1. Birnessite-type short rod-like MnO2 achieving propane low-temperature destruction: Benign synthesis strategy and reaction mechanism determination.
- Author
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Jian, Yanfei, Feng, Xiangbo, Tian, Mingjiao, Jiang, Zeyu, and He, Chi
- Subjects
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PROPANE , *CARBONATE minerals , *CARBON dioxide in water , *FOURIER transform infrared spectroscopy , *GOLD ores - Abstract
[Display omitted] • Birnessite-type short rod-like MnO 2 (MnO 2 -SR) was prepared under ambient conditions. • MnO 2 -SR exhibits the highest activity with 90% of propane oxidized at 225 °C. • Oxygen vacancies and high valent Mn4+ species promote activating of O 2 and propane. • Dissociation of propane molecules is the decisive step in propane oxidation. Developing economical and robust noble metal-free materials for obstinate light alkane low-temperature decomposition is of great significance. Here, birnessite-type short rod-like MnO 2 was firstly prepared by facile mixing KMnO 4 and ascorbic acid under ambient conditions and employed in propane catalytic decomposition. Experimental results revealed that abundant oxygen vacancies and high valent Mn4+ species, superior reducibility, and high surface oxygen mobility guarantee the remarkable low-temperature activity of MnO 2 -SR, over which 90% of propane can be oxidized (T 90) at temperature as low as 225 °C, achieving a temperature reduction over 70 °C compared with that of δ-MnO 2 (T 90 = 300 °C) and α-MnO 2 (T 90 = 355 °C). In situ diffuse reflectance infrared Fourier transform spectroscopy revealed that the dissociation and activation of propane molecules is the decisive step in propane oxidation. Gaseous propane is slowly oxidized by adsorbed oxygen directly to the final mineralization products at low temperature region (<200 °C); at high temperature region (>200 °C) however, propane molecules are firstly dissociated and activated before oxidized to carbonate intermediate products over active oxygen, and then eventually oxidized to carbon dioxide and water. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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