【作者】 雷占兰；

【导师】 高荫榆；

【作者基本信息】 南昌大学 ， 食品科学， 2007， 硕士

【摘要】 生物柴油是环保、可再生的“绿色”燃料，是优质的石化柴油替代品，但目前由于油源缺乏与成本高，未能得到大范围地推广应用。我国特有木本油料资源乌桕树，其果实种皮—乌桕脂（Chinese Vegetable Tallow，CVT）也叫皮油，占桕籽中26-27％，其脂肪酸组成相对集中，棕榈酸含量达65％左右，高于世界“油王”之称的棕榈酸，另外油酸占32％左右。乌桕具有出油率高，经济寿命长的特点，乌桕脂不仅可作食用油，还是重要的工业油，可提供稳定的油源。但由于棕榈酸含量高，会导致其脂肪酸甲酯（FAME）产物的低温流动性能差，因此限制了乌桕脂在生物柴油方面的应用。本研究以高酸价的乌桕脂为原料，采用溶剂结晶分提技术，将乌桕脂生物柴油中高熔点的棕榈酸甲酯（MP）副产物分提并纯化，该产品除了用作化工中间体外，还将其与Vc合成安全高效营养型抗氧化剂—L-抗坏血酸棕榈酸酯（AP），并对其做了进一步应用研究。原料理化特性和品质是采取技术路线的依据，乌桕脂各项理化指标为：碘价25.4 I₂／100g，过氧化值28.9 meq／kg，比重0.91g／cm³ d₅₀⁵⁰，熔点35.6-39.5℃，皂化值199.4 mgKOH／g，离心处理后，磷脂含量为168.4mg／kg，酸价达20.8mgKOH／g，说明采用先酸法预酯化后碱法酯交换的方法才能使游离脂肪酸得到最大的利用。经GC检测，乌桕脂中脂肪酸按含量依次为：棕榈酸、油酸、月桂酸、硬脂酸和亚油酸，其中棕榈酸高达66.80％，是油酸的2.4倍，其他组分总共不到5.5％，表明乌桕脂是棕榈酸、油酸及其甲酯的优良供体，乌桕脂脂肪酸甲酯中棕榈酸甲酯经分提，可用作棕榈酸制品的原料或进行更深层的开发利用，剩余部分可作燃料生物柴油或精制成更高附加值的油酸甲酯出售。离心处理的乌桕脂最佳脱胶条件为：柠檬酸加入量1.5g／kg，反应温度90℃，加水量60g／kg，搅拌时间50min，残磷量35.48mg／kg；磷脂含量仍比较高，可望在后面的甲酯化反应中进一步改善。酸法酯化最佳条件为：反应时间8h，醇油摩尔比35：1，反应温度75℃，催化剂用量为3％，由此最佳工艺，乌桕脂酸价降至0.37mg／g，酯化率为98.2％，产率99.6％；进一步碱法催化最优工艺为：反应时间35min，催化剂用量0.8％，醇油摩尔比6：1，反应温度65℃，酯化率93.1％。产品熔程23.2-24.7℃，酸价0.12mgKOH／g，磷脂含量5.76mg／kg，符合德国生物柴油标准规定中小于10mg／kg的要求；乌桕脂FAME主要组成为：棕榈酸甲酯69.02％，油酸甲酯27.66％，月桂酸甲酯1.94％和硬脂酸甲酯1.78％，可见其组成和含量相对集中，棕榈酸甲酯和油酸甲酯含量丰富，是制备棕榈酸甲酯和生物柴油的优良供体。对FAME中MP进行溶剂结晶分提，初步实验和溶解度参数计算结果表明乙醇是MP分离的良好溶剂，由于甲醇具有很强的氢键，也对MP有良好的结晶推动力；溶剂分提结果表明，相比较甲醇，乙醇分提能得到纯度更高，品质更好的产物。在物液比1：2和10℃的结晶终温下，经乙醇分离得到纯度91.2％的MP，又经2次分提后，纯度为96.9％，收率为50.8％，乙醇还兼具脱色和脱臭的作用，产品满足一般化工生产要求，说明乙醇是乌桕脂FAME分提MP的良好溶剂。以98％H₂SO₄作催化剂，抗坏血酸过量的方法将Vc与MP合成AP，25℃时，n（Vc）：n（MP）为1：0.8，反应17h，n（Vc+MP）：n（H₂SO₄）为0.14：1，收率69.4％，色泽洁白。在此条件下，AP收率高，Vc过量较少，相对损失少，纯度达到96.7％，熔点范围112.6-119.5℃，干燥失重0.11％，灼烧残渣0.053％，产品符合GB16314-1996食品添加剂使用卫生标准要求，说明生物柴油副产物—棕榈酸甲酯合成AP的工艺路线可行。相比棕榈酸甲酯过量法，Vc过量可简化操作步骤，避免使用过多有机溶剂，降低了成本及溶剂回收带来的能耗，减少其带来的身体伤害和安全隐患。AP的HLB值在8.4左右，可作油-水乳化剂。将合成的AP用于大豆油和菜籽油，结果表明，AP在大豆油中抗氧化性最好，菜籽油中与TBHQ作用基本接近，表现出良好的抗氧化效果，是安全、高效，具有推广价值的抗氧化剂；AP与V_E复配使用对提高V_E抗氧化效果，延长氧化诱导期出现有明显的作用，由于AP售价低于V_E，还可有效降低使用成本。由此，本研究由乌桕脂脂肪酸甲酯中提取的生物柴油副产物—棕榈酸甲酯为原料，制备AP路线是可行的，一方面，可合理利用副产物，生产出具有更高利润，发展前景广阔的Vc衍生物产品，提高产品附加值以降低生物柴油成本，另一方面，使乌桕脂用于生物柴油生产变得可行，同时为其他因为富含不饱和酸或饱和酸，分别影响了制得生物柴油十六烷值和低温特性的油料提供发展思路。更多还原

【Abstract】 Biodiesel can be used as perfect substituting for petroleum diesel, which is aenvironmental protection and renewable green energy, but lacking of oil source andcostly production effect its abroad using. Chinese Vegetable Tallow （CVT, i.e.Chinese tallow tegument oil）, produced by the seed-coat of Chinese Tallow Tree（CTT）, which is special woody oil plant, is one of top four wood with high oilcontent in seed, including 26-27% CVT in CTT seed. CVT has a simple fatty acidcomposition with about 65% palmitic acid, 32% oleic acid. CVT can be used as asource of edible oil and industrial oil. Moreover, CTT can extract high yield of oilthat is more than palm tree and having long economic life, can provide stable oilsource. But because including excessive palmitic acid, its ester production alsoinclude excessive methyl palmitate that had disadvantaged influence in lowtemperature fluidity of fatty acid methyl ester, confining the appliance of CVT inbiodiesel.Based on raw CVT materials behaving high acid value, the research studied themethod two step esterify and using solvent crystallizing fractionation technology,fractionated and purified the MP the outgrowth of biodiesel, continue to synthesizethe MP and Vc to be Ascorbyl Palmitate （AP）, at last, adding AP into the bean oiland rap oil, in order to test its antioxidant ability.The physical and chemical characteristics and quality of material were the baseof technical course, so we have studied its interrelated characteristics of CVT. Theresults follow as: acid value, 20.8 mgKOH/g, iodine value, 25.4 I₂/100g, peroxidevalue, 28.9 meq/kg, density, 0.91 g/cm³ (d₅₀⁵⁰), , melting point, 35.6-39.5℃,saponification value, 99.4 mgKOH/g, content of phosphatide after centrifugal is168.4mg/kg, all these show that pre-esterify with acid, transesterification with alkalican effectively advance the utilization of the free fatty acid. In virtue of GC,palmitic acid in CVT, with a content of 66.80%, is more 2.4 times than oleic acid,far more than contents of laurie acid, stearic acid、and linoleic acid, their sum content is lower than 5%, so CVT is good source of palmitic acid, oleic acid and their esters,CVT can be used as material of palmitic acid and its production or MP could used inother purpose after separated from FAME, the remains may used as fuel or to besaled as pure methyl oleate after refined which has more added value.The optimum degumming condition were: citric acid dosage, 1.5g/kg, reactiontemperature, 90℃, water dosage, 60g/kg, mixed time, 50min, content ofphosphatide, 35.48mg/kg, the last is still high than request of standard, and will beimproved by methyl esterify reaction in next step.The best esterify with acid condition were: reaction time, 8h, molar ratio ofmethanol and oil, 35:1, reaction temperature, 75℃, catalyzer dosage, 3%, accordingto this technics, acid value be fell as 0.37mg/g, esterfied ratio, 98.2%, yield is 99.6%.Subsequently, working catalytic reaction with alkali, and best condition is: reactiontime, 35min, catalyzer dosage, 0.8%, the molar ratio of methnal and oil, 6:1, reactiontemperature, 65℃, esterfied ratio 93.1%, melting point range, 23.2-24.7℃, acidvalue 0.12mgKOH/g, content of phosphatide, 5.76mg/kg, it is less than request ofGerman Standard with 10mg/kg. The main components of FAME were: methylpalmitate, 69.02%, methyl oleate 27.66%, methyl laurate, 1.94%, methyl stearate,1.78%, because its simple composing and plentiful methyl palmitate and methyloleate, it is good source of methyl palmitate and biodiesel.Separating and purifying MP from FAME with crystallizing fractionationtechnics with solvent, according to primary experiment and result of solubilityparameter, ethanol is right solvent for separating MP, and due to stronge polarityhydrogen bond of methanol, it also in favor of crystallization of MP; The result showthat, we can get more pure and good quality with ethanol. In condition of ratio ofFAME and solvent, 1:2, final crystal temperature, 10℃, the purity of MP achieve91.2%, continue to purify this product 2times and purity advanced to 96.9%, at thesame time, ethanol has effect of decolor and deodorize, its production reach therequest of of usual chemical industry product. All these results show that ethanol isexcellent solvent for the separation of MP from FAME.Using ascorbic acid （Vc） overdosage and adopting 98% H₂SO₄ as catalyzer, tosynthesized Vc and MP to be AP. At 25℃, the molar ratio of Vc and MP is 1:0.8, reaction time 17h, molar ratio of sum of Vc plus MP and H2SO4 is 0.14:1, the yieldachieve 69.4%, and it’s white. According this condition, could increasing yield of AP,reducing waste of Vc. After testing, indexs of AP as follows: purity 96.7%, metlingpoint, 112.6-119.5℃, heat loss, 0.11%, burned residue, 0.053%, and its qualityachieve the National Standard 16314-1996 of Ascorbyl Palmitate. All these showthat synthesizing MP which come form outgrowth of biodiesel and Vc to be AP is afeasible path. Using the method of overdosage Vc, can simplified the operation,avoided to use a lot of solvents, decreased the cost and energy of solvent reuse,reduced the harm and insecure factors of solvent in productive process.HLB value ofAP is about 8.4 after calculation and test, it is oil-water emulsifier.Using AP we synthesized into bean oil and rap oil, the results show that, APhave best antioxidant ability in bean oil, and its effect is close to TBHQ in rap oil,represents right antioxidant ability, so it is safe, highly efficient and worth to beextend. When AP mixed use with VE, they behaved obvious effect on promotion ofanoxidant ability and postponement of oxidated induce period. Mixed use is morecheap than using V_E alone because the price of AP is lower than V_E.Generally speaking, this research used MP that extracted from fatty acid methylester of CVT, to synthesize AP, this technics is available, on one side, could usingoutgrowth reasonable, and synthesize Vc ramification production which have moreadded value, it may reduce the cost of biodiesel, on the other hand, this technicsmade it come true that CVT used in energy. At the same time, could offered adevelopable route for these oil source which contained excessive unsaturated orsaturated fatty acid and behaved disadvantaged influence for cetane number and lowtemperature fluidity.更多还原