Glycerolysis of Fatty Acid Methyl Esters: 2. Simulation and Experiments in Continuous Reactors

The glycerolysis of methyl ester was investigated in flow reactors. This reaction represents a liquid two-phase reaction with changing reaction rates in a batch reactor. A semi-empirical model tested earlier with batch reactor data was used to simulate different continuous processes for this reaction. Among the processes simulated, a single continuous-flow stirred tank reactor (CSTR) without recycling was considered most appropriate for experimental implementation, although simulations showed that a faster reaction rate is possible with the application of a CSTR followed by a tubular reactor with certain associated residence times. The CSTR simulations were verified experimentally. A good agreement was found between the experimental data and simulation results.     

Glycerolysis of Crude Methyl Esters with Crude Glycerol from Biodiesel Production

Glycerolysis of crude fatty acid methyl esters (FAME) with crude glycerol derived from biodiesel production was performed. The reaction was accomplished at temperatures ranging between 160 and 200 °C and molar ratios of FAME to glycerol ranging between 1.5 and 3.0. Increasing the temperature improved the formation rate of monoglycerides (MG) and diglycerides (DG). However, increasing both the temperature and the molar ratio of glycerol to FAME diminished the formation of MG. Best results (43 % MG and 26 % DG in 10 min) were obtained at 200 °C using the lowest concentration of glycerol. The effects of soap and NaOH present in crude glycerol were controlled by carrying out the reaction with pure glycerol. In comparison with NaOH-catalyzed reactions, soap-catalyzed reactions resulted in a slower formation rate of products. However, soap-catalyzed reactions were less prone to secondary reactions, affording maximum yields of MG and DG, which were higher than those obtained with NaOH-catalyzed reactions at 180 and 200 °C.     

Ultrasonic Pretreatment Transesterification for Solid Basic-Catalyzed Synthesis of Fatty Acid Methyl Esters

Generally, ultrasound irradiation is required throughout the reaction for fatty acid methyl esters (FAME, namely, biodiesel) production, which is energy-consuming and difficult to scale-up. In order to improve the industrial application of ultrasonic technology, a systematic study of ultrasonic pretreatment solid basic (Na₂SiO₃)-catalyzed transesterification for FAME production from cottonseed oil was carried out, and the effect of ultrasonic waves on the properties of Na₂SiO₃ catalyst was assessed by X-ray diffraction (XRD), Fourier transform Infrared (FTIR) and scanning electron microscopy (SEM) characterization of fresh and collected catalysts. An ultrasonic frequency of 30 kHz, ultrasonic power of 200 W and ultrasonic pretreatment irradiation time of 30 min was determined to guarantee a satisfactory degree of transesterification. The optimum production was achieved in the reaction system at 45 °C with methanol/cottonseed oil molar ratio 5:1, catalyst dosage 3% and stirring speed 350 rpm resulting in a FAME yield of above 97% after 60 min of reaction under mechanical stirring with the ultrasonic pretreatment process. The new process has a shorter reaction time, a more moderate reaction temperature, a less amount of methanol and catalyst than only the mechanical stirring process without essential damage to activity and the structure of catalyst. These results are of great significance for applying the ultrasonic pretreatment method to produce FAME.     

Comparison of Fatty Acid Methyl and Ethyl Esters as Biodiesel Base Stock: a Review on Processing and Production Requirements

Fatty acid methyl esters (FAME) were the first fatty acid esters to be introduced for use as biodiesel. However, there is a growing interest in the use of fatty acid ethyl esters (FAEE) in biodiesel. Both FAME and FAEE have their own unique advantages and disadvantages. These differences are ultimately attributable to the structural differences imparted by the alcohols used in their production. Sources of reactants as well as their safety issues, are a focus of this review. Also reviewed are the comparative characteristics and properties of both biodiesel types in terms of physicochemical features and performance. Processing requirements, reaction times and molar ratios of alcohol to oil, together with problems and drawbacks, are discussed. Recent developments on improving the yield of biodiesel, include mixing methanol and ethanol in the same reaction with ethanol acting as a co-solvent, and enzymatic methanolysis and ethanolysis are also highlighted.     

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%。     

Reduction of Vegetable Oil-Derived Fatty Acid Methyl Esters toward Fatty Alcohols without the Supply of Gaseous H2

An alternative route to the conventional one for fatty alcohol synthesis was investigated. It was possible to synthesize lauryl alcohol from methyl laurate via reduction by transfer of hydrogen and hydride in liquid phase, in noncatalytic reactions and without the supply of H₂ gaseous. Pure NaBH₄ or alumina-supported NaBH₄ and methanol were used as co-reactants and 100% fatty alcohol selectivities were achieved. The aim of supporting the metal hydride was to increase its stability and achieve the full recovery of the solid at the end of reaction. When alumina-supported NaBH₄ was used, a final fatty alcohol yield of 93% was achieved. The use of methanol and NaBH₄ in amounts higher than stoichiometric is important to generate alkoxyborohydride anions which act as better reducing species than NaBH₄. The reaction conditions effect was investigated and the role of short carbon chain alcohol structure was elucidated. The effect of fatty acid methyl ester structure was also studied. Fatty acid methyl esters with shorter carbon chain length and without unsaturation (methyl laurate, methyl myristate) were easily reduced using NaBH₄/Al₂O₃ and methanol reaching high conversions and fatty alcohol selectivities. Unsaturated fatty acid methyl ester with longer carbon chain (methyl oleate) introduced steric hindrance which disfavoured interaction between ester and reducing solid surface and fatty acid methyl ester conversion was noticeably lower. A reaction mechanism based on alkoxyborohydride anions as the actual reducing species was proposed. This mechanism fully interprets results obtained during fatty acid methyl ester reduction using short carbon chain alcohols and metal hydride.     

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.     

Esterification of Fatty Acids in Greases to Fatty Acid Methyl Esters with Highly Active Diphenylamine Salts

Diphenylamine sulfate (DPAS) and diphenylamine hydrochloride (DPACl) salts were found to be highly active catalysts for esterification and substantial transesterification of inexpensive greases to fatty acid methyl esters (FAME). In the presence of catalytic amounts of DPAS or DPACl and excess methanol, the free fatty acids as well as the acylglycerols in waste greases were converted to FAME at 125 °C within 1 h. Although the DPAS and DPACl catalysts were found to have similar catalytic activities to their parent liquid acids (i.e., sulfuric and hydrochloric acids) the diphenylammonium salts are much easier to work with than concentrated liquid acids.     

Biodiesel Production from Rubber Seed Oil by Transesterification Using a Co‐solvent of Fatty Acid Methyl Esters

Rubber seed oil (RSO) is a high‐potential feedstock for the production of biodiesel fuel (BDF) in Asia. Transesterification using fatty acid methyl esters (FAMEs) as co‐solvents was developed for BDF production from RSO with high content of free fatty acids (FFAs). The homogeneous system (FAMEs/triglyceride/methanol) was attained when the FAME content was more than 30 wt %. After esterification of RSO, the crude RSO obtained was transesterified with FAMEs as a co‐solvent. The quality of BDF with high FAME content satisfied the criteria of the EN 14214/JIS K2390 standards. These results suggest that FAMEs converted from FFAs can be applied as a co‐solvent and, thus, reused for BDF production.     

A Predictive Correlation for Dynamic Viscosity of Fatty Acid Methyl Esters and Biodiesel

The viscosity of biodiesel, which is a mixture of fatty acid methyl esters (FAME), is an important physical property in the injection and efficient combustion. In this study, a simple correlation, with only one adjustable parameter, is proposed for predicting the viscosity of FAME and their mixtures (biodiesel) as a function of temperature. First, the adjustable parameter of the correlation is calculated for various FAME. The average absolute relative deviation (AARD) is obtained to be 0.97% for 226 data points. Second, the adjustable parameter of FAME is connected to the number of carbon atoms and the number of double bonds to build a predictive correlation for the calculation of viscosity. The AARD for 226 data points is obtained to be 2.28%. Third, the proposed model is employed to predict the viscosity of biodiesel without introducing any new adjustable parameter. To predict the viscosity of biodiesel, the average of the adjustable parameter is applied to the correlation. The AARD of 2.96% is obtained for 185 data points comprised of 23 different biodiesels. To better understand the ability of the correlation in the estimation of the viscosity of biodiesel and FAME, a comparison is made between the present correlation and a number of correlations available in the literature.     

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％。     

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％。     

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%。     

Branched‐Chain Fatty Acid Methyl Esters as Cold Flow Improvers for Biodiesel

Biodiesel is an alternative diesel fuel derived mainly from the transesterification of plant oils with methanol or ethanol. This fuel is generally made from commodity oils such as canola, palm or soybean and has a number of properties that make it compatible in compression‐ignition engines. Despite its many advantages, biodiesel has poor cold flow properties that may impact its deployment during cooler months in moderate temperature climates. This work is a study on the use of skeletally branched‐chain‐fatty acid methyl esters (BC‐FAME) as additives and diluents to decrease the cloud point (CP) and pour point (PP) of biodiesel. Two BC‐FAME, methyl iso‐oleate and methyl iso‐stearate isomers (Me iso‐C_18:1 and Me iso‐C_18:0), were tested in mixtures with fatty acid methyl esters (FAME) of canola, palm and soybean oil (CaME, PME and SME). Results showed that mixing linear FAME with up to 2 mass% BC‐FAME did not greatly affect CP, PP or kinematic viscosity (ν) relative to the unmixed biodiesel fuels. In contrast, higher concentrations of BC‐FAME, namely between 17 and 39 mass%, significantly improved CP and PP without raising ν in excess of limits in the biodiesel fuel standard specification ASTM D 6751. Furthermore, it is shown that biodiesel/Me iso‐C_18:0 mixtures matched or exceeded the performance of biodiesel/Me iso‐C_18:1 mixtures in terms of decreasing CP and PP under certain conditions. This was taken as evidence that additives or diluents with chemical structures based on long‐chain saturated chains may be more effective at reducing the cold flow properties of mixtures with biodiesel than structures based on long‐chain unsaturated chains.     

Molecular Weight Distribution of Low Molecular Weight Polyols Derived from Fatty Acid Methyl Esters

A series of commercial polyether polyols with well-defined molecular weights (MW) was used along with propylene glycol and dipropylene glycol as gel permeation chromatography (GPC) calibration standards to determine the MW and oligomeric composition of the synthesized low MW fatty acid methyl ester (FAME) polyols, having an MW of lower than 600 Da. This GPC analysis was compared to the one calibrated against the commercially-available polystyrene (PS) standards and to the number-average molecular weight (M _n) obtained via vapor pressure osmometry (VPO) technique. The MW of FAME polyols obtained with GPC calibrated against polyether polyols were closer to the M _n values obtained via VPO than the MW obtained via GPC calibrated against PS standards. Using the reliable GPC calibration, the MW distribution and the hydroxyl functionality of FAME polyols were determined with greater confidence.     

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。     

A New Green Method for the Production Polyvinylchloride Plasticizers from Fatty Acid Methyl Esters of Vegetable Oils

The current work has shown the potentials for the aerobic oxidation of fatty acid methyl ester (FAME) of vegetable oils in the production of polyvinylchloride (PVC) plasticizers with the exclusion of other reagents. The reaction mixtures contain epoxidized derivatives of FAME, and esters, with the quantity of the ester groups being higher than in the initial raw material. It was established that the increase in the additional ester groups resulting from the “aerobic” Baeyer-Villiger (BV) reaction has a significantly positive influence on the plasticizing ability of the oxidized FAME mixtures for PVC when compared to the formation of epoxide compounds. The development of the technology for the production of PVC plasticizers proposed in this investigation provides an opportunity for resolving some of the environmental issues normally associated with the use of phthalate-based plasticizers.     

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％。     

Fatty Acid Methyl Esters with Two Vicinal Alkylthio Side Chains and Their NMR Characterization

The addition reaction of dimethyl disulfide (DMDS) to double bonds in alkenes and monounsaturated fatty acid esters in the presence of iodine or other catalysts to give bis(methylthio) derivatives has largely served analytical purposes in mass spectrometry with scattered reports on the addition of other disulfides to alkenes also existing. In this work, this iodine-catalyzed reaction was expanded to include the addition of other dialkyl disulfides (RSSR; R=ethyl, propyl, butyl, iso-propyl) besides DMDS to the double bonds in monounsaturated fatty acid methyl esters with 16, 18, 20, and 22 carbon atoms in the fatty acid chain to give the corresponding methyl 1,2-bis(alkylthio)alkanoates. The products are obtained in high to moderate yield after a facile purification procedure and are analytically characterized not only by mass spectrometry but also ¹H and ¹³C NMR. The threo and erythro diastereomers obtained from (Z) and (E) fatty acid methyl esters, respectively, can be easily distinguished by the NMR shifts of the protons and carbons in and close to the 1,2-bis(alkylthio) moiety. Various other effects in the NMR spectra are discussed. The 1,2-bis(alkylthio) derivatives of a symmetrical alkene, 7(E)-tetradecene, serve to confirm the NMR assignments besides NMR techniques such as 2D correlations and DEPT. The compounds may show properties of interest for various applications.     

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.