Kinetics and mechanism of the KOH — catalyzed methanolysis of rapeseed oil for biodiesel production

Abstract

Kinetics and mechanism of the KOHcatalyzed methanolysis of rapeseed oil for biodiesel productionThe reaction of rapeseed oil with methanol catalyzed by KOH is described by a model consisting of two sequences of consecutive competitive reactions. The first sequence expresses the methanolysis of rapeseed oil to methyl esters (biodiesel) whereas the second sequence describes the always present side reaction-saponification of glycerides and methyl esters by KOH. The proposed chemical model is described (after rational simplifications) by a system of differential kinetic equations which are solved numerically by two independent computing methods. The thus obtained theoretical kinetic and equilibrium results are compared numerically and/or graphically with the experimental parameters. The latter were obtained by the determination of the relevant components in the actual reaction mixture by analytical methods. According to the experimental results, the proposed reaction scheme is fulfilled with the probability of ca. 78%. The optimal average rate constants and equilibrium constants of individual reaction steps of the discussed scheme are introduced. The limitations of the proposed reaction model are discussed.

Transesterification of Various Bio-oils: Application and Perspectives in Burkina Faso

“…This is due to the fact that the production of ethyl esters is limited by several factors including: water content of bioethanol, the difficult separation of ethyl esters in reaction environments, etc. that is currently Several kinetic studies have been published on transesterification process [10,11,[14][15][16]. The model proposed by Noureddini and Zhu is the most common used, but shows some weaknesses: it does not take into account side reactions that occur like the effect of saponification and water [12,17,18].…”

“…The model proposed by Noureddini and Zhu is the most common used, but shows some weaknesses: it does not take into account side reactions that occur like the effect of saponification and water [12,17,18]. In order to overcome these simplifications, some aspects of the model proposed by Komers are included in our model [11,12]. However, the difficulty of using the Komers model lies on the high number of constant rates (eleven), found for a temperature of 22.75°C and a molar ratio n=2.03.…”

“…In order to achieve this result, a method has been developed for determining through theoretical simulation, the optimum parameters required for the transesterification. This study is based on an original approach considering a combined model of Komers and Nourreddini [10][11][12]. The theoretical results was validated through experimental tests, conducted on a transesterification pilot scale with jatropha, palm and soya oils.…”

The biodiesel production from the cotton thistle seed oil (Onopordum acanthium L.)

“…Prema nekim istraživačima, povratne i direktne reakcije metanolize su reakcije drugog reda [19,20]. Pored uzastopno-paralelnih reakcija, u kinetički model reakcije metanolize uključivana je i ukupna reakcija sinteze MEMK [22,24] ili sporedna reakcija saponifikacije [25]. Zbog kompleksnosti navedenih kinetičkih modela koja zahtevaju složena matematička proračunavanja, novija istraživanja su usmerena ka razvoju jednostavnijih kinetičkih modela, koji dobro opisuju eksperimentalne podatke.…”

Biodiesel: Fuel for the Future (A Brief Review)

“…So me of the few kinetics studies that have been performed in recent times include esterification of free fatty acids in sunflower oil and oleic acid [38][39]. Trans-esterificat ion kinetics of soybean oil with five d ifferent catalysts have also been studied [40].Similarly, Divya and Tyagi [20] reported the study carried out by Ko mers et al; [41] where kinetics and mechanism o f KOH catalyzed methanolysis of rapeseed oil for b iodiesel production was investigated. The first sequence of the reaction expressed the methanolysis of rapeseed oil to biodiesel wh ile the second sequence described the always present side reaction separation of glycerides and biodiesel by KOH.…”