The fatty acids composition and the efficiency of enzymatic transesterification of different plant oils
| Autor: | Ming-Hsun Cheng, 鄭明訓 |
|---|---|
| Rok vydání: | 2010 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 98 Biodiesel, a green alternative energy, is produced from vegetable oil, animal fats and waste oil through transesterification. Because of the diminishing of conventional petroleum fuel, biodiesel is concerned gradually. For producing high quality biodiesel, the fatty acid composition of oil is very important. It can straightly influence physical and chemical properties of biodiesel. In the past, edible oil is the main resource for producing biodiesel, hence the issue of grain is provoked. For solving this problem, utilization of woody oil plant is the proper material for biodiesel, because of its high oil content over 50% from mature seeds. These materials are potential for producing biodiesel. In Taiwan, there are lots of tung tree (Euphorbiaceae family, Vernicia genus) and Chinese tallow tree (Sapium sebiferum). The oil content of their mature dried kernels seeds can reach over 50%. The analysis of their fatty acid composition, ELA (eleostearic acid) is the main composition of fatty acid of tung oil, and linolenic acid is the main composition of fatty acid of Chinese tallow tree kernel oil (C.T. oil). In the transesterification with Novozyme 435 as catalyst, temperature is a critical factor for the efficiency of conversion. Under 55oC after 24 hour, the conversion of fatty acid methyl esters (FAMEs) palm oil, soybean oil, C.T. oil and tung oil is 89.99%, 87.04%, 70.82% and 57.79% individually. In the part of fatty acid ethyl esters (FAEEs) conversion, palm oil, soybean oil and tung oil reach the best efficiency of conversion 75.75%, 25.22% and 20.36 respectively at 50oC. But, C.T. oil has the best conversion rate 51.06% under 55 oC. Compare the conversion of palm oil and soybean oil, which are common materials for biodiesel, to C.T. oil and tung oil. At the same temperature condition, palm oil has the highest efficiency of conversion, and the tung oil is the lowest. Compare the efficiency of FAMEs conversion to FAEEs conversion, the rate of FAEEs conversion is far lower than FAMEs conversion. From the aspect of the reaction rate constant, k values, indicates that normal reaction is the main mechanism in every step reaction of FAMEs conversion. For FAEEs that is opposite. Otherwise, the more saturated fatty acids content can make the normal reaction happen more easily. Hence, palm oil consists of over 80% saturated fatty acids, by contrast tung oil consists of 75%~85% unsaturated fatty acids. From this result, the fatty acid composition of oil can influence the efficiency of transesterification conversion directly. Besides the various temperature conditions, different fatty acids composition can affect the efficiency of conversion directly. The k values are another key factor for evaluating the efficiency of transesterification. Because that can explain the stepwise mechanism of reaction. Concluded these factors, temperature, fatty acids composition and k values are critical factors for the efficiency of transesterification. Otherwise, these factors are also affected mutually. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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