Transesterification Of Vegetable Oils Research Articles

Characterization of Catalysts for Glycerol Ester Production with Various Acetylating Agents

ABSTRACTThe use of raw materials from renewable sources by industries is essential to the sustainable development of modern society. The biodiesel produced by the transesterification of vegetable oils is a less polluting diesel fuel, but large amounts of glycerol (10% of total weight of product) are generated during the production process. The scientific community and industries of the sector know that, in the future, the amount of glycerol generated can cause a serious ecologic problem. Thus, it is essential to find alternatives for the consumption of this co-product, in its crude form and/or as high value-added derivatives. This work studied obtaining triacetate from the glycerol esterification reaction that was determined by electrospray ionization–mass spectrometry and gas chromatography–mass spectrometry. The reactions were carried out with sulfuric acid, phosphotungstic acid and in the absence of catalyst, using different acetylating agents (acetic acid and acetic anhydride). The phosphotungstic acid showed satisfactory performance in the catalytic esterification of glycerol when acetic acid and acid anhydride were used. The use of acetic anhydride as the acetylating agent favors the esterification reaction, decreasing the reaction time required for obtaining glycerol triacetate.

Hydrogel-Templated Solid Base Catalysts for Transesterification of Soybean Oil.

A new method for utilization of hydrogel is proposed here for the preparation of solid base catalysts for the transesterification of vegetable oil. When a solution of KF is mixed with a solution of Ca(NO3)2, CaF2 is obtained and inactive as a catalyst in the transesterification of vegetable oils. The catalysts were synthesized by the sequential incorporation of KF and/or Ca(NO3)2 solutions into the hydrogel upon microwave irradiation and then the as-obtained hydrogel was calcined at 800°C for 5 hours to eliminate the template and yield catalysts for the biodiesel productions. The prepared catalysts obtained by the different ways in the incorporation of ions into the hydrogel showed different physical properties and catalytic activities in the transesterification of soybean oil. All catalysts, except the low concentration of Ca(NO3)2, exhibiting the high activity yielding more than 90% FAME after 1 hour at 65°C, using oil to methanol molar ratio of 1:15 and 10 wt% of catalyst amounts.

Kinetics & Simulation of Non-catalytic Esterification

Transesterification of vegetable oil using alkali catalyst is the main reaction in the biodiesel production. The presence of free fatty acids in the feed oil can react with alkali and initiates the saponification reaction. Therefore, the FFA present in the oil needs to be esterified before sending it to the transesterification process. Esterification reaction can take place in the presence or absence of the catalyst. The catalytic esterification process is associated with disadvantages like corrosion of equipment, requires neutralization of the catalyst & tedious separation process. On the other hand, non-catalytic esterification is free from those issues and also offers the advantage of ease of separation of the formed esters. In the present study, the reaction of free fatty acids present in Karanja oil with methanol was studied in a batch reactor. Kinetics was modeled and the kinetic parameters were obtained. The obtained kinetic parameters were used to simulate the process in Aspen plus® ver. 8.6. The feasibility of estimating kinetic parameters through nonlinear regression was tested and compared against experimental results. Experimentally, 96.21% conversion of free fatty acids was observed at 220°C & 1:6 (w/v) Karanja oil to methanol ratio. Whereas simulation results show that more than 96% conversion may be possible under similar conditions. The reaction is found to be spontaneous only at high temperatures due to the positive values obtained for enthalpy, entropy and Gibbs free energy.

Rhizoclonium grande Bioethanol in Biofuel Production by Transesterification of Jatropha curcas Oil

There is a need for an alternative sustainable fuel based on renewable sources and efficient carbon dioxide scrubbers. Alkyl esters prepared by transesterification of vegetable oils from various plants have been evaluated. In this work the potential of sustainable macroalgae bioethanol in biofuel production by transesterification of Jatropha curcas oil was assessed. Rhizoclonium grande macroalgae was collected from Shimoni shores in Kwale, Shelly beach in Mombasa, Jamvi la Wageni in Mtongwe Likoni, English point near Kenya Marine and Fisheries Research Institute (KMFRI) Mombasa, dried and processed to obtain 5.36% ± 0.355% v/w bioethanol using Aspergilus niger for hydrolysis and Saccharomyces cerevisiae for fermentation. J. curcas seeds were collected from contracted farmers of Energy Africa in Shimba hills, Coast region. Oil from the seeds was machine cold pressed and solvent extracted using n-hexane giving 44% - 53%v/w yield. The physicochemical properties of the J. curcas oil were investigated. Transesterification of J. curcas oil was carried out using bioethanol from the algae with 63% - 70% FAEE yield. Characterisation of the bioethanol and ethyl esters was done using GC-MS. Physicochemical and fuel properties of the biofuel were investigated at Technical University of Mombasa (TUM), Jomo Kenyatta University of Agriculture and Technology (JKUAT), Government Chemist and Kenya Pipeline Laboratories in Mombasa. There was significant difference in physicochemical and fuel properties observed in density, calorific value, kinematic viscosity, pour point and cloud point between the Jatropha oil and Jatropha fatty acid ethyl esters (JAT FAEE) samples. No significant difference observed in the physicochemical and fuel properties between the JAT FAEE and standard biodiesel samples. This was according to statistical analysis of data done using STATA/SE 13.0 and Xlstat at 95% confidence level (P < 0.05) two-tailed. From the findings bioethanol from R. grande biomass used in transesterification has a potential to improve the sustainability, physicochemical and fuel properties of biofuel from J. curcas a non-food crop. The effect of the use of bioethanol and its byproduct on shelf life of the biofuel can further be investigated.

Optimization Models Type Box-Behnken in the Obtaining of Biodiesel from Waste Frying Oil using a Large-acidity Carbonaceous Catalyst

AbstractThe trans-esterification and esterification of waste vegetable oil mainly under sub-critical temperature of methanol in the presence of sulfonated char were achieved. The carbonaceous materials were analyzed by means of various physical and chemical techniques such as Raman spectroscopy, X-ray diffractometry, temperature programmed desorption and X-ray photoelectrons spectroscopy. The carbon-based large-acidity catalyst showed good chemical and thermal properties and a high performance in the production of methyl esters from waste vegetable oil, which was easily separated from the liquid mixture. A temperature of 210°C, reaction time of 20 min and a catalyst amount of 0.03 g were the optimal experimental conditions for the trans-esterification of the vegetable oil with methanol giving a conversion to triglycerides of 96.5% according to the response surface methodology. The design of experiments type Box-Behnken was successfully applied to study effects of the parameters in the production of biodiesel and it presented optimal conditions for maximum performance with values near to those experimentally found. The catalyst was recovered from the final mixture by filtration and reused without regeneration showing a catalytic activity stable up to 4 or more reaction cycles.

Kinetics of the biphasic liquid–liquid transesterification of vegetable oils into biodiesel

Alkaline transesterifications (methanolysis, ethanolysis) of vegetable oils (soybean, sunflower) were conducted under conditions selected by an experimental design, producing biodiesels (fatty methyl esters 97.5 wt%; fatty ethyl esters 96.7 wt%) with high quality characteristics identified by reduced sodium content (0.11 mg kg−1), low levels of glycerol concentration (0.01 wt%), acidity (0.31 mg NaOH g−1) and viscosity (4.81 mm2 s−1). Evidence indicated that in a first stage, the triglyceride slowly dispersed in the alcohol phase, and then promoted the rapid production of esters: the biodiesel yield increased from 52.0 to 97.5% in methanolysis and from 44. 0 to 96.7% in ethanolysis. A mathematical model was formulated, including biphasic effects between the liquid phases, with respect to partition equilibrium, mass transfer and chemical reaction. The kinetics of the biphasic transesterification processes were characterized quantitatively through the order of magnitude of the mass transfer coefficient of the triglycerides (K TG = 5.82 × 10−4 s−1, at 303 K − 5.86 × 10−2 s−1, at 353 K), and of the specific reaction rate (k = 3.48 × 10−3 s−1, at 303 K − 5.78 × 10−3 s−1 at 353 K). Resistances related to these effects indicated that they compete during the evolution of the processes.

Effect of Non-Edible Biodiesel Physical and Chemical Properties as Microturbine Fuel

The world is facing critical energy concern, in view of depleting fossil fuel reserves and increasing environment pollution. Biodiesel can potentially substitute fossil fuel, and is produced through the transesterification of vegetable oils. This paper will emphasize on the transition from first generation derived from waste cooking oil, to second generation biodiesel derived from calophyllum inophyllum, which is a non-edible plant. The objective of this paper is to optimize the performance of biodiesel blends with diesel in a 30 kW microturbine. The characterization of chemical fuel properties of distillate and biodiesel blends will be conducted to determine if it meets international standards for power generation. Temperature profiles, pressure, and flame imaging will be closely monitored to detect possible problems in operability of the combustor caused by the differences in fuel characteristics. The findings may provide useful information towards optimization of microturbine performance, considering the wide range of biodiesel feedstock that exist. The paper outcome will show the potential of non-edible biodiesel blends to be used as alternative fuel in microturbines for power generation.

ZnAl-Zr hydrotalcite-like compounds activated at low temperature as solid base catalyst for the transesterification of vegetable oils

ZnAl hydrotalcite-like compounds were modified through the incorporation of Zr+4 using molar ratios of Zr/Al(X)=0.0, 0.10 and 0.25. The synthesis of these materials was performed by the co-precipitation method and their physicochemical properties were characterized by XRD, UV-Vis-DRS, N2 physisorption, TGA, and finally, the basic properties were analyzed by titration with benzoic acid and adsorption of methanol analyzed by FT-IR. It was found that 200ºC is the most appropriate activation temperature, since the catalytic activity of ZnAl-Zr(X) materials on the transesterification reaction was enhanced, obtaining FAME yields ranging from 68% to 82%. This high catalytic activity at low activation temperature (200ºC) was attributed to the presence of a mixture of the active phases: hydrotalcite, zincite, and hydrozincite; as well as the formation of Brönsted and Lewis basic sites when the hydrotalcite-type materials are dehydrated. In addition, it was possible to calculate the apparent reaction rate constants by means of a simplified lumped first-order reaction model. The reaction rate constant for the ZnAl-Zr(0.25) catalyst was 12.4 x10-3 L/gcat.min which is 1.5 times greater than that of the catalyst without Zr.

Catalysis of vegetable oil transesterification by Sn(II)-exchanged Keggin heteropolyacids: bifunctional solid acid catalysts

Keggin heteropolyacid protons (i.e., H3PW12O40, H3PMo12O40, H4SiW12O40) were partially exchanged with Sn(II) cations generating solid acid catalysts that were used for vegetable oil transesterification reactions. These catalysts have double acidity properties, i.e., Lewis acidity and Bronsted acidity that are suitable for the conversion of vegetable oil into biodiesel. The highest efficiency (ca. 100%) was achieved on the Sn1.2H0.6PW12O40-catalyzed transesterification reactions. The relationship between the catalytic activity and acidic properties was deeply discussed and the effects of main reaction parameters were assessed. The activity of the precursor HPA, tin salts and physical mixture were compared and confirmed a synergism between Sn(II) cations and PW12O40 3− anions. The reusability of catalyst was investigated.

Transesterification of vegetable oil on low cost and efficient meat and bone meal biochar catalysts

In this manuscript, the biochar obtained from waste pig meat and bone meal was modified and served as the support for the preparation of cost-effective solid base catalysts for the transesterification reaction. The composition, structure and texture of prepared catalysts were examined by scanning electron microscope (SEM), energy dispersive spectrometer (EDS), N2 adsorption/desorption, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and the Hammett indicator method. In addition, the effects of catalyst preparation conditions, reaction conditions and the catalyst reusability were studied in detail. Meanwhile, the mechanism of catalyst was also discussed. It was found that the surface area and pore volume of the biochar were increased significantly (from 142.644m2/g and 190.63mm3/g to 430.517m2/g and 486.56mm3/g, respectively) by chemical activation treatment with KOH. The best performance is observed for the resulting 30K/AMB-550 catalyst, and over biodiesel yield of 98.2% was achieved at catalyst amount of 5wt%, methanol/oil molar ratio of 7:1 and reaction time of 150min. Besides, after reused for 10 cycles, only a slight deactivation was found (above 84% of yield obtained) due to K+ ions leached into reaction media.

Optimization of methyl ester production from waste cooking oil in a batch tri-orifice oscillatory baffled reactor

Transesterification of vegetable oils is a common route for the production of biodiesel. This reaction is a slow mass transfer limited reaction that has been shown to benefit from process intensification reactors such as the Oscillatory Baffled Reactor (OBR). The use of waste cooking oil as a resource is an attractive alternative to other virgin vegetable oils that will enable the capital costs of biodiesel production to be largely decreased, thereby making biodiesel an affordable and competitive fuel. In this study, optimization of biodiesel, or fatty acid methyl ester (FAME) production from waste cooking oil (WCO) was investigated using a batch OBR (diameter=0.06m, height=0.55m) with multi-orifice baffles, which have been recommended for scale-up. Response Surface Methodology (RSM) was applied to study the effects and interaction of different operating parameters: oscillation frequency (in the range 2.4–4.9Hz), inter-baffle spacing (in the range 0.05–0.09m) and reaction temperature (in the range 40–60°C). It was found that temperature is the main factor influencing reaction yield and the interaction between temperature and oscillation frequency is non-negligible. Inter-baffle spacing does not, however, have a significant effect on the reaction. This is different from the design recommendations of OBRs in the literature, which were originally developed for single orifice baffles. An optimal reaction yield of 81.9% was obtained with an oscillation frequency of 4.1Hz and an inter-baffle spacing of 5cm (i.e. approximately 1.5de) at a temperature of 60°C. However, similar reaction yields could be obtained for different values of inter-baffle spacing.

Shea nut shell based catalysts for the production of ethanolic biodiesel

This work focused on the synthesis of charcoal as carbonaceous catalyst support for the ethanol transesterification of vegetable oil to produce biodiesel. Shea (Vitellaria paradoxa) nut shells (SNS) were used as raw material to prepare an activated carbon based catalyst by chemical activation with potassium hydroxide (KOH). A central composite design of the response surface methodology (RSM) was used to investigate the interactive effect of the SNS-K catalyst synthesis parameters (pyrolysis temperature, residence time and KOH impregnation ratio) and its catalytic activity in sunflower ethanol transesterification. Experimental yields reached >90% ester content in the biodiesel, with a catalyst prepared under mild pyrolysis conditions. Results showed that the temperature of pyrolysis and the KOH ratio used to impregnate SNS are the most important factors influencing the SNS-K catalytic activity. Catalyst prepared between 400°C and 650°C, with 120min residence time and a biomass: KOH ratio of between 14% and 17.5% produced the highest ethyl ester content (96%) with an optimal catalyst prepared at 650°C, with 120min residence time and 14% KOH loading. SNS-K catalyst characterization by X-ray diffraction (XRD) showed potassium carbonate to be the main active potassium species responsible for catalytic activity. Recyclability tests showed that the catalyst can be reused after a thermal post treatment without catalytic activity loss. Thus, this new simple catalytic process allows biodiesel production under mild conditions, using local reactant (i.e. bioethanol, vegetable oils and char from local agricultural residues). This can be a realistic alternative process for a shift towards sustainable energy in sub-Saharan Africa.

Critical aggregates concentration of fatty esters present in biodiesel determined by turbidity and fluorescence.

Biodiesel for combustible engine is available as mixture of fossil diesel and fatty esters obtained by transesterification of vegetable oils. The use of biodiesel reduces the amount of SOx, mainly. However, it was already observed that biodiesel has a different behavior in environment in cases of accidental spill and groundwater contamination. It was noticed that the biodegradation of hydrocarbons (cyclic and aliphatic) in the presence of biodiesel are speeded, although the mechanism is still unclear. Considering the chemical structure of fatty esters, it was investigated the formation of aggregates in water solution by fatty esters present in commercial biodiesel. In Brazil, biodiesel is composed by 95% of fossil diesel and 5% of fatty esters mixture. In this work, fatty esters were treated as neutral surfactant, i.e., it was treated as a molecule with polar and non-polar part. Turbidity and fluorescence were used to determine the critical aggregates concentration (CAC). Water solutions containing fatty esters were examined exploiting changes in turbidity and fluorescence intensity of pyrene. Abrupt changes were attributed to aggregates formation, following the same behavior of traditional amphiphilic compounds. It was determined the CAC for ethyl palmitate, ethyl stearate, ethyl oleate, and ethyl linoleate. The values of CAC for fatty esters varied from 1.91 to 4.27μmol/L, while CAC for the mixture of esters (biodiesel) was 2.01 for methyl esters and 1.19 for ethyl esters, both prepared using soybean oil. The aggregates formation was also determined by fluorescence measurements considering the changes in intensity of peaks I and III of pyrene. Pyrene senses the changes in environment polarity. The values found of CAC by fluorescence for individual ethyl esters varied from 1.85 to 3.21μmol/L, while mixtures of ethyl esters was 2.23 and 2.07μmol/L for mixture of methyl esters. The results clearly showed that fatty esters form aggregates and might be responsible for speed degradation of compounds by accommodation of them in inner part of aggregates.

A review of production, properties and advantages of biodiesel

ABSTRACTContinuous use of fossil fuels (non-renewable natural resources) are depleting fastaly and its burning cousing accumulation of carbon dioxide in the environment. Renewable carbon neutral transport fuels are required for environmental and economic sustainability. Biodiesel derived from oil crops is a potential renewable carbon neutral alternative to petroleum fuels. It consists of monoalkyl esters of long-chain fatty acids and is primarily produced by direct use and blending, microemulsions, thermal cracking (pyrolysis) and transesterification. The most commonly used method for biodiesel production is transesterification of vegetable oils and animal fats. There are several processes available for the transesterification reaction including batch process, supercritical processes, ultrasonic methods and microwave methods. The factors which influence the transesterification reaction are water content of oils or fats and free fatty acids, molar ratio of glycerides to alcohol, catalysts, reaction time and reaction temperature. In this present review, the importance, history, properties, sources and techniques for production of biodiesel are described.

Production of biodiesel from jatropha curcas oil using solid heterogeneous acid catalyst

Biodiesel produced by the transesterification of vegetable oils is a promising alternative fuel to diesel because of limited fossil fuel resources and environmental concerns. The use of heterogeneous catalysts greatly simplifies the technological process by facilitating the separation of the post-reaction mixture. The use of heterogeneous catalysts greatly simplifies the technological process by facilitating the separation of the post-reaction mixture. The purpose of the present work was to examine a heterogeneous catalyst, in particular, to produce methyl esters of jatropha curcas oil (JCO). In this study, the trans esterification of JCO with methanol was studied in a heterogeneous system, using Mg-Al hydrotalcites as solid base catalysts. The dependence of the conversion of JCO on the reactions variables such as the molar ratio of methanol/ oil, the amount of catalysts used, reaction temperatures and reaction times were performed. The conversion of 99% was achieved under the optimum reaction conditions.

Improving Sorbents for Glycerol Capture in Biodiesel Refinement.

Biodiesel is produced by transesterification of animal fat, vegetable oil, or waste cooking oil with alcohol. After production costs, the economic viability of biodiesel is dependent on what steps are necessary to remove impurities following synthesis and the effectiveness of quality control analysis. Solid-phase extraction offers a potentially advantageous approach in biodiesel processing applications. Nanoporous scaffolds were investigated for adsorption of glycerol, a side product of biodiesel synthesis that is detrimental to engine combustion when present. Materials were synthesized with varying pore wall composition, including ethane and diethylbenzene bridging groups, and sulfonated to promote hydrogen bonding interactions with glycerol. Materials bearing sulfonate groups throughout the scaffold walls as well as those post-synthetically grafted onto the surfaces show notably superior performance for uptake of glycerol. The sorbents are effective when used in biodiesel mixtures, removing greater than 90% of glycerol from a biodiesel preparation.

Supercritical Transesterification of Waste Vegetable Oil: Characteristic Comparison of Ethanol and Methanol as Solvents

Transesterification of waste vegetable oil is one of the promising partial substitutes for fossil fuels. The degradation characteristics of waste vegetable oil using supercritical alcohols (ethanol and methanol) have been studied in this research. The elementary target was to conduct comparative analysis of the effect of supercritical methanol and supercritical ethanol as solvents on the transesterification along with the analysis of product obtained in terms of carbon number. The experiments were carried out at transesterification temperatures of 250, 270 and 290 °C, retention time of 0 to 60 min at an interval of 15 min and oil to alcohol molar ratios of 1:6, 1:12 and 1:18 for both alcohols. The conversion increased with increase in transesterification temperature and retention time. At 290 °C, almost 99% conversion was achieved for 60-min holding time for both alcohols. Increase in conversion of waste vegetable oil was observed as the molar ratio increased. Supercritical transesterification resulted into ester yield higher than 95% with non-ester composition and glycerol collectively less than 5%.

Development of a New Solid Catalyst for Biodiesel Production Using Local Vegetable Resources, Adapted to the Contexts of the West African Countries

African countries are increasingly interested in biofuels to provide access to energy. The development of local technologies using local resources for biodiesel production can be a promising solution. This work is a first step towards the development of a simple process of transesterification of vegetable oil using local resources. The aim of this study is to explore new solid catalysts made of a potassium phase supported on char, for the production of biodiesel by transesterification of vegetable oil with ethanol. Catalysts were prepared by impregnating shea nut shells with four selected potassium precursors KCl, KOH, K2CO3, and KNO3, and then pyrolyzed. The thermal behaviour of the impregnated biomass as well as the potassium crystalline phase in the catalysts were investigated. The effects of the type of potassium precursor, pyrolysis temperature and the amount of catalyst on the conversion of oil to ethyl ester were analyzed. Results showed that increasing pyrolysis temperature enhanced the conversion of oil. Catalysts obtained from KOH and K2CO3 precursors displayed better activity than the other catalysts. The catalytic activity was found to be related to a K2CO3 crystalline phase. For conditions of transesterification at 10 wt% of catalyst, a reaction temperature of 70 °C and only 10 min reaction time, ethyl ester contents were 97.6 wt% for KOH and 99.1 wt% for K2CO3 based catalysts. Both catalysts allowed a good ethyl-ester yield in soft temperature and pressure conditions, and in a short time.

Larvicidal activity of vegetable oils and esterified compounds against Culex quinquefasciatus (Diptera: Culicidae)

Control of Culex quinquefasciatus using chemical insecticides may result in the selection of resistant mosquito strains. Thus, the use of plant-derived products has been studied as alternative for the mosquito control. Fatty acid methyl esters (FAMEs) obtained by transesterification of vegetable oils may result in compounds with larvicidal potential against C. quinquefasciatus. However, little is known about the morphological, physiological or biochemical effects that these FAMEs may have on mosquito larvae. The present study reports the effects of these FAMEs in mosquito larvae. The FAMEs were obtained by transesterification of canola, corn, sunflower, and soybean oils with acid catalysis and the determination of FAMEs composition was done by gas chromatography-mass spectrometry (GC-MS). Larvae of C. quinquefasciatus were exposed to different concentrations of the vegetable oils and FAMEs. Thereby, different FAMEs showed LC50 values ranging from 42.32 to 196.27mg/L against C. quinquefasciatus larvae. The methyl ester obtained from sunflower oil showed the lowest LC50. Histology of C. quinquefasciatus larvae exposed to LC50 of FAMEs was performed and changes in the midgut and fat body morphology were identified. Therefore, larval mortality and changes in the internal organs suggested that FAMEs might be a promising new class of larvicidalcompounds. Cytotoxicity of FAMEs compounds was assessed with the HeLa human cell line and no effect was observed.

Highly Efficient and Recyclable Metal Salt Catalyst for the Production of Biodiesel: Toward Greener Process

AbstractA highly reactive and recyclable metal catalyst was reported for the transesterification of model vegetable oil with methanol to produce fatty acid methyl esters (FAMEs) under microwave condition. Among the screened catalysts, Al2(SO4)3 provided the highest FAME yield of 98.1 % at 130 oC within 30 min. Different reaction parameters were fully investigated which were found to have great influences on the product yields. Microwave energy showed a remarkable accelerated reaction rate as compared to that from the conventional oil heating way. The catalytic system also showed good tolerance to water and free fatty acids. The catalyst can be easily recovered through a simple extraction/evaporation, which still posed good reactivity in the recycling runs. The characters of the obtained biodiesel was also characterized. Mechanistic studies revealed that the hydrolysis of the metal salt to generate the corresponding cationic and acidic species were responsible for the good catalytic activity of the reaction.