【作者】 柳杨；

【导师】 童军茂；

【作者基本信息】 石河子大学 ， 农产品加工及贮藏工程， 2011， 硕士

【摘要】 随着世界经济的快速发展,人们对能源的需求和消耗日益增加。然而,石油资源的日益枯竭、油价的飞涨使得以石油裂解为源头的能源形式面临着严峻挑战。与此同时,石化能源的大量消耗,也对环境造成了极大的破坏,人类的生存空间受到了严重的威胁。因此,寻找可替代的资源和能源的产业势在必行。作为一种重要的可再生替代能源,生物柴油已在很多国家应用和推广。生物柴油制备方法主要采用酯交换反应,目前多使用的催化剂以均相酸或碱为主,但是均相催化反应易发生皂化反应且产物与催化剂难以分离。多相催化酯交换反应能在很大程度上弥补均相催化所存在的不足。因此,积极推进并发展新型多相催化剂(即固体催化剂)用于制备生物柴油成为科研工作者们研究的热点。介孔分子筛具有高度有序的孔道结构、高比表面积、孔径较大和可调性等其它多孔材料所不具备的优异性质,是催化剂的优良载体。以介孔材料为载体,利用其表面积大、结构稳定的特点可提高催化剂的性能。因此,本文以介孔分子筛SBA-15和MCM-41为载体,负载无机钾盐或者有机碱制备得到一批固体碱催化剂；以文冠果油为原料,用所得固体碱催化剂催化酯交换反应制备生物柴油,并以生物柴油的产率作为固体碱催化剂活性评价的指标。论文主要研究工作包括：(1)以SBA-15和MCM-41为载体,经A1或Mg镀饰后再进一步负载钾盐或者直接负载有机碱,获得碱性较强的负载型固体碱催化剂；(2)利用XRD、SEM、BET、CO2-TPD等表征手段对所得负载型固体碱催化剂进行表征；(3)利用单因素实验优化负载型固体碱催化剂的制备条件；(4)以文冠果油为原料,用制备的负载型固体碱催化剂催化酯交换反应制备生物柴油,以生物柴油的产率作为活性评价的指标；(5)采用柱层析对酯交换制备的粗生物柴油进行精制分离纯化与分析。主要结论如下：1)以介孔分子筛SBA-15及MCM-41为载体,分别采用直接合成法和后合成法镀饰A1或Mg,再将镀饰后的介孔分子筛浸渍于碱金属盐KN03溶液或有机碱氨丙基三乙氧基硅烷(APTS)中,经干燥、焙烧后得到负载型固体碱催化剂,通过活性评价得到催化活性最高的为KNO3-Al-SBA-15;2)通过XRD、SEM、BET及CO2-TPD等表征手段表明A1或Mg的加入能对SBA-15和MCM-41分子筛孔结构起到一定的耐碱侵蚀的作用。进一步负载KN03或APTS后,分子筛的碱性显著增加；3)以催化活性最高的KNO3-Al-SBA-15为例,讨论催化剂制备的单因素实验,最优的催化剂制备条件是：KNO3负载量为17%,煅烧温度为550℃,煅烧时间为6h；4)催化剂的活性通过酯交换反应制得生物柴油的产率进行评价,酯交换反应过程选择反应温度为70℃,醇油摩尔比为12：1,催化剂用量为原料油质量的5%,超声功率300W。在此条件下催化剂KNO3-Al-SBA-15的催化效果优于其他固体碱催化剂,催化酯交换反应所得生物柴油产率可达92%。催化剂重复使用5次,生物柴油产率仍能达到64.8%,说明制备的催化剂具有良好的重复利用性；5)柱层析精制生物柴油选取石油醚与甲醇的混合溶液为洗脱剂,采用梯度洗脱的方式。通过对精制得到的生物柴油进行气相色谱分析,计算得到生物柴油的纯度高达93.87%,柱层析产物的回收率为91.04%;通过红外光谱和核磁共振波谱分析技术对精制后的生物柴油进行了进一步纯度分析,光谱分析表明生物柴油经柱层析法精制后所含杂质明显减少。结果表明,柱层析法是一种很好的精制生物柴油的方法。更多还原

【Abstract】 With the rapid development of world economy, the demand and consumption of energy become increasingly pronounced. However, the exhausting petroleum resource and soaring oil prices make the energy form as petroleum cracking faced severe challenges. And the same time, the excessive consumption of fossil energy greatly destroys the natural environment and seriously threatens the human living space. So searching alternative resources and energy industry is imperative. As a renewable alternative energy sources, biodiesel had already applied and popularized in many countries. The preparation of biodiesel mainly uses transesterification. Present used catalysts are homogeneous acid or alkali, but saponification reaction easily happens and separation between products and catalysts are difficult in homogeneous catalysis. Heterogeneous catalysis can largely overcome the disadvantages in homogeneous catalysis. Therefore, research workers focus on the development in new heterogeneous catalysts (namely solid catalyst) for the preparation of biodiesel.Mesoporous molecular sieves is an excellent catalyst carrier, which possesses highly ordered mesoporous pore structure, high specific surface area, larger pore size and tenability compared with other porous materials. Mesoporous material as a carrier, using its large surface area and stabile structure can improve the catalytic performance. Therefore, this article used mesoporous SBA-15 and MCM-41 as the carriers, prepared solid base catalysts by loading inorganic potassium salts or organic base on them; then solid base catalysts catalyzed sorbifolia oil to produce biodiesel by transesterification, and biodiesel yield was an activity index of solid alkali catalyst.Research in the paper included:(1) The supported solid base catalysts were obtained, which were used the mesoporous molecular sieves SBA-15 and MCM-41 as carriers, and loaded Al and Mg,then coated potassium salt or organic base on it. (2) The solid base catalysts were characterized by XRD, SEM, BET and CO2-TPD; (3) The preparation conditions of supported solid base catalysts were optimized by single factor experiment; (4) Solid base catalysts catalyzed sorbifolia oil to produce biodiesel by transesterification, and biodiesel yield was an activity index of solid alkali catalyst;(5) The crude biodiesel produced by transesterification was purified and analysed by column chromatography.The main conclusions as following:1) The mesoporous molecular sieves SBA-15 and MCM-41 as carriers loaded Al or Mg by direct synthesis and post synthesis method. The mesoporous molecular sieves after loading were dipped in alkaline metal salt solution or organic base 3-aminopropyl triethoxysilane (APTS). The supported solid base catalysts were finally obtained by being dried and calcined. Among the catalysts, KNO3-Al-SBA-15 had the highest catalytic activity after the activity evaluation;2) Characterization of XRD, SEM, BET, CO2-TPD and other means showed that the addition of Al or Mg played a role in alkaline erosion to protect the pore structure of SBA-15 and MCM-41 zeolite. Loading APTS and KNO3 in molecular sieves can significantly increase the alkaline of them;3) Taking the KNO3-Al-SBA-15 possessing the highest activity as example, we will discuss the single factor experiments of catalyst preparation. The optimum preparation conditions were KNO3 loading about 17%, calcination temperature about 550℃, calcination time about 6h;4) The activity of the catalysts was evaluated by yield of biodiesel prepared by transesterification. Transesterification conditions were reaction temperature about 70℃, molar ratio of methanol to oil about 12:1, catalyst amount about 5%, ultrasound power about 300W. Under these conditions, the catalyst activity of KNO3-Al-SBA-15 is better than other solid base catalysts. The yield of biodiesel by transesterification can reach about 92%. Although the catalyst was reused five times, the yield of biodiesel was still able to reach 64.8%, which indicated that the prepared catalyst possessed good reusability;5) The eluent of column chromatography was the mixture of petroleum ether and methanol, adopting the way of gradient elution. The refined biodiesel was analyzed by gas chromatographic. The results showed the purity of biodiesel was up to 93.87% and the recovery of column chromatography products was about 91.04%. The refined biodiesel were further analyzed by IR and NMR spectroscopy. IR results indicated that impurities of biodiesel refined by column chromatography significantly reduced. The results showed that column chromatography was a good method to refine the biodiesel.更多还原