Optimization of Cottonseed Oil Ethanolysis to Produce Biodiesel High in Gossypol Content

Transesterification of cottonseed oil was carried out using ethanol and potassium hydroxide (KOH). A central composite design with six center and six axial points was used to study the effect of catalyst concentration, molar ratio of ethanol to cottonseed oil and reaction temperature for percentage yield (% yield) and percentage initial absorbance (%A _385nm) of the biodiesel. Catalyst concentration and molar ratio of ethanol to cottonseed oil were the most significant variables affecting percentage conversion and %A _385nm. Maximum predicted % yield of 98% was obtained at a catalyst concentration of 1.07% (wt/wt) and ethanol to cottonseed oil molar ratio of 20:1 at reaction temperature of 25 °C. Maximum predicted %A _385nm of more than 80% was obtained at 0.5% (wt/wt) catalyst concentration and molar ratio of 3:1 at 25 °C. The response surfaces that described % yield and %A _385nm were inversely related. Gossypol concentration (% wt), oxidative stability and %A _385nm of biodiesel were found to be highly correlated with each other. Hence, color %A _385nm is a measure of the amount of pigments present in biodiesel fuels that have not yet been subjected to autoxidation. High gossypol concentration also corresponds to a fuel with high oxidative stability. The fatty acid ethyl esters (FAEE) produced from cottonseed oil had superior oxidative stability to fatty acid methyl esters (FAME) produced from cottonseed oil.     

Response surface modeling and optimization of biodiesel production from Cynara cardunculus oil

Cardoon (Cynara cardunculus L.) is a perennial spontaneous thistle grown in Mediterranean countries and well adapted to marginal lands, recently considered as a non‐food energy crop. Their seeds contain 24% of oil (dry basis). In this study, modeling and optimization of the production of fatty acid methyl esters (FAME) from cardoon oil for biodiesel uses was performed at laboratory scale, via response surface methodology, following a central composite rotatable design. FAME were obtained by transesterification of crude cardoon oil with methanol in the presence of a catalyst (sodium methoxide) for 120 min. The temperature ranged from 26 to 94 °C, the amount of sodium methoxide varied between 0.12 and 2.5 wt‐% and the molar ratio methanol/oil from 0.95 : 1 to 11 : 1. The estimated yield of FAME (97%) was obtained after 30 min, at 52 °C, for a molar ratio of 6.4 : 1 and 1.4 wt‐% of catalyst. In laboratory‐scale model validation experiments, 94% of FAME yield was obtained after 30 min of reaction. Transesterification was performed in a 30‐L reactor, under previously optimized conditions: A yield of 88% FAME was obtained after 90 min of reaction time, due to mass transfer limitations. After purification, the biodiesel showed high quality according to DIN EN 14214 standard specifications.     

Biodiesel Synthesis from Styrax confusus Hemsl Catalyzed by S2O82−/ZrO2‐TiO2‐Fe3O4

Biodiesel has been identified as a suitable resource that can be produced from biomass such as Styrax confusus Hemsl. In the current study, biodiesel was synthesized from Styrax confusus Hemsl oil catalyzed by a magnetic solid acid heterogeneous catalyst S₂O₈^2?/ZrO₂‐TiO₂‐Fe₃O₄, which had a high recovery rate and reusability. The catalyst was prepared by co‐precipitation and characterized by Fourier transform infrared spectroscopy, X‐ray diffraction and Brunauer, Emmett and Teller (BET) adsorption. The properties of the catalyst, including the recovery rate, usage count, magnetic susceptibility and catalytic efficiency, were studied. The results showed that the catalyst has a BET pore diameter of 1.74 nm, BET area of 7.3 m²/g, molar magnetic susceptibility of 1.83 × 10^?5 m³/kg and tetragonal structure. In addition, the influences of reaction conditions on yields of biodiesel were also discussed. A fatty acid methyl ester (FAME) yield of 90.02 % was obtained under the conditions of reaction time 1.5 h, reaction temperature 373 K, catalyst amount 5 %, and methanol‐to‐oil molar ratio 8:1. A FAME yield of 65.5 % was obtained when the catalyst was used for the fourth time.     

Development of solid base catalyst X/Y/MgO/γ-Al2O3 for optimization of preparation of biodiesel from Jatropha curcas L.seed oil

The preparation and regeneration conditions of the identified catalyst X/Y/MgO/γ-Al₂O₃ with high catalytic activity were studied and optimized. The biodiesel was prepared by transesterification of Jatropha curcas seed oil produced in Guizhou with methanol at its reflux temoerature in the presence of X/Y/MgO/γ-Al₂O₃. The pilot plant tests were carried out in a 100 L reaction vessel. Both average yield and fatty acid methyl esters (FAME) content reached more than 96.50% under the optimum reaction conditions of the pilot plant tests designed withan oil/methanol molar ratio of 1: 10, catalyst concentration of 1.00%, and reaction time of 3 h at reflux temperature. In addition, analysis shows that the quality of biodiesel meets the standard EN 14214. __________ Translated from Modern Chemical Industry, 2007, 27(Suppl. 2): 452–455 [译自: 现代化工]     

Effect of Different Cosolvents on Transesterification of Waste Cooking Oil in a Microreactor

Biodiesel was prepared from waste cooking oil combined with methanol. The process was performed via transesterification in a microreactor using kettle limescale as a heterogeneous catalyst and various cosolvents under different conditions. n‐Hexane and tetrahydrofuran were selected as cosolvents to investigate fatty acid methyl esters (FAMEs). To optimize the reaction conditions, the main parameters affecting FAME% including reaction temperature, catalyst concentration, oil‐to‐methanol volumetric ratio, and cosolvent‐to‐methanol volumetric ratio were studied via response surface methodology. Under optimal reaction conditions and in the presence of the cosolvents n‐hexane and tetrahydrofuran, high FAME purities were achieved. Considering the experimental results, the limescale catalyst is a unique material, and the cosolvent method can reduce significantly the reaction time and biodiesel production cost.     

Oil transesterification over calcium oxides modified with lanthanum

Investigations were conducted on a series of calcium and lanthanum oxides catalyst for biodiesel production. Mixed oxides catalyst showed a superior transesterification activity over pure calcium or pure lanthanum oxide catalysts. The catalyst activity was correlated with surface basicity and specific surface areas. The effects of water and free fatty acids (FFA) levels in oil feedstock, water and CO₂ in air, mass ratio of catalyst, molar ratio of oil to methanol, and reaction temperature on fatty acid methyl ester (FAME) yield were investigated. Under optimal conditions, FAME yields reached 94.3% within 60 min at 58 °C. Mixed CaO-La₂O₃ catalyst showed a high tolerance to water and FFA, and could be used for converting pure or diluted unrefined/waste oils to biodiesel.     

Application of the immobilized bacterial recombinant lipase from <Emphasis Type="Italic">Geobacillus stearothermophilus</Emphasis> G3 for the production of fatty acid methyl esters

The heterogeneous BCL biocatalyst based on the recombinant extracellular lipase from the thermophilic bacteria Geobacillus stearothermophilus G3 with an activity of 23.6 U.A./g was prepared by covalent immobilization on aminated silica gel. The effect of the solvent, temperature (30–60°C), methanol : oil molar ratio (1 : 1 to 9 : 1), and the amounts of water (1–10%) and catalyst (0.25–25%) on the yield of fatty acid methyl esters (FAME) during the methanolysis of sunflower oil with BCL was studied. The maximum yield of FAME was 43%. The biocatalyst exhibits high operational stability: after 480 h of operation (20 cycles), it retains more than 50% of its original activity, making BCL a promising catalyst for application in manufacturing of FAME as feedstock for biodiesel production.     

Optimization of biodiesel production process in a continuous microchannel using response surface methodology

We assessed the biodiesel production process in a continuous microchannel through preparation of a heterogeneous catalyst (CaO/MgO) from demineralized water plant sediment. This mixed oxide catalyst was used for transesterification of rapeseed oil as feedstock by methanol to produce biodiesel fuel at various conditions. A microchannel, utilized as a novel reactor, was applied to convert rapeseed oil into biodiesel in multiple steps. The effects of the process variables, such as catalyst concentration, methanol to oil volume ratio, n-hexane to oil volume ratio, and reaction temperature on the purity of biodiesel, were carefully investigated. Box-Behnken experimental design was employed to obtain the maximum purity of biodiesel response surface methodology. The optimum condition for the production of biodiesel was the following: catalyst concentration of 7.875 wt%, methanol to oil volume ratio of 1.75: 3, n-hexane to oil volume ratio of 0.575: 1, and reaction temperature of 70 °C.     

Calcium oxide as a solid base catalyst for transesterification of soybean oil and its application to biodiesel production

In order to study solid base catalyst for biodiesel production with environmental benignity, transesterification of edible soybean oil with refluxing methanol was carried out in the presence of calcium oxide (CaO), -hydroxide (Ca(OH)₂), or -carbonate (CaCO₃). At 1 h of reaction time, yield of FAME was 93% for CaO, 12% for Ca(OH)₂, and 0% for CaCO₃. Under the same reacting condition, sodium hydroxide with the homogeneous catalysis brought about the complete conversion into FAME. Also, CaO was used for the further tests transesterifying waste cooking oil (WCO) with acid value of 5.1 mg-KOH/g. The yield of FAME was above 99% at 2 h of reaction time, but a portion of catalyst changed into calcium soap by reacting with free fatty acids included in WCO at initial stage of the transesterification. Owing to the neutralizing reaction of the catalyst, concentration of calcium in FAME increased from 187 ppm to 3065 ppm. By processing WCO at reflux of methanol in the presence of cation-exchange resin, only the free fatty acids could be converted into FAME. The transesterification of the processed WCO with acid value of 0.3 mg-KOH/g resulted in the production of FAME including calcium of 565 ppm.     

Conversion of biomass to fuel: Transesterification of vegetable oil to biodiesel using KF loaded nano-γ-Al2O3 as catalyst

KF-impregnated nanoparticles of γ-Al₂O₃ were calcinated and used as heterogeneous catalysts for the transesterification of vegetable oil with methanol for the synthesis of biodiesel (fatty acid methyl esters, FAME). The ratio of KF to nano-γ-Al₂O₃, calcination temperature, molar ratio of methanol/oil, transesterification reaction temperature and time, and the concentration of the catalyst were used as the parameters of the study. A methyl ester yield of 97.7 ± 2.14% was obtained under the catalyst preparation and transesterification conditions of KF loading of 15 wt%, calcination temperature of 773 K, 8 h of reaction time at 338 K, and using 3 wt% catalysts and molar ratio of methanol/oil of 15:1. This relatively high conversion of vegetable oil to biodiesel is considered to be associated with the achieved relatively high basicity of the catalyst surface (1.68 mmol/g) and the high surface to volume ratio of the nanoparticles of γ-Al₂O₃.     

Lipase‐mediated methanolysis of soybean oils for biodiesel production

BACKGROUND: Biodiesel is increasingly perceived as an important component of solutions to the important current issues of fossil fuel shortages and environmental pollution. Biocatalysis of soybean oils using soluble lipase offers an alternative approach to lipase‐catalyzed biodiesel production using immobilized enzyme or whole‐cell catalysis. The central composite design (CCD) of response surface methodology (RSM) was used here to evaluate the effects of enzyme concentration, temperature, molar ratio of methanol to oil and stirring rate on the yield of fatty methyl ester. RESULTS: Lipase NS81006 from a genetically modified Aspergillus oryzae was utilized as the catalyst for the transesterification of soybean oil for biodiesel production. The experimental data showed that enzyme concentration, molar ratio of methanol to oil and stirring rate had the most significant impact on the yield of fatty methyl ester; a quadratic polynomial equation was obtained for methyl ester yield by multiple regression analysis. The predicted biodiesel yield was 0.928 (w/w) under the optimal conditions and the subsequent verification experiments with biodiesel yield of 0.936 ± 0.014 (w/w) confirmed the validity of the predicted model. CONCLUSION: RSM and CCD were suitable techniques to optimize the transesterification of soybean oil for biodiesel production by soluble lipase NS81006. The related lipase NS81006 reuse stability, chemical or genetic modification, and transesterification mechanism should be taken into consideration. Copyright © 2007 Society of Chemical Industry     

Characterization of Trimethylolpropane‐Based Biolubricant

The oxidative stability index (OSI) of fatty acid methyl esters (FAME) and trimethylolpropane (TMP) esters or TMPE produced from five vegetable oils (Brassica rapa L., Linum usitatissimum L., Zea mays L., Brassica napus L., Camelina sativa L.) are compared. The highest stability is observed in vegetable oils while the processed products are less stable. The major causes in loss of OSI are attributed to excess FAME in the crude product and the loss of natural antioxidants due to refinement with silica and celite. The low‐temperature flow properties of TMPE produced from four different vegetable oils (B. juncea L., L. usitatissimum L., B. rapa L., and C. sativa L.) are investigated by proton nuclear magnetic resonance (¹H‐NMR). The T2 relaxations of different TMPE are measured to observe how the mobility of oil changed as temperature decreased. Increased oil mobility (represented by T2) is correlated with rising temperature. The Gaussian widths of the singlet in ¹H‐NMR spectra of each oil demonstrated increased molecular mobility as temperature increased. Extrapolation of the relation of T2 signals of these four oils indicates that T2 approached zero between 232 K and 239 K, suggesting the molecular motion leading to a T2 relaxation has largely ceased. Practical Applications: The OSI is determined for four vegetable oils as well as the product FAME and TMPE. The vegetable oils are more stable than their products. The loss of natural antioxidants during purification of FAME and TMPE contributes to the lower OSI compared to vegetable oil. The low‐temperature flow behavior of TMP‐based biolubricants is determined between 238 K and 298 K using T2 relaxation. As temperature decreases, a singlet resonance in ¹H‐NMR spectra attributed to TMP protons broadens until it disappears. The results suggest that the log of the spin‐spin relaxation time is linearly correlated with rising temperature and oil mobility.     

Transesterification of vegetable oil to biodiesel fuel using alkaline catalyst

Biodiesel is gaining more and more importance as an attractive fuel due to the depleting fossil fuel resources. Chemically biodiesel is monoalkyl esters of long chain fatty acids derived from renewable feed stock like vegetable oils and animal fats. It is produced by transesterification in which, oil or fat is reacted with a monohydric alcohol in presence of a catalyst to give the corresponding monoalkyl esters. This article reports experimental data on the production of fatty acid methyl esters from vegetable oils, soybean and cottonseed oils using sodium hydroxide as alkaline catalyst. The variables affecting the yield and characteristics of the biodiesel produced from these vegetable oils were studied. The variables investigated were reaction time (1-3 h), catalyst concentration (0.5-1.5 w/wt%), and oil-to-methanol molar ratio (1:3-1:9). From the obtained results, the best yield percentage was obtained using a methanol/oil molar ratio of 6:1, sodium hydroxide as catalyst (1%) and 60 ± 1 °C temperature for 1 h. The yield of the fatty acid methyl ester (FAME) was determined according to HPLC. The composition of the FAME was determined according to gas chromatography. The biodiesel samples were physicochemically characterized. From the results it was clear that the produced biodiesel fuel was within the recommended standards of biodiesel fuel.     

Cerbera odollam (sea mango) oil as a promising non-edible feedstock for biodiesel production

This paper explores the feasibility of converting Cerbera odollam (sea mango) oil into biodiesel. The first part of this study focused on the extraction of oil from the seeds of C. odollam fruits, whereas the second part focused on the transesterification of the extracted oil to fatty acid methyl esters (FAME). The transesterification reactions were carried out using three different catalysts; sodium hydroxide (NaOH) as a homogenous catalyst, sulfated zirconia alumina and montmorillonite KSF as heterogeneous catalysts. The seeds were found to contain high percentage of oil up to 54% while the yield of FAME can reach up to 83.8% using sulfated zirconia catalyst.     

Transesterification of sunflower oil in a countercurrent trickle-bed reactor packed with a CaO catalyst

Transesterification of sunflower oil with methanol to form biodiesel was performed in a countercurrent trickle-bed reactor, using calcium oxide particles 1-2 mm in diameter as a packed, solid base catalyst. Although biodiesel production generally requires a reaction temperature below the boiling point of methanol to maintain a heterogeneous, liquid-liquid reaction, in the present study the reaction temperature was varied from 80 to 140 °C to confirm the progress of transesterification in a gas-liquid-solid phase reaction system. Oil droplets released from a thin tube flowed downward, while vaporized methanol flowed upward in the bed. The effects of the reaction temperature, methanol and oil flow rates, and the bed height on the FAME yield were investigated. The oil residence time in the reactor, which was controlled by changing both the oil flow rate and the bed height, had a significant effect on the FAME yield. In addition, the FAME yield increased with reaction temperature and was maximal at 373 K due to the change in residence time associated with reduced oil viscosity at higher temperatures. The FAME yield was 98% at a reaction temperature of 373 K when the methanol and oil flow rates were 3.8 and 4.1 mL/h, respectively.     

Dolomite as a heterogeneous catalyst for transesterification of canola oil

In this study, the catalytic activity of dolomite was evaluated for the transesterification of canola oil with methanol to biodiesel in a heterogeneous system. The influence of the calcination temperature of the catalyst and the reaction variables such as the temperature, catalyst amount, methanol/canola oil molar ratio, and time in biodiesel production were investigated. The maximum activity was obtained with the catalyst calcined at 850 °C. When the reaction was carried out at reflux of methanol, with a 6:1 molar ratio of methanol to canola oil and a catalyst amount of 3 wt.% the highest FAME yield of 91.78% was obtained after 3 h of reaction time.     

Long term activity of modified ZnO nanoparticles for transesterification

Biodiesel can be produced by the transesterification of natural oils with methanol using modified ZnO nanoparticles as catalyst. Crude algae oil, corn oil from DDGs, crude palm oil, crude soybean oil, crude coconut oil, waste cooking oil, food-grade soybean oil and food-grade soybean oil with 3% water and 5% FFA addition were converted into FAME within 3 h using this new catalyst. The ZnO nanoparticles were reused 17 times without any activity loss in a batch stirred reactor and the average yield of FAME was around 93.7%. ZnO nanoparticles were used continuously for 70 days in a fix bed continuous reactor and the average yield of FAME was around 92.3%. XRD, ICP, TEM and HRTEM were used to characterize the long term used catalyst structure. Results show that this catalyst is a mixture of wurtzite ZnO nanoparticles and some amorphous materials and that the used catalysts have similar crystal structure to fresh catalyst. ICP results show that this catalyst does not dissolve in biodiesel, methanol, oil and glycerine-methanol solutions. It has a stable crystal structure under the reaction conditions. The high catalytic activity, long catalyst life and low leaching properties demonstrate these modified ZnO nanoparticles have potential in a commercial biodiesel production process.     

High-Area Ti/Pt Electrodes for the Electrochemically Catalyzed Transesterification of Soybean Oil with Methanol

Biodiesel fuel is a renewable energy source normally produced in industry by using an alkaline homogeneous catalyst to promote the transesterification of oil and methanol to fatty acid methyl ester (FAME). Undesirable side reactions occur when poorly refined oils are used, leading to serious problems of product separation and low FAME yield. Therefore, about 85% of the cost of biodiesel is determined by the cost of the feedstock. Here, we describe the development of high-area Pt films deposited on Ti substrates for the electrolytic synthesis of biodiesel from soybean oil containing water, without the addition of catalyst. The higher both the calcination temperature and the number of layers deposited on the Ti surface, the higher the electrochemically active area of Pt exposed to surface. Conversion into esters in electrolysis is proportional to the increase in the superficial area of the Ti/Pt electrodes. Thus, it is possible to synthesize biodiesel using electrodes containing very low amounts of Pt (<0.441 mg cm^?2), an important parameter in the industrial production of biodiesel.     

Biodiesel production from soybean oil using modified calcium loaded on rice husk activated carbon as a low-cost basic catalyst

Activated carbon was obtained by hydrothermal process using rice husk as raw materials. The study in our lab had been developed to produce high-quality biodiesel from soybean oil with the activated carbon-base catalyst. The polyethylene glycol (PEG 400) modified calcium loaded on the rice husk activated carbon (CaO/AC) catalyst was prepared via the dipping method and then was used as a heterogeneous solid-base catalyst to produce biodiesel. The effects of CaO/AC ratio and calcination time on catalytic performance were researched according to the yield of biodiesel, and the optimum reaction conditions for biodiesel from soybean oil via PEG 400–modified CaO/AC catalyst were evaluated. The results showed that the yield of fatty acid methyl ester (FAME) achieved 93.01% at the reaction temperature of 342 K, methanol/oil molar ratio of 10:1, and reaction time of 6 h. All in all, modified CaO/AC catalyst showed very high activity for transesterification of soybean oil and had catalytic repeated availability.     

A Quantitative Method of Analysis for Sterol Glycosides in Biodiesel and FAME Using GC-FID

Sterol glycosides (SG) are known to cause filter blocking problems in biodiesel use. The extraction and quantitative analysis of SG is difficult due to its low problematic concentration and its compatibility with biodiesel. The purpose of this study is to develop a method to quantify SG in FAME and biodiesel using gas chromatography and other equipment found in laboratories performing routine biodiesel analyses. SG was isolated from FAME using n‐dodecane, acidification and cold soaking, followed by cold centrifugation at ?8 to ?15 °C. The solids obtained were further separated by phase partition with a Folch wash, followed by a final n‐dodecane rinse. This solution was analyzed by GC‐FID using the operating conditions outlined in ASTM D6584. A calibration curve for SG was produced and a first order fit gave a value of r² = 0.992. Reproducibility tests were performed on soybean FAME and B100 canola biodiesel samples spiked with SG. The recovery of SG by the new method was found to be 99 % for soy FAME with a standard deviation of 0.7 and 100 % for B100 canola with a standard deviation of 3.5 %. The reproducibility based on two standard deviations of the predicted concentration for all 12 spiked samples studied in this work was 2.4 ppm.