Treatment of acidic crude palm oil using supported benzenesulfonic acid-based deep eutectic solvents in trickle bed reactor

In this study, a deep eutectic solvent (DES) from benzenesulfonic acid and choline chloride (BZSA-ChCl-DES) was prepared for the treatment of high free fatty acids (FFA) in acidic crude palm oil (ACPO). The DES was impregnated into activated carbon (AC-DES) to produce a supported catalyst used in a trickle bed reactor (TBR) for FFA esterification. Under optimal conditions, using 8 g of AC-DES at 60 °C, with ACPO and methanol flow rates of 1 mL/min and 4 mL/min, respectively, the TBR successfully treated 3.5 L of ACPO. A batch reactor, used for comparison, showed that the continuous TBR process required less catalyst per gram of treated oil (2.87 mg catalyst/g) which can enhance the recyclability. Moreover, the continuous process could sustain up to five recycle runs that can treat 1.5 L under optimal conditions (3.5 wt% catalyst dosage, 10:1 M ratio, 60 °C reaction temperature, and 30 min). This approach presents a promising continuous approach for converting high FFA to fatty acid methyl ester (FAME) for biodiesel production.