High‐temperature esterification of fatty acids with methanol at ambient pressure

Abstract

High-temperature esterification of fatty acids with methanol at ambient pressureThe article presents the results of the kinetic study of the acid-catalyzed esterification of free fatty acids (FFA) with methanol (MeOH) at elevated temperatures above the boiling point of MeOH, at ambient pressure, and at continual flow of liquid MeOH into the reaction mixture. Under these conditions, the reaction follows the rate equation valid for reactions of the first order. Beside temperature, the pseudo rate constant depends also on the flow rate of MeOH and on the concentration of a catalyst. At temperatures 50-60 7C higher than the boiling point of MeOH, the reaction rate is two to three times higher than at the temperatures close to the boiling point of MeOH. Apart from the temperature, the increase of the rate is facilitated also by a high local molar excess of MeOH in the input site with respect to FFA and by effective removal of water from the reaction mixture. The composition of the reaction mixture is then farther from the equilibrium composition. High conversion of FFA to methyl esters (above 99%) with low residual acidity of the product (acid value around 2-3 mg KOH/g) is achieved at short times of several tens of minutes and at a low total molar ratio of MeOH/FFA of around 3-4.

Hydrolysis of fatty acid esters in subcritical water

“…The OL contains usually about 30-50 wt-% of FAME. Its technical application can be envisaged mainly in two directions: either for decomposing the present FAME to FFA and thus converting the OL to technical fatty acids or, alternatively, for esterifying the FFA by methanol to FAME and using the formed FAME as, e.g., an alternative diesel fuel (Kocsisová et al [10]). There is also a series of fatty acid applications in which it is not important whether an acyl is in the form of a free acid or of a methyl ester.…”

Kinetics and mechanism of myristic acid and isopropyl alcohol esterification reaction with homogeneous and heterogeneous catalysts

“…The use of a heterogeneous catalyst has the following inherent advantages over catalysis effected by dissolved electrolytes: (a) they eliminate the corrosive environment; (b) the catalyst can be easily recycled from the reaction mixture by decantation or filtration; (c) the purity of the products is higher since the side reactions can be completely eliminated or are less significant. There are very few reports on the esterification kinetics of fatty acids for a homogeneous catalyst system [3,4] and a heterogeneous catalyst system [5][6][7][8][9]. Kinetic models and results were reported for the reaction of fatty acids and various types of alcohols with short chain such as methanol in the production of biodiesel fuel [5,6].…”

“…There are very few reports on the esterification kinetics of fatty acids for a homogeneous catalyst system [3,4] and a heterogeneous catalyst system [5][6][7][8][9]. Kinetic models and results were reported for the reaction of fatty acids and various types of alcohols with short chain such as methanol in the production of biodiesel fuel [5,6]. When the reaction of oleic acid or fatty acid mixtures with methanol was investigated in the presence of H 2 SO 4 and p-toluene sulfonic acid, it was found that p-TSA is more effective [10].…”

Process Technologies for Biodiesel Production

“…As heterogeneous catalyst also cationic ion exchange resins can be used in continuous reaction columns; however, this approach has only been used so far in pilot plants. The esterification of free fatty acids with methanol at increased temperatures above the boiling point of methanol at ambient pressure was achieved by introducing methanol into a preheated reaction mixture, 15 containing free fatty acids and an acid catalyst. The reaction rates were significantly higher than under reflux temperature.…”