Birnessite-type short rod-like MnO2 achieving propane low-temperature destruction: Benign synthesis strategy and reaction mechanism determination

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 MnO2 was firstly prepared by facile mixing KMnO4 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 MnO2-SR, over which 90% of propane can be oxidized (T90) at temperature as low as 225 °C, achieving a temperature reduction over 70 °C compared with that of δ-MnO2 (T90 = 300 °C) and α-MnO2 (T90 = 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) 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.