۱- Introduction

۲- Materials and methods

۳- Results and discussion

۴- Conclusions

References

Abstract

In the present work, an optimization method called Particle Swarm Optimization (PSO) was applied to study the kinetics of alkali-catalyzed rapeseed oil transesterification, using methanol, in a batch process.
The validation of the PSO program was realized using numerical and experimental data from literature. The PSO method resulted in a 4 times lower error compared to classic methods used in the domain, which showed its efficiency and strength.
After validation, an experimental study was led on the transesterification of rapeseed oil and methanol in a batch process using KOH as catalyst (1wt/wt %) with a methanol:oil molar ratio of 6:1 at 45 °C, 55 °C and 65 °C respectively. Then, PSO was used in order to determine the reaction rate constants () of the reversible 3-steps of transesterification mechanism as well as the kinetic parameters (activation energy Ea and pre-exponential factor A).
Then, the kinetic model was used in order to investigate the effects of methanol: oil molar ratio variation (3:1, 4:1, 5:1, 6:1, 8:1, 12:1) on rate constants, yield and conversion rate at 65 °C.
The results of the simulation showed a perfect agreement with experimental results.

Introduction

The consumption and production of biodiesel continue to increase worldwide. Biodiesel being a source of green and renewable energy, it is considered as an alternative fuel to conventional diesel oil [1]. The synthesis of biodiesel from oil can be performed by several methods such as thermochemistry [2, 3] i.e. esterification and transesterification via catalytic or non-catalytic pathways [4, 5, 6, 7]. Alkali-catalyzed transesterification is the most commonly used and consists in reacting a triglyceride molecule with three molecules of alcohol to produce three molecules of methyl ester, known as biodiesel, and one molecule of glycerol [8, 9]. The catalytic transesterification reaction follows a three-stepped reaction scheme, as illustrated in Fig. 1. During the first, step the decomposition of triglycerides (TG) to diglycerides (DG) occurs with a formation of one methyl ester, the second one transforms diglycerides to monoglycerides (MG) and methyl ester, and the last step is the decomposition of monoglycerides into glycerol and methyl ester [10]. In order to determine the kinetic parameters of the reaction (activation energy and pre-exponential factor), a kinetic study is required. This study is essential to design and upscale facilities to industrial level. Several researches on the kinetics of homogeneous and heterogeneous catalysis of transesterification have been carried out using different raw materials and synthesis methods [11, 12, 13, 14, 15]. Ramezani et al. [16] studied parameters affecting the transesterification reaction of castor oil in order to optimize its yield and used their results to adjust a kinetic correlation using the pseudo-first order hypothesis.