Correlation between the chemical structure of biodiesel and its physical properties

Abstract

ABSTRACT:Biodiesel is a renewable, biodegradable, environmentally benign, energy efficient, substitution fuel which can fulfill energy security needs without sacrificing engine's operational performance. Thus it provides a feasible solution to the twin crises of fossil fuel depletion and environmental degradation. The properties of the various individual fatty esters that comprise biodiesel determine the overall properties of the biodiesel fuel. In turn, the properties of the various fatty esters are determined by the structural features of the fatty acid and the alcohol moieties that comprise a fatty ester. Better understanding of the structure-physical property relationships in fatty acid esters is of particular importance when choosing vegetable oils that will give the desired biodiesel quality. By having accurate knowledge of the influence of the molecular structure on the properties determined, the composition of the oils and the alcohol used can both be selected to give the optimal performance. In this paper the relationship between the chemical structure and physical properties of vegetable oil esters is reviewed and engineering fatty acid profiles to optimize biodiesel fuel characteristics is highlighted.

Adsorption in Biodiesel Refining - A Review

“…Biodiesel acidity also reflects the degree of fuel ageing during storage, as it gradually increases due to hydrolytic cleavage of ester bonds. High fuel acidity of biodiesel has been discussed in the context of corrosion and the formation of deposits within the engine, particularly in fuel injectors, by catalyzing polymerization in hot recycling fuel loops (Refaat, 2009). However the main problem associated with acids is the formation of soaps as it will be discussed later.…”

REVIEW OF BIOFUEL PRODUCTION – FEEDSTOCK, PROCESSES AND MARKETS — Review Article

“…Commonly this mixture is referred to as biodiesel (Hoekman et al, 2012). Compared to pure vegetable oils the chemical structure of biodiesel molecules is closer to those of diesel fuels derived from fossil sources; nevertheless, the diesel fuel standard cannot be met (this is one reason why biodiesel is sold on the market as a mixture with fossil diesel fuel containing usually less than 10% biodiesel) (Refaat, 2009). Thus, FAME is commonly utilised as a partly substitute for fossil diesel fuel (European Biofuels Technology Platform, 2011).…”

Biofuels Get in the Fast Lane: Developments in Plant Feedstock Production and Processing

“…Castor oil has the remarkable ability to withstand high and low temperatures [41] while its high content in hydroxylated fatty acid (ricinoleic acid) makes it more stable against oxidation and higher in oxygen content than other oils. The fuel-related properties of castor oil with the high density (0.956 to 0.963 g/ml at 20°C, above the maximum limit in EN 14214 European biodiesel specification), viscosity under 50°C and hygroscopicity suggest that castor biodiesel cannot be used in its pure form [42][43][44][45][46], but rather in blends with regular diesel or biodiesel made with other lipid feedstocks. Importantly, biodiesel made of castor oil has lower cost compared to other vegetable oil feedstocks because it is the only oil that is soluble in alcohol and does not require heat and the consequent energy requirement of other vegetable oils in transforming them into fuel [47].…”