GC／MS法测定五种生物柴油中脂肪酸甲酯的研究

选用菜籽油、葵花籽油、玉米油、棕桐油、麻疯果油快速甲酯化制得生物柴油,通过气相色谱-质谱联用仪测定5种生物柴油的脂肪酸甲酯成分及其含量,共分析鉴定了14种脂肪酸甲酯,发现5种生物柴油主要由油酸、亚油酸、棕榈酸、硬脂酸的甲酯组成,并比较分析了它们的异同点,提出了研究脂肪酸甲酯成分和含量对生物柴油理化性能指标影响的必要性.     

气相色谱法测定生物柴油中脂肪酸甲酯的含量

本文采用配有分流/不分流进样口和FID检测器,HP-innowax石英毛细管色谱柱对生物柴油中的各种脂肪酸甲酯进行定量分析。在本试验条件下准确度和精密度高、重复性好,为生物柴油的研究和开发提供了一种快速有效的方法。     

地沟油酶法制生物柴油的GC-MS测定

地沟油制的生物柴油成分复杂,通过气相色谱-质谱法测定脂肪酸甲酯、游离脂肪酸的峰形和相对位置,由此可确定各成分的含量,并准确计算出生物柴油的转化率和产率.     

一种酶法催化合成生物柴油的气相色谱快速测定法

研究了酶法制备生物柴油中各种脂肪甲酯的气相色谱快速定性定量测定方法.实验采用Agilent-INNOWAX毛细管色谱柱,以十七烷酸甲酯为内标,程序升温测定生物柴油中主要脂肪酸甲酯,建立了一种简单、快速、准确的方法.各种脂肪酸甲酯的回收率在97.53%～99.67%之间,标准偏差为0.001 1～0.008 5,变异系数为0.46%～1.60%(n=6).     

固体超强酸催化生活污油制备生物柴油

用自制的SLTH固体超强酸催化剂催化生活污油与甲醇进行酯化/酯交换反应,制备生物柴油。实验表明,经处理脱色后的生活污油适合作为生产生物柴油的原料,在反应温度260℃、反应时间3h、醇油物质的量之比是14∶1和催化剂的量是1.9%的条件下,生物柴油的酯化率为达97.6%。并用气相色谱-质谱联用仪对制备的生物柴油进行表征分析,表明所得产品纯度高,其主要成分为C16~C18脂肪酸甲酯。     

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。     

氯代甲氧基脂肪酸甲酯制备及应用研究

本文以主要成分为脂肪酸甲酯的生物柴油为主要原料,以甲醇为甲氧基化试剂,以过氧化苯甲酰为催化剂,进行氯化反应合成氯代甲氧基脂肪酸甲酯,通过添加一定添加剂的方法,就提高氯代脂肪酸甲酯的分解温度进行了研究和探讨。研究了氯代脂肪酸甲酯合成的基本条件和添加剂的不同比例的热稳定剂对氯代脂肪酸甲酯热稳定性的影响。     

氯化脂肪酸甲酯合成及应用

以主要成分为十八碳脂肪酸甲酯的生物柴油为主要原料,在过氧化苯甲酰催化剂存在下,一步氯化法合成了氯化脂肪酸甲酯,在反应时间为3~4 h,温度为70~85℃的条件下合成了氯化脂肪酸甲酯,探讨氯化脂肪酸甲酯的氯含量及使用量对PVC增塑性能的影响。     

生物柴油低温流动性能的研究

生物柴油是典型的绿色能源,主要成分是脂肪酸甲酯。生物柴油的低温流动性与饱和脂肪酸甲酯的含量及分布有关,还与脂肪酸酯支链程度有关。综述了改善生物柴油低温流动性的方法,分析了降凝剂对生物柴油的降凝机理以及今后的研究方向。     

甲氧基含量对氯代甲氧基脂肪酸甲酯应用性能的影响

本文以主要成分为十八碳脂肪酸甲酯的生物柴油为主要原料,以甲醇为甲氧基化试剂,在过氧化苯甲酰催化剂存在下,一步氯化法合成了氯代甲氧基脂肪酸甲酯,在反应时间为7～8h,温度为70～85℃的条件下合成的氯代甲氧基脂肪酸甲酯,探讨氯代甲氧基脂肪酸甲酯的甲氧基含量对其在PVC中增塑性能的影响。     

A method for the determination of polyunsaturated fatty acid methyl esters in biodiesel: Results of an interlaboratory study

A gas chromatographic method for the determination of fatty acid methyl esters with four or more double bonds in biodiesel was developed and tested. The method is based on gas chromatographic separation on a wax capillary column using methyl tricosanoate as internal standard. The performance of the method was proved with the participation of 11 European laboratories by a Round Robin test on six different biodiesel samples containing different amounts of polyunsaturated fatty acid methyl esters. The results showed that the precision is sufficient around the EN 14214 limit of 1 % (m/m). At lower concentrations the variation is too high. The scope of the application can be given between as 0.6 and 1.5%.     

Improving the economics of biodiesel production through the use of low value lipids as feedstocks: vegetable oil soapstock

Semirefined and refined vegetable oils are the predominant feedstocks for the production of biodiesel. However, their relatively high costs render the resulting fuels unable to compete with petroleum-derived fuel. We have investigated the production of fatty acid methyl esters (FAME; biodiesel) from soapstock (SS), a byproduct of edible oil refining that is substantially less expensive than edible-grade refined oils. Multiple approaches were taken in search of a route to the production of fatty acid methyl esters from soybean soapstock. The most effective method involved the complete saponification of the soapstock followed by acidulation using methods similar to those presently employed in industry. This resulted in an acid oil with a free fatty acid (FFA) content greater than 90%. These fatty acids were efficiently converted to methyl esters by acid-catalyzed esterification. The fatty acid composition of the resulting ester product reflected that of soy soapstock and was largely similar to that of soybean oil. Following a simple washing protocol, this preparation met the established specifications for biodiesel of the American Society for Testing and Materials. Engine emissions and performance during operation on soy soapstock biodiesel were comparable to those on biodiesel from soy oil. An economic analysis suggested that the production cost of soapstock biodiesel would be approximately US$ 0.41/l, a 25% reduction relative to the estimated cost of biodiesel produced from soy oil.     

An ideal feedstock, kusum (Schleichera triguga) for preparation of biodiesel: Optimization of parameters

Kusum (Schleichera triguga), a non-edible oil bearing plant has been used as an ideal feedstock for biodiesel development in the present study. Various physical and chemical parameters of the raw oil and the fatty acid methyl esters derived have been tested to confirm its suitability as a biodiesel fuel. The fatty acid component of the oil was tested by gas chromatography. The acid value of the oil was determined by titration and was found to 21.30 mg KOH/g which required two step transesterification. Acid value was brought down by esterification using sulfuric acid (H₂SO₄) as a catalyst. Thereafter, alkaline transesterification was carried out using potassium hydroxide (KOH) as catalyst for conversion of kusum oil to its methyl esters. Various parameters such as molar ratio, amount of catalyst and reaction time were optimized and a high yield (95%) of biodiesel was achieved. The high conversion of the feedstock into esters was confirmed by analysis of the product on gas chromatograph-mass spectrometer (GC-MS). Viscosity and acid value of the product biodiesel were determined and found to be within the limits of ASTM D 6751 specifications. Elemental analysis of biodiesel showed presence of carbon, hydrogen, oxygen and absence of nitrogen and sulfur after purification. Molar ratio of methanol to oil was optimized and found to be 10:1 for acid esterification, and 8:1 for alkaline transesterification. The amounts of H₂SO₄ and KOH, 1% (v/v) and 0.7% (w/w), respectively, were found to be optimum for the reactions. The time duration of 1 h for acid esterification followed by another 1 h for alkaline transesterification at 50 ± 0.5 °C was optimum for synthesis of biodiesel.     

New process for catalyst-free biodiesel production using subcritical acetic acid and supercritical methanol

The production of glycerol as a by-product is unavoidable in the current conventional biodiesel manufacturing processes. Since biodiesel production is expected to increase in the near future, effective utilization of glycerol will become an issue of interest. In this study, therefore, a process consisting of subcritical acetic acid treatment to convert rapeseed oil to fatty acids and triacetin followed by conversion of the obtained fatty acids to their fatty acid methyl esters in supercritical methanol treatment was investigated. The obtained results clearly revealed that this two-step reaction could proceed effectively at a high reaction rate, and that fatty acid methyl esters and triacetin could be obtained under milder reaction condition than the one-step process utilizing supercritical methyl acetate and supercritical methanol.     

Methyl Esters (Biodiesel) from and Fatty Acid Profile of Gliricidia sepium Seed Oil

Increasing the supply of biodiesel by defining and developing additional feedstocks is important to overcome the still limited amounts available of this alternative fuel. In this connection, the methyl esters of the seed oil of Gliricidia sepium were synthesized and the significant fuel‐related properties were determined. The fatty acid profile was also determined with saturated fatty acids comprising slightly more than 35 %, 16.5 % palmitic, 14.5 % stearic, as well as lesser amounts of even longer‐chain fatty acids. Linoleic acid is the most prominent acid at about 49 %. Corresponding to the high content of saturated fatty acid methyl esters, cold flow is the most problematic property as shown by a high cloud point of slightly >20 °C. Otherwise, the properties of G. sepium methyl esters are acceptable for biodiesel use when comparing them to specifications in biodiesel standards but the problematic cold flow properties would need to be observed. The ¹H‐ and ¹³C‐NMR spectra of G. sepium methyl esters are reported.     

Determination of Polyunsaturated Fatty Esters (PUFA) in Biodiesel by GC/GC–MS and <Superscript>1</Superscript>H-NMR Techniques

In the present work, methods based on Gas Chromatography (GC), Gas Chromatography–Mass Spectrometry (GC–MS) and ¹H-NMR techniques was developed for the characterization and estimation of Polyunsaturated Fatty Esters (PUFA) in biodiesel. The GC method enables the separation, identification and estimation of these polyunsaturated fatty acid methyl esters to be carried out using a highly polar capillary column (100% cyanopropyl silicon). GC–MS was utilized for unambiguous identification and estimation of esters and isomers present in biodiesel. The estimation of PUFA content is important because PUFA content is a part of the EN 14214 specifications of biodiesel. There is no existing standard method for the estimation of total PUFA content in biodiesel. The developed GC method also quantifies EPA and DHA (C20:5 and C22:6) fatty acid methyl esters which can be used as markers for the estimation of fish oil biodiesel. The presence of EPA and DHA indicates the contamination of fish oil in biodiesel. Further, the ¹H-NMR technique has also been employed to identify and estimate PUFA containing ≥3 double bonds. The PUFA content was estimated from the integral intensities of the chemical shift region corresponding to all type of double bonds in the ¹H-NMR spectra. Based on the developed method, GC fingerprinting of various biodiesel samples was carried out to estimate a PUFA content as low as 1,000 ppm.     

Palm fatty acid biodiesel: process optimization and study of reaction kinetics

The relatively high cost of refined oils render the resulting fuels unable to compete with petroleum derived fuel. In this study, biodiesel is prepared from palm fatty acid (PFA) which is a by-product of palm oil refinery. The process conditions were optimized for production of palm fatty acid methyl esters. A maximum conversion of 94.4% was obtained using two step trans-esterification with 1:10 molar ratio of oil to methanol at 65°C. Sulfuric acid and Sodium hydroxide were used as acid and base catalyst respectively. The composition of fatty acid methyl esters (FAME) obtained was similar to that of palm oil. The biodiesel produced met the established specifications of biodiesel of American Society for Testing and Materials (ASTM). The kinetics of the trans-esterification reaction was also studied and the data reveals that the reaction is of first order in fatty acid and methanol (MeOH) and over all the reaction is of second order.     

Rapid Characterization of Fatty Acids in Oleaginous Microalgae by Near-Infrared Spectroscopy

The key properties of microalgal biodiesel are largely determined by the composition of its fatty acid methyl esters (FAMEs). The gas chromatography (GC) based techniques for fatty acid analysis involve energy-intensive and time-consuming procedures and thus are less suitable for high-throughput screening applications. In the present study, a novel quantification method for microalgal fatty acids was established based on the near-infrared spectroscopy (NIRS) technique. The lyophilized cells of oleaginous Chlorella containing different contents of lipids were scanned by NIRS and their fatty acid profiles were determined by GC-MS. NIRS models were developed based on the chemometric correlation of the near-infrared spectra with fatty acid profiles in algal biomass. The optimized NIRS models showed excellent performances for predicting the contents of total fatty acids, C16:0, C18:0, C18:1 and C18:3, with the coefficient of determination (R²) being 0.998, 0.997, 0.989, 0.991 and 0.997, respectively. Taken together, the NIRS method established here bypasses the procedures of cell disruption, oil extraction and transesterification, is rapid, reliable, and of great potential for high-throughput applications, and will facilitate the screening of microalgal mutants and optimization of their growth conditions for biodiesel production.     

Preparation of fatty acid methyl esters from hazelnut,high-oleic peanut and walnut oils and evaluation as biodiesel

Refined hazelnut, walnut and high-oleic peanut oils were converted into fatty acid methyl esters using catalytic sodium methoxide and evaluated as potential biodiesel fuels. These feedstocks were of interest due to their lipid production potentials (780–1780 L ha^?1 yr^?1) and suitability for marginal lands. Methyl oleate was the principal constituent identified in hazelnut (HME; 76.9%) and peanut (PME; 78.2%) oil methyl esters. Walnut oil methyl esters (WME) were comprised primarily of methyl esters of linoleic (60.7%), oleic (15.1%) and linolenic (12.8%) acids. PME exhibited excellent oxidative stability (IP 21.1 h; EN 14112) but poor cold flow properties (CP 17.8 °C) due to its comparatively high content of very-long chain fatty esters. WME provided low derived cetane number and oxidative stability (IP 2.9 h) data as a result of its high percentage of polyunsaturated fatty esters. HME yielded a satisfactory balance between all fuel properties when compared to the biodiesel standards ASTM D6751 and EN 14214 due to its high content of monounsaturated fatty esters. Also explored were the properties of blends of HME, PME and WME in ultra-low sulfur (<15 ppm) diesel (ULSD) fuel and comparison to petrodiesel standards ASTM D975, D7467 and EN 590. With increasing content of biodiesel, the oxidative stability, cold flow properties and calorific value of ULSD was negatively affected, whereas lubricity was markedly improved. Kinematic viscosity, specific gravity and surface tension were impacted to lesser extents by addition of biodiesel to ULSD. In summary, HME, PME and WME are suitable based on their fuel properties as biodiesel fuels and blend components in ULSD.