In Situ Spectroscopic and Computational Studies ona MnO2–CuO Catalyst for Use in Volatile OrganicCompound Decomposition

摘要

In situ near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and density functional theory calculations were conducted to demonstrate the decomposition mechanism of propylene glycol methyl ether acetate (PGMEA) on a MnO2–CuO catalyst. The catalytic activity of MnO2–CuO was higher than that of MnO2 at low temperatures, although the pore properties of MnO2 were similar to those of MnO2–CuO. In addition, whereas the chemical state of MnO2 remained constant following PGMEA dosing at 150 °C, MnO2–CuO was reduced under identical conditions, as confirmed by in situ NEXAFS spectroscopy. These results indicate that the presence of Cu in the MnO2–CuO catalyst enables the release of oxygen at lower temperatures. More specifically, the released oxygen originated from the Mn–O–Cu moiety on the top layer of the MnO2–CuO structure, as confirmed by calculation of the oxygen release energies in various oxygen positions of MnO2–CuO. Furthermore, the spectral changes in the in situ NEXAFS spectrum of MnO2–CuO following the catalytic reaction at 150 °C corresponded well with those of the simulated NEXAFS spectrum following oxygen release from Mn–O–Cu. Finally, after the completion of the catalytic reaction, the quantitiesof lactone and ether functionalities in PGMEA decreased, whereas theformation of C=C bonds was observed.