Sulphonated Chitosan‐Based Hydrochar as a Potential Catalyst to Produce Biodiesel from Oleic Acid

Abstract Our aim in this project was to prepare a chitosan‐based graphitized carbon through a hydrothermal process and then further sulfonate it. The catalyst exhibited the formation of active sites responsible for driving the biodiesel synthesis reaction. Energy dispersive X‐ray spectroscopy (EDS) analysis revealed a sulfur content of 7.56%, while the surface area was determined to be 8.134 m 2 g −1 . The catalyst synthesized through this method was thoroughly characterized using a range of analytical techniques, including FT‐IR, XRD, TGA, SEM‐EDS, BET, and XPS analyses. The catalyst was employed to optimize biodiesel production from oleic acid (OA) via an esterification reaction, achieving an impressive yield of 95.23 ± 0.4% under the optimal conditions of a methanol‐to‐oil ratio (MTOR) of 1:20, catalyst loading of 8 wt.%, reaction temperature of 120 °C, and reaction time of 55 min. On performing kinetic studies, the activation energy was found to be 26.5 kJ mol −1 and the pre‐exponential energy was found to be 1.51×10 2 min −1 . The SEM‐EDS findings reveal that the sample is porous and nitrogen is retained in it, making it apt for the attachment of sulphonic groups, which results in the acidic nature of the material. The catalyst demonstrated excellent reusability, retaining a yield of 84.5 ± 0.4% even after the seventh cycle.