Crystallization Behavior of Fatty Acid Methyl Esters

Biodiesel from most agricultural feedstocks has flow properties that are prone to startup and operability problems during cold weather. Biodiesel from soybean oil is generally a mixture of long-chain fatty acid alkyl esters composed of 0.15–0.20 mass fraction saturated esters (melting point [MP] ≫ 0 °C) mixed with unsaturated esters (MP < 0 °C). This work investigates the crystallization properties of two saturated fatty acid methyl esters (FAME) commonly found in biodiesel from soybean oil. Differential scanning calorimetry (DSC) heating and cooling scans of methyl palmitate (MeC16), methyl stearate (MeC18) and methyl oleate (MeC18:1) in pure form were analyzed. Crystallization behavior in ternary FAME mixtures was inferred by the application of thermodynamic models based on ideal solution and freezing-point depression theories. Activity coefficients for MeC16 and MeC18 in MeC18:1 solvent were determined by analyzing DSC cooling curves for binary FAME mixtures. Eutectic points were predicted by both models. Crystallization onset temperatures inferred from freezing point depression theory were more accurate than those for ideal solutions with respect to a direct DSC cooling curve analysis of corresponding ternary mixtures. This work shows that the crystallization onset temperature (cloud point) of biodiesel may be predicted by freezing-point depression theory if the activity coefficients of the component FAME are known. The use of trade, firm, or corporation names in this publication is for the information and convenience of the reader. Such use does not constitute an official endorsement or approval by USDA or ARS of any product or service to the exclusion of others that may be suitable.     

连续反应精馏合成C16～18混酸甲酯的研究

在ｄ２２ｍｍ×ｌ１４００ｍｍ的玻璃填料塔中,以硫酸为催化剂,Ｃ１６～１８混合脂肪酸和甲醇为原料,对反应精馏合成混合脂肪酸甲酯的过程进行了研究,考察了各操作参数对脂肪酸转化率的影响。适宜的工艺条件是：催化剂用量为脂肪酸质量的１．１％,醇酸摩尔比为４．６,回流比为５,相应的脂肪酸转化率为９７．６％。     

连续反应精馏合成C_(16～18)混酸甲酯的研究

在ｄ２２ｍｍ×ｌ１４００ｍｍ的玻璃填料塔中,以硫酸为催化剂,Ｃ１６～１８混合脂肪酸和甲醇为原料,对反应精馏合成混合脂肪酸甲酯的过程进行了研究,考察了各操作参数对脂肪酸转化率的影响。适宜的工艺条件是：催化剂用量为脂肪酸质量的１．１％,醇酸摩尔比为４．６,回流比为５,相应的脂肪酸转化率为９７．６％。     

Reduction of Fatty Acid Methyl Esters with Sodium Borohydride-t-Butanol-Methanol

Methyl esters of undecenoic, oleic, erucic, linoleic, gorlic, ricinoleic, 12-hydroxystearic, 9,10-dihydroxystearic, 12-ketostearic and 9,10-epoxystearic acids were reduced to alcohols by refluxing with sodium borohydride in t-butanol-methanol. The products were found by chromatographic and spectral techniques to consist of mainly alcohols and small quantities of unreduced esters. Methyl undecenoate and gorlate also yielded minor proportions of corresponding wax esters. Olefinic unsaturation was not affected. Keto and epoxy groups were reduced faster than ester groups, hydroxy esters faster than nonhydroxy esters and shorter-chain esters faster than longer-chain esters.     

脂肪酸甲酯处理含苯胺工业废水

采用正交实验设计研究了用脂肪酸甲酯处理工业苯胺废水的条件。实验表明:在影响苯胺废水萃取效果的诸因素中,影响大小的顺序为pH值、油水相比、溶液初始浓度和温度。在pH值=7,油水相比为2∶1,20℃的最佳萃取条件下,高浓度苯胺废水经萃取剂脂肪酸甲酯三级萃取后,苯胺去除率达99.98%。     

Enzymatic Production of Fatty Acid Methyl Esters by Hydrolysis of Acid Oil Followed by Esterification

Acid oil, a by-product of vegetable oil refining, was enzymatically converted to fatty acid methyl esters (FAME). Acid oil contained free fatty acids (FFA), acylglycerols, and lipophilic compounds. First, acylglycerols (11 wt%) were hydrolyzed at 30 °C by 20 units Candida rugosa lipase/g-mixture with 40 wt% water. The resulting oil layer containing 92 wt% FFA was used for the next reaction, methyl esterification of FFA to FAME by immobilized Candida antarctica lipase. A mixture of 66 wt% oil layer and 34 wt% methanol (5 mol for FFA) were shaken at 30 °C with 1.0 wt% lipase. The degree of esterification reached 96% after 24 h. The resulting reaction mixture was then dehydrated and subjected to the second esterification that was conducted with 2.2 wt% methanol (5 mol for residual FFA) and 1.0 wt% immobilized lipase. The degree of esterification of residual FFA reached 44%. The degree increased successfully to 72% (total degree of esterification 99%) by conducting the reaction in the presence of 10 wt% glycerol, because water in the oil layer was attracted to the glycerol layer. Over 98% of total esterification was maintained, even though the first and the second esterification reactions were repeated every 24 h for 40 days. The enzymatic process comprising hydrolysis and methyl esterification produced an oil containing 91 wt% FAME, 1 wt% FFA, 1 wt% acylglycerols, and 7 wt% lipophilic compounds.     

棕榈油生物柴油脂肪酸甲酯气相色谱-质谱分析

采用气相色谱-质谱法,以11酸甲酯为内标,定性、定量分析了棕榈油制备的生物柴油中主要脂肪酸甲酯的分布及含量,结果表明:脂肪酸甲酯在各自质量浓度范围内,其峰面积与内标峰面积之比分别与甲酯浓度和内标浓度之比有良好的线性(r≥0.999 3).回收率在98.3 %～101.4 %之间(n =5), 精密度实验中相对标准偏差＜3 %(n =5).     

微通道中合成环氧脂肪酸甲酯

采用盐酸H2O2/HCOOH法,在微通道反应器内对不饱和脂肪酸甲酯进行环氧化反应。考察了双氧水用量、甲酸用量、反应温度及催化剂用量对反应的影响,得到最优的反应条件为:m(脂肪酸甲酯):m(甲酸):m(双氧水)=1:1.5:2,反应温度40℃,催化剂浓盐酸质量分数为3%(即浓盐酸质量占原料脂肪酸甲酯质量的百分数,下同),反应时间为110 s。在该条件下,产品环氧值为4.32%。     

管道反应器中合成环氧脂肪酸甲酯

研究在管道反应器中采用连续化工艺方法,以质量分数70%的双氧水进行环氧化反应合成环氧脂肪酸甲酯,其改善了传统的间歇工艺方法、釜式反应器中生产环氧脂肪酸甲酯产品所存在的诸多弊端。考察了双氧水用量、甲酸用量、反应时间、反应温度等工艺参数对产品环氧值的影响,确定了最佳工艺参数:m(脂肪酸甲酯)∶m(双氧水)∶m(甲酸)=1∶0.6∶0.05、反应时间15 min、反应温度90℃,在该条件下,所得产品的环氧值高达6.0%。     

不饱和脂肪酸甲酯环氧化工艺的研究进展

以催化剂体系为主线,综述了近年来化学法和脂肪酶法制备无毒增塑剂环氧脂肪酸甲酯的研究现状。对杂多酸和离子液体等化学催化体系和酶催化体系的优缺点进行了评述;集中讨论了脂肪酶催化法中氧载体、底物物质的量比、H2O2滴加速度、反应温度等因素对不饱和脂肪酸甲酯环氧化过程的影响规律;分析了脂肪酶的固载化技术以及存在的相关问题。指出寻找合适载体固载脂肪酶、提高脂肪酶的活性和稳定性、探寻适宜的环氧化工艺条件、提高脂肪酶的利用率是下一步的开发方向。     

脲包法分离不饱和脂肪酸甲酯的研究

以混合脂肪酸甲酯为原料,采用尿素包合法（脲包法）分离不饱和脂肪酸甲酯。通过正交试验,得到了最佳工艺条件：混合脂肪酸甲酯（w）：尿素（w）：甲醇（v）为1：2．09：8．36,包合温度-10℃,包合时间18h。经过一次包合,不饱和脂肪酸甲酯的含量由原来的47．69％提高到86．74％,收率54．19％。     

Cleaning Ability of Mixed Solutions of Sulfonated Fatty Acid Methyl Esters

Here, we present results from a systematic study on cleaning of oily deposits from solid surfaces (porcelain and stainless steel) by solutions of fatty acid sulfonated methyl esters (SME), sodium salts. The zwitterionic dodecyldimethylamine oxide (DDAO) has been used as a cosurfactant. As representatives of the vegetable and mineral oils, sunflower seed oil and light mineral oil have been used. The process of oil drop detachment from the solid substrates (roll-up mechanism) has been monitored. In the case of porcelain, excellent cleaning of oil is achieved by mixed solutions of SME and DDAO. In the case of stainless steel, excellent cleaning (superior than that by linear alkylbenzene sulfonate and sodium lauryl ether sulfate) is provided by binary and ternary mixtures of SME, which may contain also DDAO. For the studied systems, the good cleaning correlates neither with the oil/water interfacial tension, nor with the surfactant chainlength and headgroup type. The data imply that governing factors might be the thickness and morphology of admicelle layers formed on the solid/water interface. The results indicate that the SME mixtures represent a promising system for formulations in house-hold detergency, having in mind also other useful properties of SME, such as biodegradability, skin compatibility, and hard water tolerance.     

甲基葡萄糖苷脂肪酸酯的合成与研究

以碱性化合物CT作为催化剂,采用甲基葡萄糖苷和十八酸为原料合成甲基葡萄糖苷硬脂酸酯,对影响反应的主要因素进行了分析,通过IR分析不同反应条件下合成产品的组成,得到较优的反应条件为:n(甲基葡萄糖苷)∶n(十八酸)=1∶1.4,催化剂CT用量为甲基葡萄糖苷质量的0.6%,反应温度控制在150℃左右,反应压力0.01MPa,产品收率可以达到85%,颜色较浅。     

不饱和脂肪酸甲酯的绿色催化环氧化研究

选用氧化钼/叔丁基过氧化氢/阴离子离子液体{MoO3/TBHP/[bmimPF6]}(I)和氧化钼/过氧化氢/阴离子离子液体{MoO3/H2O2/[bmimBF4]}(II)两种绿色催化体系,探索了反应时间、反应温度、氧化剂/不饱和双键摩尔比和催化剂/不饱和双键摩尔比4个因素对不饱和脂肪酸甲酯环氧化转化率的影响。研究表明,实验条件下催化体系Ⅰ比催化体系Ⅱ具有更高的活性,MoO3可重复使用3次。     

Isothermal Curing Kinetics of Epoxidized Fatty Acid Methyl Esters and Triacylglycerols

Plant oil triacylglycerols are attractive renewable resources for biobased epoxy resins. We investigated the curing kinetics of three model epoxidized fatty acid methyl esters and representative epoxidized triacylglycerols with varied epoxide functionalities and distributions in the presence of a latent cationic initiator. Isothermal differential scanning calorimetry (DSC) was used to analyze the curing kinetics of the epoxy systems, and kinetic parameters (i.e., rate constants, reaction orders) were determined. Both epoxidized fatty esters and triacylglycerols followed the autocatalytic curing mechanism, and the DSC data were analyzed according to the Kamal autocatalytic model. Epoxidized methyl linoleate (EMLO) had the highest maximum curing rate, followed by epoxidized methyl linolenate (EMLON), and epoxidized methyl oleate (EMO) had the lowest maximum curing rate. We conclude that EMLO with two epoxide groups has the highest reactivity in this curing system, while the EMO with one epoxide group has the lowest reactivity. For epoxidized triacylglycerols, epoxidized camelina oil had the highest curing reactivity at higher temperatures, followed by epoxidized linseed oil and soybean oil.     

The Preparation of Fatty Acid Esters by Means of Catalytic Reactions

A review of actually available techniques for the preparation of esters derived form natural oils and fats is presented. A wide choice of catalysts, either homogeneous or heterogeneous, is currently available. This paper evaluates in detail the possibilities for the preparation of fatty acid esters with different alcohols and discusses the criteria for a correct choice. The different problems related to the preparation of esters with low molecular weight monoalcohols and of polyolesters with polyalcohols are discussed. The last part of the paper is devoted to the evaluation of ion-exchange resins as effective catalysts for the preparation of fatty acid esters with low molecular weight monoalcohols.     

GC-MS法分析生物柴油中脂肪酸甲酯成分的研究

通过利用不同气相色谱-质谱条件对生物柴油中的脂肪酸甲酯成分的分析研究,优选一个 GC-MS 条件,选用PEG-20M的色谱柱,柱温用 150℃ 恒温,进样量为 0.2 μL,分析时间仅用了 12 min,能很好地分离和鉴定生物柴油中主要的10个脂肪酸甲酯,该方法可用于不同植物油制备的生物柴油样品中的脂肪酸甲酯成分的 GC-MS 分析。     

Producing Fatty Acid Methyl Esters from Free Fatty Acids with Ionic Liquids as Catalyst

Three Brønsted acidic imidazole dicationic ionic liquids (ILs) with different length of alkyl chains, [C_n(Mim)₂][HSO₄]₂ (n = 3, 6, 12), were prepared and used as catalyst for the esterification reaction of free fatty acids and methanol. Taking oleic acid as model acid, the catalytic performances of the synthesized ILs for the esterification were evaluated. The main physicochemical properties of the ILs, thermal stability, acidity, solubility in common solvents, and causticity on Austenitic stainless steel 316, were examined. [C₃(Mim)₂][HSO₄]₂ demonstrated the highest catalytic activity and enabled to assess the preliminary optimum esterification condition of oleic acid and methanol. Under optimized reaction conditions, the yield of oleic acid methyl ester was up to 95 %. The ILs have great potential as catalysts for producing fatty acid methyl esters from long‐chain free fatty acids.     

Scalable Preparation of High Purity Rutin Fatty Acid Esters

Investigations into expanded uses of modified flavonoids are often limited by the availability of these high purity compounds. As such, a simple, effective and relatively fast method for isolation of gram quantities of both long and medium chain fatty acid esters of rutin following scaled-up biosynthesis reactions was established. Acylation reactions of rutin and palmitic or lauric acids were efficient in systems containing dried acetone and molecular sieves, yielding from 70–77% bioconversion after 96 h. Thereafter, high purity isolates (>97%) were easily obtained in significant quantities following a two-step solvent purification procedure whereby excess fatty acid substrate was first removed in a heptane/water (4:1, v/v) system, followed by selective ester extraction using an ethyl acetate/water system (1:6, v/v) at elevated temperature.     

Combined Short-Path Distillation and Solvent-Assisted Crystallization of Beef Fatty Acid Methyl Esters

Solvent‐assisted crystallization has previously been employed to remove long‐chain saturated fatty acids (≥ 18 carbons) from animal fat to improve its cold temperature biofuel properties. The same technology can be used for removing long‐chain saturated fatty acids (SFA) from animal fats for human consumption, but SFA remaining (i.e., 14:0 and 16:0) are more atherogenic than longer chain SFA. In the present study, an easy and efficient method was developed using short‐path distillation prior to solvent‐assisted crystallization for the more complete removal of SFA from beef tallow, and for the first time reports the distillation and crystallization behavior of polyunsaturated fatty acid biohydrogenation products (PUFA‐BHP). Shorter chain SFA methyl esters (i.e., 14:0 and 16:0) were efficiently removed at 90 °C, 9.3 Pa, with a rotor speed of 70 rpm and either two cycles of distillation at 90 drops/min or three cycles at 110 drops/min. Stearic acid (18:0) was then effectively removed by crystallization at ?20 °C using a sample to methanol ratio of 1:10. The remaining fraction enriched with PUFA‐BHP (i.e., rumenic acid, c9,t11‐18:2, and its precursor vaccenic acid, t11‐18:1) have potential use in disease model (i.e., cell culture and animal) studies to help further elucidate their bioactivity and mode of action, and may in the future have functional food or nutraceutical potential.