Thermal Cracking of Lipids to Produce Renewable Fuels and Platform Chemicals

  • Author / Creator
    Asomaning, Justice
  • There are increasing social and economic pressures to develop renewable alternatives to fossil derived fuels and chemicals as well as renewable and biodegradable industrial and consumer products and materials. This has led to renewed focus on converting agricultural and forestry feedstocks (biomass) into multiple renewable commodities. The conversion of vegetable oils and animal fats using thermal cracking reactions represents a very promising option for the production of renewable fuels and chemicals. The first objective of this dissertation research was to study the pyrolysis behaviour of model unsaturated fatty acids with focus on identification of reaction products under different conditions. Oleic acid and linoleic acid were pyrolyzed in batch microreactors at 350 – 450 °C for reaction times 0.5 – 8 h under N2 at atmospheric pressure. The results showed the production of a series of hydrocarbons in the liquid product with the n-alkane series being the most abundant. Low molecular weight fatty acids particularly C9 and C10 carbon chains were also formed in the liquid product. The presence of the double bond resulted in simultaneous deoxygenation and cracking of the alkyl chain, particularly at the allylic carbon bond. Deoxygenation occurred through both decarboxylation and decarbonylation pathways, the predominance of which was temperature dependent. The thermal cracking of oleic acid under light hydrocarbon gas atmosphere was conducted to study the effect on reaction product yields and composition. The results showed no significant influence of saturated light hydrocarbon gases compared to inert atmosphere. On the other hand the unsaturated light hydrocarbon gases resulted in significant increases in liquid product yield, conversion, deoxygenation and formation of branched hydrocarbon compounds. The second objective was to study the thermal cracking of low cost inedible lipid feedstocks using a two-step thermal hydrolysis-pyrolysis process. Beef tallow, brown grease, yellow grease and cold pressed camelina oil were used as feedstocks. The result showed that the organic liquid product yields were not significantly affected by the feedstock source of origin. Fuel property testing of crude batch pyrolytic product revealed the organic liquid products was composed of approximately 30% gasoline boiling range and 50% in the diesel boiling range compounds.

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  • Degree
    Doctor of Philosophy
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