Abstract This paper reviews the current status of biodiesel production mainly under supercritical conditions. Various methods such as homogeneous acid- and alkali-catalyzed transesterification, heterogeneous acid and alkali-catalyzed transesterification, enzyme-catalyzed transesterification, and supercritical reactions have been employed so far to synthesize biodiesel. Herein, we review the reaction mechanisms and experimental results for these approaches. Recently, supercritical biodiesel production has undergone a vigorous development as the technology offers several advantages over other methods, including the fact that it does not require a catalyst, short residence time, high reaction rate, no pretreatment requirement, and applicability to a wide variety of feedstock. This technology was first designed for biodiesel production using methanol and ethanol. Biodiesel production without glycerol as a byproduct is attractive and has been achieved using supercritical methyl acetate and dimethyl carbonate (DMC). Most recently, biodiesel production in supercritical tert-butyl methyl ether (MTBE) has been developed also. In this review, supercritical biodiesel production will be discussed in detail. Empirical rate expressions are derived for biodiesel production in supercritical methanol, ethanol, methyl acetate, DMC, and MTBE in this study for the first time. These rate equations are critical to predicting biodiesel yields and to comparing the reaction behaviors in different solvents. Lastly challenges for improving energy recovery in supercritical biodiesel production and recommendations for future work are provided.

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在超临界条件下生产生物柴油的最新技术

摘要 本文综述了目前主要在超临界条件下生产生物柴油的现状。迄今为止，合成生物柴油的方法有多种，如均相酸碱催化酯交换、多相酸碱催化酯交换、酶催化酯交换、超临界反应等。在这里，我们回顾了这些方法的反应机制和实验结果。近来，超临界生物柴油的生产经历了蓬勃发展，因为该技术与其他方法相比具有多种优势，包括不需要催化剂、停留时间短、反应速率高、无需预处理以及适用于各种不同的方法。原料。该技术最初是为使用甲醇和乙醇生产生物柴油而设计的。没有甘油作为副产品的生物柴油生产很有吸引力，并且已经使用超临界乙酸甲酯和碳酸二甲酯 (DMC) 实现。最近，还开发了在超临界叔丁基甲基醚 (MTBE) 中生产生物柴油。在这篇综述中，将详细讨论超临界生物柴油的生产。本研究首次推导出了超临界甲醇、乙醇、乙酸甲酯、DMC 和 MTBE 中生物柴油生产的经验速率表达式。这些速率方程对于预测生物柴油产量和比较不同溶剂中的反应行为至关重要。最后提供了在超临界生物柴油生产中提高能量回收的挑战和对未来工作的建议。