【作者】 金付强；

【导师】 张建春； 杨儒；

【作者基本信息】 北京化工大学 ， 材料学， 2008， 博士

【摘要】 生物柴油是以动植物油脂、废餐饮油等为原料制成的液体燃料,主要成分为长链脂肪酸烷基酯,具有可再生、可被生物降解、无毒、对环境无害的优点,是一种可以替代普通柴油的环保燃油。但是现有的生物柴油工业化生产工艺均存在成本高的问题,而且我国的原料供应形势与欧美不同,要从总体上降低生物柴油生产成本,必须降低原料油成本。因此,本课题进行了以汉麻籽油和橡胶籽油两种廉价的非食用油为原料油制备生物柴油的研究,内容包括原料油预处理、均相催化酯交换合成生物柴油、固体碱催化剂的制备与酯交换催化性能以及生物柴油理化特性研究。研究了汉麻籽油和橡胶籽油两种非食用原料油的理化特性,并对其进行了预处理研究。结果表明,汉麻籽油属于低酸值原料油,而橡胶籽油属于高酸值原料油,并且两种原料油均含有少量水。汉麻籽油可以经过简单脱酸、脱水处理后即可作为生物柴油原料油;而橡胶籽油则必须要进行甲酯化脱酸处理,之后进行脱水处理。汉麻籽油和甲醇经NaOH催化合成生物柴油。结果表明,提高反应温度和增大催化剂用量有利于酯交换反应的发生。甲醇的转化率随反应时间的延长呈现先增大后减小的趋势。随着醇油比的增加,甲酯生成率增大,而甲醇的转化率减小。凝胶渗透色谱分析表明经二次甲醇酯交换反应汉麻油可以比较完全的转化为甲酯。以聚丙烯酸盐系高吸水性树脂为载体,以原位聚合法将NaOH担载于聚丙烯酸钠（NaPAA）上制得了NaOH/NaPAA固体碱,以Hammett指示剂法、红外光谱、X-射线衍射、²³Na核磁共振谱等手段对以原位聚合担载法制得的NaOH/NaPAA固体碱进行了表征。结果表明:（1）在碱性条件下,NaOH的存在可以促进NaAA的聚合,可制备出具有高平衡溶胀度的聚丙烯酸盐系吸水树脂基固体碱。（2）氢氧化物/NaPAA样品的碱强度可达15.0＜H≤18.4,并且碱金属氢氧化物/NaPAA的碱量较碱土金属氢氧化物/NaPAA的高。NaOH/NaPAA样品中分布在15.0＜H≤18.4、9.3＜H≤15.0和7.2＜H≤9.3区域的碱位分别归属于NaOH/NaPAA中的NaOH、Na₂CO₃和NaPAA载体。（3）XRD和²³Na NMR分析均表明在NaOH担载量小于12.5mmol/g时NaOH可高度分散于NaOH/NaPAA固体碱中,而在NaOH担载量达12.5 mmol/g时会导致NaOH/NaPAA出现NaOH相分离。在NaOH/NaPAA固体碱中Na⁺可能呈聚集态和隔离态两种状态,每个COO^-可以容纳两个呈聚集态的Na⁺,多余的Na⁺将以隔离态存在。（4）TG/DTA分析表明NaOH/NaPAA样品具有较好的热稳定性,耐热温度可达390℃。而DSC分析表明NaOH/NaPAA样品具有较强的结合水性能,所含结合水为1.0～2.0g/g干基。（5）NaOH/NaPAA固体碱在甘油、甲醇、汉麻籽油、汉麻籽油甲酯中只可以有限的溶胀。（6）研究了NaOH/NaPAA在醇中的吸水性能和碱流失行为,表明NaOH/NaPAA在甲醇、乙醇、正丙醇、正丁醇中均具有较强的吸水性能,低交联度的NaOH/NaPAA样品吸水较快,而NaOH/NaPAA含水量较小时在醇中具有较强的吸水性能。较大的交联度可抑制NaOH/NaPAA在醇中的碱流失,而较大的NaOH负载量、较大的醇初始含水量、碳链较长的醇对抑制碱流失是不利的。以NaOH/NaPAA固体碱催化剂催化汉麻籽油酯交换反应。结果表明,NaOH/NaPAA固体碱具有高活性和高选择性,并且与NaOH催化的酯交换相比,受水的影响比NaOH小,NaPAA树脂载体的高吸水性在一定程度上抑制了皂化反应的发生,推测了其催化作用机理。虽然NaOH/NaPAA具有较好的催化性能,但以其作为催化剂时存在碱流失的问题,其稳定性有待提高。以混和硝酸盐热分解法制备了锶铝复合氧化物SrO-Al₂O₃。结果表明,添加Al可以明显抑制氧化锶在高温下由于升华而导致的收率损失。在Sr含量大于60%时,SrO-Al₂O₃的碱强度可达15.0＜H≤18.4,属强碱,并在酯交换反应中表现出较高的催化活性。SrO-Al₂O₃催化剂具有制备简单、活性高、酯交换反应条件温和、产物易于分离等优点,并且碱流失较小,催化寿命较长。考察了汉麻籽油生物柴油和橡胶籽油生物柴油的理化特性。结果表明,汉麻籽油生物柴油和橡胶籽油生物柴油的脂肪酸组成中不饱和脂肪酸含量均较高,均属于高碘值的原料油。汉麻籽油生物柴油和橡胶籽油生物柴油的各项理化指标基本达到了我国生物柴油标准以及美国和德国标准,其中汉麻籽油生物柴油具有良好的低温性能,而橡胶籽油生物柴油具有较高的十六烷值和闪点。调和柴油B5和B20的硫含量较石化柴油均有降低,而十六烷值、凝点和冷滤点有所升高,其他性能指标与石化柴油相近,B5和B20均可作为石化柴油的替代品。更多还原

【Abstract】 Biodiesel, comprised of mono-alkyl esters of long chain fatty acids, is a renewable, biodegradable, environmentally benign and nontoxic alternative fuel which is derived from vegetable oils, animal fats or waste restaurant oils. However, the existing technology to produce biodiesel suffers from the high production cost. Moreover, our country has different feedstock-supplying situation from the Occident. In order to reduce the total manufacturing cost of biodiesel, low cost feedstock must be used. Thus, the study focused on the biodiesel preparation from two low-cost non-edible oils, i.e. hemp seed oil and rubber seed oil. It included the study of the pretreatment of the crude oils, biodiesel preparation by the transesterification with homogeneous catalysts, the preparation and catalytic performance of solid base catalysts, and the study of the biodiesel properties.The properties and the pretreatment of hemp seed oil and rubber seed oil was studied. It showed that hemp seed oil consisted of little free fatty acids （FFA）, while rubber seed oil contained large amounts of FFA. And the both of the oils consisted of some water. Hemp seed oil could be refined by simple deacidification and dehydration while rubber seed oil must be deacidifed by methyl esterification firstly.Biodiesel was made by transesterification of hempseed oil with methanol, using NaOH as catalysts. The experimental results showed that both enhancing reaction temperature and increasing catalyst amount were advantageous to the transesterification. The conversion of methanol increased to the max and then decreased with extending reaction time. With increasing the molar ratio of methanol to oil the yield of methyl esters increased, but the conversion of methanol decreased. Gel permeation chromatography analysis showed that twice transesterification could convert hempseed oil to methyl esters completely.Using the polyacrylate salts as catalyst supports, NaOH/poly（sodium acrylate） （NaOH/NaPAA） solid bases were prepared by in situ polymerization of sodium acrylate in presence of NaOH. And they were characterized by means of Hammett indicator method, IR, XRD and ²³Na NMR spectroscopy. （1） Results showed that adding NaOH could lead to a more complete polymerization of sodium acrylate. And the NaOH/NaPAA solid bases could have high swelling capability. （2） The basic strength of the hydroxide/NaPAA solid bases could be up to 15.0<H_&lt;18.4, and the basicity of alkaline hydroxide/NaPAA was higher than that of alkaline earth hydroxide/ NaPAA. The basic sites with H in the range of 15.0<H_&lt;18.4, 9.3<H_&lt;15.0 and 7.2<H_&lt;93 were attributed to NaOH, Na₂CO₃ and the NaPAA supporter. （3） XRD and ²³Na NMR analysis showed that good dispersion of NaOH in NaOH/NaPAA could be obtained when the loading amount of NaOH was lower than 12.5 mmol/g. And a phase separation of NaOH may have been formed when the loading amount of NaOH was up to 15.0 mmol/g. There may be aggregated and isolated Na⁺ ions in NaOH/NaPAA solid bases. The aggregates of Na⁺ ions can contain approximately two Na⁺ units for every carboxyl group. And the excess Na⁺ ions exist in isolated state. （4） TG/DTA curves indicated that the NaOH/NaPAA sample had good thermo-stabilization. Its heat-resistant temperature was up to 390℃. DSC curves suggested that the NaOH/NaPAA sample had good combination capability with water and the bonding water was 1.0～2.0 g/g dry gel. （5） The NaOH/NaPAA solid bases can only swell limitedly in glycerol, methanol, hemp seed oil and the methyl esters of hemp seed oil. （6） The water absorbance and the alkali loss of the NaOH/NaPAA solid bases were studied. Results showed that the NaOH/NaPAA had strong water absorbability in methanol, ethanol, n-propanol and n-butanol. The sample with lower crosslinking degree could absorb water more rapidly, and with water content had higher water absorbability. Higher crosslinking degree could letdown the alkali loss, while higher NaOH loading amount, higher water content of alcohol and longer chain alcohol accelerate the alkali loss.The NaOH/NaPAA solid bases were applied to catalyze the transesterification of hemp seed oil. Results showed that the samples had high transesterification catalytic activity and catalytic selectivity. The transesterification was less seriously affected than the NaOH-catalyzed one, likely due to that the saponification was restrained by the high water absorbency. The catalysis mechanism of NaOH/NaPAA solid bases were brought forward. In despite of high catalytic performance, the stability of NaOH/NaPAA should be improved since the alkali loss took place.Multiple strontium and aluminum oxides （SrO-Al₂O₃） were prepared by calcinations of mixed nitrate salts. Results showed that the addition of aluminum nitrate could improved the yield of SrO-Al₂O₃ by restraining the sublimation of SrO. The SrO-Al₂O₃ solid bases had basic strength of 15.0<H_&lt;18.4 and high catalytic activity with Sr content higher than 60%. The SrO-Al₂O₃ catalysts can be prepared easily and are noncorrosive, environmentally benign and present fewer disposal problems. More importantly, they had little alkali loss and high catalytic life in the transesterification. The physicochemical characteristics of biodiesel prepared from hemp seed oil and rubber seed oil were determined. It showed that the two oils had higher iodine value, and the fatty acid composition of them consisted of large amounts of unsaturated acids. Most of the biodiesel properties could meet the standards established by our country, America and Germany. The biodiesel form hemp seed oil had good performance at low temperature, while the biodiesel form rubber seed oil had higher cetane number and flash point. The biodiesel/diesel blends of B5 and B20 had lower sulphur content, higher cetane number, solidifying point and cold filter plugging point than the petroleum diesel fuels. And other properties were close to the petroleum diesel fuels. B5 and B20 could be used as alternative fuels of the corresponding petroleum diesel fuels.更多还原