Nanosized Cu-In spinel-type sulfides as efficient sorbents for elemental mercury removal from flue gas

Mercury emitted from human activities has received increasing attention because of its extreme toxicity, persis-tence and bioaccumulation. The development of highly-efficient sorbent with abundant active sites that exhibit high affinity toward Hg-0 is the key challenge for elemental mercury capture at low temperature. Herein, Cu-In spinel-type sulfides were synthesized through a hydrothermal synthesis. The Hg-0 removal performance of CuxIn2-xS2 sorbents was evaluated in the temperature range of 75 degrees C to 175 degrees C. The synthesized CuxIn2-xS2 sorbents showed excellent performance for Hg-0 removal at low temperatures, which perfectly matches the optimal temperature of flue gas at the downstream of desulfurization system. Hg-0 removal efficiency of CuxIn2-xS2 sor-bents significantly improved as the Cu proportion increased. CuInS2 sorbent showed superior mercury removal performance, the mercury removal efficiency reached 99.6% at 125 degrees C. O-2 and NO showed a slight inhibition on Hg-0 capture. The coexistence of SO2 and H2O showed no obvious negative effects on Hg-0 removal. The CuInS2 sorbent displayed a superior tolerance to SO2 and H2O. TPD and XPS analyses demonstrated that the adsorbed mercury mainly existed in the form of mercuric sulfides (HgS). Hg-0 adsorption over CuInS2 sorbent occurred via the Mars-Maessen mechanism. In this mechanism, Hg-0 vapor was physically adsorbed on CuInS2 sorbent and then converted to HgS. This study provides future potential for applying CuxIn2-xS2 sorbents to capture gaseous mer-cury at low temperature. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

A highly-efficient sorbent, Cu-In spinel-type sulfides, was synthesized through a hydrothermal synthesis and showed excellent mercury removal performance at low temperatures. The mercury removal efficiency significantly improved as the Cu proportion increased, with CuInS2 sorbent reaching 99.6% removal efficiency at 125 degrees C. The study demonstrated a potential for applying CuxIn2-xS2 sorbents to capture gaseous mercury at low temperature.