Comparative catalytic efficacy of cost-effective MIL-101(Cr) based PET waste for biodiesel production

Polyethylene terephthalate (PET) use has increased, causing more PET trash and environmental and health issues. Disposal and burning alone cannot solve this problem. Thus, PET recovery methods with low byproducts are the priority. The recycling rate is still below 30%, so different cleaning methods are being investigated. Therefore, studies have focused on extracting terephthalic acid from PET bottles for MOF synthesis to reduce their cost of production. Herein, MIL-101(Cr) was synthesized from PET bottles and used as a solid catalyst for oleic acid esterification with methanol to produce methyl oleate (biodiesel), an alternative energy source to fossil fuels—the highest biodiesel yields at 1:39 molar ratio of oleic acid to MeOH, 6 wt% loading, 65 °C, and 4 h reactions time were attained at 86.9 and 80% for MIL-101(Cr) on a pristine and scrap basis, respectively. The kinetic study revealed that activation energies were 25.27 kJ/mol and 28.3 kJ/mol for original and waste-derived MIL-101(Cr). The waste-derived MIL-101(Cr) was reused three times while five-time cycles for the original MIL-101(Cr).