Submitted to: Energy and Fuels
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/20/2009
Publication Date: 4/15/2009
Citation: Knothe, G.H., Cermak, S.C., Evangelista, R.L. 2009. Cuphea Oil as Source of Biodiesel with Improved Fuel Properties Caused by High Content of Methyl Decanoate. Energy and Fuels. 23:1743-1747. Interpretive Summary: Biodiesel is an alternative diesel fuel usually obtained from vegetable oils such as soybean oil or other sources such as animal fats and waste frying oils. However, there are not enough oils and fats available for biodiesel production to replace all diesel fuel obtained from petroleum. For this reason, oils that have not been commonly studied or used for biodiesel production are of significant interest. One such oil is cuphea oil, which can be obtained from plants native to the Americas, including the east-central United States. This work describes the biodiesel fuel obtained from cuphea oil. It is also shown that, due to its composition, biodiesel derived from cuphea oil has fuel properties that likely make it superior to most other biodiesel fuels.
Technical Abstract: Biodiesel, defined as the mono-alkyl esters of vegetable oils and animal fats, is an alternative to conventional petroleum-based diesel fuel. Biodiesel has been prepared from numerous common vegetable oils or fats as well as new or less common feedstocks. Major issues facing biodiesel include several technical aspects such as cold flow and oxidative stability as well as availability of sufficient quantities of fuel. Solutions to the technical problems include the use of additives or modifying the fatty ester composition of biodiesel. While esters of oleic acid possess good fuel properties, esters of other fatty acids also exhibit advantageous fuel properties, even surpassing those of oleic acid esters. Decanoic acid has been shown to be an acid whose esters possess good fuel properties. In this work, a vegetable oil containing high amounts (> 65%) of decanoic acid, cuphea oil (PSR 23; a cross of Cuphea viscosissima x C. lanceolata), is reported for the first time as potential biodiesel feedstock. The methyl esters of cuphea oil (biodiesel) were prepared by conventional transesterification and the 1H-NMR spectrum of cuphea methyl esters is reported. The significant fuel properties influenced by fatty ester composition such as cetane number, kinematic viscosity, cold flow as well as lubricity were determined and evaluated in comparison to biodiesel fuel standards. Cuphea methyl esters generally display more favorable fuel properties than biodiesel fuels derived from other feedstocks due to the high content of decanoic acid and as expressed by a cloud point in around -9 to -10 deg C. Thus, cuphea oil appears to be a good potential feedstock for biodiesel and can serve as model for other potential feedstocks with high decanoic acid content.