碱催化酯交换法制备生物柴油的研究

对以食用菜籽油、甲醇为原料,采用碱催化酯交换法制备了生物柴油.结果表明,该生物柴油的主要组分为:油酸甲酯、9-二十二烯酸甲酯、棕榈酸甲酯、硬脂酸甲酯、9-二十烯酸甲酯和亚油酸甲酯;在强烈搅拌条件下,当温度为70℃、NaOH用量为1.0%、醇油摩尔比为8:1、反应时间为2～3 h时,菜籽油的转化率可达到94%.     

生物柴油组分对低温流动性能影响的多元回归分析

为更好地了解生物柴油组分对其低温流动性的影响,探究组分与生物柴油低温流动性的关系,采用碱催化酯交换法制备生物柴油,对生物柴油进行低温流动性检测以及气相色谱-质谱联用仪(GC-MS)分析,同时利用多元回归的方法建立组分与低温流动性的关联式。结果表明,生物柴油之间低温流动性具有很大差异,菜籽油生物柴油的冷滤点和凝点温度最低,分别为-13和-10℃,棕榈油生物柴油的冷滤点和凝点温度最高分别为12和16℃,生物柴油的低温流动性主要由其组分的含量以及组分自身性质决定。通过GC-MS分析,生物柴油主要由5种脂肪酸甲酯构成,含量达90%以上;采用多元回归的方法,分析生物柴油组分对低温流动性影响,建立基于生物柴油主要组分(硬脂酸甲酯、棕榈酸甲酯、油酸甲酯、亚油酸甲酯、亚麻酸甲酯)的凝点、冷滤点、运动黏度的预测模型,相关系数均在0.95以上,可以很好地预测生物柴油的低温流动性。     

全二维气相色谱法测定柴油和生物柴油混合燃料中7种脂肪酸甲酯含量

建立了全二维气相色谱法测定柴油和生物柴油混合燃料中7种常见脂肪酸甲酯(月桂酸甲酯、肉豆蔻酸甲酯、软脂酸甲酯、硬脂酸甲酯、油酸甲酯、亚油酸甲酯、亚麻酸甲酯)含量的方法。采用外标法定量,7种脂肪酸甲酯的标准曲线的线性相关系数r为0.999 13~0.999 97,检出限为2.2~5.2 mg,加标回收率在92.0%~104.0%之间,相对标准偏差为2.3%~4.7%(n=8)。方法操作简单、快速、重复性好,适用于柴油和生物柴油混合燃料中脂肪酸甲酯的测定。     

多混合比生物柴油中脂肪酸甲酯成分分析的探索研究

以水杨酸甲酯为内标物,采用气相色谱法对生物柴油中的脂肪酸甲酯(棕榈酸甲酯、硬酯酸甲酯、油酸甲酯、亚油酸甲酯、亚麻酸甲酯)进行定量分析。5种脂肪酸甲酯的标准曲线的线性相关系数在0.99926～0.99986之间,加标回收率在100.0%～105.0%之间,相对标准偏差均小于1.1%,将该方法应用于生物柴油与0#车用柴油配制的7种混合比燃油样品(B0、B5、B10、B20、B50、B80、B100)中的脂肪酸甲酯检测,方法快速准确。     

生物柴油脂肪酸甲酯的成分及含量分析

采用GC/MS技术分析了由精棉籽油和棕榈油为原料通过酯交换反应得到的脂肪酸甲酯。结果表明,精棉籽油脂肪酸甲酯主要为棕榈酸甲酯、亚油酸甲酯和油酸甲酯,含量分别为22.23%,53.18%和18.09%。棕榈油脂肪酸甲酯主要为棕榈酸甲酯、油酸甲酯和硬脂酸甲酯,含量分别为40.3%,50.07%和7.02%。     

GC-MS外标法分析核桃仁中的脂肪酸含量

利用气相色谱-质谱联用(GC-MS)的外标法对核桃仁中的脂肪酸进行定量分析。核桃仁脂肪酸种类丰富,常见的4种脂肪酸在核桃仁中的含量:亚油酸油酸棕榈酸硬脂酸。相对标准偏差RSD(n=5)在2.27%~11.98%之间,样品回收率测定在81.0%~109.0%之间。     

Ag~+-树脂络合吸附分离乌桕梓油中α-亚麻酸

建立了乌桕梓油的定性、定量分析方法,用气相色谱GC测定了乌桕梓油的脂肪酸组成,乌桕梓油中2,4-癸二烯酸、棕榈酸、油酸、亚油酸和亚麻酸的质量分数分别为4.0%,7.6%,14.6%,28.2%,38.4%。测定了Ag+-树脂吸附亚麻酸甲酯和亚油酸甲酯的吸附动力学曲线,吸附时间为5 h时吸附达到平衡。考察了Ag+负载量、溶剂种类对亚麻酸甲酯和亚油酸甲酯分离选择性的影响,在实验范围内,Ag+负载量越高,二者的分离度越大。乙醇作为溶剂时,Ag+-树脂能够选择性的吸附亚麻酸甲酯,亚麻酸甲酯和亚油酸甲酯的分离度为13.9;石油醚为溶剂时,Ag+-树脂对亚油酸甲酯和亚麻酸甲酯基本没有吸附。测定了不同流速时亚麻酸甲酯和亚油酸甲酯的穿透曲线,亚麻酸甲酯/亚油酸甲酯的穿透点和饱和点均随着流量的降低而推迟,而流量的增加有利于提高粒外扩散速率,减小传质带宽度。以乙醇为吸附溶剂,石油醚为洗脱溶剂,经过Ag+-树脂固定床吸附,亚麻酸甲酯的纯度从38%提高到65%。     

鲩鱼脂肪酸的组成及其含量的GC-MS分析

采用气相色谱-质谱法分析了鲩鱼中脂肪酸的化学组成及各成分的含量。鲩鱼中的脂肪经石油醚提取、酸碱结合法甲酯化、GC-MS测定、总离子流图峰面积归一化法测定各组分相对含量。鲩鱼中检出26种脂肪酸,其中饱和脂肪酸含量为38.46%,不饱和脂肪酸61.54%。,含量较高的脂肪酸是亚麻油酸31.83%,油酸29.89%,棕榈油酸11.36%。     

气相色谱法测定工业甲醇中氧化物组分

建立了气相色谱法测定工业甲醇中氧化物含量的方法,根据实际样品中氧化物种类,以甲醇为溶剂,配制标准溶液,通过Stabilwax色谱柱进行组分分离,用氢火焰离子化检测器检测,用保留时间进行定性分析,采用外标法进行定量分析。分析结果表明,该法能达到将各组分较好分离的效果。选取有代表性的氧化物进行加标回收实验,加标回收率在96.87%~98.97%,精密度小于2.11%,该法可用于工业甲醇中主要氧化物组分含量的快速测定。     

高效液相色谱法测定防晒类化妆品中邻甲氨基苯甲酸甲酯

建立了一种高效液相色谱法测定防晒类化妆品中邻甲氨基苯甲酸甲酯含量的方法。样品经提取、超声、过滤后,采用Welch Xtimate^?C₁₈色谱柱分离,高效液相色谱-二极管阵列检测器进行定性、定量分析。在本实验条件下,邻甲氨基苯甲酸甲酯能与防晒类化妆品中常见的22种防晒剂进行分离,其质量浓度与峰面积之间呈良好的线性关系(r=0.999 6),检出限为0.009%,定量限为0.029%,在高、中、低三种质量浓度的添加回收率实验中,回收率在99.33%～111.5%之间,RSD在0.3%～3.0%之间。该方法专属性强、准确度高,适用于防晒类化妆中邻甲氨基苯甲酸甲酯含量的测定。     

Effects of ultrasonification and mechanical stirring methods for the production of biodiesel from rapeseed oil

This study was conducted to compare the effects of ultrasonic energy and mechanical stirring methods in bio-diesel production from rapeseed oil under base catalysis conditions. With the transesterification of rapeseed oil, the molar ratio of methanol to vegetable oil was 6: 1, and the amount of catalysts added to the vegetable oil was 0.3, 0.5 and 1.0% (wt/wt). The main components of methyl esters from the transesterification of rapeseed oil were oleic acid (48.5%, C18:1) and linoleic acid (18.1%, C18:2). In addition, the optimum conditions to produce fatty acid methyl esters (96.6%) were 0.5% KOH after 25 min of ultrasonification at 40 °C as compared to mechanical stirring at 60 °C. The maximum conversion ratio was 75.6% with 1.0% NaOH after 40 min of ultrasonification at 40 °C. These results indicate that ultrasonic energy could be a valuable tool for transesterification of fatty acids from rapeseed oil in terms of the reaction time and temperature.     

Kinetics and mechanism of the KOH — catalyzed methanolysis of rapeseed oil for biodiesel production

The reaction of rapeseed oil with methanol catalyzed by KOH is described by a model consisting of two sequences of consecutive competitive reactions. The first sequence expresses the methanolysis of rapeseed oil to methyl esters (biodiesel) whereas the second sequence describes the always present side reaction‐saponification of glycerides and methyl esters by KOH. The proposed chemical model is described (after rational simplifications) by a system of differential kinetic equations which are solved numerically by two independent computing methods. The thus obtained theoretical kinetic and equilibrium results are compared numerically and/or graphically with the experimental parameters. The latter were obtained by the determination of the relevant components in the actual reaction mixture by analytical methods. According to the experimental results, the proposed reaction scheme is fulfilled with the probability of ca. 78%. The optimal average rate constants and equilibrium constants of individual reaction steps of the discussed scheme are introduced. The limitations of the proposed reaction model are discussed.     

Cold flow properties of fuel mixtures containing biodiesel derived from animal fatty waste

The aims of the present study were to evaluate the cold temperature behavior of methyl esters of vegetable and animal origin and of their mixtures with fossil diesel fuel, as well as to investigate the effectiveness of different depressants. Various blends of rapeseed oil methyl esters, linseed oil methyl esters, pork lard methyl esters and fossil diesel fuel were prepared, and both cloud point and cold filter plugging point (CFPP) were analyzed. It was found that mixtures with CFPP values of –5 °C and lower may contain up to 25% of pork lard methyl esters; whereas the ratio of summer fossil diesel fuel and rapeseed oil methyl esters may vary over a wide range, i.e. such mixtures can be used in a diesel engine in the summer. In the transitory periods it is possible to use up to 20% animal and vegetable ester blends (3 : 7) with winter fossil diesel, whereas only up to 5% of esters can be added to the fuel used in winter. In order to improve the cold properties of rapeseed oil, pork lard and linseed oil methyl ester mixtures, various additives were tested. Depressant Viscoplex 10–35 with an optimal dose of 5000 mg/kg was found to be the most effective.     

Biodegradability of biodiesel fuel of animal and vegetable origin

One of the positive features of biofuel concerning environmental protection is its high biodegradability. Fuel is considered to be biodegradable if not less than 90% of it degrades within 21 days. The aim of this work was to determine the biodegradability of various kinds of fatty acid methyl esters and their mixtures with fossil diesel fuel in natural environments. It was determined that fatty acid methyl esters meet the requirements for biodegradability set by the EU. Of rapeseed oil fatty acid methyl esters (RME), 91.2% degraded within 21 days, compared to 94.2% of rapeseed oil fatty acid ethyl esters, 98.3% of linseed oil fatty acid methyl esters (LSME), 90% of tallow fatty acid methyl esters, and 92.5% of pork lard fatty acid methyl esters (LME), while the amount of degraded fossil diesel fuel reached only 57.3%. The biodegradability of multi‐component biofuels containing RME, LSME and LME is similar; the best is of a mixture of 70% RME, 6% LSME and 24% LME. It was determined that more than 90% of multi‐component biofuel and fossil diesel fuel mixtures degrade within 21 days when they contain 35% and more of multi‐component biofuel.     

Offset printing inks based on rapeseed oil and sunflower oil. Part II: Varnish and ink formulation

Two sets of variable oil length, alkyd resins modified by sunflower oil (SOA) and by rapeseed oil (ROA), were evaluated in offset formulations with mineral oils as diluent. The more suitable alkyds for this kind of application were determined. In a second experiment, hydrocarbon solvents were substituted by the fatty acid methyl esters derived from rapeseed oil or sunflower oil to produce ecologically friendly offset printing inks. Finally, the ROA and the SOA were associated with the methyl esters derived from the same vegetable oil. New properties of the varnishes composed of a vegetable diluent were evaluated. The quickset formulations with the methyl esters do not need important modifications, as opposed to the heatset formulations.     

高酸价油脂制备生物柴油的研究

以高游离脂肪酸含量的大豆酸化油为原料,在较高的压力和温度条件下,经催化甲酯化制备生物柴油,研究了甲酯化的优化反应条件并在此条件下对大豆酸化油、菜籽酸化油、地沟油的甲酯化效率进行了验证试验。结果表明在醇油质量比1:1.25,催化剂NaA/MgR用量为油质量的 1%,压力 3.0 MPa,温度 188℃,反应时间 120 min,3种原料油脂总脂肪酸甲酯含量达到 95%,生物柴油得率在 94% 左右。所得生物柴油产品质量指标符合ASTM 6751-03a的质量指标,且本工艺可以实现工业化。     

Biodiesel from rapeseed oil,methanol and KOH. 3. Analysis of composition of actual reaction mixture

Detailed analysis is described of the samples taken after suitable reaction times from the actual reaction mixture during the production of biodiesel fuel using methanolysis of rapeseed oil catalyzed by KOH. Three methods for stoppage of reaction (neutralisation of catalyst, dilution by two suitable solvents) in the sample are used. The contents of mono‐, di‐ and triacylglycerols, methylesters of fatty acids (biodiesel) and potassium salts of fatty acids of rapeseed oil, glycerol (by HPLC method), basicity (by potentiometric titration) and water (by GC and Karl‐Fischer method) in the samples are determined. An example of these determinations is described.     

Production of alkenyl succinic anhydrides from low‐erucic and low‐linolenic rapeseed oil methyl esters

Fatty acid methyl esters from low‐erucic and low‐linolenic rapeseed oil were used to produce alkenyl succinic anhydrides. A second‐order Doehlert uniform network design was used to investigate the influence of the reaction temperature and the molar ratio between the maleic anhydride and the main unsaturated rapeseed oil methyl esters on the yield of alkenyl succinic anhydride from methyl oleate. Further subjects of investigation were the conversion of methyl oleate, the formation of side reaction products, the Gardner color of the product and its viscosity, and finally the content of maleic anhydride remaining in the medium after the reaction. Alkenyl succinic anhydride from methyl oleate was isolated by column chromatography and analyzed by IR, ¹H‐ and ¹³C‐NMR and MS. The optimal reaction conditions for obtaining the maximum yield of alkenyl succinic anhydride from methyl oleate in the experimental domain (80%) were 210‐220 °C and a maleic anhydride/rapeseed oil methyl ester molar ratio of 1.5. However, the products synthesized in these conditions showed a high degree of viscosity (0.45 kg m^?1 s^?1), a very dark color (18 Gardner color) and a high content of undesirable side products (6%), which could hinder their industrial use. A molar ratio of less than 1.5 led to a clearer and less viscous product, although with a lower alkenyl succinic anhydride content.     

Oxidation stability of methyl esters studied by differential thermal analysis and rancimat

The oxidation stability of methyl esters derived from fresh rapeseed oil and waste frying oil, used as alternative biodiesel fuels, both distilled and undistilled, unstabilized and stabilized by pyrogallol and BHT, was studied by differential thermal analysis (DTA) under nonisothermal conditions at various heating rates and by the Rancimat test under isothermal conditions at 110°C. The results obtained by both techniques are compared. Both techniques show that oxidation stability increases considerably with the addition of antioxidants and that pyrogallol is very efficient. Distillation of the methyl esters prepared from rapeseed oil decreases their oxidation stability, obviously owing to the removal of natural antioxidants. The stability of methyl esters prepared from the waste frying oil is determined mainly by the history of the oil. From the DTA measurements, the kinetic parameters of an Arrhenius-like equation describing the temperature dependence of the oxidation induction period were obtained. The parameters enable one to assess the protective factor of antioxidants for temperatures outside the measuring region, estimate the residual stability, and model the process of biodiesel oxidation under nonisothermal conditions.     

Biodiesel fuel from rapeseed oil,methanol, and KOH. Analytical methods in research and production

The enumeration of the analytical methods used in the production of biodiesel from rapeseed oil and methanol catalyzed by KOH and published till 1997 is given. Some of our original methods for individual or simultaneous determination of the main components in the reaction mixture are described. All these methods can be also used to analyse the non-equilibrium complex and heterogeneous mixture.