Esterification of free fatty acids: experiments, kinetic modeling, simulation & optimization

ABSTRACT

The development of the process which can mitigate the drawbacks of catalytic esterification and handles high free fatty acid (FFA) containing oils is the highly focused area in biodiesel production. In view of attaining the cleaner biodiesel production, the present research efforts are focused on studying the methyl esterification of FFA present in Karanja oil non-catalytically in a batch reactor. Kinetics of the reaction was modeled as the pseudo first order in the forward direction & second order bimolecular type in the backward direction to deduce kinetic parameters. The obtained parameters were used to simulate the process in Aspen plus®. Experimental results show that 96% conversion of FFA can be achieved at 220°C and 1:6 (w/v) oil to methanol ratio. The calculated activation energy and rate constant are 48.53 kJ/mol and 0.641 min⁻¹, respectively, for the forward reaction and 18.74 kJ/mol and 4.18E⁻⁴ (g)/(mgKOH.min) respectively, for the backward reaction. Simulation results showed a little higher conversion (99.85%) of oleic acid compared to the experimentally observed conversion (96%) at similar reaction conditions. The optimal process parameters were estimated using sensitivity analysis of Aspen Plus along with heat integration.

KEYWORDS:

• Aspen plus
• Karanja oil
• kinetics modeling
• non-catalytic esterification
• simulation

Acknowledgments

We would like to acknowledge the Rajiv Gandhi Institute of Petroleum Technology (RGIPT), Jais, India for providing the facilities & financial support for this work.