Single‐step ultrasonic synthesis of biodiesel from crude Jatropha curcas oil

A novel single‐step process with chlorosulfonic acid catalyst for ultrasonic biodiesel synthesis using feedstock with high free fatty acid content is investigated.Jatropha curcas oil has been used as the model feedstock with methanol as alcohol. The distinct merit of chlorosulfonic acid is that it catalyzes both esterification and transesterification reactions. Moreover, chlorosulfonic acid also counteracts inhibition caused by water formed during esterification, which is the cause for very slow kinetics of acid catalyzed transesterification. In addition, sonication of the reaction mixture also causes strong micromixing and emulsification that enhances the transesterification kinetics. Statistical optimization of the process shows 93% yield for 8.5 wt % catalyst, 20:1 alcohol to oil molar ratio and temperature of 333 K. Peculiar feature of this process is that high yield is seen at moderate temperature and molar ratio, which are much smaller than that for conventional sulfuric acid catalyzed processes. The activation energy for the process (57 kJ/mol) is at least 3× lower than the energy for sulfuric acid catalyzed transesterification. The thermodynamic analysis reveals that the net Gibbs energy change for the single‐step process is almost same as that for sulfuric acid catalyzed process. © 2014 American Institute of Chemical Engineers AIChE J, 60: 1572–1581, 2014     

Heterogeneous esterification of oil with high amount of free fatty acids

Frying oils have become the newest raw material for the transesterification reaction for the production of biodiesel. However, these compounds usually come with a certain amount of free fatty acids. These impurities can be transformed into esters and the production of biodiesel could be increased.The use of basic resins to perform the esterification reaction into biodiesel is studied in this work. The effect of the most relevant variables of the process such as reaction temperature, molar ratio between alcohol and oil, amount of catalyst and amount of free fatty acids fed with the oil have been analyzed. For this purpose, an ideal frying oil using oleic acid and soybean oil was made. The alcohol used was ethanol.The esterification of free fatty acid using this heterogeneous catalyst appears as a great alternative to purify frying oil; in this case, the final conversion achieved was around 80%.     

Biodiesel production from high FFA rubber seed oil

Currently, most of the biodiesel is produced from the refined/edible type oils using methanol and an alkaline catalyst. However, large amount of non-edible type oils and fats are available. The difficulty with alkaline-esterification of these oils is that they often contain large amounts of free fatty acids (FFA). These free fatty acids quickly react with the alkaline catalyst to produce soaps that inhibit the separation of the ester and glycerin. A two-step transesterification process is developed to convert the high FFA oils to its mono-esters. The first step, acid catalyzed esterification reduces the FFA content of the oil to less than 2%. The second step, alkaline catalyzed transesterification process converts the products of the first step to its mono-esters and glycerol. The major factors affect the conversion efficiency of the process such as molar ratio, amount of catalyst, reaction temperature and reaction duration is analyzed. The two-step esterification procedure converts rubber seed oil to its methyl esters. The viscosity of biodiesel oil is nearer to that of diesel and the calorific value is about 14% less than that of diesel. The important properties of biodiesel such as specific gravity, flash point, cloud point and pour point are found out and compared with that of diesel. This study supports the production of biodiesel from unrefined rubber seed oil as a viable alternative to the diesel fuel.     

An ideal feedstock, kusum (Schleichera triguga) for preparation of biodiesel: Optimization of parameters

Kusum (Schleichera triguga), a non-edible oil bearing plant has been used as an ideal feedstock for biodiesel development in the present study. Various physical and chemical parameters of the raw oil and the fatty acid methyl esters derived have been tested to confirm its suitability as a biodiesel fuel. The fatty acid component of the oil was tested by gas chromatography. The acid value of the oil was determined by titration and was found to 21.30 mg KOH/g which required two step transesterification. Acid value was brought down by esterification using sulfuric acid (H₂SO₄) as a catalyst. Thereafter, alkaline transesterification was carried out using potassium hydroxide (KOH) as catalyst for conversion of kusum oil to its methyl esters. Various parameters such as molar ratio, amount of catalyst and reaction time were optimized and a high yield (95%) of biodiesel was achieved. The high conversion of the feedstock into esters was confirmed by analysis of the product on gas chromatograph-mass spectrometer (GC-MS). Viscosity and acid value of the product biodiesel were determined and found to be within the limits of ASTM D 6751 specifications. Elemental analysis of biodiesel showed presence of carbon, hydrogen, oxygen and absence of nitrogen and sulfur after purification. Molar ratio of methanol to oil was optimized and found to be 10:1 for acid esterification, and 8:1 for alkaline transesterification. The amounts of H₂SO₄ and KOH, 1% (v/v) and 0.7% (w/w), respectively, were found to be optimum for the reactions. The time duration of 1 h for acid esterification followed by another 1 h for alkaline transesterification at 50 ± 0.5 °C was optimum for synthesis of biodiesel.     

Continuous production of soybean biodiesel with compressed ethanol in a microtube reactor

This work investigates the production of fatty acid ethyl esters (FAEEs) from the transesterification of soybean oil in supercritical ethanol in a continuous catalyst-free process. Experiments were performed in a microtube reactor in the temperature range of 523 K to 598 K, from 10 MPa to 20 MPa, varying the oil to ethanol molar ratio from 1:10 to 1:40, and evaluating the effects of addition of carbon dioxide as co-solvent. Results showed that ethyl esters yield obtained in the microtube reactor (inner diameter 0.76 mm) were higher than those obtained in a tubular reactor (inner diameter 3.2 mm) possibly due to improved mass-transfer conditions attained inside the microtube reactor. Non-negligible reaction yields (70 wt.%) were achieved along with low total decomposition of fatty acids (< 5.0 wt.%). It is shown that the use of carbon dioxide as co-solvent in the proposed microtube reactor did not significantly affect the ethyl esters yield within the experimental variable ranges investigated.     

A novel ultrasonic reactor for continuous production of biodiesel from waste acid oil

FAME was produced by a two-step in-situ transesterification of acid oil (AO) with methanol in a novel continuous flow ultrasonic reactor system composed of four ultrasonic reactors with different frequency. The hydrodynamic behavior of the reactor was investigated by a step response technique, and the effect of ultrasonic frequency on mono-alkyl esters of long chain fatty acids (FAMEs) formation was also investigated. The production process includes an in-situ sulfuric acid-catalyzed esterification of AO with methanol in the first two ultrasonic reactors successively followed by an in-situ base-catalyzed transesterification in the other two ultrasonic reactors. The AO initial free fatty acids (FFA) content about 17.5 w% was cut down to less than 1 w% by sulfuric acid-catalyzed esterification. FAME yields in excess of 97.0% identified by gas chromatography/mass spectrometry (GC/MS) were obtained by the two-step in-situ reaction. The maximum and minimum volumetric productivity could reach 13.76 L·h^?1 and 10.24 L·h^?1 respectively.     

Biodiesel synthesis via homogeneous Lewis acid-catalyzed transesterification

Lewis acids (AlCl₃ or ZnCl₂) were used to catalyze the transesterification of canola oil with methanol in the presence of terahydrofuran (THF) as co-solvent. The conversion of canola oil into fatty acid methyl esters was monitored by ¹H NMR. NMR analysis demonstrated that AlCl₃ catalyzes both the esterification of long chain fatty acid and the transesterification of vegetable oil with methanol suggesting that the catalyst is suitable for the preparation of biodiesel from vegetable oil containing high amounts of free fatty acids. Optimization by statistical analysis showed that the conversion of triglycerides into fatty acid methyl esters using AlCl₃ as catalyst was affected by reaction time, methanol to oil molar ratio, temperature and the presence of THF as co-solvent. The optimum conditions with AlCl₃ that achieved 98% conversion were 24:1 molar ratio at 110 °C and 18 h reaction time with THF as co-solvent. The presence of THF minimized the mass transfer problem normally encountered in heterogeneous systems. ZnCl₂ was far less effective as a catalyst compared to AlCl₃, which was attributed to its lesser acidity. Nevertheless, statistical analysis showed that the conversion with the use of ZnCl₂ differs only with reaction time but not with molar ratio.     

Production of ethyl ester from crude palm oil by two-step reaction with a microwave system

The production of ethyl esters of fatty acids from a feed material of crude palm oil (CPO) with a high free fatty acid (FFA) content under microwave assistance has been investigated. Parametric studies have been carried out to investigate the optimum conditions for the esterification process (amount of ethanol, amount of catalyst, reaction time, and microwave power). As a result, a molar ratio of FFA to ethanol of 1:24 with 4% wt./wt. of H₂SO₄/FFA, a microwave power of 70 W, and a reaction time of 60 min have been identified as optimum reaction parameters for the esterification process aided by microwave heating. At the end of the esterification process, the amount of FFA had been reduced from 7.5 wt.% to less than 2 wt.%. Similar results were obtained following conventional heating at 70 °C, but only after a reaction time of 240 min. Transesterification of the esterified palm oil has been accomplished with a molar ratio of CPO to ethanol of 1:4, 1.5 wt.% KOH as a catalyst, a microwave power of 70 W, and a reaction time of 5 min. This two-step esterification and transesterification process provided a yield of 80 wt.% with an ester content of 97.4 wt.%. The final ethyl ester product met with the specifications stipulated by ASTM D6751-02.     

微量酸催化麻疯树籽油制备生物柴油(英文)

Biodiesel produced from crude Jatropha curcas L.oil with trace sulfuric acid catalyst(0.02%-0.08% oil) was investigated at 135-184 ℃.Both esterification and transesterification can be well carried out simultane-ously.Factors affecting the process were investigated,which included the reaction temperature,reaction time,the molar ratio of alcohol to oil,catalyst amount,water content,free fatty acid(FFA) and fatty acid methyl ester(FAME) content.Under the conditions at 165 ℃,0.06%(by mass) H2SO4 of the oil mass,1.6 MPa and 20:1 methanol/oil ratio,the yield of glycerol reached 84.8% in 2 hours.FFA and FAME showed positive effect on the transesterification in certain extent.The water mass content below 1.0% did not show a noticeable effect on trans-esterification.Reaction kinetics in the range of 155 ℃ to 175 ℃ was also measured.     

In situ esterification of rice bran oil with methanol and ethanol

In situ esterifications of high-acidity rice bran oil with methanol and ethanol and with sulfuric acid as catalyst were investigated. In the esterification with methanol, all free fatty acids (FFA) dissolved in methanol were interesterified within 15 min, and it was possible to obtain nearly pure methyl esters. The amount of methyl esters obtained from a given rice bran was dependent on the FFA content of the rice bran oil. In the esterification with ethanol, it was not possible to obtain pure esters as in methanol esterification, because the solubilities of oil components in ethanol were much higher than those in methanol.     

Synthesis of Phytosteryl Esters by Using Alumina-Supported Zinc Oxide (ZnO/Al<Subscript>2</Subscript>O<Subscript>3</Subscript>) from Esterification Production of Phytosterol with Fatty Acid

The feasibility of zinc oxide-catalyzed esterification of natural phytosterols with oleic acid was investigated well by a chemical process. The influences of various reaction parameters were evaluated. Basic solid zinc oxide is the most desirable catalyst due to its high selectivity (more than 90%), reusability, activity and less corrosivity, whereas sterol selectivity with other catalysts, such as H₂SO₄, NaHSO₄ and NaOMe, did not exceed 80%. Further results showed that during zinc oxide-catalyzed synthesis, the nature of the acyl donor was of paramount importance with direct esterification with fatty acids, which gives better results with higher conversion rate selectivity and more mild reaction conditions than transesterification with methyl esters. The substrate molar ratio of 2:1 (oleic acid/phytosterol) was optimal. Other parameters such as optimal catalyst load (0.5%) and temperature (170 °C) showed a maximum production of steryl esters close to 98% after 8 h. It was also found that the amount of trans fatty acid formed in esterification was low, and the trans fatty acid content (%) in the phytosterol oleate ester fraction (3.26%) was much lower than that in free oleic oil (7.35%), which suggested that fatty acids in esters were more stable than free fatty acids regarding the combination with sterol. Immobilized ZnO could be a promising catalyst for replacing homogeneous and corrosive catalysts for esterification reactions of sterol.     

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.     

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.     

Comprehensive utilization of the mixture of oil sediments and soapstocks for producing FAME and phosphatides

Comprehensive utilization of the mixture of oil sediments (OS) and soapstock (SS) for producing FAME and phosphatides was investigated. A process consisting of three steps was employed for obtaining high conversion and by-product. In the first step, the OS–SS mixture was extracted with ethyl ether and the mixture was divided into three phases. The organic top phase contained triglycerides and phosphatides was extracted with cooled acetone and the acetone insoluble (phosphatides) was obtained. At the same time, triglycerides were separated also. In the second step, soap phase was then acidified with sulfuric acid to yield fatty acid. This “high-acid” acid oil was efficiently converted to methyl esters by acid-catalyzed esterification. The esterification reaction has been carried out with 5:1 methanol/oil (mol/mol) in the presence 3% H₂S0₄ (wt.%) as an acid catalyst at 85 °C for 5 h. FAME recovery under these conditions was 92.1% of theoretical. In the third step, alkaline catalyzed transesterification process converts the triglycerides to its mono-esters and glycerol. The optimized variables, 6:1 methanol/oil (mol/mol) with 1% NaOH (wt.%) reacted at 65 °C for 1 h, giving a maximum ester yield of 94%. Five important fuel properties of FAME from the OS–SS mixture were found to be comparable to those of No. 2 diesel fuel and conforming to both the American and German standards for biodiesel.     

Statistical optimization for biodiesel production from waste frying oil through two-step catalyzed process

The aim of this work was to investigate the optimum conditions in biodiesel production from waste frying oil using two-step catalyzed process. In the first step, sulfuric acid was used as a catalyst for the esterification reaction of free fatty acid and methanol in order to reduce the free fatty acid content to be approximate 0.5%. In the second step, the product from the first step was further reacted with methanol using potassium hydroxide as a catalyst. The Box-Behnken design of experiment was carried out using the MINITAB RELEASE 14, and the results were analyzed using response surface methodology. The optimum conditions for biodiesel production were obtained when using methanol to oil molar ratio of 6.1:1, 0.68 wt.% of sulfuric acid, at 51 °C with a reaction time of 60 min in the first step, followed by using molar ratio of methanol to product from the first step of 9.1:1, 1 wt.% KOH, at 55 °C with a reaction time of 60 min in the second step. The percentage of methyl ester in the obtained product was 90.56 ± 0.28%. In addition, the fuel properties of the produced biodiesel were in the acceptable ranges according to Thai standard for community biodiesel.     

Selectivity of lipases: isolation of fatty acids from castor,coriander, and meadowfoam oils

The lipase‐catalyzed hydrolysis of castor, coriander, and meadowfoam oils was studied in a two‐phase water/oil system. The lipases from Candida rugosa and Pseudomonas cepacia released all fatty acids from the triglycerides randomly, with the exception of castor oil. In the latter case, the P. cepacia lipase discriminated against ricinoleic acid. The lipase from Geotrichum candidum discriminated against unsaturated acids having the double bond located at the Δ‐6 (petroselinic acid in coriander oil) and Δ‐5 (meadowfoam oil) position or with a hydroxy substituent (ricinoleic acid). The expression of the selectivities of the G. candidum lipase was most pronounced in lipase‐catalyzed esterification reactions, which was exploited as part of a two‐step process to prepare highly concentrated fractions of the acids. In the first step the oils were hydrolyzed to their respective free fatty acids, in the second step a selective lipase was used to catalyze esterification of the acids with 1‐butanol. This resulted in an enrichment of the targeted acids to approximately 95—98% in the unesterified acid fractions compared to the 70—90% content in the starting acid fractions.     

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%).     

Optimization of transesterification of castor oil with ethanol using a central composite rotatable design (CCRD)

In the present study, the synthesis of fatty acid esters from castor oil using an alkaline catalyst was optimized. The variables reaction time, catalyst amount and oil:ethanol molar ratio were studied using a central composite rotatable design. The effects and significance of the models on the response variable and on ethyl biodiesel yield derived from pure castor oil were evaluated using a response surface curve and analysis of variance. All the variables significantly affected the reaction yield, the amount of catalyst being the most effective. The highest yield was obtained using an oil:ethanol molar ratio of 1:11, 1.75% KOH and a reaction time of 90 min.     

A kinetic study of the esterification of free fatty acids (FFA) in sunflower oil

The kinetics of the esterification of free fatty acids (FFA) in sunflower oil with methanol in the presence of sulphuric acid at concentrations of 5 and 10 wt% relative to free acids as catalyst and methanol/oleic acid mole ratios from 10:1 to 80:1 was studied. The experimental results were found to fit a first-order kinetic law for the forward reaction and a second-order one for the reverse reaction.The influence of temperature on the kinetic constants was determined by fitting the results to the Arrhenius equation. The energy of activation for the forward reaction decreased with increasing catalyst concentration from 50 745 to 44 559 J/mol.Based on the experimental results, a methanol/oleic acid mole ratio of 60:1, a catalyst (sulphuric acid) concentration of 5 wt% and a temperature of 60 °C provided a final acid value for the oil lower than 1 mg KOH/g oil within 120 min. This is a widely endorsed limit for efficient separation of glycerin and biodiesel during production of the latter.     

Ethanolysis of castor and cottonseed oil: A systematic study using classical catalysts

Several classical catalytic systems for the transesterification reaction have been used to produce FA ethyl esters (FAEE) from castor and cottonseed oils The effects of the amount and nature of the catalyst, and of the reaction temperature, on the yields of FAEE were determined. The most efficient transesterification of castor oil was achieved in the presence of methoxide and acid catalysts, whereas for cottonseed oil, which has a composition that is much more similar to most vegetable oils than is castor oil, the highest yields of FAEE were obtained following base-catalysed ethanolysis.