The outstanding performance of LDH-derived mixed oxide Mn/CoAlOx for Hg0 oxidation

Abstract

Layered double hydroxide (LDH)-derived Mn/CoAlO_x catalysts prepared by coprecipitation showed excellent performance in the oxidation of elemental mercury (Hg⁰). The Hg⁰ conversion on 1Mn/CoAlO_x was above 95% at 200–350 °C under a space velocity (GHSV) of 480 000 h⁻¹. Mn dopants dramatically improved both the adsorption capacity and oxidation ability of Hg⁰ due to the enhancement of surface oxygen species and surface-exposed transition metal cations. Correlations between the Mn dopants, the adsorption of catalysts for Hg⁰ oxidation and the redox behaviors of the catalysts were established. The results revealed that two chemical reaction equilibria may have existed between adsorbed Hg⁰ and O₂ on the surface of Mn/CoAlO_x. HCl promoted the chemical reaction equilibria to the positive direction. 1Mn/CoAlO_x catalysts had a certain ability to resist water and sulfur poisoning. These LDH-derived Mn/CoAlO_x catalysts were first reported for Hg⁰ oxidation in flue gas, which could be used for practical applications.