Master of Science in Chemical Engineering (MSChE)
Tall oil is a byproduct of the standard wood pulping process in the paper industry. It is primarily made up of C:18 fatty acids, rosin acids and a minor fraction of neutrals. Normally, tall oil is further distilled into fractions and then hydrogenated or dehydrogenated into different products. In this project, three heterogeneous catalytic methods of producing byproducts of various distilled tall oil fractions were examined at lower temperatures and pressures than the industry norm in an attempt to develop cheaper production processes. Reactions were conducted in stirred batch reactors of different sizes and product compositions were analyzed primarily by GC/MS and GC. The selective hydrogenation of abietic acid, a common rosin acid, to abietyl alcohol in the presence of fatty acids was examined first. For the conditions and catalysts used, the yield to abietyl alcohol was small and the reaction was not selective, giving both ring hydrogenation and dehydrogenation. Second, the dehydrogenation of abietic acid to dehydroabietic acid in a primarily rosin feed was studied. The Pd/C class of catalysts had the greatest activity. There was a maximum yield of 58% associated with equilibrium, and the reaction took place predominantly as a disproportionation. The reaction was very slow at temperatures less than 230oC, and decarboxylation occurred in greater abundance as time or temperature of the reaction was increased. In the mainly rosin feed (HYR), some polymerization occurred; however, the amount of polymer was relatively small, the polymer was thermally labile and most likely thermal in origin. Finally, the gas environment (H2, N2, air) did not have a significant effect on the reaction. The final reaction studied was the selective hydrogenation of unsaturated fatty acids to unsaturated fatty alcohols in a mainly fatty acid feed. The results showed that the hydrogenation could not occur to a significant degree at conditions less than 250oC and 87 bar, for any of the common classes of hydrogenation catalysts.
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O'Brien, Edward, "The stereospecific hydrogenation and dehydrogenation of rosin and fatty acids" (2011). LSU Master's Theses. 2081.