A Transesterification Double Step Process — TDSP for biodiesel preparation from fatty acids triglycerides

This study introduces a two consecutive steps basic–acid transesterification process, (denominated Transesterification Double Step Process — TDSP) for biodiesel production from vegetable oils. The process involves homogeneous consecutive basic–acid catalysis steps and is characterized by formation of well-defined phases, easy separation procedures, high reaction velocity and high conversion efficiency. The proposed TDSP is different in relation to other traditional two-step procedures which normally include acid esterification followed by basic transesterification, or enzymatic or even supercritical transesterification conditions. The biodiesel (fatty acid methyl esters) was analyzed by standard biodiesel techniques in addition to ¹H-NMR, indicating high quality and purity biodiesel products. The transesterification of sunflower and linseed oils resulted in oil conversions higher than 97% corresponding to yields of 85%. A probable reaction mechanism responsible for the process is presented.     

Selection of Direct Transesterification as the Preferred Method for Assay of Fatty Acid Content of Microalgae

Assays for total lipid content in microalgae are usually based on the Folch or the Bligh and Dyer methods of solvent extraction followed by quantification either gravimetrically or by chromatography. Direct transesterification (DT) is a method of converting saponifiable lipids in situ directly to fatty acid methyl esters which can be quantified by gas chromatography (GC). This eliminates the extraction step and results in a rapid, one-step procedure applicable to small samples. This study compared the effectiveness of DT in quantifying the total fatty acid content in three species of microalgae to extraction using the Folch, the Bligh and Dyer and the Smedes and Askland methods, followed by transesterification and GC. The use of two catalysts in sequence, as well as the effect of reaction water content on the efficiency of DT were investigated. The Folch method was the most effective of the extraction methods tested, but comparison with DT illustrated that all extraction methods were incomplete. Higher levels of fatty acid in the cells were obtained with DT in comparison with the extraction-transesterification methods. A combination of acidic and basic transesterification catalysts was more effective than each individually when the sample contained water. The two-catalyst reaction was insensitive to water up to 10% of total reaction volume. DT proved a convenient and more accurate method than the extraction techniques for quantifying total fatty acid content in microalgae.     

Isolation of pure linolenate as its mercuric acetate adduct

After addition of mercuric acetate to the unsaturated methyl esters obtained from the methanolysis of linseed oil, linolenate of 99% minimum purity was isolated by means of a liquid-liquid continuous extraction technique and subsequent decomposition of the mercurial adduet. The methyl linolenate-mercuric acetate addition compound was extracted with 10% methanol in water from an ether solution of the reaction mixture. Infrared analysis of the regenerated methyl linolenate showed the complete absence oftrans-linkages. The yield, at least 60% of the linolenic acid present in linseed oil, was considerably higher than that obtained by bromination-debromination procedures. The solubility in aqueous solutions of fatty acid derivatives having 3 or more acetoxymer-euri-groups/molecule provides an approach to the fractionation of highly unsaturated oils. For example, a fraction having an iodine value of 395 was isolated readily from the methyl esters of pilchard oil by this technique. Journal Paper No. 1787, Purdue Agricultural Experiment Station.     

Lipase-Catalyzed Synthesis of Fatty Acid Pyridylcarbinol Ester for the Analysis of Seed Lipids

Numerous derivatives of fatty acids (FA), including esters of methanol/3‐hydroxymethylpyridine or dimethyloxazoline, are used for the analysis of FAs in biological specimens. Picolinyl derivatives are frequently prepared for structural determination by gas chromatography–mass spectrometry (GC‐MS) since they provide characteristic fragments. The ester can be prepared by chemical methods‐multistep methodologies or basic transesterification. Microbial lipases catalyze a number of transesterification reactions, and their catalytic activities are often stable at extreme conditions. Although these characteristic features may be useful in the application of typical FA structure analysis by picolinyl ester, detailed studies have not been reported. To address the problems, a simple and quantitative methodology for the synthesis of picolinyl esters from lipids has been developed. It involves the transesterification with Novozym 435 (Novozymes Biopharma US Inc., Franklinton, USA), resin‐immobilized lipase from Candida antartica in toluene. Mild reaction conditions allow for complete derivatization of perilla seed oil in 30 min at 50 °C. The procedure was further studied with various TAGs and fatty wax from 17 plants. The optimized procedure was as follows; 1 mg lipid and 20 mg catalyst in 2 mL toluene at 50 °C for 1 h. Quantitative analysis of marker FAs was performed with the proposed method. The results coincided well with those from potassium t‐butoxide‐catalyzed reaction. The optimized method, however, was not applicable for the determination of some epoxy FAs, fatty wax, and parinaric acid.     

Reactive extraction and in situ esterification of Jatropha curcas L. seeds for the production of biodiesel

Jatropha curcas L. has recently been hailed as the promising feedstock for biodiesel production as it does not compete with food sources. Conventional production of biodiesel from J. curcas L. seeds involve two main processing steps; extraction of oil and subsequent esterification/transesterification to fatty acid methyl esters (FAME). In this study, the feasibility of in situ extraction, esterification and transesterification of J. curcas L. seeds to biodiesel was investigated. It was found that the size of the seed and reaction period effect the yield of FAME and amount of oil extracted significantly. Using seed with size less than 0.355 mm and n-hexane as co-solvent with the following reaction conditions; reaction temperature of 60 °C, reaction period of 24 h, methanol to seed ratio of 7.5 ml/g and 15 wt% of H₂SO₄, the oil extraction efficiency and FAME yield can reached 91.2% and 99.8%, respectively. This single step of reactive extraction process therefore can be a potential route for biodiesel production that reduces processing steps and cost.     

Two approaches in preparation for cogeneration α‐tocopherol and biodiesel from cottonseed

A two‐step process and a direct alkaline transesterification process in preparation for cogeneration α‐tocopherol and biodiesel (fatty acid methyl esters, FAME) from cottonseeds were studied in this article. The effects of some factors on recovery of α‐tocopherol and conversion of cottonseed oil (triacylglycerols, TAGs) to biodiesel in the two processes were systematically studied by single factor experiments and orthogonal design method. In the two‐step process, α‐tocopherol and biodiesel were produced from extraction with two‐phase solvent followed by base‐catalysed transesterification. Approximately 95.5% TAGs was converted into biodiesel, and 1.008 mg/g (wet basis) α‐tocopherol was detected on the condition: 1:3 petroleum ether/methanol volume rate, 40°C extraction temperature; 7:1 methanol/cottonseed oil molar ratio, 1.1% KOH (w/v) concentration in methanol and 60°C esterification temperature. And in the direct alkaline transesterification reaction, 98.3% conversion of TAGs and 0.986 mg/g content of α‐tocopherol could be achieved at 60°C in 2 h. Both of the two processes were feasible from the economic point of view for further utilisation of cottonseed. © 2011 Canadian Society for Chemical Engineering     

Biodiesel from extracted fat out of meat and bone meal

Nine non‐halogenated solvents for the extraction of fat from meat and bone meal (MBM) were evaluated by the accelerated solvent method. Yields of about 15% were obtained with all solvents, but n‐hexane was found to be the most suitable extraction solvent, because it is relatively cheap and has a low boiling point. Fat was also extracted from MBM on preparative scale (600 g) by immersion, and the extracted material was analysed for impurities that could affect the subsequent transesterification. The extracted material was converted into fatty acid methyl esters (FAME) via a two‐step process. For further purification, the raw FAME were distilled under reduced pressure. The final product was analysed according to the European specification for biodiesel (EN 14214). Almost all of the values were within the specifications, except the cold‐temperature behaviour and the oxidation stability. All in all, extracted fat from MBM is a potential feedstock for the production of biodiesel.     

Fatty acid methyl ester as reactive diluent in thermally cured solvent-borne coil-coatings—The effect of fatty acid pattern on the curing performance and final properties

Four different fatty acid methyl esters (FAMEs): rape seed methyl ester (RME), tall oil methyl ester (TOME), and two types of linseed oil methyl ester (Linutin) have been studied as reactive diluents in thermally cured solvent-borne coil-coatings. The purpose was to evaluate the effect of fatty acid methyl ester structure on the curing performance and final properties of the coating. The permanent incorporation of the reactive diluent via transesterification reaction has been followed with ¹H NMR analysis of model systems. Dynamic mechanical analysis (DMA) measurements, of free-standing films, show that the glass transition temperature (T_g) decreases upon addition of the reactive diluent. Both the amount of incorporated reactive diluent and the final film properties are affected by the number and placement of alkene-bonds in the FAME.     

Production of phytosterol esters from soybean oil deodorizer distillates

Enzymatic esterification and supercritical fluid extraction was used to produce phytosterol esters from soybean oil deodorizer distillates. The raw material was first subjected to a two‐step enzymatic reaction; the product obtained mainly comprised fatty acid ethyl esters, tocopherols and phytosterol esters, together with minor amounts of squalene, free fatty acids, free sterols and triacylglycerols. The phytosterol esters were then purified from this mixture using supercritical carbon dioxide. Experimental extractions were carried out in an isothermal countercurrent column (without reflux), with pressures ranging from 200 to 280 bar, temperatures of 45–55 °C and solvent‐to‐feed ratios from 15 to 35 kg/kg. Using these extraction conditions, the fatty acid esters were completely extracted and, thus, the fractionation of tocopherols and phytosterol esters was studied. At 250 bar, 55 °C and a solvent‐to‐feed ratio of 35, the phytosterol esters were concentrated in the raffinate up to 82.4 wt‐% with satisfactory yield (72%).     

Enzymatic synthesis of medium‐chain triacylglycerols by alcoholysis and interesterification of copra oil using a crude papain lipase preparation

We have examined the possibility of producing analogs of medium‐chain triglycerides (MCT) from copra oil, i.e. a triacylglycerol mixture with a high content of medium‐chain fatty acid moieties (C₆–C₁₀). A two‐step enzymatic process was used in which copra triacylglycerols were first split with papain lipase by alcoholysis with an alkyl alcohol and then subjected to interesterification with the alkyl esters recovered using papain lipase. Effects of temperature, water activity content, substrate ratio, biocatalyst amount, and alcohol chain length were also investigated. On the one hand, the sn‐3 stereoselectivity of the lipase in the alcoholysis of copra oil with butanol has permitted a direct enrichment of caproic, caprylic and capric moieties in the synthesized butyl esters. Thus, in the batch reactor, the reaction led to about 31% conversion of the oil after 24 h, and the content of C₆–C₁₀ acids in the synthesized esters increased from about 16% in the starting oil to almost 42%. A similar enzymatic alcoholysis in a packed‐bed column bioreactor gave 31% conversion of the oil after 120 min of reactor residence time. The reaction was also very selective because the C₆–C₁₀ fatty acyl groups represented about half of the newly formed butyl esters, whereas they accounted for only 16% of total fatty acids in the starting oil. On the other hand, the transesterification of the alkyl esters recovered (highly enriched in C₆–C₁₀ fatty acyl groups) with native copra oil directly led to an increase in the content of MCT in the oil, from 18 mol‐% at the beginning of the reaction to 61 mol‐% of MCT after a time period of 72 h in the batch reactor.     

The Impact of Linseed Oil Lipids on the Physical Properties of Corn Crisps and the Possibility of Obtaining Crisps Enriched with n‐3 Fatty Acids

Linseed oil, also known as flaxseed oil, is obtained from the dried, ripened seeds of the flax plant (Linum usitatissimum). The oil is obtained by pressing, sometimes followed by solvent extraction supported by a refining process. Linseed oil is an edible oil that is in demand as a nutritional supplement, as a source of α‐linolenic acid an n‐3 fatty acid. The aim of this work was to investigate: (1) the influence of the corn crisp extrusion process on the degradation of fatty acids in linseed oil (LO) and some preparations obtained from the linseed oil such as ethyl ester (EE) and free fatty acids (FFA) added to the corn in order to increase the nutritional value of the crisps, (2) influence of the oil and two fatty preparations obtained from it on the quality of corn crisps, (3) interaction of the lipid fraction with starch. The extrusion process did not degrade the fatty acids significantly. Expansion ratio obtained in the corn crisp extrusion process decreased from 620 % down to 153 %, the size of pores/thickness of the starch–protein walls forming the structure of the extruded product decreased from 10 μm down to 4 μm, the hardness of the crisps increased from 20 to 75 N, and number of lipid–starch complexes increased with rising polarity of the lipid fraction. FFA were complexed mostly by starch (about 90 %), to a lesser degree by EE (about 60 %) and to the least extent by triacylglycerols (about 10 %). The studies performed under industrial conditions using the single screw extruder for the production of corn crisps with the application of standard parameters of the extrusion process indicated that the addition of a mass of 5 % of the various lipids (triacylglycerols of linseed oil, ethyl esters and fatty acids obtained from linseed oil) to corn grits prior to the extrusion process significantly affect the quality of corn crisps.     

The decomposition of secondary esters of castor oil with fatty acids

In this study, thermal splitting of secondary fatty acid esters of castor oil was investigated to determine the reaction kinetics under various conditions. Zinc oxide,p toluenesulfonic acid and sulfuric acid were used as catalysts. Reactions were carried out at 260, 270, and 280°C. Experimental data fitted the first-order rate equation for the catalyzed and noncatalyzed reactions. In addition to the kinetic investigation, the splitting (pyrolysis) mixture was evaluated in the preparation of a synthetic drying oil. For this purpose, the mixed fatty acids of linseed, sunflower andEcballium elaterium seed oils were used in the esterification stage of the process. Pyrolysis mixtures were converted to drying oils by combining the liberated acids with equivalent amounts of glycerol. The oils thus obtained show good drying oil properties.     

Transesterification double step process modification for ethyl ester biodiesel production from vegetable and waste oils

In this study, the transesterification double step process (TDSP) was modified to enable the usage of ethanol as a transesterification agent in the production of biodiesel from vegetable and waste oils. The TDSP comprises a two-step transesterification procedure, which is initiated by a homogeneous basic catalysis step and followed by an acidic catalysis step. To optimize the transesterification parameters, different reaction mixtures and conditions were tested. Compared with methanol transesterification, larger ethanol and catalyst amounts as well as higher reaction times and temperatures were required. However, the results were consistent with those usually reported for ethanol transesterification. The obtained biodiesels (i.e., fatty acid ethyl esters (FAEEs)) were analyzed by standard physico-chemical techniques in addition to ¹H NMR, ¹³C NMR and FTIR spectroscopies, indicating high quality and purity biodiesel products. The obtained conversions were evaluated by ¹H NMR spectroscopy. For the optimized process, the triglyceride conversion to biodiesel was ?97% for all oils used. The overall process yields are considerably high when compared to the single basic catalysis yields.     

Simulation and optimization of supercritical fluid purification of phytosterol esters

Supercritical carbon dioxide extraction to separate phytosterol esters from fatty acid esters and tocopherols was simulated and optimized using the group contribution equation of state. Experimental extraction data at 328 K, pressures ranging from 200 to 280 bar and solvent‐to‐feed ratio around 25, was employed to verify the performance of the thermodynamic model. The raw material is the product obtained after a two‐step enzymatic reaction carried out on soybean oil deodorizer distillates, and contains mainly fatty‐acid ethyl esters, tocopherols and phytosterol esters. The extraction process was simulated using model substances to represent the complex multicomponent feed material. Nonlinear programming techniques were applied to find out optimal process conditions for a steady‐state countercurrent process with partial reflux of the extract. The process optimization procedure predicts that a product with 94.2 wt % of phytosterol ester purity and 80% yield could be achieved. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Chemoenzymatic synthesis and characterization of urethane oils for surface coatings

Two-step chemoenzymatic synthesis of urethane oils has been studied. Initially, the partial esters were prepared by lipase-catalyzed transesterification of soybean and linseed oils with n-butanol. Partial esters were further reacted with different diisocyanates to obtain urethane oils. The composition of the partial esters was varied with reaction time in the transesterification step. Among all the lipases, the lipozyme was found to be the most suitable lipase for the transesterification reaction, yielding 80–85%. All of the urethane oils were of low molecular weights irrespective of the type of oil used in their preparation. Urethane oils, based on MDI, exhibited the best scratch resistance. All of the urethane oils showed good acid and alkali resistance and excellent solvent resistance. These oils also satisfactorily passed the impact resistance and the flexibility tests. Department of Chemistry, Vidyanagari, Mumbai-400 098, India.     

Integrated synthesis and extraction of short‐chain fatty acid esters by supercritical carbon dioxide

We developed an efficient, integrated reaction‐extraction process for the production of short‐chain fatty acid ethyl esters (FAEE) from milk fat, using carbon dioxide as the only processing solvent. FAEE were synthesized using a short‐chain fatty acid selective lipase. The expansion of the liquid mixture of reactants by dense carbon dioxide enhanced the apparent lipase selectivity. In situ extraction of FAEE by a continuous flow of supercritical carbon dioxide proved to increase the lipase production rate. When the integrated process was operated with alternated periods of synthesis and product removal, the overall selectivity for short‐chain FAEE increased as well, as a result of the combination of the selectivities of lipase and extraction solvent. A two‐fold increase of the lipase productivity was achieved at these conditions, compared to a single batch reaction. The developed process enables the synthesis and isolation of high‐value fatty acid derivatives from a natural source such as milk fat. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

FAME Production and Fatty Acid Profiles from Moist Chlorella sp. and Nannochloropsis oculata Biomass

In the present study, we investigated the production of fatty acid methyl esters (FAME) from moist Chlorella sp. and Nannochloropsis oculata biomass using a hydrolysis–esterification process. Additionally, we evaluated for the first time the fatty acid profile before and after this process. Hydrolysis of the lipid fraction was performed on a moist biomass in the presence of differing amounts of an acid catalyst in both 50 and 100 % w/w water relative to the biomass. The esterification of the crude extracts of the free fatty acids (FFA) was then investigated. The experiments show that in the presence of 50 % w/w water relative to the biomass, the hydrolysis–esterification process results in higher FFA and FAME yields. The analysis of the fatty ester profiles did not reveal any degradation of the FFA from the microalgae biomass under the hydrolysis–esterification conditions. The results were compared with both extraction–transesterification and direct transesterification processes using dry biomass. The extraction–transesterification and hydrolysis–esterification processes resulted in similar FAME yields and similar profiles of the fatty esters from dry and moist biomass materials, respectively.     

Lipase‐catalyzed alcoholysis of vegetable oils

Fatty acid alkyl esters were produced from various vegetable oils by transesterification with different alcohols using immobilized lipases. Using n‐hexane as organic solvent, all immobilized lipases tested were found to be active during methanolysis. Highest conversion (97%) was observed with Thermomyces lanuginosa lipase after 24 h. In contrast, this lipase was almost inactive in a solvent‐free reaction medium using methanol or 2‐propanol as alcohol substrates. This could be overcome by a three‐step addition of methanol, which works efficiently for a range of vegetable oils (e.g. cottonseed, peanut, sunflower, palm olein, coconut and palm kernel) using immobilized lipases from Pseudomonas fluorescens (AK lipase) and Rhizomucor miehei (RM lipase). Repeated batch reactions showed that Rhizomucor miehei lipase was very stable over 120 h. AK and RM lipases also showed acceptable conversion levels for cottonseed oil with ethanol, 1‐propanol, 1‐butanol and isobutanol (50‐65% conversion after 24 h) in solvent‐free conditions. Methyl and isopropyl fatty acid esters obtained by enzymatic alcoholysis of natural vegetable oils can find application in biodiesel fuels and cosmetics industry, respectively.     

Fatty acids of Thespesia populnea: Mass spectrometry of picolinyl esters of cyclopropene fatty acids

Thespesia populnea belongs to the plant family of Malvaceae which contain cyclopropane and cyclopropene fatty acids. However, previous literature reports vary regarding the content of these compounds in Thespesia populnea seed oil. In this work, the content of malvalic acid (8,9‐methylene‐9‐heptadecenoic acid) in the fatty acid profile of Thespesia populnea seed oil was approximately 7% by GC. Two cyclopropane fatty acids were identified, including dihydrosterculic acid. The methyl and picolinyl esters of Thespesia populnea seed oil were also prepared. The mass spectrum of picolinyl malvalate was more closely investigated, especially an ion at m/e 279, which does not fit the typical series of ions observed in picolinyl esters. It is shown that this ion is caused by cleavage at the picolinyl moiety and contains the fatty acid chain without the picolinyl moiety. This type of cleavage has previously not been observed prominently in picolinyl esters and may therefore be diagnostic for picolinyl esters of cyclopropene fatty acids. The NMR spectra of Thespesia populnea methyl esters are also discussed. Practical applications: The work reports the fatty acid composition of Thespesia seed oil whose derivatives have not yet been extensively utilized for industrial purposes, for example, biodiesel. Knowing this composition is essential for understanding potential uses and, for example, in case of biodiesel the fuel properties. Besides this issue, some data (mass spectrometry and NMR) crucial for obtaining the composition information are analyzed in detail. The biodiesel properties of methyl esters of Thespesia populnea will be reported separately.     

Transesterification Catalysts from Iron Doped Hydrotalcite-like Precursors: Solid Bases for Biodiesel Production

Abstract Described are new solid base catalysts for transesterification of seed oil triglycerides to fatty acid methyl esters, a key step in biodiesel production. These were prepared by substituting Fe3+ ions substitute for a fraction of the Al3+ ions in the Mg/Al layered double hydroxide lattices of hydrotalcites (HTC) and calcining to give porous metal oxides (PMOs). These iron-doped PMOs are much stronger bases than those derived from undoped or Ga3+ doped HTCs and are effective catalysts for the methanol transesterification of triacetin (glycerol triacetate) and of soybean oil. Graphical Abstract New solid base catalysts for transesterification of seed oil triglycerides to fatty acid methyl esters, a key step in biodiesel production, were prepared by substituting Fe³⁺ for Al³⁺ cations in hydrotalcite (HTC) structures and calcining to give porous metal oxides.