Lipase-catalyzed esterification of lactic acid in supercritical carbon dioxide

• Published in: The Journal of supercritical fluids 2012-06, Vol.66, p.192-197
• Main Authors: Knez, Željko, Kavčič, Sabina, Gubicza, László, Bélafi-Bakó, Katalin, Németh, Gergely, Primožič, Mateja, Habulin, Maja
• Format: Article
• Language: English
• Subjects: Butyl lactate; Candida antarctica; Candida antarctica lipase B; Carbon dioxide; Conversion; Cosmetics; Esterification; Esters; Lactates; Lactic acid; Organic solvent; Supercritical carbon dioxide
• ISSN: 0896-8446; 1872-8162
• DOI: 10.1016/j.supflu.2011.11.006

[Display omitted] ► Lipase-catalyzed esterification of lactic acid in supercritical media. ► Presence of co-solvent does not influence the phase-behavior of the studied system. ► Improvement of conversion using SC CO2/n-hexane reaction medium. Lactate esters can be used in food industry for preservation and flavouring purpose, as well as in the pharmaceutical and cosmetic industries. Direct esterification of n-butanol and lactic acid (LA), catalyzed by immobilized lipase B from Candida antarctica (Novozyme 435), was performed in supercritical carbon dioxide (SC CO2) with or without co-solvent. Process conditions (pressure and temperature) were optimized performing experiments in a high-pressure batch stirred-tank reactor. Experiments were carried out in the operative pressure range from 7.5 to 40MPa and at temperatures 35°C and 55°C. The highest conversion of LA after 26h of reaction performance was obtained in SC CO2 with n-hexane serving as a co-solvent, at 40MPa and 55°C. The optimal temperature and pressure for butyl lactate (BL) synthesis in SC CO2 medium was determined at 55°C and 30MPa. Phase behavior for LA/n-butanol/SC CO2 system and LA/n-butanol/n-hexane/SC CO2 system at different pressures and temperatures was also studied.