Green valorisation of waste cooking oil into biodiesel using copper metal-organic framework (Cu-MOF) catalyst in a packed-bed continuous process

Waste cooking oil (WCO) has the benefit of conversion to biodiesel, which has both ecological and economic benefits. This paper presents a copper-based metal-organic framework (Cu-MOF) catalyst that was used in the WCO transesterification reaction and then the separation of the product in a packed bed column. The thermogravimetric analysis was used in the determination of catalyst stability and showed a degradation temperature of 250°C. Other structural and morphological characterisation was done through FESEM, FTIR, and XRD. Optimisation of the process was conducted based on the response surface using a central composite design that showed a maximum biodiesel yield of 88% when the ratio of methanol to oil was 6:1 and 5.28 g of the Cu-MOF was used. Sustained activity in reusability tests was demonstrated up to the tenth cycle, with a 70% yield observed until the yield dropped. The results indicate high catalytic efficiency and recyclability of Cu-MOF, which has a strong potential for producing sustainable biodiesel by using WCO.