Methyl esters were produced by transesterification of palm oil with methanol in the presence of a catalyst (KOH). The rate of transesterification in a batch reactor increased with temperature up to 60°C. (Higher temperatures did not reduce the time to reach maximal conversion. The conversion of triglycerides (-TG), diglycerides (-DG) and monoglycerides (-MG) appeared to be second order up to 30 mins of reaction time. Reaction rate constants for TG, DG and MG hydrolysis reactions were 0.018 -0.191 (wt % @ min) -1 , and were higher at higher temperatures and higher for the MG reaction than for the TG hydrolysis. Acti vation energies were : 14.7, 14.2 and 6.4 kcal/mol for the TG, DG and MG hydrolysis reactions respectively. The optimal catalyst concentration was 1% KOH.
An HPLC method was developed using the C-30 carotenoid column to separate and identify the major xanthophylls in corn (lutein, zeaxanthin, and beta-cryptoxanthin). A photodiode array detector and a mobile phase consisting of methyl tert-butyl ether/methanol/water was used. All three xanthophylls eluted in less than 25 min. Yellow dent corn had a total xanthophyll content of 21.97 microg/g with lutein content of 15.7 microg/g, zeaxanthin content of 5.7 microg/g, and beta-cryptoxanthin of 0.57 microg/g. Commercial corn gluten meal had a 7 times higher concentration of xanthophylls (145 microg/g), and deoiled corn contained 18 microg/g, indicating that the xanthophylls are probably bound to the zein fraction of corn proteins.
A system for continuous transesterification of palm oil was developed using a continuous stirred-tank reactor (CSTR) and pumps for continuous delivery of oil and catalyst and for continuous removal of product. Potassium hydroxide was used as the catalyst, the methanol-to-oil molar ratio was 6:1, and reaction temperature was 60°C. The yield of methyl esters increased from 58.8% of theoretical yield at a residence time of 40 min to 97.3% at a residence time of 60 min. However, higher residence times decreased the production rate. During long-term continuous operation, the CSTR displayed steady state conditions in terms of product profile and methyl ester concentration. This process has good potential in the manufacture of biodiesel.
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