Experimental and theoretical investigations on H2S-enhanced elemental mercury adsorption over the La2CuO4/ZSM-5 sorbent

A novel Cu 2 LaO 4 /ZSM-5 sorbent was synthesized using the sol–gel method, and the role of H 2 S in enhancing Hg⁰ removal was investigated through experimental and theoretical approaches. Mercury removal performance was evaluated in a fixed-bed reactor under simulated syngas conditions, revealing that H 2 S significantly promoted removal efficiency, achieving 95.6 % at 200 °C. In contrast, H 2 and CO inhibited Hg 0 removal by depleting surface oxygen species. The addition of H 2 S mitigated these effects, facilitating Hg 0 adsorption and oxidation via a Langmuir–Hinshelwood mechanism. Density functional theory (DFT) calculations confirmed strong chemisorption of Hg 0 and H 2 S on the Cu 2 LaO 4 surface, with adsorption energies of −123.71 kJ/mol and −168.98 kJ/mol, respectively. The reaction to form HgS had a manageable energy barrier of 25.80 kJ/mol and an exothermic enthalpy of −196.82 kJ/mol, with HgS formation as the rate-limiting step. This study highlights the effectiveness of Cu 2 LaO 4 /ZSM-5 for mercury capture and its potential application in industrial syngas purification.