028e - Transesterification of Glycerol Triacetate with...

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Transesterification of Glycerol Triacetate with Methanol on Acid and Base Catalysts Dora E. Lopez, James Goodwin Jr. 1 , Edgar Lotero, and David Bruce Department of Chemical Engineering, Clemson University, Clemson, SC 29634, USA 1 To whom correspondence should be addressed: Phone (864)656-0784 e mail: [email protected] Introduction There is much interest in the conversion of fats and vegetable oils to biodiesel due to its desirable environmental, renewable and biodegradable properties. A major problem of the conventional industrial process, which uses homogenous base catalysts (NaOH or KOH), is that the reaction does not tolerate the presence of water or free fatty acids. In addition to the need of a high quality feedstock, the catalyst cannot be recovered. The homogeneous acid catalyzed process is not practical due to corrosion and environmental problems. The use of solid catalysts has the potential to reduce environmental and process costs. Triglycerides are the major components of oils and fats. The transesterification reaction of a triglyceride (TG) consists of three consecutive and reversible reactions which can be catalyzed by acids or bases. The overall reaction requires 3 mol of alcohol per 1 mol of TG to produce 1 mol of glycerol and 3 mol of ester. Biodiesel is the resulting mixture of ester products obtained from the transesterification of TGs contained in vegetable oils and fats. Scheme 1 shows the transesterification reaction of glycerol triacetate (triacetin) with methanol, a model compound for larger triglyceride molecules. Scheme 1 2. 1. 3. Stepw ise reactions: Glycerol Methanol M onoacetin Diacetin M ethyl Acetate Triacetin H 3 CO C H 3 O OH HO CH 3 O O H 3 C H 3 C H 3 O O O H 3 C O O O O R 3 H 3 C 3 H 3 C H 3 O O O O O 3 H 3 C 3 O O O O O O 3 3 H 3 C catalyst cataly st
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Triacetin is a clear oily liquid with a b.p of 258&C and presents good solubility in alcohols. This small molecule can be used as a model compound for larger TG molecules without the drawback of analysis difficulties. The results obtained from the transesterification of triacetin with methanol cannot be directly extrapolated to real oils and fats. However, they do give an idea of the activity of the different catalyst materials on the transesterification reaction. The purpose of this research was to investigate the catalytic activities and selectivities of different types of catalyst materials for the transesterification reaction of triacetin. Transesterification of triacetin was carried out using methanol to produce methyl acetate and glycerol at 60&C in the presence of a variety of solid and liquid catalysts. The solid acid catalysts used were, Amberlyst-15, supported phosphoric acid, sulphated zirconia, tungstated zirconia, zeolite H β and, ETS-10 (H). The solid base catalysts used were MgO, and ETS-10 (Na). These results were compared to reactions using H 2 SO 4 and NaOH.
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This note was uploaded on 10/21/2010 for the course S a taught by Professor S during the Spring '10 term at Glasgow Caledonian University.

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028e - Transesterification of Glycerol Triacetate with...

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