Cetane number biodiesel

Biodiesel methyl esters blend quite easily into petroleum based conventional diesel fuel. Biodiesel esters typically have better lubricity properties and higher cetane number ratings than conventional diesel fuel, but have poorer water demulsibility and color stability properties. At sub-zero temperatures, the handling characteristics of biodiesel becomes more difficult to control than conventional diesel fuel. 

To improve the cold properties of biodiesel, the use of alcohol with longer alkyl chain has been studied in the alkaline-catalyzed method. The cloud point for ethyl esters is approx 2°C lower than that of the corresponding methyl esters, while butyl esters are 10°C lower than methyl esters (6). Furthermore, cetane number is appropriate for alkyl esters from the alcohol with the longer alkyl chain (7). 

TABLE 1.1. Cetane number (CN) of biodiesel and selected fatty acid alkyl esters. 

Van Gerpen, J. H. 1996. Cetane Number Testing of Biodiesel. In Cundiff, J. S., Gavett, E. E., Hansen, C., Peterson, C., Sanderson, M. A., Shapouri, H., and Van Dyne, D. L. (Eds.), Proc., Third Liquid Fuel Conference Liquid Fuel and Industrial Products from Renewable Resources (pp. 197-206). St. Joseph MI American Society of Agricultural Engineers. 

Standard canola oil is high in CIS fatty acids, about 95%, which is higher than the other commodity vegetable oils. It is high in CIS In - 9 oleic acid at about 60%, much higher than any other vegetable oils, and it is relatively low in polyunsaturated fatty acids, linoleic at about 21%, and linolenic at about 10%. Viscosity, cold hlter plugging point, and cetane number are some of the most important biodiesel fuel properties influenced by fatty acid composition. 

The optimization of biodiesel production by transesterification of sunflower oil was studied (122). The best combination of process parameters was found to be three stoichiometric doses of methanol, 0.28% w/w of KOH, and 70°C temperamre. Several reports have been published on the properties of biodiesel manufactured with different fatty materials and on their performance in compression ignition engines, including information about sunflower oil and its esters (30, 31, 41, 123). Table 19 shows major properties of sunflower oil and its methyl esters. The physicochemical characteristics of these esters meet the norm specifications of different countries, even with improvements of some properties, such as the cetane number. 

Furthermore, biodiesel is variable depending on the source of the fuel and its age (27). For example, Monyem and Van Gerpen (27) observed decreased carbon monoxide and hydrocarbon emissions from oxidized neat biodiesel when compared with unoxidized biodiesel. In addition, cetane number is inversely proportional to iodine value (28) and proportional to biodiesel age (29). 

The Calculated Cetane Index (CCI), though not an accurate predictor of Cetane Number for biodiesel, since it is based on a calculation using specific gravity and the distillation curve, was used to estimate the Cetane Number of the biodiesel and two diesel fuels. From the results it can be seen that biodiesel has a CCI value higher (55) than that of diesel No.2 (49). This accords the biodiesel with better cold-start properties, minimizes the formation of white smoke (emissions), and leads to less engine noise and hence improved engine durability and reduced fuel consumption. ... 

Biodiesel (fatty acid methyl esters) is an alternative and renewable energy source, the development of which is hoped to reduce global dependence on petroleum, as well as air pollution. Biodiesel generated Ifom a variety of vegetable oils and animal fats has characteristics similar to those associated with petro-diesel, including viscosity, volumetric heating value, cetane number, and flash point [1-3]. Several processes have thus far been developed for the production of biodiesel via acid-, alkali-, and enzyme-catalyzed... 

The fatty acid profile determines the properties of the oil and the resulting biodiesel. Oils with higher levels of saturated fatty acids have more resistance to oxidation and higher cetane numbers but tend to gel at temperatures that limit their usefulness in cold climates (Klopfenstein, 1985 Knothe et al., 2003 1997 Dunn, 2005a). Oils with high levels of polyunsaturates are prone to oxidation but frequently contain natural antioxidants that protect the oil. 

Biodiesel. Biodiesel appears as one of the attractive renewable energy sources. It refers to all biofuels of similar cetane number as that of diesel. Most commonly used biodiesel consists of fatty acid methyl esters (FAME), with physical characteristics close to fossil fuel. FAMEs are usually prepared by... 

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