近年來，由於石油存量有限，生質柴油因可再生的關係，愈來愈受到重視。傳統上，生質柴油是利用動植物油脂中的三酸甘油酯與短碳鏈醇的轉酯化反應製造而得。但是在油脂中，除了三酸甘油酯外，還含有一部分的脂肪酸。這些脂肪酸可以與短碳鏈醇利用酯化反應，使生質柴油的產量增加。酯化反應中須要用到酸性觸媒，而常用到的酸有勻相觸媒的硫酸、鹽酸及硝酸，然而，勻相觸媒在再生與分離的步驟中比較困難，會造成成本上的增加。因此，便考慮以非勻相的固體酸性觸媒取代勻相的液體酸性觸媒。
在本研究中，以月桂酸及棕櫚酸與甲醇進行酯化反應，並利用帶有硫酸根的氧化鋯來進行催化，藉此找出較佳的反應條件。一般酯化反應會選擇在無水的條件下進行會有較高的轉化率，但是考慮到原料可能會含有水分，所以實驗中也試著加入水分來探討對於生質柴油酯化反應的影響。
從本研究發現，酯化反應中利用帶有硫酸根的氧化鋯，會有不錯的催化效果，而反應物中脂肪酸碳鏈愈長，反應速率也會愈快。水分對於酯化反應的影響，系統在單一相時，轉化率下降會較兩相時來得顯著。

Biodiesel has received much attention, because it is renewable. In general, biodiesel is produced from transesterification of oils or esterification of free fatty acids (FFAs) with alcohols of low molecular weight by using alkaline catalysts. However, if the raw oils contain high levels of free fatty acids, acidic catalysts are preferentially used for efficient production of biodiesel to avoid saponification under basic conditions. Among various acidic catalysts, sulfuric acid, hydrochloric acid and nitric acid are commonly used. Nonetheless, it is difficult to regenerate these catalysts after esterification process. Consequently, heterogeneous acidic catalysts are considered, instead. In this study, a solid acid catalyst, viz. sulfated zirconia (SO42-/ZrO2), was employed to catalyze the esterification of selected free fatty acids, namely lauric and palmitic acids, with methanol. Generally, a high production yield of fatty acid methyl ester (FAME) near 96% could be obtained in this work. Furthermore, water is one of the main products in FFA esterification and, therefore, its presence in excess undoubtedly will hinder the esterification reaction. Unfortunately, water is always unavoidably present in raw FFA materials. Hence, effect of water on FFA esterification in presence of sulfated zirconia was also investigated. Even with presence of water in the reacting system as much as 10 wt% compared to the combined weight of FFAs and methanol, sulfated zirconia can still catalyze the esterification process.

Alcantara R and Amores J, Catalytic production of biodiesel from soybean oil, used frying oil and tallow, Biomass and Bioenergy, 18, 515-527, 2000.

Arata K, Preparation of superacids by metal oxides for reactions of butanes and pentanes, Applied Catalysis A-General, 146, 3-32, 1999

Azcan N and Danisman A, Alkali catalyzed transesterification of cottonseed oil by microwave irradiation, Fuels, 86, 2639-2644, 2007.

Berrios M, Siles J,Martin MA, Martin A, A kinetic study of the esterification of free fatty acids (FFA) in sunflower oil, Fuel, 86, 2383-2388, 2007.

Connemann J and Fischer J, Biodiesel quality Y2K and market experiences with FAME, CEN/TC 19 Automotive Fuels Millennium Symposium, Amsterdam, The Netherlands, 25-26 Nov, 1999.

Demirbas A, Biodiesel production from vegetable oils via catalytic and non-catalytic supercritical methanol transesterification methods, Progress in Energy and Combustion Science, 31, 466-487, 2005.

Demirbas A, Importance of biodiesel as transportation fuel, energy policy, 35, 4661-4670, 2007.

Dorado MP, Ballesteros E, Exhaust emissions from a diesel engine fueled with transesterified waste olive oil, Fuel, 82, 1311-1315, 2003.

European Biodiesel Board網站，http://www.ebb-eu.org

Freedman B, Pryde EH, Mounts TL, Variables affecting the yields of fatty esters from transesterified vegetable oils, Journal of the American Oil Chemists’ Society, 61, 1638-1643, 1984.

Freedman B, Butterfield RO, Pryde EH, Transesterification kinetics of soybean oil, Journal of the American Chemists’ Society, 63, 1375-1380, 1986.

Furuta S, Matsuhashi H, and Arata K, Biodiesel fuel production with solid superacid catalysis in fixed bed reactor under atmospheric pressure, Catalysis Communications, vol.5, 721-723.

Georgogianni KG, Kontominas MG, Tegou E, Avlonitis D, and Gergis V, Biodiesel production: reaction and process parameters of alkali-catalyzed transesterification of waste frying oils, Energy and Fuels, 21, 3023-3027, 2007.

Gregg SJ and Sing KSW, Adsorption, Surface Area and Porosity, New York：Academic Press, 1982

Haas MJ, Michalski PJ, Runyon S, Nunez A, and Scott KM, Production of FAME from acid oil, a by-product from vegetable oil refining, Journal of American Chemists’ Society, 80, 97-102, 2003

International Panel on Climate Change網站，http://www.ipcc.ch

Ji J and Wang J, Preparation of biodiesel with the help of ultrasonic and hydrodynamic cavitation, Ultrasonics, 44, e411-e414, 2006.

Juan AM, Jose I and Gabriel M, Heterogeneous acid catalysts for biodiesel production: current status and future challenges, Green Chemistry, 11, 1285-1308, 2009

Khan AK, Research into biodiesel kinetics & catalyst development, University of Queensland, Brisbane, Queensland, 2002

Kocsisova T, Cvengros J, and Lutisan J, High-temperature esterification of fatty acids with methanol at ambient pressure, European journal of Lipid Science and Technology, 107, 87-92, 2005.

Linko YY, Biodegradable products by lipase biocatalysis, Journal of Biotechnology, 66, 41-50, 1998.

Lotero E, Liu Y, Lopez DE, Suwannakarn K, Bruce DA, and Goodwin JG, Synthesis of biodiesel via acidic catalysis, Industrial and Engineering Chemistry Research, 44, 5353-5363, 2005.

Lowell S and Shields JE, Powder Surface Area and Porosity, Chapman and Hall, London, 1991

Ma Fangrui and Hanna Milford A., Biodiesel production: a review, Bioresource Technology, 70, 1-15, 1999.

Niehaus RA, Goering CE, Savage LD, Jr. Sorenson SC, Cracked soybean oil as a fuel for a diesel engine, Transactions of the ASAE, 29, 683-689, 1986.

Noureddini H and Gao X, Immobilized Pseudomonas Cepacia lipase for biodiesel fuel production from soybean oil, Bioresource Technology, 96, 769-777, 2005.

Pasias S, Barakos N, Alexopoulos C, Papayannakos N, Heterogeneously catalyzed esterification of FFAs in vegetable oils, Chemical Engineering and Technology, 29, 1365-1371, 2006.

Ruthven DM, Principles of Adsorption and Adsorption Process, New York：Wiley, 1984

Saka S and Dadan K, Biodiesel fuel from rapeseed oil as prepared in supercritical methanol, Fuel, 80, 225-231, 2001.

Schwab AW, Bagby MO, Freedamn B, Preparation and properties of fuels from vegetable oils, Fuel,66, 1372-1378, 1987.

Schwab AW, Dykstra GJ, Selke E, Sorenson SC, Pryde EH, Diesel fuel from thermal decomposition of soybean oil, Journal of the American Oil Chemists’ society, 65, 1781-1786, 1988.

Sendzikiene E, Makareviciene V, Janulis P, Kitrys S, Kinetics of free fatty acids esterification with methanol in the production of biodiesel fuel, European Journal of Lipid Science and Technology, 106, 831-836, 2004.

Soumanou MM, Bornscheuer UT, Improvement in lipase-catalyzed synthesis of fatty acid methyl esters from sunflower oil, Enzyme Microbial Technology, 33, 97-103, 2003.

Tesser R, Di Serio M, Guida M, Nastasi M, Santacesaria E, Kinetics of oleic acid esterification with methanol in presence of triglycerides, Industrial and Engineering Chemistry Research, 44, 7978-7982, 2005.

Tiwari AK, Kumar A, Raheman H, Biodiesel production from jatropha oil (Jatropha curcas) with high free fatty acids: An optimized process, Biomass and Bioenergy, 31, 569-575, 2007.

United States of Department Agriculture網站，http://www.usda.gov/wps/portal/usda/usdahome

University of Idaho (Department of Biological and Agricultural Engineering), Biodegradability of biodiesel in the aquatic environment. development of rapeseed biodiesel for use in high-speed diesel engine, Progress report, 96-116, 1996.

University of Idaho (Department of Biological and Agricultural Engineering), Acute toxicity of biodiesel to freshwater and marine organisms. development of rapeseed biodiesel for use in high-speed diesel engine, Progress report, 117-131, 1996.

Vincente G, Martinez M, Aracil J, Integrated biodiesel production: a comparison of different homogeneous catalysts system, Bioresource Technology, 92, 297-305, 2004.

Watanabe Y, Nagao T, Nishida Y, Takagi Y, Shimada Y, Enzymatic production of fatty acid methyl esters by hydrolysis of acid oil followed by esterification, Journal of the American Oil Chemists’ Society, 84, 1015-1021, 2007.

Watanabe Y, Shimada Y , Sugihara A, Noda H, Tominaga Y, Continuous production of biodiesel fuel in a fixed-bed bioreactor, Journal of the American Oil Chemists’ Society, 77, 355-360, 2000.

Weiliang C and Hengwen H, Preparation of biodiesel from soybean oil using supercritical methanol and co-solvent, Fuel, 81, 347-351, 2004.

陳介武，拯救地球環保系列報導─生質柴油發展與趨勢，美國黃豆出口協會台灣辦事處，2000年。http://www.asaim.org.tw/texh6-3.htm

陳恭府，超低硫柴油摻配生質柴油之油品特性及污染排放分析，碩士論文，國立中山大學環境工程研究所，臺灣高雄，2005年。

蔡文田，”含揮發性有機物廢氣之活性碳吸附與觸媒焚化處理研究”，國立台灣大學環境工程學研究所博士論文，1994

謝志強，歐洲生質柴油發展勢態，IT IS智網，2007年。

謝志強，面對全球生質燃料產業快速發展─台灣準備好了嗎？，IT IS智網，2007年。

經濟部能源局網站，http://www.moeaboe.gov.tw

龐德、胡興中，觸媒原理與應用，高立出版社，1991年。