Polyol-Derived Alkoxide/Hydroxide Base Catalysts II: Transesterification Reactions
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Biodiesel, fatty acid methyl ester (FAME), was produced by transesterification of canola oil with methanol in the presence of a series of alkoxide/hydroxide base catalysts produced from glycerol, 1,2-propanediol, 1,3-propanediol, xylitol, or sorbitol produced by dehydration reaction of sodium hydroxide in the presence of polyols. Transesterification reactions proceeded efficiently in the presence of sodium alkoxide catalysts prepared at three different mole ratios of sodium hydroxide to glycerol (1:1, 2:1, and 3:1). The production of methyl ester during the course of the reaction was determined repeatedly and the reaction progress was compared with that achieved in a reaction catalyzed by freshly prepared anhydrous sodium methoxide as a standard catalyst. Sodium alkoxide/hydroxide catalysts activity during the first 2 min of the reaction was in the order of: sorbitol < xylitol < sodium methoxide < 1,2-propanediol < 1,3-propanediol < glycerol regardless of the mole ratio of sodium hydroxide to glycerol. All catalysts showed a higher methyl ester accumulation at higher ratios of sodium hydroxide to polyol and had the following order 1:1 < 2:1 < 3:1 (sodium hydroxide:glycerol). Several of these catalysts were as powerful as sodium methoxide in catalyzing the transesterification reaction at the same mole concentration. All alkoxide/hydroxide catalysts resulted in a high FAME accumulation (>95 wt%) in a single transesterification batch reaction.
KeywordsPolyol Metal alkoxide Sodium hydroxide Glycerol Catalyst Transesterification Biodiesel Methyl ester
The results of this research were obtained from an unpublished MSc thesis in the University of Saskatchewan. The authors appreciate all the support provided by university authorities, professors and researchers to accomplish this research. They are grateful for financial support provided by the Natural Sciences and Engineering Research Council of Canada (NSERC) and Agriculture and Agri-Food Canada (AAFC) through the NSERC/AAFC Research Partnerships program, the Saskatchewan Ministry of Agriculture, Agriculture Development Fund, Milligan Biotechnology Inc., SaskCanola and Saskatchewan Mustard Development Commission.
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