高酸值地沟油制备生物柴油工艺研究

发布时间：2019-06-07 15:33

【摘要】：生物柴油作为一种可再生的环保燃料,可用以替代传统的化石燃料,在能源、资源日益枯竭的今天,其对社会的可持续发展具有重要意义。传统的生物柴油制备过程中,原料油的高酸值问题一直是亟待解决的问题之一。原料油的酸值高,生物柴油制备过程就会变得复杂,且对产品生物柴油的品质有较大影响。本文以酸值较高的地沟油为原料,研究了从原料脱酸,到酯交换反应,再到粗产品精制的整个生产工艺,并对副产物甘油的精制工艺进行了探讨。主要研究内容如下:(1)本文采用“萃取-碱炼联合法”对地沟油进行脱酸处理。得到萃取脱酸的最佳工艺条件:以95%乙醇为萃取剂,萃取液液比1:2.0(w/w),萃取次数2次,萃取时间每次10min,萃取温度30℃,在此条件下可将原料地沟油的酸值由40.35mg KOH/g降至2.36mg KOH/g;再用碱炼法将地沟油的酸值降低至0.28mg KOH/g。(2)以KOH为催化剂催化酯交换过程的进行。得到酯交换过程的最佳条件:反应操作时间60min,反应操作温度60℃,甲醇用量18%(w/w),催化剂用量0.7%(w/w)。在该条件下,油脂的转化率可达97.53%,粗生物柴油层产率达98.36%。(3)分别探讨了“酸洗-水洗法”和“盐析-酸洗-水洗法”对生物柴油除杂过程的影响,并对两种方法的处理结果进行了比较。得到最佳的“酸洗-水洗法”工艺条件:1次酸洗2次水洗,用水20%,用酸0.1%,温度60℃。在所得条件下,除杂后的产品的酸值为0.36mg KOH/g,总甘油含量为0.34%,油品回收率为98.54%。后在“酸洗-水洗法”的基础上,增加一步盐析过程,得到最佳的盐析条件为:NaCl溶液浓度10%,NaCl溶液用量15%(w/w),盐析温度60℃。在“盐析-酸洗-水洗法”的最佳操作条件下,生物柴油的酸值降至0.24mg KOH/g,总甘油含量降至0.25%,油品回收率为98.12%。(4)分别用活性炭和过氧化氢对生物柴油进行两次脱色。得到最佳的活性炭脱色工艺条件为:脱色操作温度60℃,脱色操作时间2h,活性炭用量3%(w/w)。在该最佳条件下,油品的脱色率可达70.65%,油品的回收率达98.84%。得到过氧化氢二次脱色最佳工艺条件为:H_2O_2用量15%(w/w),脱色操作温度60℃,脱色操作时间5h,H_2O_2浓度15%,在该最佳工艺条件下,油品的脱色率为15.89%,油品的回收率为99.12%。经两次脱色处理后,油品的总脱色率可达到76.28%,油品的回收率为97.97%,同时,生物柴油中的总甘油含量可降至0.12%,游离甘油含量为0.012%。(5)对副产物甘油的精制工艺进行了研究。得到最佳粗甘油除杂工艺参数为:操作温度50℃,甲醇用量50%(w/w),操作时间40min,溶液pH值在4左右,在所得最佳工艺条件下,甘油的含量由61.08%提升至88.04%,甘油的回收率为87.34%。甘油脱色的最佳工艺条件为:脱色温度60℃,脱色时间2h,活性炭用量3%(w/w)。,甲醇用量50%(w/w)。在所得最佳脱色工艺下,甘油含量进一步提升至95.41%,最终回收率达85.47%。
[Abstract]:Biodiesel, as a renewable environmental protection fuel, can be used to replace traditional fossil fuels. Nowadays, energy and resources are increasingly exhausted, which is of great significance to the sustainable development of society. In the traditional preparation process of biodiesel, the problem of high acid value of feedstock oil has always been one of the problems to be solved urgently. When the acid value of raw oil is high, the preparation process of biodiesel will become complex, and it will have a great influence on the quality of biodiesel. Using furrow oil with high acid value as raw material, the whole production process from deacification of raw material to transesterification reaction to refining of crude product was studied, and the refining process of by-product glycerol was discussed. The main research contents are as follows: (1) in this paper, the extraction-alkali refining method was used to deacify the furrow oil. The optimum extraction conditions were as follows: 95% ethanol as extractant, extraction liquid-liquid ratio 1 鈮，

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