Improved biodiesel manufacture at low temperature and short reaction time

Biodiesel, which is derived from oil/fat by transesterification with alcohol, has attracted considerable attention over the past decades due to its ability to subsidise fossil fuel derived energy as a renewable and carbon neutral fuel. Several approaches for biodiesel fuel production have been developed, among which transesterification using a catalyst gives high yields of methyl ester. This method has therefore been widely utilized for biodiesel production in a number of countries. In this study, a Downflow Liquid Contactor Reactor (DLCR) has been used for the liquid–liquid transesterification reaction of sunflower oil with alcohol with extraordinary results. The reactor provides great potential for chemical reactions, which are normally limited by mass transfer and possesses a number of distinctive advantages over conventional multiphase reactors. Inside the reactor a high velocity liquid jet stream is produced which generates powerful shear and energy, causing vigorous agitation in the upper part of the reactor. The high mixing intensity in the DLCR enabled the manufacture of biodiesel to European Standard EN14214 (ester content 96.5%) in 2.5 min at 40 °C with 0.43 wt.% alkali catalyst and alcohol to oil molar ratio of 4.5 to 1.0. The separation of FAME from glycerol is done by gravity settling only without water washing. The effect of the alcohol type (methanol, ethanol) on biodiesel yield was also investigated. The process offers the advantage of continuous large scale production with limited reactor volume.

► Downflow Liquid Contactor Reactor enables biodiesel yields >96.5 wt.% to be achieved.
► Biodiesel can be produced in 2.5 min at 40 °C in yields >96.5 wt.%.
► Low methanol to sunflower oil ratio and low NaOH catalyst loading are used.
► The process can be easily scaled without any loss of mass transfer.
► The biodiesel product does not require washing with water.