Hg⁰ removal by palygorskite (PG) supported MnO_x catalyst

The MnO_x/PG catalysts were prepared by supporting Mn oxides to palygorskite (PG) and used to remove Hg⁰ in simulated flue gas, which were analyzd and characterized by the specific surface area analysis (BET), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results show that the co-effect of MnO_x and PG significantly enhances the Hg⁰ removal performance; the MnO_x/PG catalyst with 8% MnO_x loading has the highest Hg⁰ removal activity. The Hg⁰ removal efficiency can maintain above 95% at 210 ℃ with a space velocity of 6000 h^-1 and an inlet Hg⁰ concentration of 80 μg/m³ for 400 min. O₂ can promote the Hg⁰ removal by MnO_x/PG catalysts, while SO₂ and H₂O have inhibitory effects. In the presence of O₂, the inhibitory effect of SO₂ can be obviously weakened. The results of XRD, XPS and temperature programmed desorption experiments (TPD) indicate that the active components MnO_x disperse well on the surface of PG. The removal process of Hg⁰ on the MnO_x/PG catalyst includes the steps of adsorption, oxidation and reaction, and HgO and HgSO₄ are generated and adsorbed on the catalyst.