Reusable Amberlyst 16 catalyst for acetic acid esterification relevant for pyrolysis bio-oil upgrading process

Abstract

The current research article addresses the ability of heterogeneous Amberlyst 16 to catalyze the esterification reaction between acetic acid and ethanol, as well as the modelling of the chemical kinetics. The effects of pretreatment, reaction temperature, ethanol-to-acid molar ratio, catalyst dose and time on the rate of ethyl acetate production were systematically investigated. Furthermore, the recyclability of Amberlyst 16 to accelerate the esterification reaction was carefully examined. Amberlyst 16 was found to be a suitable catalyst for this process giving a final acid conversion of 93.3% using reaction temperature of 60 °C, ethanol-to-acid molar ratio of 6:1, catalyst dose of 10 wt% and 200 rpm stirring intensity after 1680 min, and can be successfully utilized for 4 recycle tests. A detailed kinetic model has been developed and tested for the described process, which was based on a four-step mechanism equivalent to the Langmuir–Hinshelwood one. It was found that that the esterification reaction occurred between ethoxide ions and acetic acid chemisorbed on the neighboring catalytic surfaces, whereas, the overall process was controlled by the surface reaction step.