Batch Biodiesel Production by Esterification from Palm Fatty Acid Distillate with Microwave heating

Abstract

This study demonstrated a batch microwave-assisted biodiesel (MWBD) conversion system. It uses two magnetrons with a 1,270 Watt total microwave (MW) power placed asymmetrically on opposite sides of the MW cavity. It was used to produce methyl ester from palm fatty acid distillate (PFAD) with 2 %wt. acid catalyst (H2SO4). The response surface method applied Box-Behnken experimental design to find the optimal point giving the maximal %free fatty acid (FFA) at the minimum cost (USD). This was at mol ratio PFAD to MeOH 1:9; reaction temperature 80 °C; and reaction time 20 min. The regression models predicted the %FFA conversion and the cost (USD) with coefficients of determination (R2) of 0.9519 and 0.8654, respectively. Simulations with the finite element method (FEM) were also performed. The temperature profiles from simulations fit well the experimental data on temperature measured. Finally, the most important fuel properties of the MWBD were analyzed and compared with Thai agricultural engine diesel (AED) and high-speed diesel (HSD) standards, and the standards were satisfied. Then, the MWBD, the liquid fuel blend (LFB; MWBD: CHSD 50:50 by volume), and commercial high-speed diesel (CHSD) were tested in a diesel engine over the power range 1.28-5.09 kW at the fixed 2,200 rpm speed. All the fuels performed similar to the CHSD in the test and no problems were found in the runs.