Esterification of tripalmitin using calcined scallop shell as a heterogeneous basic catalyst

Calcined waste scallop shell (Patinopecten yessoensis) was used as a basic heterogeneous solid catalyst for the transesterification of tripalmitin as a model triglyceride for assuming biodiesel production. The scallop shell was pulverized and calcined at 900 and 1000°C for 4 h. Calcined reagent calcium carbonate was also used as a control catalyst. The transesterification experiments were carried out at 30°C with varying catalyst dosage and calcination conditions. In the most experimental condition, the yield reached ~90% within 8–10 h. The overall reaction rate constant, k, was determined by simple first-order reaction kinetics. The calcined catalyst was characterized using SEM, EDS, and XRD analysis. The number of basic active sites on the surface was determined by titration with benzoic acid. A linear relationship between k and the number of the basic active sites was obtained. The time course of the concentration of the products could be estimated using this relationship.