Author
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Knothe, Gerhard |
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Submitted to: Biomass and Bioenergy
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 9/7/2013 Publication Date: 9/29/2013 Citation: Knothe, G.H. 2013. Avocado and olive oil methyl esters. Biomass and Bioenergy. 58:143-148. Interpretive Summary: Biodiesel is an alternative to petroleum-derived diesel fuel. Biodiesel is commonly produced from vegetable oils such as soybean oil or other sources such as animal fats and waste frying oils. Biodiesel has advantages such as renewability, domestic origin, biodegradability, safer handling, lower sulfur content, and reduced exhaust emissions when compared to petroleum diesel. However, problems related to behavior at low temperatures and storage stability affect biodiesel. Oils with high oleic acid content, a major constituent of most vegetable oils, have found special interest as they may lead to biodiesel fuels with overall better fuel properties. Avocado and olive oil, although mainly used in physiological applications, are oils with high oleic acid content. Biodiesel fuels were prepared from these two oils. The biodiesel fuels had good combustion properties as shown by the so-called cetane number with low-temperature properties not quite those of soy biodiesel and otherwise performing well within expectations. Technical Abstract: Biodiesel, the mono-alkyl esters of vegetable oils, animal fats or other triacylglycerol-containing materials and an alternative to conventional petroleum-based diesel fuel, has been derived from a variety of feedstocks. Numerous feedstocks have been investigated as potential biodiesel sources, including commodity oils, however, the methyl esters of avocado and olive oil would likely be suitable as biodiesel fuel. In order to expand the database and comprehensive evaluation of the properties of vegetable oil esters, in this work, the fuel-related properties of avocado and olive oil methyl esters, which exhibit similar fatty acid profiles including high oleic acid content, are determined. The cetane numbers of avocado oil methyl esters and olive oil methyl esters are relatively high, determined as 59.2 and 62.5, respectively, due to their elevated content of methyl oleate. Other properties are well within the ranges specified in biodiesel standards. The cloud points of both esters are slightly above 0°C due to their content of saturated esters, especially methyl palmitate. Overall, avocado and olive oil yield methyl esters with fuel properties comparable to methyl esters from other commodity vegetable oils. The 1H- and 13C-NMR spectra of avocado and olive oil methyl esters are reported. |
