叔戊醇体系酶促大豆油制备生物柴油

叔戊醇作为反应介质,固定化脂肪酶Novozym 435催化大豆油与甲醇的转酯反应制备生物柴油。叔戊醇消除了反应底物甲醇及反应副产物甘油对酶活的负面影响。定量分析表明,叔戊醇与油脂的体积比为1,甲醇与油脂的摩尔比为3,2%脂肪酶,反应体系含水量2%,40 ℃、180 r/min条件下反应15 h,生物柴油得率可达97%。在最适条件下反应进行160批次,酶仍保持了较高的活性和良好的稳定性。     

Optimized synthesis of lipase‐catalyzed biodiesel by Novozym 435

The ability of immobilized lipase from Candida antarctica (Novozym 435) to catalyze the alcoholysis of canola oil and methanol was investigated. Response surface methodology (RSM) and five–level–five–factor central composite rotatable design (CCRD) were employed to evaluate the effects of synthesis parameters, such as reaction time, temperature, enzyme concentration, substrate molar ratio of methanol to canola oil, and added water content on percentage weight conversion of canola oil methyl ester by alcoholysis. Reaction temperature and enzyme concentration were the most important variables. High temperature and superabundant methanol inhibited the ability of Novozym 435 to catalyze the synthesis of biodiesel. Based on the analysis of ridge max, the optimum synthesis conditions were as follows: reaction time 12.4 h, temperature 38.0 °C, enzyme concentration 42.3%, substrate molar ratio 3.5:1, and added water 7.2%. The predicted value was 99.4% weight conversion, and the actual experimental value was 97.9% weight conversion. Copyright © 2004 Society of Chemical Industry     

Biodiesel preparation catalyzed by compound-lipase in co-solvent

Besides high cost, the most important reasons that immobilized lipases are limited in industrialization of biodiesel production are the toxicity of methanol and the adsorption of glycerol onto the surface of immobilized vector. Solvent engineering method was employed to the reaction where compound-lipase with synergistic effect, Novozym 435 and Lipozyme TL IM, catalyzed preparation of biodiesel from stillingia oil with methanol. The treatment accelerated the solubility of methanol in oil and dissolved glycerol, which helped maintain lipase activity. It is found that the yields of biodiesel in co-solvent exceeded those in the pure organic solvents. The mixture system of co-solvent with 60% acetonitrile and 40% t-butanol (v/v) was proved to be an optimal one, and RSM was used to optimize the reaction factors and the optimal conditions: methanol/oil molar ratio 6.4:1, compound-lipase 4.32% (wt/wt) and molecular sieve 5.5% (wt/wt). R²= 98.86% showed good coincidence between predicted and experimental values. There was nearly no loss inactivity of compound-lipase after being recycled for 30 times. Other oils were also investigated in the mixture system, and we got the same results, which indicated that the mixture system could be an ideal prospective medium applied to biodiesel production.     

Continuous enzymatic production of biodiesel from virgin and waste sunflower oil in supercritical carbon dioxide

A continuous process for biodiesel production in supercritical carbon dioxide was implemented. In the transesterification of virgin sunflower oil with methanol, Lipozyme TL IM led to fatty acid methyl esters yields (FAME) that exceeded 98% at 20 MPa and 40 °C, for a residence time of 20 s and an oil to methanol molar ratio of 1:24. Even for moderate reaction conversions, a fractionation stage based on two separators afforded FAME with >96% purity. Lipozyme TL IM was less efficient with waste cooking sunflower oil. In this case, a combination of Lipozyme TL IM and Novozym 435 afforded FAME yields nearing 99%.     

Production of biodiesel from palm oil using liquid core lipase encapsulated in κ-carrageenan

This work deals with the enzymatic transesterification of palm oil with methanol in a solvent-free system. Among the five lipases tested in the initial screening, lipase PS from Burkholderia cepacia resulted in the highest triglyceride conversion. Lipase PS was further investigated in a novel immobilized form by encapsulating within a biopolymer, κ-carrageenan. Using the immobilized lipase the production parameters of biodiesel from palm oil were optimized. The optimal conditions for processing 10 g of palm oil was: 30 °C, 1:7 oil/methanol molar ratio, 1 g water, 5.25 g immobilized lipase, 72 h reaction time and 23.7g relative centrifugal force. At the optimal conditions, triglyceride conversion of up to 100% could be obtained. The immobilized lipase was stable and retained 82% relative transesterification activity after five cycles. Liquid core lipase encapsulated in κ-carrageenan could be a potential immobilized catalyst for eco-friendly production of biodiesel.     

Continuous production of fatty acid methyl esters from corn oil in a supercritical carbon dioxide bioreactor

Continuous production of fatty acid methyl esters (FAMEs) from corn oil was studied in a supercritical carbon dioxide (SC-CO₂) bioreactor using immobilized lipase (Novozym 435) as catalyst. Response surface methodology (RSM) based on central composite rotatable design (CCRD) was employed to investigate and optimize the reaction conditions: pressure (11-35 MPa), temperature (35-63 °C), substrate mole ratio (methanol:corn oil 1-9) and CO₂ flow rate (0.4-3.6 L/min, measured at ambient conditions). Increasing the substrate mole ratio increased the FAME content, whereas increasing pressure decreased the FAME content. Higher conversions were obtained at higher and lower temperatures and CO₂ flow rates compared to moderate temperatures and CO₂ flow rates. The optimal reaction conditions generated from the predictive model for the maximum FAME content were 19.4 MPa, 62.9 °C, 7.03 substrate mole ratio and 0.72 L/min CO₂ flow rate. The optimum predicted FAME content was 98.9% compared to an actual value of 93.3 ± 1.1% (w/w). The SC-CO₂ bioreactor packed with immobilized lipase shows great potential for biodiesel production.     

Transesterification for biodiesel production catalyzed by combined lipases: Optimization and kinetics

Preparation of biodiesel from waste cooking oil catalyzed by combined lipases in tert‐butanol medium was investigated. Several crucial parameters affecting biodiesel yield were optimized by response surface methodology, such as dosage of combined lipases of Novozym 435 and Lipozyme TLIM, weight ratio of Novozym 435 to Lipozyme TLIM, amount of tert‐butanol, reaction temperature, and molar ratio of oil to methanol. Under the optimized conditions, the highest biodiesel yield was up to 83.5% The proposed model on biodiesel yield had a satisfactory coefficient of R² (= 94.02%), and was experimentally verified. The combined lipases exhibited high‐operational stability. After 30 cycles (300 h) successively, the activity of combined lipases maintained 85% of its original activity. A reaction kinetic model was proposed to describe the system and deduced to be a pseudo‐first‐order reaction, and the calculated activation energy was 51.71 kJ/mol. © 2009 American Institute of Chemical Engineers AIChE J, 2010     

固定化脂肪酶催化制备香叶树籽生物柴油研究

研究了Novozym 435和Lipozyme TLIM混合脂肪酶催化香叶树籽油制备生物柴油,2种酶按1:3质量比混合使用时,既可提高反应转化率,又可降低酶的使用成本.应用响应面优化法确定了固定化酶催化香叶树籽生物柴油的最优工艺参数,采用叔丁醇作为反应体系的溶剂,最优反应条件为反应温度38.5℃、甲醇与油摩尔比4:1、叔丁醇与油体积比1:1.5、酶用量为油质量的4%,此时反应转化率达90.09%.分析表明香叶树籽油的甘油三酯主要由短链脂肪酸甘油酯组成,生物柴油中原油的甘油三酯已完全转变成脂肪酸甲酯.     

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.     

In situ transesterification of coconut oil using mixtures of methanol and tetrahydrofuran

The conventional biodiesel production method requires oil extraction followed by transesterification with methanol. The solubility of vegetable oils in methanol is low which decreases the overall rate of reaction. To eliminate the oil extraction step and improve the overall reaction rate, simultaneous extraction, esterification and transesterification were conducted by directly mixing methanol and tetrahydrofuran (THF) co-solvent and sulfuric acid catalyst with ground, desiccated coconut meat (copra) in a batch process and continuing the reaction until the system reached steady state. After separation of the mixture, yield was obtained by measuring the content of triglycerides, diglycerides and monoglycerides in the biodiesel phase. The yield increases with THF:methanol ratio, methanol:oil molar ratio and temperature. Within the range of conditions tested, the highest yield achieved was 96.7% at 60 °C, THF:methanol volume ratio of 0.4 and methanol:oil molar ratio of 60:1. The methanol:oil molar ratio is necessarily high in order to completely wet the copra mass, but is still lower than in previous studies by other researchers on in situ transesterification. Product assays show that the resulting biodiesel product is similar to conventionally produced coconut biodiesel. The results indicate that the in situ transesterification of copra using methanol/THF mixtures merits further study.     

新型反应介质中脂肪酶催化多种油脂制备生物柴油

用叔丁醇作为反应介质,利用固定化脂肪酶催化油脂原料甲醇醇解反应制备生物柴油,消除了甲醇和甘油对酶的负面影响,酶的使用寿命显著延长. 用菜籽油作原料,叔丁醇和油脂的体积比为1:1,甲醇与油脂的摩尔比为4:1,3%的Lipozyme TLIM和1%的Novozym 435结合使用,35℃下130 r/min反应12 h,生物柴油得率可达95%. 该工艺在200 kg/d的规模下制得的生物柴油产品完全满足美国和德国生物柴油标准,脂肪酶重复使用200批次,酶活性基本没有下降. 且在叔丁醇介质体系中大豆油、桐籽油、棉籽油、乌桕油、泔水油、地沟油和酸化油都能被有效转化成生物柴油且脂肪酶保持很好的稳定性.     

Optimization of the synthesis of lower glycerides rich in unsaturated fatty acid residues obtained via enzymatic ethanolysis of sesame oil

The lipases Novozym 435, Lipozyme TL IM and Lipozyme RM IM were employed in the production of lower acylglycerols (LG), i.e. mono‐ (MAG) and diacylglycerols (DAG), rich in unsaturated fatty acids from sesame oil in batch reactors. The effect of the molar ratio of ethanol to fatty acids on the reusability of these immobilized lipases was studied in detail. The effects of pretreatment on lipase activity for ethanolysis were investigated. Glycerol had a strong product inhibition effect on the ethanolysis reaction, and a relatively large excess of ethanol was necessary to remove the glycerol adsorbed on these biocatalysts. The enzymatic activity was drastically reduced by addition of water to the reaction medium. The presence of organic solvents (hexane and acetone) did not favor the production of LG. For the Novozym 435‐catalyzed reaction, optimum conditions were a molar ratio of ethanol to fatty acid residues of 5 : 1, 15 wt‐% lipase and 50 °C. For Lipozyme TL IM, the optimum conditions were a molar ratio of ethanol to fatty acid residues of 5 : 1, 20 wt‐% biocatalyst, and 30 °C. Novozym 435 and Lipozyme TL IM produced LG with molar ratios of unsaturated to saturated fatty acids of 20.4 in 1 h and 25.3 in 5 h, respectively. In the original oil, this ratio was 5. For trials conducted under optimum conditions, the products from the Novozym 435 trials contained 21.8 wt‐% triacylglycerols (TAG), 24 wt‐% DAG and 54.2 wt‐% MAG. The products of the Lipozyme TL IM trials consisted of 12.9 wt‐% DAG and 87.1 wt‐% MAG. No TAG species were detected.     

Synthesis and component confirmation of biodiesel from palm oil and dimethyl carbonate catalyzed by immobilized-lipase in solvent-free system

The transesterification of palm oil and dimethyl carbonate (DMC) for preparing biodiesel has been carried out at the catalysis of immobilized-lipase in solvent-free system. The components were all confirmed by GC and GC–MS analysis. The fatty acid methyl esters (FAMEs) were analyzed with internal standard method. The fatty acids glycerol carbonate esters (FAGCs) were characterized as the intermediates. And, glycerol dicarbonate (GDC) was confirmed as the byproduct by comparing with the model compound. Moreover, the effects of the reaction conditions (type of lipases, molar ratio of DMC and palm oil, amount of catalyst, reaction temperature and time) on the yield of FAMEs were investigated. The yield of FAMEs could reach 90.5% at 55 °C for 24 h with the molar ratio of DMC to oil 10:1 and the catalyst amount of 20% Novozym 435 (based on the oil weight). There was no obvious loss in the FAMEs yield after Novozym 435 having been used for eight cycles.     

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.     

Synthesis of biodiesel from edible and non-edible oils in supercritical alcohols and enzymatic synthesis in supercritical carbon dioxide

Biodiesel is an attractive alternative fuel because it is environmentally friendly and can be synthesized from edible and non-edible oils. The synthesis of biodiesel from edible oils like palm oil and groundnut oil and from crude non-edible oils like Pongamia pinnata and Jatropha curcas was investigated in supercritical methanol and ethanol without using any catalyst from 200 to 400 °C at 200 bar. The variables affecting the conversion during transesterification, such as molar ratio of alcohol to oil, temperature and time were investigated in supercritical methanol and ethanol. Biodiesel was also synthesized enzymatically with Novozym-435 lipase in presence of supercritical carbon dioxide. The effect of reaction variables such as temperature, molar ratio, enzyme loading and kinetics of the reaction was investigated for enzymatic synthesis in supercritical carbon dioxide. Very high conversions (>80%) were obtained within 10 min and nearly complete conversions were obtained at within 40 min for the synthesis of biodiesel in supercritical alcohols. However, conversions of only 60–70% were obtained in the enzymatic synthesis even after 8 h.     

An enzymatic/acid-catalyzed hybrid process for biodiesel production from soybean oil

The present study is aimed at developing an enzymatic/acid-catalyzed hybrid process for biodiesel production using soybean oil as feedstock. In the enzymatic hydrolysis, 88% of the oil taken initially was hydrolyzed by binary immobilized lipase after 5 h under optimal conditions. The hydrolysate was further used in acid-catalyzed esterification for biodiesel production and the effects of temperature, catalyst concentration, feedstock to methanol molar ratio, and reaction time on biodiesel conversion were investigated. By using a feedstock to methanol molar ratio of 1:15 and a sulfuric acid concentration of 2.5%, a biodiesel conversion of 99% was obtained after 12 h of reaction at 50 °C. The biodiesel produced by this process met the American Society for Testing and Materials (ASTM) standard. This hybrid process may open a way for biodiesel production using unrefined and used oil as feedstock.     

Enzymatic Synthesis of Biodiesel from Transesterification Reactions of Vegetable Oils and Short Chain Alcohols

Biodiesel synthesis by alcoholysis of three vegetable oils (soybean, sunflower and rice bran) catalyzed by three commercial lipases (Novozym 435, Lipozyme TL-IM and Lipozyme RM-IM), and the optimization of the enzymes stability over repeated batches is described. The effects of the molar ratio of alcohol to oil and the reaction temperature with methanol, ethanol, propanol and butanol were also studied. All three enzymes displayed similar reaction kinetics with all three oils and no significant differences were observed. However, each lipase displayed the highest alcoholysis activity with a different alcohol. Novozym 435 presented higher activity in methanolysis, at a 5:1 methanol:oil molar ratio; Lipozyme TL-IM presented higher activity in ethanolysis, at a 7:1 ethanol:oil molar ratio; and Lipozyme RM-IM presented higher activity in butanolysis, at a 9:1 butanol:oil molar ratio. The optimal temperature was in the range of 30–35 °C for all lipases. The assessment of enzyme stability over repeated batches was carried out by washing the immobilized enzymes with different solvents (n-hexane, water, ethanol, or propanol) after each batch. When washing with n-hexane, approximately 90% of the enzyme activity remained after seven synthesis cycles.     

生物柴油的制备

通过正交试验得出了菜籽油在NaOH作用下与甲醇经转酯反应合成生物柴油的最适宜工艺条件:摩尔比6:1、反应温度40℃、反应时间1h、催化剂用量1%。考察了工业甲醇、搅拌速度等工艺条件对反应的影响,对脂肪酶催化反应进行了探索性研究。采用气相色谱(氢火焰)内标法分析产品中脂肪酸甲酯的含量,研究了生物柴油与O#柴油的调和油性质。结果表明,合成的生物柴油其各项性能指标基本达到国外同类产品的标准,与O#柴油调和后低温流动性得到明显改善。     

Microwave irradiation-assisted transesterification of soybean oil to biodiesel catalyzed by nanopowder calcium oxide

This study examined the effect of a heterogeneous base catalyst on the transesterification of soybean oil assisted by microwave irradiation. The results showed that nanopowder calcium oxide (nano CaO) was very efficient in converting soybean oil to biodiesel, and microwave irradiation is more efficient than the conventional bath for biodiesel production. However, the water content of methanol can not improve the conversion rate catalyzed by nano CaO.The suitable reaction conditions that can reach a 96.6% of conversion rate were methanol/oil molar ratio, 7:1; amount of catalyst used, 3.0 wt.%; reaction temperature, 338 K; and reaction time, 60 min. The biodiesel produced is within the limits prescribed by the standard of EN-14214.     

Transesterification of soybean oil to biodiesel using CaO as a solid base catalyst

In this study, transesterification of soybean oil to biodiesel using CaO as a solid base catalyst was studied. The reaction mechanism was proposed and the separate effects of the molar ratio of methanol to oil, reaction temperature, mass ratio of catalyst to oil and water content were investigated. The experimental results showed that a 12:1 molar ratio of methanol to oil, addition of 8% CaO catalyst, 65 °C reaction temperature and 2.03% water content in methanol gave the best results, and the biodiesel yield exceeded 95% at 3 h. The catalyst lifetime was longer than that of calcined K₂CO₃/γ-Al₂O₃ and KF/γ-Al₂O₃ catalysts. CaO maintained sustained activity even after being repeatedly used for 20 cycles and the biodiesel yield at 1.5 h was not affected much in the repeated experiments.