胆碱类低共熔溶剂催化酯化反应及生物柴油的合成

发布时间：2018-04-01 00:08

  本文选题：低共熔溶剂　切入点：酯化　出处：《辽宁科技大学》2015年硕士论文

【摘要】：随着社会经济的快速发展,能源短缺与环境污染问题日益严重,生物柴油是一种可替代化石燃料的生物燃料,引起了广泛的关注。使用高酸值油脂作为生物柴油二步法(先预酯化反应降酸,再转酯化反应)的生产原料,在成本控制和环境污染控制方面具有明显优势。传统预酯化反应采用浓硫酸作催化剂,存在腐蚀设备、催化剂不能重复使用,需水洗除酸且废液不易处理等问题。固体催化剂可以避免液体酸分离困难和有毒废弃物的产生,但固体酸的高成本和高反应条件,制约了其发展。基于以上原因,国内外均已开始研究应用低共熔溶剂作为催化剂降低生物柴油生产成本,减少环境污染。本文通过自制氯化胆碱/甲基磺酸的新型低共熔溶剂(DES),催化高酸值原料油和地沟油中游离脂肪酸的甲酯化反应。探讨了氯化胆碱/甲基磺酸不同摩尔比对酯化率的影响,以及物理性质的变化;并对自制DES的催化能力、催化活性和稳定性进行了探讨;利用了响应面法得到此DES在酯化反应中的最优条件,并在最优条件下,将不同酸值的地沟油、原料油合成生物柴油,并进行气相色谱分析,得出生物柴油中甲酯的组成,为DES从制备到生物柴油合成的工业化生产提供可行性的参考。本研究得到了如下结论:(1)在氯化胆碱/甲基磺酸摩尔比为1:2时合成的DES催化能力最强,同时不同摩尔比对DES的密度、PH值、导电性都有很大的影响。随着摩尔比的增大,这三个物理参数均增大。(2)为了探讨自制DES的活性及催化能力时,用DES催化不同酸值的原料油,并与工业上常用的催化剂和固体催化剂进行了比较,并对DES进行回收重利用,最终发现DES是这些催化剂中催化能力最强的,并且对于高低酸值都有很好的催化效果,当DES重复使用6次后,酯化率变化非常小,这打破了液体酸不能重复利用的缺点。(3)响应面法得到在氯化胆碱/甲基磺酸的摩尔比为1:2时,DES催化酯化反应的最优条件:反应温度:70℃、反应时间为75min,催化剂用量为3%,醇酸比为18%,此时酯化率为99%,酸值降低到1 mg KOH/g一下,完全满足工业上的需要。在最优条件下,地沟油可以达到生产生物柴油的标准,并且在实验中得到了较好的效果,符合工业上的生产要求,降低了工业成本。
[Abstract]:With the rapid development of social economy, the problem of energy shortage and environmental pollution is becoming more and more serious. Biodiesel is a kind of biofuel that can replace fossil fuel. High acid value oil is used as the raw material for the production of biodiesel in two steps (reducing acid first by preesterification, then transesterification). It has obvious advantages in cost control and environmental pollution control. Traditional pre-esterification reaction uses concentrated sulfuric acid as catalyst, and corrosion equipment exists, the catalyst can not be reused. The solid catalyst can avoid the difficult separation of liquid acid and the generation of toxic waste, but the high cost and high reaction conditions of solid acid restrict its development. The application of low eutectic solvent as catalyst to reduce the production cost of biodiesel has been studied both at home and abroad. In this paper, a new low eutectic solvent of choline chloride / methanesulfonic acid was developed to catalyze the methyl esterification of free fatty acids in high acid value feedstock oil and gutter oil. The difference between choline chloride and methyl sulfonic acid was discussed. The effect of molar ratio on esterification, The catalytic ability, catalytic activity and stability of self-made DES were discussed. The optimum conditions of DES in esterification reaction were obtained by using the response surface method, and the gutter oil with different acid values was obtained under the optimal conditions. Biodiesel was synthesized from raw oil and analyzed by gas chromatography. The composition of methyl ester in biodiesel was obtained. In this study, we obtained the following conclusion: 1) the catalytic activity of DES was strongest at 1:2 when the molar ratio of choline chloride to methyl sulfonic acid was 1:2, which provided a feasible reference for the industrial production of DES from preparation to biosynthesis of biodiesel. At the same time, the density and PH value and electrical conductivity of DES were greatly influenced by different molar ratios. With the increase of molar ratio, these three physical parameters all increased. (2) in order to study the activity and catalytic ability of DES, DES was used to catalyze feedstock with different acid values. Compared with industrial catalysts and solid catalysts, the DES was recycled and reused. Finally, it was found that DES was the most effective catalyst and had good catalytic effect for high or low acid value. When DES was reused for 6 times, the esterification rate changed very little. This breaks down the disadvantage that liquid acid can't be reused.) response surface method is used to get the optimum condition for esterification of acetylcholine chloride / methyl sulfonic acid at 1:2: reaction temperature: 70 鈩，

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