Simultaneous esterification/transesterification of waste cooking oil and Jatropha curcas oil with MOF-5 as a heterogeneous acid catalyst

Metal–organic framework MOF-5 was used for the first time as a heterogeneous acid catalyst for the simultaneous esterification/transesterification of two nonedible oils, waste cooking oil and Jatropha curcas oil. Fatty acid methyl ester (biodiesel) production was evaluated using an experimental central composite design. A surface response methodology allowed the determination of optimal reaction conditions in terms of methanol/oil molar ratio (3:1–45:1), reaction time (1–15 h), temperature (118–152 °C) and catalyst amount (0.1–0.9 wt%) with a variation lower than 10% with respect to the experimental yield value. The best oil to biodiesel yield conversions were 90.8% (36:1 M/O molar ratio, 12 h, 145 °C, and 0.75 wt% catalyst amount) for waste cooking oil and 88.3% (36:1 M/O molar ratio, 9.59 h, 145 °C, and 0.75 wt% catalyst amount) for Jatropha curcas oil together with respective 93.3% and 94.8% decreases in the free fatty acid content, respectively. It was also verified that the produced biodiesel meets the ASTM D6751 quality standard for some properties of the biofuel and the cost analysis of biodiesel production has also been provided.