生物基脂肪酸水相原位酯化制备生物柴油方法研究

发布时间：2018-02-04 03:16

  本文关键词： 生物柴油 脂肪酸 发酵液 水相反应 催化剂 疏水功能化　出处：《青岛科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：脂肪酸酯是重要的化工产品,迫于化石资源短缺及环境压力,以生物基脂肪酸为原料制备脂肪酸酯衍生物已成为国际上的研究热点。然而,基于生物转化手段的脂肪酸产物浓度仅为5 g/L,远低于化学手段的百克每升级别,产物分离、提纯困难、高衍生成本一直是制约生物基脂肪酸酯产业化的重要因素。本文通过沉淀法,水热法和溶胶-凝胶法分别合成了表面活性剂-金属离子(S-M)络合材料,磷钨酸改性的多孔配位聚合物材料(PCP(Cr)-PTA)和负载磷钨酸MCM-41分子筛并进行疏水功能化处理的改性材料(OTS-PTA-MCM-41),将三种材料运用到在水相中催化合成生物柴油的反应中,通过材料疏水功能化实现催化剂对底物分子及溶剂水分子的选择性通过,探讨催化剂用量、反应温度、反应时间和不同醇水比例等反应条件对棕榈酸酯化率的影响,得到了以下实验结果。DBS-Sn(IV)在醇相催化棕榈酸制备生物柴油的最佳反应条件为:棕榈酸甲醇摩尔比为1:25,催化剂加入量50 mg,反应温度70℃,反应时间3 h。此时的棕榈酸甲酯的产率高达97.4%。催化剂在重复五个反应周期,棕榈酸产率基本没有下降。DBS-Sn(IV)催化发酵液脂中肪酸酯化实验,反应温度为110℃,反应时间3 h,催化剂加入量为100 mg,此时棕榈酸甲酯产率为87.4%。同样的条件,催化发酵液中的棕榈酸酯化产率也达到89.1%。PCP(Cr)-PTA在水相催化棕榈酸植被生物柴油的最佳反应条件为:醇水比1:9,反应温度130℃,反应时间3小时,催化剂的加入量为反应物的5%,棕榈酸甲酯的产率达到84.7%,催化剂在重复五个反应周期,棕榈酸产率基本没有下降。将PCP(Cr)-PTA运用到催化发酵液脂中肪酸酯化反应中,使用上述反应条件,棕榈酸甲酯的产率为80.0%。七种不同孔径的OTS-PTA-MCM-41催化剂实现了对底物分子及溶剂水分子遵守N-2规律的选择性通过,OTS-PTA-MCM-41(C14)催化发酵液脂中肪酸酯化,在150℃,反应3小时,月桂酸甲酯、肉豆蔻酸甲酯、棕榈酸甲酯的产率分别为91.1%、87.9%和90.7%。此外,通过催化剂表征并关联反应效率、效果,明确最佳杂多酸活性中心三级结构、负载率、疏水性等关键参数,建立构效关系,指导催化剂优化调变;并在阻断发酵液内主要杂质干扰机制的前提下,最终实现发酵液内脂肪酸的原位酯化。
[Abstract]:Fatty acid ester is an important chemical product. Due to the shortage of fossil resources and environmental pressure, the preparation of fatty acid ester derivatives from biological fatty acids has become a hot spot in the world. The concentration of fatty acid products based on bioconversion is only 5 g / L, which is far lower than that of 100 grams per liter by chemical means, so it is difficult to separate and purify the products. High derivatization cost has been an important factor to restrict the industrialization of bio-base fatty acid esters. In this paper, surfactant metal ion S-M complex materials were synthesized by precipitation method, hydrothermal method and sol-gel method, respectively. The porous coordination polymer modified by phosphotungstic acid (MCM-41) and the modified material supported on phosphotungstic acid MCM-41 molecular sieve and treated with hydrophobic functionalization (. OTS-PTA-MCM-41). Three kinds of materials were used to catalyze the synthesis of biodiesel in water phase. The selective passage of catalyst to substrate and solvent water was realized by hydrophobic functionalization. The amount of catalyst and reaction temperature were discussed. The effects of reaction time and ratio of alcohol to water on the esterification rate of palmitic acid were studied. The following results were obtained: 1: 25 molar ratio of palmitic acid to methanol and 50 mg catalyst was used to prepare biodiesel from palmitic acid catalyzed by alcohol in the presence of DBS-SnCIV. the optimum reaction conditions were as follows: 1: 25 molar ratio of palmitic acid to methanol and 50 mg of catalyst. The reaction temperature was 70 鈩，

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