Transesterification Yield Research Articles

Desempenho de diferentes lipases imobilizadas na síntese de biodiesel de óleo de palma

Optimized conditions for palm oil and ethanol enzymatic biodiesel synthesis were determined with different immobilized lipases SiO 2 -PVA-immobilized lipase from Pseudomonas fluorescens and acrylic resin-immobilized lipase, Novozym ® 435, from Candida antartica , in solvent-free medium. A full factorial design assessed the influence of temperature (42 – 58°C) and ethanol: palm oil (6:1 – 18:1) molar ratio on the transesterification yield. Main effects were adjusted by multiple regression analysis to linear models and the maximum transesterification yield was obtained at 42°C and 18:1 ethanol: palm oil molar ratio. Mathematical models featuring total yield for each immobilized lipase were suitable to describe the experimental results.

Studies on the Catalyzing Transesterification of Soybean Oil with Methanol for Biodiesel Using a Novel Porous CaO Microsphere Catalyst

A novel porous CaO microsphere catalyst was synthesized by calcining spherical CaCO3 precursor which was prepared easily by mixing CaCl2 with Na2CO3. After characterized by scanning electron microscope and X-ray diffraction analysis, the synthesized CaO was studied on Studies on the catalyzing transesterification of soybean oil with methanol for biodiesel. The effects of calcining temperature, reaction time and temperature, amounts of catalyst and methanol on the catalytic activity of CaO microsphere had been evaluated by catalyzing transesterification of soybean oil with methanol for biodiesel. It expressed excellent catalytic activity with a transesterification yield of more than 98% at 65 °C in one hour with 3 wt% of CaO microsphere calcined at 800 °C.

Biodiesel production from Tung oil and blended oil via ultrasonic transesterification process

The effects of ultrasonic irradiation time ( t US) on the transesterification yield ( Y F) of biodiesel from Tung ( Vernicia fordii) and blended oils with CH 3OH and KOH, and on some properties of biodiesel such as acid value (AV), iodine value (IV), kinematic viscosity (KV), density and cold filter plugging point (CFPP) were investigated. The blended oil is consisted of 20, 50 and 30% of Tung, canola and palm oils, respectively. The molar ratio of methanol to oil is 6:1 and the catalyst concentration is 1 wt.%. Temperature and ultrasonic frequency were kept at 20–30 °C and 25 kHz, respectively. The t US was set in the range of 1–30 min. The results showed that Y F reaches high value of 87–91% for Tung oil as t US ≥ 5 min, while of about 92–94% for blended oil as t US ≥ 1 min. At t US = 10 min, the properties of biodiesel produced from Tung oil are with AV of 0.11 mg KOH/g, IV of 159.36 mg I 2/100 g, KV of 9.17 mm 2/s, density of 905 kg/m 3 and CFPP of −16 °C, while those from blended oil are with AV of 0.11 mg KOH/g, IV of 120.35 mg I 2/100 g, KV of 5.54 mm 2/s, density of 887 kg/m 3 and CFPP of −5 °C. Comparing these values with the ASTM-D6751 standards with AV < 0.5 mg KOH/g, KV = 1.9–6 mm 2/s and density = 860–900 kg/m 3 pointed out that the Tung oil should be blended with other oils in order to produce biodiesel satisfying the biodiesel standards. Moreover, the results indicated that a certain enough time, say 5 min, is needed to provide sufficient cavity heating and mixing via ultrasonic wave ensuring good properties of biodiesel produced. The KV of biodiesel using blended oil decreases from 6.26 mm 2/s at t US = 1 min to 5.54 mm 2/s at t US = 5 min, thus meeting the ASTM-D6751 value of 1.9–6.0 mm 2/s. The information obtained in this study is useful for the proper use of Tung oil in conjunction with other edible oils for the production of biodiesel with satisfactory qualities and the rational design and operation of ultrasonically catalytic transesterification process.

The effect of support material on the transesterification activity of CaO–La2O3and CaO–CeO2supported catalysts

The effects of support materials—lanthanum oxide, cerium oxide, zirconium oxide, titanium oxide, γ-alumina, and ZSM-5—on the transesterification activity of CaO–La2O3 and CaO–CeO2 catalysts were investigated. The metal composition and surface acidity (or basicity) of the supported catalysts played a significant role in determining the activity of the catalyst. Results showed that both catalytic activity and basicity of the supported catalysts decreased in the following order: CaO–La2O3/La2O3 ≥ CaO–La2O3/CeO2 > CaO–La2O3/ZrO2 > CaO–La2O3/γ-Al2O3 > CaO–La2O3/ZSM-5 > CaO–La2O3/TiO2. In addition, leaching of Ca species from the catalyst was more pronounced with basic supports. However, Ca leaching could be minimized by coupling with La2O3 or CeO2 on an appropriate support. This was verified in a flow reactor study of the CaO–CeO2/La2O3 catalyst, where, over 200 h of continuous operation, the transesterification yield held constant at 88∼90% while the initial Ca concentration in the product decreased from 194 ppm to below 5.0 ppm after 144 h. This further suggests that Ca leaching had little long-term effect on the overall FAME activity of the catalyst.

Influence of vegetable oils fatty-acid composition on biodiesel optimization

Biodiesel is an alternative fuel for diesel engines produced through transesterification of oleaginous feedstocks. To analyze the influence of the fatty-acid composition on biodiesel optimization, transesterification of several vegetable oils has been studied. Reactions were carried out in flasks filled with vegetable oils, heated to the reaction temperature and stirred at 1100 rpm. The reactions started when the methanol and potassium hydroxide solutions were added to the flasks. Concentration of catalyst, amount of methanol, reaction temperature and time were optimized using a factorial design and a surface response design. Also, a kinetics study was carried out to optimize the reaction time. Results showed that reaction parameters optimal values depend on the oil chemical and physical properties. It can be concluded from this field trial that the effect of both catalyst concentration and reaction time over the transesterification yield is greatly influenced by the saturation degree and fatty-acid chain length.

Biodiesel production from tung (Vernicia montana) oil and its blending properties in different fatty acid compositions

The feasibility of biodiesel production from tung (Vernicia montana) oil was investigated with respect to the transesterification yield and biodiesel properties. Tung oil has poor oxidation stability due to the instability of the conjugated carbon-carbon double bonds in the alpha-elaeostearic acid. The methyl elaeostearate is the predominant component (82.2 wt.%) of the tung oil biodiesel. The tung oil biodiesel has the low cold filter plugging point of -11 degrees C, ester content of 94.9 wt.%, and oxidation stability (110 degrees C) of 0.3h. Moreover, the tung oil biodiesel exhibits the high density of 903 kg/m(3)at 15 degrees C, kinematic viscosity of 7.84 mm(2)/s at 40 degrees C, and iodine value of 161.1g I(2)/100g. The properties of the tung oil biodiesel can be improved by blending with canola and palm oil biodiesels to satisfy the biodiesel specifications. In addition, multiple linear correlations between biodiesel properties and its methyl ester composition were established.

Factors Influencing the Use of Various Low-Value Oils in Biodiesel Production

Various low-value oils, namely, crude palm oil (CPO), crude jatropha oil (CJO), and used frying oil (UFO), were investigated by comparing them as feed oils used in biodiesel (BD) production, with the objective of clarifying the effects of various factors that influence the feed oil characteristics on the required feed pretreatment (FP), operating conditions in transesterification, and the obtained biodiesel yield and purity. First, the low-value oils were characterized in terms of fatty acid compositions and the contents of undesirable impurities. All the feed oils contained mainly C16 and C18 fatty acid chains, and the content of C16 in CPO was higher than the contents of C16 in the other feed oils. The highest contents of impurities, namely, a phospholipid, free fatty acid (FFA), and water were found in CJO. Then, the feed oils were pretreated under various conditions and subsequently transesterified to convert triglycerides to BD in the methyl ester form. The BD productivity and quality could be improved by proper feed pretreatment; deacidification and dehydration were particularly effective. Alkali deacidification is not appropriate for treating CJO since significant oil loss was observed during neutralization of FFA in deacidification. Lastly, the pretreated oils whose impurity contents were sufficiently low were transesterified under varying operating conditions. CPO gave a relatively lower yield but higher purity than the other oils because of the higher C16 content in the feed oil, which had a negative effect on yield but increased the purity in the BD product. For all feed oils, the purity of the obtained BD met the standard for BD purity, and the transesterification yields were improved by carrying out the appropriate FP, as well as adjusting the amounts of alcohol and catalyst in transesterification according to the type of feed oil. The obtained results can be applied to select the appropriate feed oils and maximize BD productivity in the BD production from various low-value oils.

Operation variables in transesterification of vegetable oil: an enzymatic catalysis review

This paper presents the results of a literature review regarding how operating conditions influence vegetable oil enzymatic transesterification yield. The following parameters were studied: temperature and time reaction, alcohol:oil molar ratio, alcohol type, biocatalyst type and concentration, solvent, mixed intensity, reagent purity and free fatty acid and moisture concentration. Yields greater than 90% can be achieved in the enzymatic catalyst of vegetable oil using 35-50°C temperatures, long time reactions (7-90h) and a 3:1 alcohol:vegetable oil molar ratio; however, such values would intrinsically depend on the type of lipase and oil used. It was also found that free fatty acid and moisture concentration were parameters which did not require rigorous control due to high enzyme specificity. Lipases immobilized from Pseudomona cepacia bacteria and Rhizopus orizae fungi were most used in vegetable oil enzymatic transesterification.

An integrated approach to produce biodiesel and monoglycerides by enzymatic interestification of babassu oil ( Orbinya sp)

Two screenings of commercial lipases were performed to find a lipase with superior performance for the integrated production of biodiesel and monoglycerides. The first screening was carried out under alcoholysis conditions using ethanol as acyl acceptor to convert triglycerides to their corresponding ethyl esters (biodiesel). The second screening was performed under glycerolysis conditions to yield monoglycerides (MG). All lipases were immobilized on silica–PVA composite by covalent immobilization. The assays were performed using babassu oil and alcohols (ethanol or glycerol) in solvent free systems. For both substrates, lipase from Burkholderia cepacia (lipase PS) was found to be the most suitable enzyme to attain satisfactory yields. To further improve the process, the Response Surface Methodology (RSM) was used to determine the optima operating conditions for each biotransformation. For biodiesel production, the highest transesterification yield (>98%) was achieved within 48 h reaction at 39 °C using an oil-to-ethanol molar ratio of 1:7. For MG production, optima conditions corresponded to oil-to-glycerol molar ratio of 1:15 at 55 °C, yielding 25 wt.% MG in 6 h reaction. These results show the potential of B. cepacia lipase to catalyze both reactions and the feasibility to consider an integrated approach for biodiesel and MG production.

Biont shell catalyst for biodiesel production

A novel high performance solid biodiesel catalyst derived from biont shell has been prepared by a tri-step procedure: incomplete carbonization–KF impregnation–activation. The effects of carbonization temperature, concentration of KF solution and activation temperature on the activity of the catalyst were investigated. The activity of the biont shell catalyst was evaluated by transesterification of rapeseed oil with methanol and the mechanism of catalytic activity is discussed. The results indicate that the transesterification yield of rapeseed oil to biodiesel reaches 97.5% with 3 hours reaction and 3 wt% catalyst dosage (based on rapeseed oil mass). The activity of the catalyst for the transesterification came from the active sites formed by reaction of incompletely carbonized biont shell with KF in the procedure of synthesis catalyst. The matrix of the biont catalyst is weakly polar in nature, favoring transesterification of rapeseed oil to biodiesel and hindering the reverse glycerolysis reaction. Therefore, the biont catalyst displayed a higher catalytic activity compared with conventional solid base catalysts tested for biodiesel production.

Biodiesel Synthesis by Enzymatic Transesterification of Palm Oil with Ethanol Using Lipases from Several Sources Immobilized on Silica–PVA Composite

This work deals with the transesterification of palm oil with ethanol in a solvent free system using lipase from different sources (Thermomyces lanuginosus, Pseudomonas fluorescens, Burkholderia cepacia, Penicillium camembertii, and Candida antarctica, porcine pancreatic) immobilized on hybrid support polysiloxane–poly(vinyl alcohol). This is an exceptional option for the Brazilian biodiesel production, because both palm oil and ethanol are readily available in the country. The enzyme source showed strong influence on the transesterification yields, and the best performance was attained with the lipase from Pseudomonas fluorescens that reached almost full conversion (≅98 %) in less than 24 h of reaction. The purified product (biodiesel) was straw yellow in color and essentially odorless. Purity of the fatty acid ethyl ester was found to be high having no glycerol bound as verified by NMR 13C (APT, attached proton test). In addition, the other properties such as low water content (0.02%), specific gravity ...

Lipase-catalyzed transesterification of dihydrocaffeic acid with flaxseed oil for the synthesis of phenolic lipids

Lipase-catalyzed transesterification reaction of dihydrocaffeic acid (DHCA) with flaxseed oil in organic solvent media was investigated. Using equal molar concentration of DHCA and flaxseed oil, only phenolic monoacylglycerols were obtained with a transesterification yield (TY) of 18.9%. A 1:4 DHCA to flaxseed oil ratio resulted in the production of both phenolic mono and diacylglycerols, with TY of 39.6 and 27.8%, respectively. On the other hand, when 1:8 ratio of DHCA to flaxseed oil was used, the TY of phenolic diacylglycerols (46.0%) was higher than that of the phenolic monoacylglycerols (33.3%). The TY of phenolic diacylglycerols increased from 25.1 to 55.8%, when the ratio of the hexane/2-butanone reaction medium was changed from 65:35 to 85:25 (v/v); however, the TY of phenolic monoacylglycerols decreased slightly from 34.0 to 31.8%. The relative proportion of the C(18:3)n-3 was higher in the phenolic mono and diacylglycerols, 64.9 and 59.5%, respectively, as compared to the original flaxseed oil, 53.1%. The radical scavenging ability of phenolic lipids was significant; however, it was about half than that of alpha-tocopherol.

Chemoenzymatic synthesis of structured triacylglycerols with conjugated linoleic acids (CLA) in central position

A chemoenzymatic process for the production of structured triacylglycerols (TAG) containing CLA at sn2 position and lauric acid at external ones is proposed. First, castor bean oil was chemically dehydrated and isomerised to obtain a new modified oil with very high proportion of CLA (>95%). Then, this new oil was used for enzymatic transesterification allowing the grafting of lauric acid at external positions of the TAG backbone by using 1,3 regioselective enzymes. Among these, Aspergillus niger lipase was not satisfactory giving very low lauroyl incorporation (<5%) On the contrary, lipases from Thermomyces lanuginosa (Lipozyme TL IM) and from Carica papaya latex allowed good reaction yields. The effect of the type of acyl donor was studied. With alkyl esters T. lanuginosa lipase provided a final incorporation of 58.9% after 72 h corresponding to 88.4% transesterification yield. Concerning C. papaya lipase, incorporation of lauroyl residues was lower than Lipozyme TL IM. This lipase exhibited higher performance with lauric acid accounting for 44.7% lauroyl incorporation at the end of reaction for a 67.1% transesterification yield. The effect of the substrates mole ratio was also evaluated. It was observed that a 1:3 TAG/acyl donor mole ratio was the most efficient for both lipases. Finally, fatty acids regiodistribution of the newly formed structured TAG was determined. With Lipozyme TL IM, the proportion of lauric acid incorporated at the sn2 position did not exceed 5.4% after 72 h while with C. papaya lipase a more pronounced incorporation of lauroyl residues at the central position (8.8%) was observed.

Biodiesel: an overview

The importance of biodiesel production was analyzed based on scientific articles and patents. A critical analysis was presented on the most used oil sources, the catalysts and the methods to verify the transesterification yields. Also analyzed were the comparative studies on emissions from pure fossil diesel and mixtures with biodiesel in variable proportions. Finally some challenges and considerations focused on technological, agronomic and infrastructure aspects of biodiesel production were indicated.

Comparison of esterification and transesterification of fructose by porcine pancreas lipase immobilized on different supports

The syntheses of fructose butyrate with five different immobilized porcine pancreas lipases were studied in acetonitrile with butyric acid and tributyrin as acyl donors. The hydrolytic activities of the enzymes were measured during the syntheses. The transesterification yield was the highest with the Celite-adsorbed enzyme: 57% (1.42 g fructose butyrate l−1), and this form exhibited the highest degree of hydrolytic activity preservation (57%) after operation for 20 days.

An original transesterification route for fatty acid ester production from vegetable oils in a solvent‐free system

AbstractWax ester production from a long‐chain alcohol and methyl ester has been investigated with an immobilized thermostable lipase (lipozyme IM from Novo Nordisk). The transesterification reaction rate was monitored in solvent‐free medium that was exclusively composed of the reactants and the enzyme. The transesterification is performed by simply mixing the two substrates in various stoichiometric amounts at a temperature range from 55 to 65°C under constant stirring in the presence of low concentrations of enzyme preparation (0.12 to 2%, w/w). Long‐chain reactants produce waxes of high molecular mass that induce low solubility and high viscosity. On average, high transesterification yields are obtained (around 95%). Thermodynamic parameters involving substrate concentration and temperature have also been investigated. The balance between optimal working temperature and the molar ratio of substrates in such a complex medium appears to be 60°C, with a molar ratio methyl oleate/stearyl alcohol of 1:0.5. Substrate inhibition due to stearyl alcohol has been observed. A study of kinetic parameters has confirmed these results.

Influence of the reaction medium on enzyme activity in bio-organic synthesis: behaviour of lipase from Candida rugosa in the presence of polar additives.

Lipase from Candida rugosa immobilized on Celite was employed as the biocatalyst in order to examine the effect of the reaction medium upon enzymic activity and selectivity. As the model reaction, transesterification between tributyrin and pentan-2-ol in iso-octane (2,2,4-trimethylpentane) was chosen. A small amount of water (0.05%, v/v) was added to the reaction medium. Enhanced transesterification yields and increased selectivity of the lipase could be obtained by manipulating the microenvironment of the catalyst. Addition of 0.2% NN-dimethylformamide allowed a 93% higher ester yield compared with that obtained when no extra addition was made. Under the same conditions, the ratio of the amount of transesterification product over the amount of hydrolysis product after 48 h, became 52% higher than the ratio determined in the absence of additives. It was concluded that addition of compounds that have low logP3 (P is the partition coefficient in the octanol/water two-phase system) values and high dielectric constant was advantageous in order to favour transesterification over hydrolytic processes.