Enhancement of Hg0 adsorption performance at high temperature using Cu-Zn bimetallic sulfide with elevated thermal stability

• Hg adsorption efficiency of Cu 0.95 Zn 0.05 S increase by 48% compared with the pure CuS. • Cu-Zn bimetallic sulfides are much thermal-stable than that of the pure CuS. • Adding Zn significantly inhibits the formation of inactive SO 4 2- on metal sulfides. • S x existed as high-active short-chain S x on Cu0 .95 Zn 0.05 S. In this work, a series of Cu-Zn bimetallic sulfides were synthesized to improve the mercury adsorption performance at high temperatures. Results showed that the adsorption performance of Cu-Zn bimetallic sulfides are much better than CuS and ZnS at high temperature. Compared with the pure CuS, the mercury adsorption efficiency greatly increased from 40% to 88% at 220 °C for the optimal Cu 0.95 Zn 0.05 S. XRD results showed that Zn can enter into the lattice structure of CuS, which significantly promoted the thermal stability of CuS. TG analysis indicated that the weight loss for the Cu-Zn bimetallic sulfides was only 14%-19%, while the weight loss for CuS is as high as 42%. Moreover, the adding of Zn can significantly inhibit the formation of inactive SO 4 2- during the synthesis process, enabling more S x and S 2 2- sites exposed on the surface. Raman spectra indicated that the S x sites mainly existed in the form of long-chain S x (L- S x ) or ring S x on the pure CuS, while existed as short-chain S x (S-S x ) on Cu 0.95 Zn 0.05 S. The S-S x sites are more active in mercury adsorption, resulting in the better performance of Cu-Zn bimetallic sulfides.