The benefits of biodiesel have been well documented, however, problems related to fuel quality, filter plugging, injector failure, material compatibility, and fuel economy still remain and must be resolved before wide spread use of biodiesel can be addressed. Some of these problems are inter-related, but all are inherent to the composition of the biodiesel. In particular, the presence of double bonds in the fatty acid residues impacts its oxidation and storage stability. Furthermore the relatively high average molecular weight composition of biodiesel affects its flow properties and compatibility compared with a petroleum-based diesel. These inherent problems require blending biodiesel with petroleum-based fuel, hinder its use in cold temperature, negatively affect fuel economy, increase particulate emission, and lead to power loss. The overall objective of this proposal is to improve the quality of biodiesel by chemical modification.. Improved quality will improve the cold temperature properties, extend the oxidation and storage stability, and will eliminate the need for blending with petroleum-based diesel. The replacement of 1% of current on-road diesel fuel with biodiesel would result in a 300 million gallon demand that would require 215 million bushels of soybeans. The gross impact on the farm economy would be of the order of $800million. In addition (at this level) a small reduction in imported crude oil would result. Higher market penetrations would result in significant reductions in imported oil. OBJECTIVES: The overall objective of this proposal is to improve the quality of methyl soyate biodiesel by chemical modification that will yield fully saturated esters (no double bonds) having a lower average molecular weight than methyl soyate. Improved quality will improve the cold temperature properties, extend the oxidation and storage stability, and will eliminate the need for blending with petroleum-based diesel. This objective will be achieved by cleavage of the fatty esters at the double bonds by ozonolysis to yield saturated, short alkyl esters and diesters. Although this concept is general and can be used with any biodiesel that contains double bonds, this project will be focused only on the reaction of ozone with methyl soyate to yield methyl esters and methyl diesters. Statement of goals and objectives Project Objective- The objective is to demonstrate cleavage of double bonds in methyl soyate by ozonolysis to yield methyl esters and diesters in order to improve the cold temperature properties and oxidative stability of soy-derived biodiesel. This category 1 project will be completed in 6 months for a total proposed budget of $40,000. APPROACH: We intend to react methyl soyate with ozone under similar conditions to remove the double bonds and attach a methyl ester instead. It is expected that eliminating the double bonds will enhance the thermal and oxidative stability of the biodiesel. Methyl (or ethyl) ester at the terminal position is further expected to enhance the cold flow properties (e.g. depress the cloud point) and should prevent wax-like crystallization and precipitation. Furthermore, the cleavage of the fatty acid residues at the double bond will lower the molecular weight of biodiesel and will improve its flow properties. It is expected that this treatment will negate the need for blending biodiesel with petroleum-based diesel. Technical feasibility: We wish to improve the quality of biodiesel by cleaving the fatty esters at the double bonds to yield saturated esters and diesters. It is well known that the oxidation and thermal stability of fatty acids is directly related to the number of double bonds present . It was clearly shown that the double bond is the initial point of attack during autoxidation and the rate of oxygen absorption are much higher in fatty acids containing multiple double bonds. For example, the relative autoxidation rate of methyl stearate, methyl oleate, methyl linoleate, and methyl linolenate was found to be 1:11:114:170 at comparable temperatures . Based on the mechanism, it was further concluded that the rate of oxidation of nonconjugated polyunsaturated fatty acids is the highest because of the activation of methylene groups between the two double bonds . However, irrespective if the oxidation rate, the mechanism in every unsaturated fatty acid involves the formation and decomposition of hydroperoxides, which is an autocatalytic reaction in nature and eventually leads to crosslinking and chain scission reactions. The autoxidation of saturated fatty acids is much slower and these compounds are essentially inert at temperatures below 100 Centigrade. The cleavage of the fatty esters in methyl soyate biodiesel will be achieved by ozonolysis in alcoholic solution of methanol as described in the previous section. Since methyl stearate and methyl palmitate contain no unsaturation, they should not be affected and remain the product mixture. Using a typical mixture of methyl soyate with methyl linoleate (51%), methyl oleate (23%), methyl palmitate (11%), methyl linoleneate (7%), and methyl stearate (4%), one would expect the product mixture after ozonolysis to consist of shorter, saturated methyl esters
