Vasudevan Palligarnai T, Briggs Michael
Department of Chemical Engineering, University of New Hampshire, Durham, NH, USA.
Department of Physics, University of New Hampshire, Durham, NH, USA.
J Ind Microbiol Biotechnol. 2008 May;35(5):421. doi: 10.1007/s10295-008-0312-2. Epub 2008 Jan 18.
Biodiesel is a clean-burning fuel produced from grease, vegetable oils, or animal fats. Biodiesel is produced by transesterification of oils with short-chain alcohols or by the esterification of fatty acids. The transesterification reaction consists of transforming triglycerides into fatty acid alkyl esters, in the presence of an alcohol, such as methanol or ethanol, and a catalyst, such as an alkali or acid, with glycerol as a byproduct. Because of diminishing petroleum reserves and the deleterious environmental consequences of exhaust gases from petroleum diesel, biodiesel has attracted attention during the past few years as a renewable and environmentally friendly fuel. Since biodiesel is made entirely from vegetable oil or animal fats, it is renewable and biodegradable. The majority of biodiesel today is produced by alkali-catalyzed transesterification with methanol, which results in a relatively short reaction time. However, the vegetable oil and alcohol must be substantially anhydrous and have a low free fatty acid content, because the presence of water or free fatty acid or both promotes soap formation. In this article, we examine different biodiesel sources (edible and nonedible), virgin oil versus waste oil, algae-based biodiesel that is gaining increasing importance, role of different catalysts including enzyme catalysts, and the current state-of-the-art in biodiesel production.
生物柴油是一种由油脂、植物油或动物脂肪生产的清洁燃烧燃料。生物柴油通过油与短链醇的酯交换反应或脂肪酸的酯化反应来生产。酯交换反应包括在醇（如甲醇或乙醇）和催化剂（如碱或酸）存在的情况下，将甘油三酯转化为脂肪酸烷基酯，副产物为甘油。由于石油储量减少以及石油柴油废气对环境的有害影响，在过去几年中，生物柴油作为一种可再生且环境友好的燃料受到了关注。由于生物柴油完全由植物油或动物脂肪制成，它是可再生且可生物降解的。如今，大多数生物柴油是通过用甲醇进行碱催化酯交换反应生产的，这导致反应时间相对较短。然而，植物油和醇必须基本无水且游离脂肪酸含量低，因为水或游离脂肪酸或两者的存在会促进皂的形成。在本文中，我们研究了不同的生物柴油来源（食用和非食用）、原生油与废油、日益重要的基于藻类的生物柴油、不同催化剂（包括酶催化剂）的作用以及生物柴油生产的当前技术水平。
