It is well known fact that energy is a big issue for this world and substantial amount of research is going on worldwide for alternative fuels that are environmentally friendly, especially because of the fact that crude petroleum reserves are dwindling. Also, research on alternative fuels is essential for increased energy security. Biodiesel is a renewable, biodegradable, and nontoxic fuel. At present, when homogeneous catalysts are used, biodiesel is primarily produced in batch reactors in which the required energy is provided by heating accompanied by mechanical mixing. Alternatively, ultrasonic processing could be an effective way to attain required mixing while providing the necessary activation energy. We found that, using ultrasonication, a biodiesel yield in excess of 99% can be achieved in a short time duration of five minutes or less in comparison to one hour or more using conventional batch reactor systems. Homogeneous acid or base catalysts dissolve fully in the glycerol layer and partially in the fatty acid methyl esters (biodiesel) layer during the triglyceride transesterification process. Heterogeneous (solid) catalysts, on the other hand, can prevent catalyst contamination making product separation much easier. In the present work, one of the objective was to determine the transesterification kinetics of different pure metal oxide catalysts, mixed metal oxide catalysts, layered double hydroxides with their corresponding yield is presented. It was found that heterogeneous catalysts require much higher temperatures (215oC) and pressures to achieve acceptable conversion levels compared to homogeneous catalysts. For some of the mixed metal oxide solid catalysts a conversion level of 99% was observed. The present study also deals with the catalyst characterization on the basis of their acidity/ basicity and site strength, and surface area. Finally the deoxygenation of fatty acid methyl esters was carried out in order to upgrade the biodiesel. As a result, several aliphatic and aromatic hydrocarbons were detected in the mass spectrometric studies. This dissertation consists of five chapters. Chapter I presents a brief introduction to biodiesel production and the objectives of the study. Chapter II contains a review of literature. Chapter III contains the materials and methods used in this study. In this chapter different principles and theories will be mentioned with regard to the use of ultrasonication towards biodiesel production, reaction kinetics of biodiesel production, catalyst characterizations and thermodynamic analysis of deoxygenation of fatty acid methyl esters. Chapter IV presents the results and its discussions. Finally, Chapter V discusses the summary and conclusions of the study.
| Identifer | oai:union.ndltd.org:MSSTATE/oai:scholarsjunction.msstate.edu:td-2408 |
| Date | 03 May 2008 |
| Creators | Singh, Alok Kumar |
| Publisher | Scholars Junction |
| Source Sets | Mississippi State University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Theses and Dissertations |
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