Kinetic model for esterification of oleic acid catalyzed by a green catalyst in ethanol

Abstract

Bio-oil produced from biomass fast pyrolysis process is an organic liquid that can be transformed into high quality biofuel through upgrading process. Bio-oil comprises a large amount of carboxylic acids, which cause its corrosiveness, hence, difficulty for storage and utilization. Esterification may be considered as an intermediate upgrading method to convert the acids in bio-oil into esters by reacting with alcohol. This work presents kinetic studies of the esterification of a bio-oil model compound in ethanol catalyzed by 12-tungstosilicic acid. Oleic acid was used to represent the main component of bio-oil derived from agro-residues. Conditions considered were the molar ratio of ethanol to oleic acid of 9.11:1, catalyst loading of 10 wt%, and reaction temperatures in the range of 35-75 °C. It was found that the pseudo-homogeneous kinetic model was suitable to represent the esterification of the bio-oil model compound. Average reaction order n = 1.9, activation energy Ea=50.1kJ/mol, and pre-exponential factor A = 11.11×103 min−1 were obtained by fitting the kinetic model with experimental results.

Keywords

• Bioenergy
• Bio-oils
• Chemical conversion
• Esters
• Fuel upgrading
• Renewable energy