高酸值油脂制备生物柴油反应的催化剂研究
发布时间：2018-09-19 20:04
【摘要】：随着世界工业化和现代化进程的加快,对石油资源的需求量越来越大,然而大量使用石化燃料将会带来能源危机和环境问题,因此寻找新型的可替代能源越来越受到关注。生物柴油由于具有可再生、绿色环保、可降解等优点,被认为是石化燃料最好的替代品。以高酸值油脂代替纯植物食用油可以降低生产成本,提高生物柴油的竞争力。目前使用高酸值油脂制备生物柴油的过程可分为两步:预酯化和酯交换。催化剂多以均相酸碱为主,而均相酸碱催化剂带来产物不易分离、催化剂回收困难、水洗产生大量废水、不能连续化生产等问题,针对这些问题,本文对两种不同的固体催化剂(介孔碳基固体酸和硅酸锂固体碱)及其在高酸值油脂制备生物柴油中的应用进行系统研究。(1)以蔗糖为碳源、SiO_2为模板剂,采用碳化-磺化法制备介孔碳基固体酸催化剂,采用酸碱滴定、BET、XRD、FT-IR、SEM等方法对其进行表征,考察碳化温度、磺化温度、模板剂用量对催化剂表面-SO3H数量、比表面积和孔径的影响,并将其用于大豆油与甲醇的酯交换反应,结果表明:制备催化剂的适宜条件为碳化温度400℃、磺化温度170℃、m二氧化硅:m蔗糖=1:2;大豆油与甲醇酯交换反应的最佳条件为醇油摩尔比30:1、反应时间4h、催化剂用量8%,生物柴油收率最高达95.94%。在此反应条件下,考察催化剂的耐酸性,当油脂中脂肪酸含量高达15%时,酯交换转化率可达到90.87%,脂肪酸转化率达到99%,为高酸值油脂一步法制备生物柴油奠定了基础。(2)在低温、常压下,考察介孔碳基固体酸催化剂催化油酸的酯化反应,在油醇摩尔比1:15、反应温度70℃、反应时间3h、催化剂用量8%的条件下,酯化转化率达到最大97.47%,催化剂重复使用5次,转化率依然达到96%以上;并对介孔碳基固体酸催化酯化反应动力学进行初步研究,反应级数1.38,表观活化能为58.7kJ/mol。(3)以二氧化硅和氢氧化锂为原料,通过沉淀法制备硅酸锂固体碱催化剂,采用SEM、XRD等手段对催化剂进行表征,将制备的催化剂用于催化大豆油与甲醇的酯交换反应,通过单因素优化法考察最佳反应条件:醇油摩尔比12:1、催化剂用量6%、反应温度65℃、反应时间2h,生物柴油转化率达到99.64%,催化效果与液体碱相当,可以用于高酸值油脂制备生物柴油的第二步催化反应,也可用于一般油脂一步酯交换法制备生物柴油。催化剂重复使用5次后,转化率达到96.36%,表现出非常好的稳定。
[Abstract]:With the acceleration of industrialization and modernization in the world, the demand for petroleum resources is increasing. However, the extensive use of fossil fuels will bring about energy crisis and environmental problems. Therefore, more and more attention has been paid to the search for new alternative energy sources. Biodiesel is considered to be the best substitute for fossil fuels because of its renewable, green and biodegradable properties. Replacing pure vegetable cooking oil with high acid oil can reduce the production cost and improve the competitiveness of biodiesel. The process of preparing biodiesel from high acid oil can be divided into two steps: preesterification and transesterification. Most of the catalysts are homogenous acid-base, but homogeneous acid-base catalysts bring about the product is difficult to separate, the recovery of catalyst is difficult, the washing produces a large amount of waste water, and can not be continuously produced, and so on. In order to solve these problems, In this paper, two kinds of solid catalysts (mesoporous carbon-based solid acid and lithium silicate solid base) and their applications in the preparation of biodiesel with high acid value oil were systematically studied. (1) Sucrose was used as carbon source and SiO-2 as template. The mesoporous carbon-based solid acid catalyst was prepared by carbonation and sulfonation method. It was characterized by acid-base titration method. The effects of carbonation temperature, sulfonation temperature and the amount of template on the amount of -SO3H on the surface, specific surface area and pore size of the catalyst were investigated. It was used in the transesterification of soybean oil and methanol. The results showed that the suitable conditions for the preparation of the catalyst were carbonization temperature 400 鈩，
本文编号：2251189
[Abstract]:With the acceleration of industrialization and modernization in the world, the demand for petroleum resources is increasing. However, the extensive use of fossil fuels will bring about energy crisis and environmental problems. Therefore, more and more attention has been paid to the search for new alternative energy sources. Biodiesel is considered to be the best substitute for fossil fuels because of its renewable, green and biodegradable properties. Replacing pure vegetable cooking oil with high acid oil can reduce the production cost and improve the competitiveness of biodiesel. The process of preparing biodiesel from high acid oil can be divided into two steps: preesterification and transesterification. Most of the catalysts are homogenous acid-base, but homogeneous acid-base catalysts bring about the product is difficult to separate, the recovery of catalyst is difficult, the washing produces a large amount of waste water, and can not be continuously produced, and so on. In order to solve these problems, In this paper, two kinds of solid catalysts (mesoporous carbon-based solid acid and lithium silicate solid base) and their applications in the preparation of biodiesel with high acid value oil were systematically studied. (1) Sucrose was used as carbon source and SiO-2 as template. The mesoporous carbon-based solid acid catalyst was prepared by carbonation and sulfonation method. It was characterized by acid-base titration method. The effects of carbonation temperature, sulfonation temperature and the amount of template on the amount of -SO3H on the surface, specific surface area and pore size of the catalyst were investigated. It was used in the transesterification of soybean oil and methanol. The results showed that the suitable conditions for the preparation of the catalyst were carbonization temperature 400 鈩，
本文编号：2251189
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