生物柴油低温流动性改进方法研究综述

综述了生物柴油低温流动性的主要影响因素,改进方法及基本原理等相关研究进展。着重介绍了生物柴油的低温流动性的改进方法,包括冷滤法、添加剂法、产品调和法以及一些其他方法。最后对低温流动性改进方法进行了展望。     

生物柴油降凝剂的研究进展

生物柴油是绿色可再生能源,许多国家开始研究和使用生物柴油替代石化柴油。然而生物柴油低温流动性差,限制了其发展。从柴油降凝剂、生物柴油低温流动改进剂这两方面改善生物柴油低温流动性进行综述,并着重介绍作为生物柴油潜在添加剂的研究进展,最后对开发专门针对生物柴油降凝剂进行展望。     

生物柴油的组成对低温流动性的影响

生物柴油的化学组成是影响其低温流动性的重要因素。通过用气质联用仪和多功能低温试验器分别测定常见的6种生物的组成分布和浊点、倾点、冷滤点等低温流动性指标,用控制变量法研究生物柴油的组成和冷滤点的关系。结果表明,生物柴油中饱和脂肪酸甲酯的含量越高,饱和脂肪酸甲酯的脂肪酸碳链越长,生物柴油的低温流动性越差;不饱和脂肪酸甲酯的含量越高,脂肪酸甲酯的不饱和度越大,生物柴油的低温流动性越好;与饱和脂肪酸甲酯相比,不饱和脂肪酸甲酯对生物柴油低温流动性的影响可以忽略。     

生物柴油的组成对低温流动性的影响

生物柴油的化学组成是影响其低温流动性的重要因素。通过用气质联用仪和多功能低温试验器分别测定常见的6种生物的组成分布和浊点、倾点、冷滤点等低温流动性指标,用控制变量法研究生物柴油的组成和冷滤点的关系。结果表明,生物柴油中饱和脂肪酸甲酯的含量越高,饱和脂肪酸甲酯的脂肪酸碳链越长,生物柴油的低温流动性越差;不饱和脂肪酸甲酯的含量越高,脂肪酸甲酯的不饱和度越大,生物柴油的低温流动性越好;与饱和脂肪酸甲酯相比,不饱和脂肪酸甲酯对生物柴油低温流动性的影响可以忽略。     

生物柴油降凝方法的研究

以废油脂为原料通过酯交换法制备了生物柴油,测定其凝点为-2℃,闪点为114.5℃,说明生物柴油比-10号柴油具有更高的安全性,但其凝点限制了它的使用范围。采用不同的方法改善生物柴油的低温流动性能,结果表明以生物柴油降凝剂及-10号柴油对生物柴油进行混合降凝的方法,能有效降低生物柴油的凝点,并使其低温流动性能得到改善。     

LDY柴油降凝剂的性能评价

在分析中国石油辽化炼油厂0^#柴油的烃族组成、蜡碳分布的基础上，研制出一种柴油低温流动性改进剂。实验结果表明，这种柴油低温流动性改进剂能十分有效地提高中国石油辽化炼油厂0^#柴油的低温使用性能。并在实验室评价了LDY柴油降凝剂对几种0^#柴油的低温流动性能的改进效果。     

生物柴油高性能结晶抑制剂的研究

生物柴油是典型的"绿色能源",但相比石化柴油,低温流动性较差,这一性质严重限制了其在低温环境下的应用。添加低温流动改进剂是一种方便、快捷、有效的改善生物柴油低温流动性的方式。本文以四聚蓖麻油酸酯、马来酸酐、蓖麻油酸、环氧丙烷等为原料,合成了一种以长链树状脂肪酸酯为主要成分的化合物。在生物柴油中添加一定条件下制得的树状长链脂肪酸酯分子可有效地降低生物柴油的凝固点,从而对改进生物柴油低温流动性起到积极作用,可使生物柴油得到更广泛的推广和应用,对新能源的开发利用具有重要意义。     

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。     

生物柴油低温流动性及改进方法研究进展

介绍了目前生物柴油的国内外标准,以及生物柴油低温流动性的主要影响因素,并结合国内外的研究进展综合分析:冬化、掺混法、改变分子结构、添加低温改进剂等四种改进方式,并对目前研究存在的问题提出建议和展望.     

生物柴油低温流动改进剂复配研究

采用碱催化法制备菜籽油生物柴油和棕榈油生物柴油,对其主要品质指标进行分析;考察了添加不同的柴油低温流动改进剂及其复配物对生物柴油低温流动性能的影响。结果表明,柴油低温流动改进剂能够改善生物柴油低温流动性能;将其进行复配后,能表现出协同效应,取得更好的降滤效果,尤其能使饱和脂肪酸甲酯含量高的棕榈油生物柴油冷滤点降低8℃;不同生物柴油对柴油低温流动改进剂或其复配物感受性存在较大差异,不饱和脂肪酸甲酯含量高,且脂肪酸甲酯种类较多、分布较广的菜籽油生物柴油对单一低温流动改进剂感受性好,而饱和脂肪酸甲酯含量高,且脂肪酸甲酯种类分布较集中的棕榈油生物柴油对复配物感受性好。     

生物柴油低温流动改进剂的制备及其降滤效果评价

为降低大豆油生物柴油的冷滤点,合成了马来酸酐-丙烯酰胺-苯乙烯醇解衍生物（AAS）以及助剂环己醇脂肪酸酯（CF）,并对其进行红外表征。通过正交实验,优化了三元共聚物（AAS）的工艺条件,同时考察了自制AAS分别与助剂CF以及德国蜡晶分散剂的复配效果。实验结果表明,合成AAS的最佳工艺条件为：单体配比2：1.5：0.75,引发剂（BPO）用量1.5%,催化剂加量1.0%,共聚温度75℃,共聚时间5 h,醇解时间3 h,酐醇比7：12。当AAS添加量为0.3%时,可使大豆油生物柴油冷滤点降低4℃。与助剂CF以1：1质量配比复配可使大豆油生物柴油冷滤点降低6℃,并可使菜籽油生物柴油降低5℃。     

生物柴油低温流动性改进方法研究进展

随着工业发展,人口增长,世界能源需求增加,石油资源却正面临枯竭的危机,在石油馏分油中消耗最大的柴油资源不可再生,生物柴油作为柴油替代燃料得到广泛发展,但其较差的低温流动性影响其在实际中使用,因此改善生物柴油低温流动性是一个亟需解决的问题。论述了生物柴油的低温流动性的评价指标和改进方法的研究进展。     

Partial hydrothermal oxidation of unsaturated high molecular weight carboxylic acids for enhancing the cold flow properties of biodiesel fuel

Biodiesel fuel has become more attractive recently because of its environmental benefits and the fact that it is a product made from renewable resources. However the less favorable cold flow properties or the low temperature operability of biodiesel fuel compared to conventional diesel is a major drawback limiting its use. The poor flow properties of biodiesel at cold temperatures are mainly due to biodiesel fuel being composed of long-chain fatty acids with an alcohol molecule attached. If the double bond of unsaturated fatty acids in these long-chain fatty acids could be ruptured selectively, then the cold flow properties of biodiesel fuel would be enhanced by reducing its viscosity.In this study, the selective hydrothermal oxidation of oleic acid, as a model compound of unsaturated high molecular weight carboxylic acids, was studied experimentally. The objective was to use this as a model to investigate whether the double bond of unsaturated fatty acids can be ruptured selectively by partial hydrothermal oxidation. Demonstration of this method could then be used to show the potential to improve the cold flow properties of biodiesel. Results showed that the amount of mono-carboxylic acids, aldehyde, di-carboxylic acids, and aldehyde-acids with a carbon number of 9 was significantly higher than other oxidative products. This suggests that the oxidative cleavage may principally occur at the double bond in hydrothermal conditions. The cloud and pour points for biodiesel fuel (B100) and B100 blend with a mixture of methyl esters or acetals were measured. These are the most important indicators for the cold flow properties of biodiesel fuel. The methyl esters or acetals used were made from the esterification of carboxylic acids or aldehydes by simulating the major oxidation products. These were obtained from the hydrothermal oxidation of oleic acid at different oxygen supply rates. Results showed that the cloud and pour points of the blend were significantly enhanced compared to those of B100.     

Improving the cold flow properties of biodiesel from waste cooking oil by ternary blending with bio-based alcohols and diesel from direct coal liquefaction

The utilization and popularization of biodiesel are always limited by its poor cold flow properties. Both bio-based alcohol and diesel from direct coal liquefaction (DDCL) has potential to enhance the cold flow properties of biodiesel. In this study, ternary blends of waste cooking oil biodiesel (BWCO) with DDCL and bio-based ethanol (ET) or 1-butanol (BT) were conducted to improve the cold flow properties of biodiesel. The pour point (PP), cold filter plugging point (CFPP), and cloud point (CP) of BWCO-ET, BWCO-BT, and BWCO-DDCL binary blends, and BWCO-ET-DDCL and BWCO-BT-DDCL ternary blends were comparatively assessed. Ternary phase diagrams were also applied to analyze the blending effect of the three components on the cold flow properties of biodiesel. Results showed that both DDCL, ET, and BT can remarkably enhance the cold flow properties of BWCO. When the ternary blends contain 20 vol.% BWCO and less than 40 vol.% ET or BT, DDCL together with ET or BT exerted positive effects on enhancing the low-temperature flow properties of BWCO, especially on the CP and CFPP. For ternary blends in 20:10:70 blending ratio, BWCO-BT-DDCL exhibited the lowest PP, CFPP, and CP of −23, −19, and −17°C, respectively. The crystallization behavior and crystal morphology of blended fuels are also observed via a polarizing optical microscope, and find that DDCL together with BT in biodiesel can effectively retard the aggregation of large crystals and inhibit crystals growth.     

Effects of fatty acid derivatives on the ignition quality and cold flow of diesel fuel

The biodiesel that is considered as a possible substitute or extender of conventional automotive diesel fuel is commonly composed of fatty acid methyl esters that are prepared from the glycerides in vegetable oils by transesterification with methanol. This form of biodiesel is compatible with diesel fuel but offers no improvement in its ignition quality. This work describes the results of a series of experiments aimed at assessing other common fatty acid derivatives that could provide the desired biofuel component and, at the same time, improve the performance of the fuel. It was found that tertiary fatty amines and amides are significantly more effective than methyl esters in enhancing the ignition quality of the finished diesel fuel without having any negative effect on its cold flow properties.     

Improving the cold flow properties of biodiesel from waste cooking oil by surfactants and detergent fractionation

The use of surfactants and detergent fractionation to improve the cold flow properties of biodiesel from waste cooking oil (BWCO) was investigated. The effect of five types of surfactants, including sugar esters (S270 and S1570), silicone oil (TSA 750S), polyglycerol ester (LOP-120DP) and diesel conditioner (DDA) on the reduction of the cold filter plugging point (CFPP) of the BWCO, was evaluated, with the greatest reduction to the CFPP of the BWCO (from −10 °C to −16 °C) being was achieved by the addition of 0.02 wt% of polyglycerol ester (LOP-120P). Detergent fractionation of the BWCO was performed by first mixing partially crystallized biodiesel with a chilled detergent (sodium dodecylsulfate) solution accompanied by an electrolyte (magnesium sulfate), and then separating the mixture by centrifugation to obtain the BWCO liquid. An orthogonal experimental design was utilized to investigate the effects of the various parameters on detergent fractionation. The optimal parameters, as obtained by range analysis, were as follows: detergent loading 0.3 wt%, electrolyte loading 1.0 wt%, and water loading 150 wt%. The CFFP of the liquid biodiesel from waste cooking oil (LBWCO) was −17 °C with a yield of 73.1% when the detergent fractionation was performed under these conditions. A limited number of biodiesel physical and chemical properties were analyzed before and after the addition of surfactants and detergent fractionation.     

油酸异丁酯的合成及其对生物柴油降凝效果研究

油酸与异丁醇在离子液体催化剂的作用下发生酯化反应制备油酸异丁酯。研究了催化剂用量、醇酸配比、反应时间、反应温度等对酯化反应转化率的影响,并通过测定凝固点、冷滤点、粘度来考察脂肪酸异丁酯对生物柴油的降凝效果。结果表明,当催化剂用量为2%,醇酸体积比2∶1(摩尔比6.8∶1),反应温度100℃,反应时间3 h,转化率达到95.6%。降凝实验结果表明,把一定量的脂肪酸异丁酯添加到生物柴油中可有效地降低生物柴油的凝固点、冷滤点,改善其低温流动性能。     

Effect of trace contaminants on cold soak filterability of canola biodiesel

A cold soak filtration test (CSFT; ASTM D 7501-09b) was included in B100 specifications under ASTM D 6751-09, bringing new challenges to biodiesel producers and researchers investigating B100 quality. For a plant breeding program evaluating canola biodiesel quality traits, rapid assessment of biodiesel quality is important. Typically, a limited amount of seed from new canola lines is available; therefore, obtaining the required volume of biodiesel for evaluating cold soak filterability (300 mL) is not possible. In order to rapidly screen canola breeding lines for B100 quality, cold soak filterability must be assessed with reduced volumes of biodiesel. The primary objective of this study was to evaluate the impact of saturated monoglycerides, glycerin, and soap on cold soak filterability. Biodiesel filtration time rapidly escalated when the SMG concentration was above 0.28%. The influence of saturated monoglycerides (0.04-0.46% w/w) on biodiesel precipitate formation was also evaluated. A regression model was generated to predict the filterability of biodiesel against the concentrations of trace contaminants. The results will be instrumental to scaling down biodiesel CSFT for a canola breeding program.