生物柴油低温流动性及其降凝剂的研究进展

生物柴油是典型的"绿色可再生能源".然而生物柴油的凝点一般在0℃时,其低温结晶和凝胶化限制了生物柴油在低温时的应用.生物柴油低温流动性能主要与生物柴油中的饱和脂肪酸甲酯的含量和分布有关,还与脂肪酸酯的支链程度有关.综述了改善生物柴油低温流动性的方法,降凝剂的作用机理及生物柴油降凝剂的研究、应用及发展前景.     

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。     

生物柴油低温流动性及改进方法研究进展

综述了生物柴油低温流动性评价指标、主要影响因素及改进方法等相关研究进展。介绍了生物柴油中的脂肪酸组成和分布、酯基结构及杂质组成与生物柴油低温流动性能的关系。论述了改善生物柴油低温流动性的几种主要方法:加入添加剂法、改变生物柴油结构、冬化处理等。其中加入添加剂法成本低,操作方便,将成为改进生物柴油低温流动性能的研究方向。     

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。     

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。     

支链醇生物柴油油酸异丙酯对生物柴油的降凝作用及机理研究

利用支链醇生物柴油油酸异丙酯作为降凝剂,对生物柴油的低温流动性进行了研究,实验结果表明,油酸异丙酯作为一种典型的支链醇生物柴油,对改善生物柴油的低温流动性具有明显的效果;同时将油酸异丙酯与柴油降凝剂复配,将其应用于地沟油制生物柴油,结果表明,油酸异丙酯与聚α-烯烃柴油降凝剂之间出现了明显的协同降凝作用,取得了较好的降凝效果。同时还研究了支链醇生物柴油降凝机理,并对协同降凝作用提出了观点。     

生物柴油原料资源开发及深加工技术研究进展

生物柴油（脂肪酸甲酯）是一种绿色清洁的再生能源。我国生物柴油产业发展速度很快,但受原料价格高及产品多元化程度低等因素的影响,生物柴油价格高,产业缺乏竞争力。开发多样化的原料资源,进行产品深加工,对于生物柴油产业的发展具有重要的意义。本文综述了国内外生物柴油原料开发利用进展,介绍了国外生物柴油原料资源分布、资源特点及不同原料生物柴油的特点。简述了我国生物柴油原料资源现状及发展策略。介绍了生物柴油深加工技术研究进展,重点阐述了在制备第二代生物柴油、生物降解润滑油基础油、脂肪醇、烷醇酰胺、脂肪酸甲酯磺酸盐及绿色增塑剂等方面的研究进展及面临的问题,指出开发高效催化剂是发展生物柴油深加工技术的关键。     

Production of biodiesel with glycerol carbonate by non‐catalytic supercritical dimethyl carbonate

New biodiesel production processes comprising one‐step and two‐step supercritical dimethyl carbonate methods have been pioneered. The use of dimethyl carbonate allows the reaction conditions to be mild and thus avoid unwanted deterioration of substrates during reaction. In this process, without any catalyst applied, supercritical dimethyl carbonate converts triglycerides (rapeseed oil) into fatty acid methyl esters (FAME) along with glycerol carbonate as a value‐added by‐product, instead of glycerol. Free fatty acids could be also converted into FAME so that the total yield of biodiesel for both methods resulted in over 96 wt%. In addition, the produced FAME satisfy the fuel requirements for the international standards of biodiesel specification.     

An Empirical Equation for Estimation of Kinematic Viscosity of Fatty Acid Methyl Esters and Biodiesel

Kinematic viscosity (µ) is an important physical property of fatty acid methyl esters (FAME) and biodiesel. In this work, the Martin's rule of free energy additivity is extended to cover the kinematic viscosity of saturated and unsaturated FAME commonly found in nature. The proposed model can also be extended to estimate kinematic viscosity of biodiesel. The kinematic viscosity of a FAME or a biodiesel can be easily estimated from its carbon number (z), number of double bonds (n_d) at different temperatures (T) without a prior knowledge of the viscosity of individual FAME. Both z_ave and n_d(ave) can be derived from its fatty acid composition. Thus, kinematic viscosity of biodiesel at temperatures between 20 and 100 °C and at atmospheric pressure can be estimated. The average absolute deviation (AAD) estimated at 20–100 °C for saturated, unsaturated FAME, biodiesels and biodiesel blends are 4.15, 3.25, 6.95 and 2.79 %, respectively. The biodiesels collected in this study (191 data points) have the z_ave and n_d(ave) between 14.10 and 17.96 and 0.21–1.54, respectively. The standard deviation was 0.249. The proposed model would be good for estimation of viscosity of biodiesel containing normal fatty acids, generally found in biodiesel feed stocks.     

Cetane Number Prediction of Biodiesel from the Composition of the Fatty Acid Methyl Esters

In the present work, the measured cetane numbers (CN) of pure fatty acid methyl esters (FAME), as well as the FAME compositions and the reported CN of 59 kinds of biodiesels collected from literature were used to develop a simple model involving as more FAME component as possible for predicting CN of biodiesel from its FAME composition. Two different regression equations correlating the CN of pure FAME with the carbon number of fatty acid chain were obtained by regression analysis, which shows that the dependence of the CN on the carbon number varies with the unsaturated degree of fatty acid chain. The 59 biodiesels were divided into two categories and used, respectively to develop and test a multiple linear regression model (MLRM) correlating the CN of biodiesel with its FAME composition. A simple and convenient regression equation with a high accuracy and a good reproducibility (average absolute error of 0.49 CN for testing set and 1.52 CN for all data) were developed, showing excellent correlation (R ²: 0.9904 for testing set). The model developed in the present work can be used conveniently to give a satisfactory predicted CN of biodiesel from the FAME composition.     

Effect of Soybean Oil Fatty Acid Composition and Selenium Application on Biodiesel Properties

Biodiesel consisting principally of monounsaturated fatty acid methyl esters (FAME) has been reported to have the optimal balance between cold flow properties and oxidative stability, therefore producing a superior fuel. In addition, treating biodiesel with antioxidants such as selenium (Se) also increases oxidative stability. Fuel properties including acid value (AV), cloud point (CP), iodine value (IV), pour point (PP), peroxide value (PV), induction period (IP), onset temperature (OT), and kinematic viscosity (KV) were used to evaluate a newly developed Roundup Ready^® soybean recombinant inbred line (RIL) and a commercial cultivar. The RIL had a fatty acid profile with elevated levels of monounsaturated FAME. TN07-93RR was determined as the more desirable line for production of biodiesel, based on its fatty acid composition and subsequent fuel properties. The commercial cultivar AG3906 contained the highest abundance of polyunsaturated FAME and exhibited comparatively high IV and low oxidative stability. AG3906 was therefore not acceptable under the European biodiesel standard, EN 14214. However, TN07-93RR and AG3906 both were considered satisfactory according to the American biodiesel standard, ASTM D6751. Foliar treatment of soybean plants with varying amounts of Se had no effect on subsequent biodiesel oxidative stabilities.     

Estimation of the content of fatty acid methyl esters (FAME) in biodiesel samples from dynamic viscosity measurements

In order for biodiesel to be commercialized as pure biofuel or blending stock for diesel fuels, it must meet a set of requirements defined in standard specifications for a safe and satisfactory engine operation, one of these specifications is the content of fatty acid methyl esters (FAME). Besides, this parameter indicates the performance of the transesterification reaction for biofuel production from vegetable oils. There are several methods to determinate FAME content in biodiesel samples (chromatography, nuclear magnetic resonance spectroscopy and FTIR spectroscopy); however, they take long times and high cost for FAME content determination. From a practical point of view, in industrial biodiesel production is usually necessary to estimate the FAME value quickly. This paper presents correlations experimentally obtained from different oil feedstocks in order to estimate the biodiesel FAME content from the biodiesel dynamic viscosity, a fast determination parameter.     

A Quantitative Method of Analysis for Sterol Glycosides in Biodiesel and FAME Using GC-FID

Sterol glycosides (SG) are known to cause filter blocking problems in biodiesel use. The extraction and quantitative analysis of SG is difficult due to its low problematic concentration and its compatibility with biodiesel. The purpose of this study is to develop a method to quantify SG in FAME and biodiesel using gas chromatography and other equipment found in laboratories performing routine biodiesel analyses. SG was isolated from FAME using n‐dodecane, acidification and cold soaking, followed by cold centrifugation at ?8 to ?15 °C. The solids obtained were further separated by phase partition with a Folch wash, followed by a final n‐dodecane rinse. This solution was analyzed by GC‐FID using the operating conditions outlined in ASTM D6584. A calibration curve for SG was produced and a first order fit gave a value of r² = 0.992. Reproducibility tests were performed on soybean FAME and B100 canola biodiesel samples spiked with SG. The recovery of SG by the new method was found to be 99 % for soy FAME with a standard deviation of 0.7 and 100 % for B100 canola with a standard deviation of 3.5 %. The reproducibility based on two standard deviations of the predicted concentration for all 12 spiked samples studied in this work was 2.4 ppm.     

生物柴油低温流动性能研究进展

生物柴油是清洁可再生燃料,越来越多的国家开始研究和使用生物柴油替代石化柴油。然而生物柴油凝点和冷滤点很高,低温情况下容易结晶析出,堵塞发动机的管道和过滤器而无法正常使用。如何降低生物柴油凝点和冷滤点成为生物柴油研究的一个十分重要的课题,本文综述了目前国内外改进生物柴油低温流动性能的研究进展,生物柴油降凝剂及其降凝机理研究。     

Production and characterization of biodiesel from trap grease

The feasibility of the production of biodiesel from trap grease containing 51.5% free fatty acids (FFAs) was investigated. The esterification of FFAs by an acid catalyst followed by the transesterification of triglycerides by an alkali catalyst was examined. The esterification of trap grease by sulfuric acid as a homogeneous catalyst or by Amberlyst-15 as a heterogeneous catalyst was optimized through a response surface methodology. After the two-step esterification of trap grease by sulfuric acid, the acid value decreased from 102.9 mg KOH/g to 2.75 mg KOH/g. Through the transesterification by potassium hydroxide, fatty acid methyl ester (FAME) content reached 92.4%. Following the esterification of trap grease by Amberlyst-15, the acid value decreased to 3.23 mg KOH/g. With the transesterification by potassium hydroxide, FAME content increased to 94.1%. After the distillation of the produced biodiesel, FAME content increased again, to 97.6%. The oxidation stability of the trap grease biodiesel was 0.17 h, and its cold filter plugging point was 4 °C. As the FAME content of the trap grease biodiesel satisfies the Korean Biodiesel Standard, the trap grease biodiesel seems to be applicable for use as an engine fuel after properties improvement.