Cite this article: Lin, H., Chen, D., Liu, H., Zou, X. and Chen, T. (2017). Effect of MnO2 Crystalline Structure on the Catalytic Oxidation of Formaldehyde.
Aerosol Air Qual. Res.
17: 1011-1020. https://doi.org/10.4209/aaqr.2017.01.0013
MnO2 with different crystalline structure were synthesized by hydrothermal method.
Among the four MnO2 catalysts, γ-MnO2 has the best destruction and removal efficiency.
Mechanism of catalytic oxidation of formaldehyde has been suggested.
Manganese oxides prove to be a promising catalyst for formaldehyde (HCHO) elimination in catalytic oxidation. In this study, MnO2 with different crystalline structure (α-MnO2, β-MnO2, γ-MnO2, and δ-MnO2) were synthesized by hydrothermal method to investigate their catalytic performances towards the abatement of formaldehyde. The prepared catalysts were characterized and analyzed by the X-ray diffraction (XRD), hydrogen-temperature programmed reduction (H2-TPR), BET specific surface area, X-ray photoelectron spectroscopy (XPS), and ammonia-temperature programmed desorption (NH3-TPD). In addition, the apparent activation energy was also calculated by using Arrhenius plots. Among the above four prepared catalysts, the γ-MnO2 has the best destruction and removal efficiency (DRE), which was approaching to 100% for HCHO at 155°C. The catalytic activity of γ-MnO2 is associated with abundant mesopores, higher reducibility of surface oxygen species, and more oxygen vacancies as compared to other types of crystalline MnO2.
Keywords: Catalytic oxidation; Formaldehyde; MnO2; Surface oxygen; Temperature programmed reduction