed on the spent sorbent. The surface Cu cations and chemisorbed/lattice oxygens participate in Hg adsorption and transformation. HCl promotes Hg removal by forming surface active chlorine species. H, CO, and HO inhibit Hg removal under N atmosphere. However, they exhibit no obvious effect on Hg removal with the assistance of HS. The excellent Hg capture performance, good regenerability and HO resistance of CuMnO make it to be a very promising sorbent for Hg removal from syngas at higher temperature.