Highly Active MnO₂ for the Catalytic Combustion of Ethyl Acetate at Low Temperature

Abstract—A highly active MnO₂ catalyst with mixed crystal forms for the catalytic combustion of ethyl acetate was successfully prepared. The characterization results showed that increasing the hydrothermal temperature promotes the transformation of MnO₂ from α phase to β phase, and the microscopic morphology gradually evolves from stacked granular to rod-like structure, thereby obtaining biphasic mesoporous MnO₂. In particular, the lattice fringes of α and β phases observed in HRTEM further proved that MnO₂ possesses a dual-phase structure. XPS verified that MnO₂–180°C has the highest O_ads/O_latt (0.45) and Mn³⁺/Mn⁴⁺ (0.90) ratio, and as oxygen vacancies appear together with the formation of Mn³⁺ ions. The MnO₂–180°C catalyst displayed the best performance that T₉₉ (the temperature needed for 99% conversion) is as low as 170°C even though under the high space velocity of 68 000 mL g^–1 h^–1. Furthermore, the catalytic activity remained unchanged after 24 h of continuous reaction, demonstrating excellent low-temperature catalytic performance and good stability.