Shrimp Shell Catalyst for Biodiesel Production

A high-performance and environmentally friendly shrimp shell catalyst for biodiesel production was prepared by incomplete carbonization of shrimp shell, loading KF on the resultant, and activation at a desired temperature. The dependence of catalytic activity on preparation conditions such as carbonization temperature, loading amount of KF, and activation temperature was investigated. The shrimp shell catalyst was characterized by the Hammett indicator method, thermogravimetric analysis (TGA) and differential thermal analysis (DTA), scanning electron microscope (SEM), N₂ adsorption−desorption, X-ray diffraction (XRD), energy dispersive spectrometer (EDS), element analyzer, and Fourier transform infrared spectrometer (FT-IR). The catalytic performance was evaluated by the transesterification of rapeseed oil with methanol. The results indicated that the optimum preparation conditions were carbonization at 450 °C, loading KF of 25 wt %, and activation at 250 °C. The conversion reached 89.1% using the shrimp shell catalyst when the reaction was carried out at 65 °C with a catalyst amount 2.5 wt %, a methanol/rapeseed oil molar ratio 9:1, and a reaction time of 3 h. The shrimp shell catalyst possesses a porous framework structure, and its catalytic activity for the transesterification came from the active sites formed by the reaction of incompletely carbonized shrimp shell with KF during the activation process. It was found that the shrimp shell catalyst shows high catalytic activity and ecologically friendly properties, having the potential opportunity to be used in biodiesel production process as heterogeneous base catalyst.