Kinetic Studies of Biodiesel Production from Jatropha curcas Oil

Abstract

The world is confronted with the twin crisis of fossil fuel depletion and environmental degradation caused by fossil fuel usage. Biodiesel produced from renewable feedstocks such as Jatropha seed oil or animal fats by transesterification offers a solution. Although biodiesel has been produced from various vegetable oils such as Jatropha seed oil, the reaction kinetics studies are very few in literature, hence the need for this study. Jatropha curcas seed oil was extracted and analyzed to determine its free fatty acid and fatty acid composition. The oil was transesterified with methanol at a molar ratio of methanol to oil 8:1, using 1% sodium hydroxide catalyst, at different temperatures ranging from 32oC to 65oC, at atmospheric pressure. The order of the reactions with respect to the triglyceride's disappearance in the forward reaction at the chosen temperatures was found to be pseudo-first-order and found to be first-order for the reaction at 32oC. The rate constants of the three consecutive reaction steps at 65oC, namely, triglyceride to diglyceride, diglyceride to monoglyceride, and monoglyceride to glycerol, were found to be 0.422 min-1 0.117 min-1, and 0.037min-1, respectively. Their corresponding activation energies in J/mol were 22.165, 3.136, and 19.770, respectively.

Recent Advances in Biodiesel from Plants

“…Knowing the average molecular weight of an oil is an important step in knowing the required amount of alcohol needed for transesterification reaction for a given oil to alcohol molar ratio. For example, the average molecular weight of Jatropha oil is 900 moles, while that of algae oil is 274.4 moles [11,12]. Certain variables are known to affect the transesterification reaction of vegetable oil or animal fats.…”

“…Their reports also include the effect of these variables on the quality of biodiesel produced and how these variables can be modified to give higher yield and best quality biodiesel [21,40,53,77,85]. Of these variables oil to alcohol molar ratio, temperature, catalyst type, and catalyst concentration or catalyst amount play vital roles [12,77,82]. To cause the reaction to proceed at a reasonable speed, a catalyst must be involved.…”

“…and enzyme catalyst example is lipase. Researchers have observed that liquid catalysts cause transesterification reactions to proceed fasters and products are formed in a shorter time than solid and enzyme catalysts [4,12,82].…”

“…(2) [3,12] is an equilibrium reaction that occurs in three consecutive steps forming intermediates. Stoichiometrically, 3 moles of alcohol were required to react with 1 mole of TG to form 3 moles of esters and 1 mole of Glycerol [12,77,82]. Therefore, we have [3],…”

“…One biofuel which has captured the interest of so many scientists and researchers is biodiesel. Biodiesel is the alkyl ester of vegetable oil or animal fats produced by transesterification under suitable reaction conditions [8,9,[11][12][13].…”