BIODIESEL PRODUCTION FROM PALM OIL VIA HETEROGENEOUS TRANSESTERIFICATION: OPTIMIZATION STUDY

Abstract

Fatty acid methyl ester (FAME) prepared by transesterification process using a heterogeneous catalyst has received a lot of interest lately as it could overcome the limitations of the current commercial homogeneous catalytic process. Apart from that, palm oil, being the cheapest edible oil in the world, will always remain the most economical source of FAME. Therefore, in this study, the use of sulfated zirconia alumina as a heterogeneous catalyst to catalyze the transesterification of palm oil with methanol to FAME was carried out using design of experiment (DOE), specifically response surface methodology (RSM) based on four-variable central composite design (CCD) with α = 2. The transesterification process variables are reaction temperature (60–180°C), reaction period (1–5 h), methanol-to-oil ratio (4–12 mol mol−1), and amount of catalyst (2–10 wt.%). In this study involving many multiple process variables, the design of experiment approach was found to be superior to the conventional one-variable-at-one-time approach. Interactions between variables were found to have significant effect on the yield of FAME. At the conditions of 3 h of reaction period, 127°C reaction temperature, methanol-to-palm oil ratio of 8, and 6 wt.% of catalyst, an optimum FAME yield of 83.3% can be obtained, indicating that sulfated zirconia alumina has potential as a heterogeneous catalyst for the production of FAME from palm oil.