Sustainable biodiesel production: catalyst-free palm fatty acid distillate conversion to methyl esters by using a superheated methanol vapor process

Abstract

To achieve sustainable and low-waste biodiesel production, a catalyst-free process was investigated by using superheated methanol vapor (SMV) at atmospheric pressure. This process eliminates catalyst procurement costs, reduces requirements for water washing and associated equipment, and lowers expenses for catalyst waste treatment. The effects of bubble column reactor design such as the use of packing, reaction time, and reaction temperature on the conversion of palm fatty acid distillate (PFAD) into fatty acid methyl ester (FAME) have been investigated. The application of packing at temperatures of 240–270 °C successfully increases the contact area between methanol bubbles and the oil, hence providing better reaction performance of the SMV process while applying lower temperature and pressure compared to supercritical processing. The results showed that the FAME concentration in the product can reach 97.5 wt% which meets the quality standard. The highest conversion is obtained at 90.6% exceeding the previous research on the SMV process. The effects of reaction temperature, time, and reactor design on the conversion of PFAD into FAME have been elucidated.