Microwave-Assisted Esterification of Tall Oil Fatty Acids with Methanol Using Lignin-Based Solid Catalyst

Abstract

During alkaline pulping significant amounts of lignin, carbohydrates (mostly hemicelluloses), and extractives (tall oil soap and turpentine) are removed from wood feedstock. In this study, the catalytic esterification of fatty acids in tall oil with methanol to produce fatty acid methyl esters under microwave irradiation was performed at 100 °C for 10-60 min. A novel heterogeneous acid catalyst tested for this purpose was synthesized from the hardwood alkali lignin that was precipitated by acidification from the black liquor from soda-AQ pulping. The comparative reaction data were obtained by using other solid catalysts, Amberlyst 15 and ptoluenesulfonic acid. The results showed the highest esterification yields 93, 88, and 80 % with the p-toluenesulfonic acid, lignin-based, and Amberlyst 15 catalysts, respectively, at 100 °C with a reaction time of 60 min and the corresponding yield without catalyst was 20 %. It was also observed that the lignin-based catalyst could be easily recovered and reused without any notable deactivation.

Separation and Purification of ω-6 Linoleic Acid from Crude Tall Oil

“…These results confirm previous findings. For example, TOFAs from Farmchem Oy (Finland) contained 49% w/w LA [18]. CTO from Stora Enzo Oyj Mills (Finland) contained 19.1% w/w LA corresponding to 40% w/w LA in the TOFA fraction of CTO [37], and in another report, 27.6% of CTO [38].…”

“…The main TOFAs in CTO are LA (C18:2n6) ( Figure 1), oleic acid (C18:1), GLA (C18:3n6), and palmitic acid (C16:0) [17]. Typically, the TOFAs consist of 75-85% unsaturated fatty acids (UFAs), mainly polyunsaturated fatty acids (PUFAs), with LA comprising about half the total TOFAs [13,18]. LA is an 18 carbon polyunsaturated fatty acid with the two double bonds at C9 and C12 in a cisconfiguration (all-cis-9,12-octadecadienoic acid) ( Figure 1).…”