One-step synthesis of sludge-derived MnOx catalysts for highly efficient removal of gaseous ozone from industrial flue gas

A series of sludge-derived MnOx catalysts were successfully obtained by a one-step sludge disintegration process using KMnO4. The obtained S-MnOx-1.2 catalyst exhibited excellent activity and superior water resistance under industrial flue gas conditions (5 vol% H2O, 40–80 ℃, 300,000–600,000 mL/(g·h) of GHSV). β‐MnOOH was the predominant component generated on the sludge surface by a redox reaction between KMnO4 and organic matter. The superior ozone decomposition performance was mainly ascribed to its large surface area, plentiful oxygen vacancies and interlayer hydroxyl groups. There were two types of surface oxygen vacancies, denoted as ozone-friendly and hydrophilic oxygen vacancies, participated in the ozone elimination process. Surface hydroxyl groups physically adsorbed abundant water molecules and hindered the chemisorption of water on ozone-friendly oxygen vacancies, thereby increasing the water resistance of the catalyst. The present work produced a potential catalyst in favor of ozone elimination, and promoted the high value-added utilization of waste sludge. [Display omitted] •Sludge-derived MnOx catalysts were obtained by a one-step KMnO4 sludge disintegration process.•The S-MnOx-1.2 exhibited excellent ozone removal activity and superior water resistance.•β‐MnOOH was the predominant Mn oxide species on the sludge surface.•Hydroxyl groups hindered water chemisorption, consequently promoted water resistance.•Oxygen vacancies-involved mechanism for ozone elimination was proposed.