微波外场协同下吸微波、疏水型固体酸催化低品质油脂一步合成生物柴油的研究

In China, the raw materials applied in biodiesel synthesis are usually low-quality fats with water and free fatty acid. The synthesis method mostly is the complicated two-step method, which is used in conjunction with acid, alkali catalysts. In this study, simple one-step biodiesel synthesis is investigated in the presence of acid catalyst, which can catalize both free fatty acid and fat. A novel microwave absorption hydrophobic solid acid catalyst were developed to enhance the efficiency of acid catalyst and against the water in the system. The catalyst can produce the high temperature area with hot spots due to the microwave-absorption properties under microwave, which can drive a high efficient biodiesel synthesis reaction. The hydrophobic characteristics significantly reduced the catalyst poison by water, and its service life increases. In our study, the solid acid catalysts were prepared by hydrophobic charcoal materials, which have excellent microwave-absorption. The energy absorption and "microwave hot spot" formatting ability were studied. The reaction kinetics mechanism model under microwave will be established. Based on the above researches, different low-quality fats were applied to synthesis biodiesel under microwaves. The optimum values of operation parameters were obtained by response surface methodology.

国内生产生物柴油的原料基本为含游离脂肪酸、水的低品质油脂，合成方法多为联合使用酸、碱催化的工艺复杂的两步法。本研究利用酸可同时催化游离脂肪酸、油脂生成生物柴油的特性，开发酸催化一步合成生物柴油的简单工艺。针对酸催化效率低、反应体系含水等问题，开发吸微波、疏水型固体酸催化剂。在微波外场下，由于催化剂具有吸微波特性，可在其上形成热点高温区，协同微波场下原料中醇的极化作用，实现高效的酸催化生物柴油合成，利用催化剂的疏水性能，减弱水对催化剂酸性位破坏，延长催化剂的使用寿命。为实现以上目标，本研究将采用具有良好吸微波特性及疏水性能的炭材料为基体制备固体酸催化剂，研究催化剂吸收微波外场能量，形成"微波热点"的能力，催化剂对反应体系中极性物质的排斥能力，建立机理型微波外场作用下反应体系的动力学方程，在此基础上，进行微波外场下，不同低品质原料油脂一步合成生物柴油的研究，并采用响应面法设计优化工艺条件。

国内生产生物柴油的原料基本为含游离脂肪酸、水的低品质油脂，合成方法多为联合使用酸、碱催化的工艺复杂的两步法。本研究利用酸可同时催化游离脂肪酸、油脂生成生物柴油的特性，制备了同时具有吸微波、疏水性能的固体酸催化剂，如：H3PW12O40•xH2O /C、H3PW12O40•xH2O /C(改性)、改性SO42-/ZrO2@C-SiC在微波外场协同作用下，实现高效地一步催化低品质油脂合成生物柴油的目标。此外，还制备了具有较好吸微波性能力的固体酸H2SO4/C、SO42-/Fe2O3、Cs2.5H0.5PW12、Cs0.5H2.5PW12 ，在微波外场下高效催化非食用植物油合成生物柴油，又制备了耐水型固体酸K2.5H0.5PW12用于游离脂肪酸含量较高的废油脂体系的生物柴油合成，催化剂显示了良好的催化效果及重复使用性。针对微波外场下，H3PW12O40•xH2O /C的催化体系进行“微波热点”温度的模拟计算，并在此基础上进行了基于“微波热点”温度为基础的本征反应动力学研究，最终得到了热点温度范围及反应活化能等动力学参数值，为生物柴油外场协同化学法合成过程，提供坚实的科学理论基础。采用上述制备的催化剂，H3PW12O40•xH2O /C、H3PW12O40•xH2O /C(改性)、改性SO42-/ZrO2@C-SiC、H2SO4/C、SO42-/Fe2O3、Cs2.5H0.5PW12、Cs0.5H2.5PW12、K2.5H0.5PW12对不可食用植物油如：蓖麻油、棉籽油及餐饮废油为原料的生物柴油合成体系，在微波外场辅助下，进行一步法生物柴油合成的研究，并对H2SO4/C催化油脂、脂肪酸体系采用响应面法设计合成的工艺条件，得到最优工艺条件。