In-situ biodiesel production from sunflower seeds using liquefaction

Abstract

One of the most expensive steps in the bio-diesel value chain is the extraction of oil from the seeds. Simultaneous extraction and transesterification will lower the overall capital costs of the process while enhancing FAME conversion. In this study, the extraction of oil with supercritical CO2 was combined with the liquefaction of sunflower seeds and transesterification with sub-critical methanol to enhance biodiesel yield from sunflower seed oil. Supercritical CO2 was used as a reaction atmosphere at elevated pressures to extract oil from the seeds while continuously reacting the oil with methanol. Reaction temperature, biomass loading, catalyst loading and methanol to biomass loading were varied and the oil and fatty acid methyl acid (FAME) yields were determined using GC-MS. Biodiesel quality was assessed using FTIR and gas chromatography. All variables investigated had an effect on the FAME yield with 330°C, 2wt% CaCO3 as catalyst and a reaction time of 15 minutes resulting in the highest product (550 g.kg-1) and FAME (900 g.kg-1) yields. The FAME yields obtained indicated that both the oil originally present in the seeds and some of the lignocellulose parts of the seeds were converted to biodiesel. This result shows the potential of in-situ biodiesel production to increase production yields while lowering the overall capital cost and separation cost of the value chain