Kinetic model for the esterification of free fatty acids from palm oil with methanol using sulfuric acid as catalyst and sensitivity analysis in tubular reactors

Abstract

Industrial biodiesel production from crude palm oil (CPO) by homogeneous transesterification requires some conditioning stages. One is deodorization, where free fatty acids (FFA) are stripped out from the CPO. The FFA from the deodorizer is esterified using a homogeneous acid catalyst to produce more biodiesel and improve process profitability. This work studied the sulfuric acidcatalyzed esterification of FFA with methanol. The factors evaluated were temperature (between 40 and 60 C) and catalyst concentration (between 0.15 and 1.5 wt% based on the mixture). The parameters of a reversible second-order kinetic model were adjusted from experimental data using a genetic algorithm. The kinetic model, which adequately represents the esterification reaction, according to the Fisher-Snedecor test, was used to perform a sensitivity analysis in isothermal, adiabatic, and non-isolated continuous tubular esterification reactors using ASPEN HYSYS V10. The results showed that the highest conversion ($96%) was predicted using an isothermal reactor. However, its installation and operational costs could also be the highest. An adiabatic reactor was preferred, which optimal conversion of 94.5% was predicted at temperature, catalyst concentration, residence time, and methanol-to-FFA molar ratio of 140 C, 0.3 wt%, 47 min, and 6.7, respectively, its predicted operational cost was 0.63 dollars per biodiesel kilogram. Therefore, the adjusted and validated model has a relevant importance in the biofuel sector, not only in Colombia, but also worldwide.

Design and Simulation of the Biodiesel Process Plant for Sustainable Fuel Production

“…Bio-oil is the mixture of different TAG components, where these TAG components will be converted to methyl esters [60,61]. As shown in reactions 8,9 and 10, triglycerides react with methanol and will be converted to di-glycerides, leaving a methyl ester component [62,63].…”

“…As the reactions between the conversions of triglycerides to monoglycerides are elementary the study has included the kinetic parameters, rate constants, and activation energy rates from the literature provided by the Aspen [65]. Bio-oil is the mixture of different TAG components, where these TAG components will be converted to methyl esters [60,61]. As shown in reactions 8,9 and 10, triglycerides react with methanol and will be converted to di-glycerides, leaving a methyl ester component [62,63].…”