Enhanced La0.875Ce0.125CoO3 catalyst for Hg0 removal from low-temperature flue gas: H2O and SO2 resistance performance and mechanism

The catalysts utilized for low-temperature catalytic oxidation of Hg0 from flue gas typically suffer from issues related to H2O and SO2 poisoning. This study focused on doping modification of La0.875Ce0.125CoO3 perovskite with promoters and conducted a thorough investigation on the H2O and SO2 resistance through characterization and DFT methods. Experimental results demonstrated that the LCeCO/30 wt% ZrO2 possessed optimal H2O and SO2 resistance. Under high sulfur (1500 ppm SO2) and high humidity (10 % H2O(g)) conditions, it maintained approximately 91 % Hg0 removal efficiency after thermal regeneration cycles. Characterization results indicated that ZrO2 doping facilitated the formation of three-dimensional macroporous structure and protected active Co3+ sites on the surface. Based on DFT calculations, the H2O poisoning is attributed to competitive adsorption between H2O(g) and Hg0 on the active sites. Also, the SO2 poisoning occurs due to competitive adsorption of SO2 and the toxicity of sulfates to the surface active sites. Meanwhile, ZrO2 doping can lower the adsorption energies of H2O(g) and SO2 by modifying their adsorption configuration, thus weakening the competitive adsorption of H2O(g) and SO2 with Hg0. Overall, LCeCO/ZrO2 is a promising Hg0 removal catalyst with superior H2O and SO2 resistance.