Experimental and kinetic modeling of acid oil (trans)esterification in supercritical ethanol. (15th July 2018)

• Record Type: Journal Article
• Authors: dos Santos, Kallynca Carvalho; Hamerski, Fabiane; Pedersen Voll, Fernando A.; Corazza, Marcos L.
• Is Part Of: Fuel. Volume 224(2018)
• Page Start: 489
• Page End: 498
• Publication Date: 2018-07-15
• Subjects: Biodiesel -- Supercritical ethanol -- Continuous process -- Acid oil -- Kinetics; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2018.03.102
• Languages: English
• ISSNs: 0016-2361

Abstract

Highlights: High conversions of acid oil to ethyl esters was reached at supercritical conditions. The FAEE decreased above 300 °C due to thermal decomposition. The autocatalytic kinetic model represented well the kinetic behavior. Low content of by-products generated under supercritical conditions. High ester yields were obtained at low ethanol to acid oil molar ratio. Abstract: This work reports experimental and kinetic modeling of the coupled esterification and transesterification reactions ((trans)esterification) of a model acid oil (a mixture of soybean oil and oleic acid) using ethanol at sub and supercritical conditions in a continuous tubular reactor. Process variables, namely temperature (220–350 °C), pressure (100–200 bar) and ethanol to acid oil molar ratio (2:1–20:1) as well as the effect of the initial amount of free fatty acids in the raw material were studied. The best condition for the ethylic supercritical (trans)esterification of soybean oil with 20 wt% of oleic acid was 280 °C, 100 bar, and ethanol to acid oil molar ratio of 4:1, where 80% of ester yield was reached in 60 min. It was observed that increasing the free fatty acid content increased the reaction rate and reaction yield. The proposed autocatalytic kinetic model presented a good fit in relation to the experimental data.