The problem of finding economically viable and environmentally friendly renewable energy sources is a pressing matter. Biodiesel, a liquid fuel derived from plant or animal oils, represents a renewable energy source.. We must make the reaction faster and more energy efficient. We have been studying the combination of heterogeneous base catalysts with heating by microwave radiation (@2.45Ghz) and the use of ultrasonic mixing.
We find that the reaction rates can approach and even exceed the rates for conventionally heated homogeneous catalysts as employed by industry. Heterogeneous catalysts can make biodiesel production more energy efficient, and therefore less expensive, by eliminating the need for expensive purification processes that separate the catalyst from reaction products . Microwave reaction systems both speed up biodiesel production and make them more energy efficient by accelerating the rate of reaction while decreasing energy losses involved in heating the reaction mixture and vessel . The ultrasonic excitation appears to be of considerable advantage in increasing the interfacial area for reaction between the reactant phases. Further we have developed a method to analyze the products and to extract the individual rate constants for the sequential processes of Tri-glyceride (oil)-> di-glyceride->mono-glyceride -> glycerine (+ fatty-acid methyl esters, FAME, BioDiesel). These sequential rate constants differ by orders of magnitude from each other and the relative rate constants differ for different catalyst systems. These calculations are providing new understanding of the heterogeneous trans-esterification process by which BioDiesel could be produced.
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