钙锆固体碱催化大豆油制备生物柴油

发布时间：2018-07-09 09:44

  本文选题：生物柴油 + 酯交换反应　； 参考：《上海应用技术学院》2015年硕士论文

【摘要】：生物柴油(即脂肪酸甲酯)以其良好的再生性和环保性正逐渐成为化石燃料的替代品。生物柴油通常是通过植物油或动物油脂与甲醇的酯交换反应而制得。催化剂的性能是酯交换反应的关键,目前主要集中于多相催化剂尤其是固体碱催化剂的研究。本论文对生物柴油产物的分析方法进行了比较研究；采用燃烧法制备了钙锆复合氧化物固体碱,研究了钙锆摩尔比对固体碱物化性能和催化酯交换反应性能的影响,并对其碱性与催化活性之间的关系进行了初步探讨；考察了稀土金属La对钙锆固体碱的促进作用。得到以下主要结论：1、甘油滴定法测定生物柴油产率步骤繁琐,且由于测定原理上存在一定局限导致重复性和准确性不够理想。色谱法需要大量的标准样品,测试时间较长。核磁共振法(NMR)相对简单方便且准确性和重复性好。2、随着钙锆摩尔比的增加,催化剂的BET比表面减小,表面的总碱性位则先增加后减小,在钙锆摩尔比为8：2时,总的碱性位数量达最大值。随着钙锆摩尔比的增加,碱位强度逐渐增强,并导致TOF值的增大。最佳组成的催化剂在催化剂用量为1.25 wt%,醇油比为25：1,反应温度为65℃的条件下,反应时间为2h和3 h,生物柴油的转化率分别达到93.9%和98.0%。3、尿素硝酸盐燃烧法是一种快速有效的制备CaO-ZrO2固体碱催化剂的方法。最佳制备条件为：燃料用量为化学计量比的150%,起燃温度为500℃,燃烧产物不需要进一步焙烧。4、La的添加显著增加了CaO-ZrO2催化剂的BET比表面,增大了孔容孔径。90%转化率的时间由2 h缩短至0.5 h。催化活性提高与催化剂的孔径和比表面变大有关。5、La的添加提高了CaO-ZrO2固体碱的抗水性和使用寿命。当大豆油中含有8.0 wt%的水时,反应1h转化率达90%以上,相同条件下的CaO-ZrO2转化率仅15%。当La的添加量为5%时,催化效率为95%,催化剂的循环使用次数从3次提高到了6次。
[Abstract]:Biodiesel (fatty acid methyl ester) is becoming a substitute for fossil fuels for its good reproducibility and environmental protection. Biodiesel is usually produced by transesterification of vegetable oil or animal oil with methanol. The performance of catalyst is the key of transesterification, and it is mainly focused on heterogeneous catalyst, especially solid base catalyst. In this paper, the analytical methods of biodiesel products were compared, the solid base of calcium zirconium composite oxide was prepared by combustion method, and the effects of molar ratio of calcium to zirconium on the physicochemical properties and catalytic transesterification of solid bases were studied. The relationship between the alkalinity and the catalytic activity was discussed, and the promoting effect of rare earth metal La on the calcium zirconium solid base was investigated. The main conclusions are as follows: 1. The steps of measuring biodiesel yield by glycerin titration are tedious, and the repeatability and accuracy are not satisfactory due to the limitation of the determination principle. Chromatography requires a large number of standard samples, the test time is longer. Nuclear magnetic resonance (NMR) method is relatively simple and convenient, and has good accuracy and repeatability. With the increase of the molar ratio of calcium to zirconium, the BET specific surface of the catalyst decreases, while the total basic potential of the surface increases first and then decreases, at 8:2 the molar ratio of calcium to zirconium increases. The total number of basic sites reached the maximum. With the increase of the molar ratio of calcium to zirconium, the base potential strength increases and the TOF value increases. The optimum composition of the catalyst is 1.25 wt, the ratio of alcohol to oil is 25: 1, the reaction temperature is 65 鈩，

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