Low-temperature property and engine performance evaluation of ethyl and isopropyl esters of tallow and grease

Three monoalkyl fatty acid esters derived from tallow and grease were prepared by lipase-catalyzed transesterification and evaluated as prospective diesel engine fuels. The low-temperature properties of the esters, both neat and as 20% blends in No. 2 diesel fuel, were evaluated. Those properties included cloud point, pour point, cold filter plugging point, low-temperature flow test, and crystallization onset temperature. Other properties of the esters, such as kinematic viscosity, heating value, and calculated cetane number, also were determined. All three esters had acceptable physical and low-temperature properties, as well as acceptable fuel properties at the 20% level in diesel blends. Engine performance and emissions for the ester blends were determined in a direct-injection, matched two-cylinder diesel engine. Among the monoalkyl esters studied, ethyl greasate had better properties and engine performance characteristics than the two tallow esters. For the latter esters, isopropyl tallowate had better properties than ethyl tallowate. Presented in part at the 88th Annual Meeting of American Oil Chemists’ Society, Seattle, WA, May 1997.     

Low-temperature properties of alkyl esters of tallow and grease

The low-temperature properties of mono-alkyl esters derived from tallow and recycled greases were determined for neat esters and 20% ester blends in No. 2 low-sulfur diesel fuel. Properties studied included cloud point, pour point, cold filter plugging point, low-temperature flow test, crystallization onset temperature, and kinematic viscosity. Compositional properties of the alkyl esters determined included water, residual free fatty acids, and free glycerol content. In general, the secondary alkyl esters of tallow showed significantly improved cold-temperature properties over the normal tallow alkyl ester derivatives. The low-temperature flow test did not show a 1:1 correlation with cloud point as previously observed with methyl soyate and methyl tallowate. For the homologous series methyl to n-butyl tallowate, ethyl tallowate had the best broad-spectrum low-temperature properties, both neat and when blended in diesel fuel. For the greases studied, both the normal and branched alkyl ester derivatives showed improved properties over corresponding tallow esters, especially with neat esters.     

Improving the low-temperature properties of alternative diesel fuels: Vegetable oil-derived methyl esters

This work explores near-term approaches for improving the low-temperature properties of triglyceride oil-derived fuels for direct-injection compression-ignition (diesel) engines. Methyl esters from transesterified soybean oil were evaluated as a neat fuel and in blends with petroleum middle distillates. Winterization showed that the cloud point (CP) of methyl soyate may be reduced to −16°C. Twelve cold-flow additives marketed for distillates were tested by standard petroleum methodologies, including CP, pour point (PP), kinematic viscosity, cold filter plugging point (CFPP), and low-temperature flow test (LTFT). Results showed that additive treatment significantly improves the PP of distillate/methyl ester blends; however, additives do not greatly affect CP or viscosity. Both CFPP and LTFT were nearly linear functions of CP, a result that compares well with earlier studies with untreated distillate/methyl ester blends. In particular, additives proved capable of reducing LTFT of neart methyl esters by 5–6°C. This work supports earlier research on the low-temperature properties; that is, approaches for improving the cold flow of methyl ester-based diesel fuels should continue to focus on reducing CP.     

Low-temperature properties of triglyceride-based diesel fuels: Transesterified methyl esters and petroleum middle distillate/ester blends

This work examines low-temperature properties of triglyceride-based alternate fuels for direct-injection compression-ignition engines. Methyl esters from transesterified soybean oil were studied as neat fuels and in blends with petroleum middle distillates (No. 1 or No. 2 diesel fuel). Admixed methyl esters composed of 5–30 vol% tallowate methyl esters in soyate methyl esters were also examined. Pour points, cloud points, and kinematic viscosities were measured; viscosities at cooler temperatures were studied to evaluate effects of sustained exposure. Low-temperature filterability studies were conducted in accordance with two standard methodologies. The North American standard was the low-temperature flow test (LTFT), and its European equivalent was the cold-filter plugging point (CFPP). With respect to cold-flow properties, blending methyl esters with middle distillates is limited to relatively low ester contents before the properties become preclusive. Under most conditions, cold-flow properties were not greatly affected by admixing the methyl esters with up to 30 vol% tallowate (before blending). Least squares analysis showed that both LTFT and CFPP of formulations containing at least 10 vol% methyl esters are linear functions of cloud point. In addition, statistical analysis of the LTFT data showed a strong 1:1 correlation between LTFT and CP. This result may prove crucial in efforts to improve low-temperature flow properties of alternate diesel fuels that contain methyl esters derived from triglycerides.     

Low-temperature flow properties of vegetable oil/cosolvent blend diesel fuels

Vegetable oils are an attractive renewable source for alternative diesel fuels. However, the relatively high kinematic viscosity of vegetable oils must be reduced to make them more compatible with conventional compression-ignition engines and fuel systems. Cosolvent blending is a low-cost and easy-to-adapt technology that reduces viscosity by diluting the vegetable oil with a low-M.W. alcohol (methanol or ethanol). The cosolvent (A), which consists of one or more amphiphilic compounds, is added to solubilize the otherwise nearly immiscible oil-polar alcohol mixture. This work investigates cold flow properties and phase equilibrium behavior associated with blends consisting of soybean oil (SBO) and methanol where A=8∶1 (mol) n-butanol/oleyl alcohol; 6∶1 (mol) 2-octanol/triethylammonium linoleate; and 4∶1 (mol) 2-octanol/Unadol 40 (alcohols from SBO FA); and a blend of 2∶1 (vol/vol) No. 2 diesel fuel/SBO and 95% ethanol where A=n-butanol. Cloud point (CP), pour point, cold filter plugging point (CFPP), and low-temperature flow test (LTFT) results were compared with corresponding phase separation temperature (T _ϕ) data measured at equilibrium. Although CP data were measured under non-equilibrium experimental conditions, a nearly linear correlation was found between T _ϕ and CP. Statistical analysis showed that T _ϕ may also be correlated with CFPP and LTFT. Analysis of heating and cooling DSC curves indicated that peak temperatures may be employed to predict cold flow properties and T _ϕ behavior for SBO/cosolvent blends. Cooling curve parameters correlated more readily than heating curve parameters. Finally, relatively low quantities of heat evolved during freezing indicated that crystallization in the SBO/cosolvent blends studied in this work occurs easily during cooling.     

Thermal analysis of alternative diesel fuels from vegetable oils

The relatively poor cold-flow properties of monoalkyl esters of vegetable oils and animal fats (biodiesel) present a major obstacle to their development as alternative fuels and extenders for combustion in direct injection compressionignition (diesel) engines. In this work, differential scanning calorimetry (DSC) heating and cooling curves of methyl soyate (SME), methyl tallowate (TME), SME/TME admixtures, and winterized SME were analyzed. Completion of melt, crystallization onset (Onset), and other temperatures corresponding to melting and freezing peaks were correlated to predict cloud point (CP), pour point (PP), cold filter plugging point (CFPP), and low-temperature flow test (LTFT) data. Effects of treating methyl esters with cold-flow improvers were examined. Low-temperature flow properties of biodiesel may be accurately inferred from subambient DSC analyses of high-melting or freezing (β-form) peaks. The temperature of maximal heat flow for freezing peaks gave the best accuracy for predicting CP, PP, and CFPP, while freezing point gave the best accuracy for predicting LTFT. Onset also gave good correlations with respect to predicting PP, CFPP, and LTFT. Cooling scan parameters were more reliable than heating scan parameters. Presented at the 88th American Oil Chemists’ Society’s Annual Meeting & Expo, Seattle, Washington, May 11–14, 1997.     

对GB19147-2009《车用柴油》标准的思考与分析

柴油按用途分类为车用柴油与普通柴油,阐述二者用途及区别;新标准将硫含量、多环芳烃、润滑性、脂肪酸甲酯和密度检测项目及技术指标限值进行设定,通过数据论证表明标准与国外发达国家通用做法接轨,体现节能环保作用,达到减炭减排功效。本文对标准的不足提出了建议。     

柴油降滤剂CDC-SO的合成表征与降滤性质研究

对柴油降滤剂进行了研究,以一缩二丙二醇、柠檬酸为原料,首次合成了以一缩二丙二醇为核心的多羟基多酸CDC小分子,再利用酯化反应依次与带有功能化基团的硬脂酸、十八醇接枝合成了新型的多元酯类CDC-SO大分子,并研究了单体配比、催化剂用量、溶剂用量和酯化反应时间对目的产物助滤效果的影响.将该添加剂以600 μg/g的加剂量添加于0#轻柴油中,柴油的冷滤点降低达6℃,其性能优于市场上普遍使用的T1804和T1805.     

MA-St型低温流动改进剂的制备及性能评价

采用"先酯化,后聚合"的方法,以马来酸酐、苯乙烯、十六醇、二十二醇为原料,合成了低温流动性改进剂马来酸酐混合酯-苯乙烯共聚物,最佳制备条件为:①酯化:n(马来酸酐)∶n(混合醇)=0.5∶1,w(催化剂)=1.8%、w(溶剂)=90%,酯化时间2.5 h;②聚合:n(苯乙烯)∶n(马来酸酐混合酯)=1∶1,w(引发剂)=1.25%,聚合温度为75℃,聚合时间4 h,溶剂用量为55%。将合成的产物按1.0‰的剂量加入到俄罗斯原油提炼的俄柴油中,冷滤点可降低12℃。     

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℃。     

Synthesis and evaluation of comb‐type copolymers prepared via atom transfer radical polymerization as possible cold flow improvers in GTL diesel fuels

Statistical comb‐type copolymers of styrene (Sty) and stearyl methacrylate (C18 MA) with varying [styrene]:[C18MA] ratios were synthesized by a controlled/living radical polymerization technique called atom transfer radical polymerization. The polymeric materials were evaluated in selected SASOL Fischer Tropsch gas‐to‐liquid diesels as possible cold flow improvers. Crystallization studies revealed that as the styrene content of the copolymer increased, a crystal growth inhibition mechanism was exhibited. With an increase in styrene content of the copolymer, differential scanning calorimetry and the cloud filter plugging point (CFPP) revealed a delay in onset of crystallization and lowered CFPP, respectively, whereas low‐temperature microscopy indicated modifications and size reduction of wax crystals. However, there appeared to be a styrene content, beyond which the additive's efficiency decreased. Homopolymer and copolymers with the highest styrene content led to long unfavorable needle‐shaped crystals. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

柠檬酸-新戊二醇-柠檬酸-环烷酸-十八醇爪形大分子的合成、表征与降滤性质

以新戊二醇、柠檬酸为原料,以对甲苯磺酸为催化剂,甲苯为溶剂,在120℃油浴中反应,合成了以新戊二醇为核的多羟基多酸爪状物小分子柠檬酸-新戊二醇-柠檬酸(CNC);再利用酯化反应依次与带有功能化基团的环烷酸、十八醇分别在140℃和180℃油浴中接枝,合成了新型的多元酯类爪形大分子柠檬酸-新戊二醇-柠檬酸-环烷酸-十八醇(CNC-NO)。用1HNMR及IR对合成的两种化合物进行了结构表征;结果表明,合成的CNC和CNC-NO与所设计的分子结构吻合。用元素分析确定了CNC的化学组成为C17H24O14。合成的CNC-NO不溶于水,溶于非极性的有机溶剂。将CNC-NO按600μg/g添加到轻柴油中,柴油的冷滤点可降低6℃。     

Fuel properties and nitrogen oxide emission levels of biodiesel produced from animal fats

FAME of lard, beef tallow, and chicken fat were prepared by base-catalyzed transesterification for use as biodiesel fuels. Selected fuel properties of the neat fat-derived methyl esters (B100) were determined and found to meet ASTM specifications. The cold-flow properties, lubricity, and oxidative stability of the B100 fat-derived fuels also were measured. In general, the cold-flow properties of the fat-based fuels were less desirable than those of soy-based biodiesel, but the lubricity and oxidative stability of the fat-based biodiesels were comparable to or better than soy-based biodiesel. Nitrogen oxide (NO_x) emission tests also were conducted with the animal fat-derived esters and compared with soybean oil biodiesel as 20 vol% blends (B20) in petroleum diesel. The data indicated that the three animal fat-based B20 fuels had lower NO_x emission levels (3.2–6.2%) than did the soy-based B20 fuel.