Birnessite-type short rod-like MnO2 achieving propane low-temperature destruction: Benign synthesis strategy and reaction mechanism determination
Yanfei Jian, Xiangbo Feng, Mingjiao Tian, Zeyu Jiang, Chi He
Abstract
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 Mn 4+ 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.