(660b) Synthesis of Biodiesel Via Cavitation-Enhanced Homogeneous and Solid Acid Catalyzed Processes
Biodiesel is an oxygenated diesel fuel consisting of mono alkyl esters of long chain fatty acids derived from renewable lipid feedstocks such as vegetable oils or animal fats, made up of triglycerides (TGs) and free fatty acids (FFAs) and is produced via the chemical process of transesterification. Biodiesel is not only biodegradable but it is also free of sulfur and aromatics. Biodiesel is produced by reacting the lipid feedstocks with an alcohol, such as methanol or ethanol in the presence of a catalyst (sodium or potassium hydroxide, or sodium methoxide) to yield methyl esters (biodiesel) and byproduct glycerin used to make soaps and cosmetics. This reaction does not tolerate the presence of water or fatty acids and the use of acids such as H2SO4, H3PO4, and HCl pose environmental and corrosion problems. The use of solid acids such as zeolites or zirconium sulfate would eliminate the need to use liquid acids or bases, the subsequent corrosion of process equipment and soap formation, and would make catalyst separation from products trivial and permit the use of continuous rather than batch processing. Cavitation is the formation, growth and implosive collapse of gas- or vapor-filled microbubbles and can be induced acoustically or hydrodynamically in a body of liquid. The collapse of these bubbles leads to local transient high temperatures ( 5000 K) and pressures ( 1000 atm), resulting in the generation of highly reactive species including hydroxyl (?OH), hydrogen (H?) and hydroperoxyl (HO2?) radicals, and hydrogen peroxide. Cavitation effects also increase the mass transfer and accelerates the reaction rate and yield of esters. However, little fundamental research has been carried out to date on the production of biodiesel via ultrasound enhanced homogeneous and heterogenous catalysis of esterificationa nd transesterification. This talk will present extensive review of the literature, our results of our current research effort and future research directions.