Soybean-Derived Fuel Liquids from Different Sources as Blending Stocks for Middle Distillate Ground Transportation Fuels

Abstract

It has been proposed that biodiesel liquids be used in blends with middle distillate ground transportation fuels by the various services in the Department of Defense. The U.S. Navy is considering allowing up to 20% biodiesel to be added as a blending stock to petroleum diesel fuels. It is important for operational considerations to examine the many problems this could present. Among the more important considerations are storage stability, filterability, fuel solubility, oxidative stability, and induced instability reactions. This paper reports on two different soybean-derived fuel liquids. The first is a fuel liquid that contains an antioxidant, and the second is a fuel liquid that was derived from recycled restaurant cooking oil with no added antioxidant. We compare both biodiesels in blends of 10% and 20% with both stable and unstable petroleum middle distillate fuels for storage stability, oxidative stability, solubility, and chemical instability results.

Biodiesel production, properties, and feedstocks

“…When blended with petrodiesel, biodiesel does not impact flash point up to B20, but beyond B20, the flash point increases significantly (Alptekin and Canakci 2009). The oxidative stability of petrodiesel is negatively impacted upon blending with biodiesel (Mushrush et al 2003(Mushrush et al , 2004. This is because the hydrocarbon constituents of petrodiesel are more stable to oxidation than FAME (especially in the case of unsaturated FAME).…”

Soybean Oil Derivatives for Fuel and Chemical Feedstocks

“…Although similar in carbon chain length and cetane number, biodiesel differs from diesel significantly in its vapor pressure, liquid viscosity, and vapor diffusion coefficient. The properties of the biodiesel depend on the length and unsaturation of the fatty acid chains, Although successfully blended up to 20 volume% for commercial and military use [16], methyl ester content in vehicle fuel is limited by a number of factors, including the performance in cold weather, the effect of oxygen content on engine components (particularly in the case of older engines), shelf-life and thermal stability [17], and higher NO x emissions from engines that are not tuned to handle the higher temperature conditions of methyl ester combustion [18]. Results from simulations presented in Figures 2 and 3 show on a microscopic scale how the combustion of biodiesel can differ from diesel (represented as n-heptane in the engine simulations) in terms of temperature and emissions [15].…”

“…However, the unsaturation can also lead to issues with shelf life and thermal stability [28] in comparison with more hydrogenated oils such as palm oil. The process of oxidation and its effects on the properties of biodiesel has been studied using chemical and thermal analysis by Tan and colleagues [29], and reviewed by Mushbrush [17] and Knothe [30]. Oxidation of the double bonds can occur through an autocatalytic mechanism simplistically depicted below, Reaction (2), initiated by hydrogen abstraction from an unsaturated carbon atom.…”

Corrosion and Engine Test Analysis of Neem <i>(Azadirachta indica)</i> Oil Blends in a Single Cylinder, Four Stroke, and Air-cooled Compresion Ignition Engine

“…The flash point of petrodiesel is increased upon blending with biodiesel [8]. The oxidative stability of petrodiesel is negatively impacted upon blending with biodiesel [9,10], this negative impact results to increase rate of corrosion seen in biodiesel and its blends. This is because the hydrocarbon constituents of petrodiesel are more stable to oxidation than FAME (especially in the case of unsaturated Fatty Acid Methyl Ester).…”