Development of a zeolite supported CaO derived from chicken eggshell as active base catalyst for used cooking oil biodiesel production

Herein, used cooking oil (UCO) was upgraded to fatty acid methyl ester (FAME) via methanolysis process using zeolite based eggshell (ZE/ES) composite catalyst. The ZE/ES catalyst was prepared using wet impregnation technique followed by calcination at different temperatures (700–900 °C), and its properties were evaluated by various characterization techniques (BET, TGA/DTA, FTIR, CO₂-TPD, XRD, SEM and surface basicity). Optimization of methanolysis of UCO was studied using central composite design. Under the optimum transesterification conditions (at 69.1 °C for 238.8 min using methanol/UCO molar ratio of 9.7:1 with 2.1 wt% catalyst dosage), the maximum FAME content was 93.7% when composite catalyst synthesized by loading 2 g of zeolite with 5 g of eggshell and calcined at 800 °C (2ZE/ES-800) was utilized. The remarkable performance of 2ZE/ES-800 could be attributed to its high basic strength (1181.1 μ mol/g) and dominance of the CaO on its surface. Reusability study showed that the 2ZE/ES-800 catalyst could be reused for five successive cycles with no significant decrease in catalyst activity.