NOVEL SCHEMES FOR PRODUCTION OF BIODIESEL AND VALUE-ADDED CO-PRODUCTS FROM MICROALGAL OIL USING HETEROGENEOUS CATALYSTS
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Microalgae are promising sources of biofuels primarily because of their higher potential productivity compared to terrestrial biofuel crops. However, the production of liquid fuels from microalgae suffers from a lack of viable methods of extraction, conversion and fractionation of various components of the algal biomass. In this dissertation study, a rapid method was developed to accurately evaluate the biodiesel potential of microalgae biomass. The major advantage of this method is in situ fatty acid methyl ester (FAME) preparation directly from wet fresh microalgal and yeast biomass, without prior solvent extraction or dehydration. FAMEs were prepared by a sequential alkaline hydrolysis and acidic esterification process. This method can be used even with high amount of water in the biomass and is applicable to a vast range of microalgae and yeast species. A two-step in situ process was also investigated in this study to obtain a high FAME yield from microalgae biomass that had high free fatty acids (FFA) content. This process has the potential to reduce the production cost of microalgae-derived FAME and be more environmental compatible due to the higher FAME yield with reduced catalyst consumption. A cost-effective bio-char based catalyst was tested for the two-step biodiesel production. The results indicated that the bio-char catalyst was superior to commercial Amberly-15. A scalable chlorophyll remove process was also developed as a part of the system. The research resulted in a practical and cost-effective approach for producing biodiesel from crude microalgal oil.An integrated approach was explored in the fourth part of the study to produce biodiesel and fractionate high-value polyunsaturated fatty acid (PUFA). Zeolites were employed as the catalyst for selective esterification of fatty acids according to their chain length and degree of saturation. Low-value short chain FFA could be largely converted into FAME, while PUFA would remain unreacted due to steric hindrance. Both a high quality biodiesel and high-value PUFA could be obtained by employing this novel approach.