Study On Heterogeneous Base Catalyzed Transesterification For Biodiesel Production

Considerable attention has been given to biodiesel as a surrogate to diminishingfossil fuel reserves and associated environmental problems of burning them. Biodieselis the most attractive alternative energy sources due to its similar characteristics asdiesel fuel and lower combustion emissions. At the moment, homogeneous alkali(base) catalyzed transesterification is the most common means to yield fatty acidmethyl esters. However, ester saponification reaction, expensive separation cost and agreat deal of waste solution limit the development of homogeneous alkali catalyzedtransesterification. Heterogeneous base-catalyzed transesterification process, withseveral merits, like easy to separate the catalyst and reaction product and reusabilityof catalysts, has become a hotspot research.The study was to explore the transesterification process in the presence ofheterogeneous based catalyst using palm oil and methanol as raw materials. The maincomponents, which consists of methyl tetradecanoate, hexadecanoic acid methyl ester,8,11-Octadecadienoic acid methyl ester,9-Octadecenoic acid methyl ester andoctadecanoic acid methyl ester, of biodiesel were analyzed by GC-MS apparatus.Biodiesel yield was tested with external standard method via gas chromatography.The heterogeneous base catalyst, Magnesium oxide loaded with KF, showedstrong catalytic activity and stability through characterization of catalysts andtransesterification reaction.65%KF/MgO, which was calcination for500℃for4hours, provided excellent catalytic performance. Furthermore, the indicators includingmethanol to oil molar ratio, reaction time, reaction temperature, catalyst amount, thereusability of catalyst, were also studied. Biodiesel yield can reach91.33%based onthe following reaction conditions: reaction temperature of60℃, methanol to oil molarratio of15:1,12wt%catalyst amount, reaction time of5hours.The biodiesel production was investigated in a stirred tank with anion-exchangeresin D296R as heterogeneous catalysts in a range of methanol to oil molar ratio,reaction time, reaction temperature, catalyst amount. The reusability of D296R resinwas also validated in the experiment. The results based on orthogonal experimentsverify optimum conditions:12wt%catalyst amount, reaction temperature of55℃,reaction time of three hours, methanol to oil molar ratio of12:1. Under the optimum condition, the FAME yield is99.34%.The influences of reaction, including reaction temperature, methanol to oil molarratio, residence time, were studied and verified in the fixed bed reaction system. Thebiodiesel yield of D296R-catalyzed transesterification is89.54%based on thecondition of55℃and one hour residence time, using methanol and palm oil with amolar ratio of9:1as raw materials. Increasing the residence time could enhance theyield of FAME.