【作者】 薄采颖；

【导师】 毕良武；

【作者基本信息】 中国林业科学研究院 ， 林产化学加工工程， 2009， 硕士

【摘要】 生物柴油是一种环境友好的、可再生的新型替代能源,贮存稳定性较差是生物柴油的不足之处。添加各种抗氧化剂能提高生物柴油稳定性。本研究设计了一类新型稳定剂没食子酸萜醇酯,研究没食子酸萜醇酯的合成和结构鉴定,稳定性评价用生物柴油的制备,在与没食子酸烷基酯、合成抗氧化剂、天然抗氧化剂和复配稳定剂等对比研究的基础上,研究没食子酸萜醇酯对生物柴油室温稳定性和高温稳定性的影响,探讨没食子酸萜醇酯等稳定剂对生物柴油稳定化作用机理。本研究为探求稳定剂分子结构与性能关系及筛选生物柴油高效稳定剂提供前期基础。提出一种新的没食子酸萜醇酯合成路线,即:没食子酸先经乙酰化保护,分别与6种萜醇进行室温超声波辅助的DCC(N,N’-二环己基碳二亚胺)脱水酯化,再经水合肼脱乙酰化,生成对应的没食子酸萜醇酯。合成得到的6种没食子酸萜醇酯均经过结构鉴定。该方法反应温度低,反应时间短,收率较高。没食子酸金合欢酯、没食子酸香叶酯、没食子酸芳樟酯、没食子酸橙花叔醇酯、没食子酸薄荷酯和没食子酸氢化松香醇酯的总收率分别为86.2 %、85.3 %、76.3 %、87.5 %、79.2 %和82.5 %。为寻求合适的生物柴油稳定性研究的载体,开展了低功率密度超声波室温辅助酯交换制备生物柴油的研究,大豆油与甲醇的物质的量之比1:6(mol/mol)、氢氧化钾与大豆油的质量比0.01:1(g/g)、超声波功率密度0.032 W·cm-3、超声波反应时间20～60 min,反应温度30℃时,生物柴油收率为85.9 %～86.4 %(折光指数法),所得生物柴油的质量符合要求。以生物柴油的过氧化值、酸值和折光指数为评价指标,研究了没食子酸萜醇酯等稳定剂对生物柴油室温稳定性的影响。其稳定作用的大小次序为:没食子酸金合欢酯>没食子酸芳樟酯>没食子酸橙花叔醇酯>没食子酸薄荷酯>没食子酸香叶酯>没食子酸氢化松香醇酯。6个月时,没食子酸金合欢酯和没食子酸甲酯的抑制率分别为31.7 %和76.6 %,协同增效剂柠檬酸可使没食子酸金合欢酯的抑制率提高到74.1 %。以生物柴油的酸值为评价指标,研究了没食子酸萜醇酯等稳定剂对生物柴油高温稳定性的影响。6种没食子酸萜醇酯对生物柴油高温稳定性作用相差不大,其中没食子酸香叶酯和没食子酸金合欢酯的高温稳定化效果略好。推导了稳定性回归方程,探讨了没食子酸萜醇酯对生物柴油稳定化作用机理。更多还原

【Abstract】 Biodiesel was a new alternative energy which has the advantages of environmental friendliness and renewability. The stability of biodiesel could be improved by addition of different antioxidants. A series of new stabilizers, terpenyl gallates, were designed in this study. The synthesis and identification of terpenyl gallates, preparation of biodiesel used for stability evaluation were studied. The effects of terpenyl gallates on room temperature stability and high temperature stability were studied based on comparison with alkyl gallates, synthetic antioxidants, natural gallates and complex stabilizers. The stabilization mechanism of biodiesel acted by stabilizers of terpenyl gallates was discussed. This study could provide a primary foundation for searching relationship of molecular structure of stabilizers with their properties, and selecting highly effective stabilizers for biodiesel.A new synthetic route of terpenyl gallates was advanced. Gallic acid was acetylated at first, esterificated respectively with six terpenyl alcohols by DCC dehydration and ultrasound assistance at room temperature, and then deacetylated by hydrazine hydrate to form corresponding terpenyl gallates. The chemical structures of six terpenyl gallates obtained were all identified. The synthetic method had lower reaction temperature, shorter reaction time, and higher conversion. The total yield of farnesyl gallate, geranyl gallate, linalyl gallate, nerolidyl gallate, menthyl gallate, and hydroabietyl gallate was respectively 86.2 %, 85.3 %, 76.3 %, 87.5 %, 79.2 % and 82.5 %.In order to search a suitable research carrier for biodiesel stability, the preparation of biodiesel by transesterification and assistance of low-power-density ultrasound at room temperature was studied. The yield of biodiesel was 85.9 %-86.4 % at the condition of molar ratio of soybean oil to methanol 1: 6, mass ratio of potassium hydroxide to soybean oil 0.01:1, ultrasonic power density 0.032 W·cm-3, reaction time 20-60 min, and reaction temperature 30℃. The quality of obtained biodiesel reached the requirement of biodiesel standard.The effect of terpenyl gallates on room temperature stability was studied by evaluation of peroxide value, acid value, refractive index of biodiesel. The sequence of stabilization to biodiesel was: farnesyl gallate> linalyl gallate> nerolidyl gallate> menthyl gallate> geranyl gallate> hydroabietyl gallate. The inhibition rate of farnesyl gallate and methyl gallate at the sixth month was respectively 31.6 % and 76.6 %. Meanwhile, the inhibition rate of farnesyl gallate added citric acid as synergistic agent could rise to 74.1 %. The effect of terpenyl gallates on high temperature stability was studied by evaluation of acid value of biodiesel. There were slight differences between six terpenyl gallates on high temperature stability of biodiesel. Geranyl gallate and farnesyl gallate were slightly better. The regression equations of stability were deduced. The stabilization mechanism of biodiesel acted by terpenyl gallates was discussed at last.更多还原