介孔碳基固体酸催化高酸值油脂气相酯化降酸研究

The non-edible oils such as food waste oil and Jatropha curcas oil are considered as raw materials to produce biodiesel, which can reduce production cost and has widely application. However, high contain of free fatty acid in these raw materials would lead to occurrence of saponification reaction in the system with alkali catalysis, which is harmful for producing biodiesel with alkali-catalyzied transesterification, so it is need to reduce acid value through the esterification reaction. Because of being limited easily by chemical balance, the traditional homogeneous esterification catalyzied by acid has features with long reaction time, low conversion rate, the acid value of oil can not reach requirement for later transesterification reaction, at the same time the acidic waste liquids is produced in system. Breaking reaction balance and promoting reaction toward main direction are the keys of realizing the rapid esterification reducing high-acid of oils with high acid value. The gas-phase esterification reducing high-acid reaction system catalyzied by mesoporous carbon-based solid super acid will be taken as research object in the study. The thermodynamic and kinetic properties of multiphase reaction process in the system will be studied. The mechanism of transmitting process of multiphase reaction under the condition of many variables coupling will be explored, the effect mechanism of component properties on reaction transmitting process will be studied, which supply science basis for adjusting and optimizing materials movement in reactor. The basic theory of reducing high-acid of oils and fats with high acid value by gas-phase esterification catalyzed by mesoporous carbon-based solid super acid will be established, which supplies science basis for the technology of biodiesel fuel production with features of high efficiency, short procedure and less contamination, and also promotes development of biodiesel fuel industry.

以餐饮废油脂、小桐子油等非食用油为原料制备生物柴油，可降低生产成本，应用潜力大。但这些原料中游离脂肪酸含量高，易导致碱催化体系发生皂化反应，对碱催化酯交换法制备生物柴油十分不利，需进行酯化反应降酸处理。传统均相酸催化酯化法受化学平衡限制，反应时间长、转化率低，油脂的酸值达不到后续酯交换反应要求，同时产生酸性废液。打破化学平衡，促进反应向正方向进行是实现高酸值油脂快速酯化降酸的关键。项目拟以介孔碳基固体超强酸为催化剂的气相酯化降酸反应体系为研究对象，研究该体系内多相反应过程的热力学和动力学特性；探索多变量耦合状况下的多相反应传递过程机理，探明组分特性对反应传递过程的作用机制，为调控和优化反应器内的物料运动提供科学依据，建立介孔碳基固体超强酸催化高酸值油脂精馏分水气相酯化快速降酸反应体系的基础理论，为效率高、流程短、污染小的生物柴油高效清洁制备技术提供理论依据，支撑生物柴油产业的发展。

生物柴油产业发展是生物质能资源开发利用的重要组成部分，对云南省生物质能产业的发展具有重要意义。取得主要成果如下：. 1）发酵残留物合成多孔碳基固体酸的催化活性比葡萄糖、淀粉和蔗糖的高，固体酸孔道以微孔为主，比表面积为176m2/g，孔径0.987nm，集中在微孔，不含介孔，孔容为0.29cm3/g。酯化降酸的最佳条件如下：醇油比为8:1、催化剂用量为4%、反应温度80℃、反应时间2h，转化率可达76.32%。. 2）以淀粉为碳源、水热碳化温度180℃、水热碳化时间24h所获得的碳微球多孔碳基固体酸催化剂具有高的表面酸密度，对高酸值混合脂肪酸的酯化降酸反应表现出较好催化效果。在气相酯化降酸中的最优条件为：催化剂用量4wt%、反应时间90 min、反应温度110 ℃，最佳转化率为98.65%，具有较好的稳定性和重复使用性。. 3）研究表明，EISA为最理想的合成方法，酚醛树脂预聚体为最理想的有机前驱体。混合模板剂F127/P123配比对制备的有序介孔碳基固体酸有着显著影响。以PF为前驱体制备的催化剂性能最好，而混合模板剂F127/P123制备的催化剂，酯化降酸效果优于单一模板剂的情况，转化率达到95.1%。. 4）汽液相平衡研究结果表明，随着添加在甲醇-水溶液体系中的小桐子油酸值的增加，体系的沸点呈上升趋势，液相中甲醇的摩尔分数也随之增大，而汽相中甲醇的摩尔分数却中降低。Wilson方程关联不同酸值小桐子油存在下的甲醇-水的温度平均偏差为0.12%、汽相组成的平均偏差为0.16%。. 5）在75℃条件下制备的催化剂介孔有序性最佳，预聚时间增加催化剂有序性越好，升温速率的增加催化剂有序性变差，模版配比为2：1时催化剂有序性最好。比表面积为678m2/g的催化剂进行气相酯化降酸反应，得到最佳反应条件为：催化剂用量3wt%、反应温度110℃、反应时间120min，此时转化率达到95.48%。介孔炭基固体酸的催化活性明显高于多孔固体酸，催化剂孔道有序性对酯化降酸反应的速率以及转化率均存在一定的影响，孔径大小对催化剂酯化降酸转化率的影响不是很大或基本上不影响。