超临界下萃取酯交换耦合反应制备生物柴油
发布时间：2019-02-23 18:18
【摘要】：随着全球能源发展战略的调整,绿色可再生能源在能源产业发展中占有越来越重要的地位,并将逐渐代替传统石化能源。作为典型的绿色能源,生物柴油近年来备受各个国家和地区的重视。超临界低碳醇酯交换反应是制备生物柴油的新型工艺,具有绿色、快速、高产、高效等优势。相较间歇型制备工艺,连续型制备工艺能够降低生产成本与能源消耗,有利于实现工业化生产。为此,本文以超临界甲醇酯交换反应制备生物柴油为研究背景,探讨不同反应器对连续过程的影响,优化反应工艺,并把超临界萃取技术与超临界甲醇酯交换反应耦合起来,直接以大豆片为原料,一步法制备生物柴油,确定耦合工艺控制步骤和最佳耦合条件。同时,从理论上计算连续反应动力学和热力学行为,为工艺生产推广提供理论基础。主要研究内容如下：1.为了缩短系统稳定时间,提高酯交换反应产率,首先以大豆油为原料分别在盘管式反应器、直管式填料床反应器内进行超临界连续酯交换反应的实验研究。考察了稳定时间、温度、压力、醇油摩尔比、进料流量等影响参数。研究结果发现,直管式填料床反应器的反应效果优于盘管式反应器,稳定时间短,产物产率高。在直管式填料床反应器内,当条件满足300℃、22MPa、醇油摩尔比42：1时,系统稳定时间为30mmin,甲酯产率为80.26%,铁丝网填料可连续重复使用11次。2.对超临界萃取耦合酯交换过程进行系统研究发现,反应达到稳定之前,反应过程是耦合工艺的控制步骤,反应稳定之后,则萃取过程是控制步骤。因此,在研究反应器和反应过程的基础上,对萃取过程进行优化。发现在超临界CO2中添加适量夹带剂正己烷可以显著提高大豆片出油率,具体条件为20g分层填料0.4mmm厚大豆片、40℃、20MPa、CO2与正己烷质量比21：1,120mmin后萃取率可达到99.99%。3.发现超临界萃取夹带剂正己烷对超临界酯交换反应起到强化作用。综合考虑操作参数对甲酯产量和产率的影响情况,优化匹配萃取动力学和反应动力学,得到最佳耦合反应条件为：萃取温度40℃、反应温度300℃、压力18MPa～20MPa、CO2与正己烷质量流量比14：1、CO2流量2L/mmin,正己烷流量0.4ml/min。4.为了深入探讨在超临界环境下连续酯交换工艺的过程机理,为未考察的实验过程提供推断依据,有益于扩大生产和工业应用,从反应动力学和热力学行为方面进行研究计算。确定了反应速率常数、平衡常数、大豆油-甲醇临界参数和溶解度参数。
[Abstract]:With the adjustment of global energy development strategy, green renewable energy plays an increasingly important role in the development of energy industry, and will gradually replace the traditional fossil energy. As a typical green energy, biodiesel has been paid much attention by many countries and regions in recent years. Supercritical low carbon alcohol transesterification is a new technology for the preparation of biodiesel, which has the advantages of green, fast, high yield and high efficiency. Compared with batch preparation process, continuous preparation process can reduce production cost and energy consumption, and is conducive to industrial production. Therefore, under the background of supercritical methanol transesterification to prepare biodiesel, the effects of different reactors on the continuous process were discussed, the reaction process was optimized, and the supercritical extraction technology was coupled with the supercritical methanol transesterification reaction. Biodiesel was prepared directly from soybean slices by one step method, and the control steps and the optimum coupling conditions were determined. At the same time, the kinetic and thermodynamic behaviors of continuous reaction are calculated theoretically, which provides a theoretical basis for the popularization of process production. The main contents are as follows: 1. In order to shorten the time of system stabilization and improve the yield of transesterification, the supercritical continuous transesterification was studied in a coil reactor and a straight tube packed bed reactor using soybean oil as raw material. The influences of time, temperature, pressure, molar ratio of alcohol to oil, feed flow rate and so on were investigated. The results show that the reaction effect of the straight tube packed bed reactor is better than that of the coil reactor, the stabilization time is short and the yield of the product is high. In a straight tube packed bed reactor, when the conditions are 300 鈩，
本文编号：2429082
[Abstract]:With the adjustment of global energy development strategy, green renewable energy plays an increasingly important role in the development of energy industry, and will gradually replace the traditional fossil energy. As a typical green energy, biodiesel has been paid much attention by many countries and regions in recent years. Supercritical low carbon alcohol transesterification is a new technology for the preparation of biodiesel, which has the advantages of green, fast, high yield and high efficiency. Compared with batch preparation process, continuous preparation process can reduce production cost and energy consumption, and is conducive to industrial production. Therefore, under the background of supercritical methanol transesterification to prepare biodiesel, the effects of different reactors on the continuous process were discussed, the reaction process was optimized, and the supercritical extraction technology was coupled with the supercritical methanol transesterification reaction. Biodiesel was prepared directly from soybean slices by one step method, and the control steps and the optimum coupling conditions were determined. At the same time, the kinetic and thermodynamic behaviors of continuous reaction are calculated theoretically, which provides a theoretical basis for the popularization of process production. The main contents are as follows: 1. In order to shorten the time of system stabilization and improve the yield of transesterification, the supercritical continuous transesterification was studied in a coil reactor and a straight tube packed bed reactor using soybean oil as raw material. The influences of time, temperature, pressure, molar ratio of alcohol to oil, feed flow rate and so on were investigated. The results show that the reaction effect of the straight tube packed bed reactor is better than that of the coil reactor, the stabilization time is short and the yield of the product is high. In a straight tube packed bed reactor, when the conditions are 300 鈩，
本文编号：2429082
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