Departamento de Química Orgánica e Inorgánica, Universidad de Extremadura, Badajoz, Spain.
Ultrason Sonochem. 2010 Aug;17(6):985-9. doi: 10.1016/j.ultsonch.2009.12.003. Epub 2009 Dec 21.
In recent years, chemistry in flowing systems has become more prominent as a method of carrying out chemical transformations, ranging in scale from microchemistry up to kilogram-scale processes. Compared to classic batch ultrasound reactors, flow reactors stand out for their greater efficiency and flexibility as well as lower energy consumption. This paper presents a new ultrasonic flow reactor developed in our laboratory, a pilot system well suited for reaction scale up. This was applied to the transesterification of soybean oil with methanol for biodiesel production. This reaction is mass-transfer-limited initially because the two reactants are immiscible with each other, then because the glycerol phase separates together with most of the catalyst (Na or K methoxide). In our reactor a mixture of oil (1.6 L), methanol and sodium methoxide 30% in methanol (wt/wt ratio 80:19.5:0.5, respectively) was fully transesterified at about 45 degrees C in 1h (21.5 kHz, 600 W, flow rate 55 mL/min). The same result could be achieved together with a considerable reduction in energy consumption, by a two-step procedure: first a conventional heating under mechanical stirring (30 min at 45 degrees C), followed by ultrasound irradiation at the same temperature (35 min, 600 W, flow rate 55 mL/min). Our studies confirmed that high-throughput ultrasound applications definitively require flow reactors.
近年来，流动系统中的化学已成为进行化学转化的一种方法，其规模从微化学到公斤级过程不等。与经典的间歇超声反应器相比，流动反应器因其更高的效率和灵活性以及更低的能耗而脱颖而出。本文介绍了我们实验室开发的一种新型超声流动反应器，这是一种适用于反应放大的中试系统。该系统应用于大豆油与甲醇的酯交换反应以生产生物柴油。该反应最初受到传质限制，因为两种反应物彼此不混溶，然后因为甘油相与大部分催化剂（甲醇中的钠或钾甲醇盐）一起分离。在我们的反应器中，将油（1.6 L）、甲醇和 30%甲醇中的甲醇钠（分别以质量比 80:19.5:0.5 的比例混合）完全酯交换在 45 度下约 1 小时（21.5 kHz，600 W，流速 55 mL/min）。通过两步法可以实现相同的结果，并显著降低能耗：首先在机械搅拌下进行常规加热（45 度下 30 分钟），然后在相同温度下进行超声辐射（600 W，流速 55 mL/min，35 分钟）。我们的研究证实，高通量超声应用确实需要流动反应器。
