Pre-treatment of acidic crude palm oil using trickle bed reactor packed with polyethylene-activated carbon hybrid support

A novel approach for the esterification of free fatty acid (FFA) in acidic crude palm oil (ACPO) was investigated using a trickle bed reactor (TBR). The TBR was packed with 4-ethylbenzenesulfonic acid (EBSA) supported on a low-density polyethylene (LDPE) and activated carbon (AC) hybrid support. This study introduces the use of a polyethylene-activated carbon hybrid supported catalyst in continuous TBR system which is not explored in the past research of FFA esterification. ACPO with an FFA content of 10.17 wt% was fed counter-currently with methanol vapor through the catalyst bed. Under optimum conditions, the EBSA supported on AC (EBSA/AC) achieved 92.40% FFA conversion and was successfully recycled for 3 times while the EBSA supported on LDPE:AC (1:1 mass ratio) achieved 90.20% and was recycled for once. The optimum conditions for both supported catalysts were 14 g of EBSA impregnated onto 6 g of supports, oil flow rate of 3 mL/min, 50 mL of methanol fed to the reboiler, reaction temperature of 65 °C and reaction time of 30 mins. The EBSA/AC showed a catalyst consumption of 42.50 mg/g, while the EBSA/LDPE:AC(1:1) which had 3 g of LDPE and 3 g of AC consumed 85.00 mg/g. The EBSA/AC also produced twice of the yield of treated oil compared to the EBSA/LDPE:AC(1:1). Hydrodynamic analysis indicated that the TBR operated under a trickle flow regime. The catalyst wetting efficiencies of EBSA/AC and EBSA/LDPE:AC(1:1) were 71.70% and 57.59% respectively, suggesting partial catalyst wetting in both cases. While EBSA/AC demonstrated superior performance, this study highlights the feasibility and potential utilization of polyethylene-activated carbon hybrid supported catalyst in continuous FFA esterification.