Green synthesis of heterogeneous polymeric bio-based acid decorated with hydrophobic regulator for efficient catalytic production of biodiesel at low temperatures

Biodiesel is being deemed a kind of important renewable energy source and also shows the great potential to replace fossil fuels to respond to global primary energy demands. However, by-product water generated during the esterification reaction of biodiesel production is not conducive to the forward progress of the reaction, and even affects the pristine structure and activity of the employed catalytic material. In this work, the hydrophobic polymeric bio-based solid acid catalyst FDCA/SA-UiO-66(Zr) was prepared by a facile grinding method using biomass-derived stearic acid (SA) and 2,5-furandicarboxylicacid (FDCA) as hydrophobic ligand and green organic linker, respectively. Accordingly, the corresponding characterization results showed that the relevant material had a good particle shape along with a highly hydrophobic network (136.4°), wherein the significant hydrophobic environment was determined to promote the adsorption of lipophilic acid and the desorption of water on the Lewis acid site. Compared with traditional heterogeneous and homogeneous acid catalysts, just at a low temperature (60.2 °C, 98.4% yield), FDCA/SA-UiO-66(Zr) exhibited superior or equivalent catalytic performance in the esterification of FFAs for biodiesel manufacture. More importantly, thanks to the stable skeleton structure of UiO-66(Zr), the catalyst demonstrated a stable structure and good reusability during 6 consecutive recycles (92.5% biodiesel yield).