Biodiesel production by combined fatty acids separation and subsequently enzymatic esterification to improve the low temperature properties

Abstract

The poor low-temperature properties of biodiesel, which provokes easy crystallization at low temperature, can cause fuel line plugging and limits its blending amount with petro-diesel. This work aimed to study the production of biodiesel with a new process of improving the low temperature performance of biodiesel. Waste cooking oil was first hydrolyzed into fatty acids (FAs) by 60. g immobilized lipase and 240. g RO water in 15. h. Then, urea complexation was used to divide the FAs into saturated and unsaturated components. The conditions for complexation were: FA-to-urea ratio 1:2 (w/w), methanol to FA ratio 5:1 (v/v), duration 2. h. The saturated and unsaturated FAs were then converted to iso-propyl and methyl esters by lipase, respectively. Finally, the esters were mixed together. The CFPP of this mixture was decreased from 5. °C to -3. °C. Hydrolysis, urea complexation and enzymic catalyzed esterification processes are discussed in this paper.