Waste alkaline Mn–Zn batteries as efficient catalysts applied in ketonization of fatty acids

Hazardous waste alkaline batteries and waste fatty acids significantly threaten the environment. In this study, waste alkaline batteries were simply transferred to r-MnZn catalysts, which were then applied in the ketonization of fatty acids. The assessment results show that r-MnZn can efficiently convert n-octanoic acid to 8-pentadecanone. The conversion and yield are evaluated as 100% and 92.9%, respectively, which are much better than those of TiO2, ZrO2, CeO2 and other metal oxides. The excellent catalytic efficiency is derived from the MnO2 nanorods in r-MnZn materials which are characterized by XRD, TEM, and XPS. In addition, when using different kinds of fatty acids in ketonization, longer carbon chains require a higher activation energy, and the conversion of fatty acids was lower. Furthermore, the ketone products have a short carbon chain that induces side reactions, leading to a low yield. The above results indicate that r-MnZn is an efficient catalyst applied in the ketonization of fatty acids.