Kinetic studies on the esterification of free fatty acids in jatropha oil

Abstract

Kinetic studies have been carried out on the esterification of free fatty acids (FFAs) in jatropha oil with methanol in the presence of sulphuric acid catalyst at 5 and 10 wt% concentrations relative to free fatty acids (0.4–0.8 wt% relative to oil) and methanol–FFA mole ratios ranging from 20:1 to 80:1. It has been found that a 60:1 methanol–FFA mole ratio and 5 wt% catalyst at 60°C and 500 rpm or above provided a final acid value lower than 1 mg KOH/g oil within 60 min. A kinetic model has been proposed with second‐order kinetics for both the forward and backward reactions. The effect of temperature on the reaction rate constants and equilibrium constant has been determined using Arrhenius and von't Hoff equations, respectively. The heat of reaction was found to be −11.102 kJ/mol.

Esterification of oleic acid for biodiesel production catalyzed by 4-dodecylbenzenesulfonic acid

“…The results found in the literature also seem to disagree about whether the reaction is exothermic or endothermic. Thus, in some works it was found that the esterification reaction of fatty acids was endothermic, with a very low reaction heat (between 7 and 20 kJ/mol) [27,29,30,44,45], whereas there is apparently only one work that reports an exothermic esterification reaction, with a reaction heat of -11.1 kJ/mol [9].…”

“…Several authors have investigated the kinetics of the esterification of short chain carboxylic acids [38,46,47] and of the esterification of fatty acids contained in the oils for the production of biodiesel [9,29,32,44].…”

“…To circumvent this problem, the esterification of the fatty acids present in these lowcost raw materials has been studied in depth using different types of liquid and solid catalysts [6][7][8][9][10]. One of the best known solutions is probably the synthesis of biodiesel in two steps: in a first step, the fatty acids are esterified using an acid catalyst and, in the second step, triglycerides are transesterified using a basic catalyst [11][12][13][14].…”

“…(6) the number of moles of water, methanol and catalyst in the organic phase, given by Eqs (8),(9). and (12), we have:…”

Dynamical modeling for biodiesel production from grease trap wastes

“…For instance, Freedman et al (1986), Noureddini and Zhu (1997) and Darnoko and Cheryan (2007) have proposed diverse mathematical models for describing batch transesterification processes; Kamarudin et al (1998), Sendzikiene et al (2004), Zheng et al (2006), Berrios et al (2007), Aranda et al (2008), Rani et al (2013) and Vinjamur (2013, 2014) have obtained noteworthy results concerning the mathematical description of the batch esterification processes. The transesterification and esterification processes conducted within batch reactors show flexibility in deployment and relatively high yields; however, it is well-known that the batch processes could increase their production level and can be performed still more efficiently when they are developed within a continuous stirred tank reactor (CSTR) (Levenspiel, 1999).…”