LAUSR

Abstract The capture of Hg0 in syngas is challenging since the reducing atmosphere is disadvantageous to oxidize Hg0. Spinel CoxMn3−xO4 sorbents synthesized by a low-temperature sol-gel auto-combustion method were employed for the first time to remove Hg0 under simulated syngas. The Hg0 capture performance of CoxMn3−xO4 sorbents increased with Co mole ratio increases. CoMn2O4 showed the highest Hg0 capture performance among the CoxMn3−xO4 sorbents, attained over 95% Hg0 removal efficiency at 40–160 °C. The characterization results indicated that the mobile-electron environment, higher contents of surface Co and chemisorbed oxygen, larger BET surface area of CoMn2O4 sorbent were responsible for its superior performance. Ten repeated adsorption-regeneration cycles demonstrated that the regenerability of CoMn2O4 sorbent is excellent. Density functional theory (DFT) calculations were performed to determine the active sites of CoMn2O4 and to reveal Hg0 adsorption mechanism. The results suggested that Hg0 was chemisorbed on CoMn2O4 with a high adsorption energy (−1.04 eV). The two-fold coordinated surface Co atom was determined as the major active site for Hg0 adsorption. The strong orbital hybridization between Hg and Co atoms resulted in the strong chemisorption of Hg0 on CoMn2O4 surface.