Effect of MnO2 Crystalline Structure on the Catalytic Oxidation of Formaldehyde

Huiqi Lin,Dong Chen,Tianhu Chen,Haibo Liu,Xuehua Zou

doi:10.4209/aaqr.2017.01.0013

Huiqi Lin, Dong Chen + Show 3 more

Open Access

https://doi.org/10.4209/aaqr.2017.01.0013

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Abstract

ABSTRACTManganese 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.

Highlights

Formaldehyde (HCHO), one of typical Volatile organic compounds (VOCs), is considered to be the major pollutant in indoor air (Wang and Li, 2010; Wu et al, 2015a; Zeng and Bai, 2016)
Four different crystal forms of MnO2 nanoparticles were prepared by hydrothermal method and were tested for the destruction and removal (DRE) of formaldehyde
The physicochemical properties of the catalysts were characterized by the X-ray diffraction (XRD), BET, H2-TPR, NH3-TPD, and X-ray photoelectron spectroscopy (XPS) techniques

Summary

Introduction

Formaldehyde (HCHO), one of typical Volatile organic compounds (VOCs), is considered to be the major pollutant in indoor air (Wang and Li, 2010; Wu et al, 2015a; Zeng and Bai, 2016). Four different types of MnO2 crystal structures were prepared and their properties, performance and reaction mechanism of the formaldehyde catalytic oxidation were investigated and discussed. It turns out that there are big differences between the specific surface area of MnO2 catalysts with diverse crystal type, and the average pore size variation law is α-MnO2 > β-MnO2 > δ-MnO2 > γ-MnO2, while the change law of the total pore volume is Manganese oxides α-MnO2 β-MnO2 γ- MnO2 δ- MnO2

Results

Conclusion