Oxygen-deficient layered ε-MnO2 nanosheets derived from acid-etched La3Mn2O7 for robust adsorption-catalytic oxidation of toluene

Abstract

Manganese dioxide (MnO2) stands out as a promising catalyst for toluene degradation yet refining its synthesis for optimal efficiency poses a significant challenge. In this study, we presented an up-bottom synthesis approach for ε-MnO2 by selectively removing inactive La ions from La3Mn2O7 (LLM) through acid etching, yielding stacked nanosheets with enriched oxygen vacancies. The resulting H2SO4-LLM catalyst exhibited efficient synergistic adsorption-catalytic oxidation effects, attributed to its exceptional specific surface area (307.0 m2/g) and abundant acidic sites, achieving almost 90 % removal of 2000 mg/m3 toluene (T90) at 196 ℃ and complete oxidation to CO2 at 205 °C at a space velocity of 18000 mL/(g·h), outperforming most state-of-the-art catalysts for toluene removal. The study elucidates the role of lattice oxygen in catalyzing toluene oxidation and reveals the intricate interplay between oxygen adsorption, lattice oxygen mobility, and redox capability, paving the way for the development of robust catalysts for environmental remediation.