脂肪酶催化食用废油制备生物柴油

利用脂肪酶为催化剂,食用废油与甲醇反应,制备生物柴油,最佳酯化反应条件为反应温度50℃、脂肪酶催化剂用量为原料量的3%、甲醇与食用废油体积比为3∶1、共溶剂丁酮量为甲醇量的1/6、pH=7,反应时间4h,生物柴油产率可达到78%,对产品的各项指标测定,均达到GB/T20828-2007要求,指标并与0#石化柴油相接近。     

Enzymatic conversion of waste edible oil to biodiesel fuel in a fixed-bed bioreactor

The conversion of waste edible oil to biodiesel fuel in a fixed-bed bioreactor was investigated. Three-step methanolysis of waste oil was conducted using three columns packed with 3 g of immobilized Candida antarctica lipase. A mixture of waste oil and 1/3 molar equivalent of methanol against total fatty acids in the oil was used as substrate for the first-step reaction, and mixtures of the first- and second-step eluates and 1/3 molar equivalent of methanol were used for the second- and third-step reactions, respectively. Ninety percent of waste oil was converted to the corresponding methyl esters (ME) by feeding substrate mixtures into the first, second, and third reactors at flow rates of 6, 6 and 4 mL/h, respectively. We also attempted one-step methanolysis of waste oil. When a mixture of waste oil and 90% ME-containing eluate (1∶3, wt/wt) and an equimolar amount of methanol against total fatty acids in the waste oil was fed into a reactor packed with 3 g of immobilized C. antarctica lipase at a flow rate of 4 mL/h, the ME content in the eluate reached 90%. The immobilized biocatalyst could be used for 100 d in the two reaction systems without significant decrease in its activity. Waste oil contained 1980 ppm water and 2.5% free fatty acids, but these contaminants had little influence on enzymatic production of biodiesel fuel.     

废食用油脂固定床酶法合成生物柴油研究

利用废食用油脂合成生物柴油,既能够实现废弃物的清洁利用,又能提供可再生的绿色能源。采用固定化假丝酵母脂肪酶为催化剂,在三级固定床反应器内,采用分级流加甲醇的方式,每级醇油摩尔比为1∶1,探讨了酶质量分数、溶剂质量分数、水质量分数、温度、反应液流速等与产物中甲酯质量分数的关系。实验结果表明,当油中酶、溶剂、水的质量分数分别为25%,15%,10%,反应液流速为1.2 mL/min,温度为45℃时,产物中甲酯质量分数达到最大值91.08%,其中油酸甲酯质量分数最高。产品经过精制后,理化性质符合美国和德国生物柴油标准,绝大多数指标优于我国0#柴油。     

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.     

酸性离子液体［(CH2)4SO3HMIM］［HSO4］催化潲水油制备生物柴油的研究

制备了酸性离子液体[(CH₂)₄SO₃HMIM］［HSO₄］并用于催化潲水油制备生物柴油,研究了反应时间、反应温度、醇油物质的量比和剂油物质的量比等对酯交换反应转化率的影响,确定了较适宜的反应条件。结果表明,在反应时间4 h、反应温度140 ℃、醇油物质的量比12和剂油物质的量比0.08条件下,酯交换反应转化率为92.13%。制备的生物柴油达到了中国柴油机燃料调合用生物柴油(BD100)标准GB/T20828-2007。     

甲醇钠催化地沟油制备生物柴油研究

以浓硫酸为催化剂,高酸值地沟油与甲醇酯化反应降酸的最优工艺条件为:n(甲醇):n(地沟油)=9:1,m(浓硫酸):m(地沟油)=1.1％,反应温度60℃,反应时间5h.制备生物柴油的最优工艺条件为:以甲醇钠为催化剂,反应时间2h,反应温度65℃,n(甲醇):n(地沟油)=7:1,m(甲醇钠):m(地沟油)=0.8％.制...     

Effect of methanol content on enzymatic production of biodiesel from waste frying oil

The enzymatic production of biodiesel from waste frying oil with methanol has been studied using immobilized lipase Novozym 435 as catalyst. The effects of methanol to oil molar ratio, dosage of enzyme and reaction time were investigated. The optimum reaction conditions were methanol to oil molar ratio of 25:1, 10% of Novozym 435 based on oil weight and reaction period of 4 h at 50 °C obtaining a biodiesel yield of 89.1%. Moreover, the reusability of the lipase over repeated cycles was also investigated under standard conditions.     

Metakaolinite as a catalyst for biodiesel production from waste cooking oil

The use of metakaolinite as a catalyst in the transesterification reaction of waste cooking oil with methanol to obtain fatty acid methyl esters (biodiesel) was studied. Kaolinite was thermally activated by dehydroxylation to obtain the metakaolinite phase. Metakaolinite samples were characterized using X-ray diffraction, N₂ adsorption-desorption, simultaneous thermo-gravimetric analyse/differential scanning calorimetry (TGA/DSC) experiments on the thermal decomposition of kaolinite and Fourier-transform infrared spectrometer (FTIR) analysis. Parameters related to the transesterification reaction, including temperature, time, the amount of catalyst and the molar ratio of waste cooking oil to methanol, were also investigated. The transesterification reaction produced biodiesel in a maximum yield of 95% under the following conditions: metakaolinite, 5 wt-% (relative to oil); molar ratio of oil to methanol, 1∶23; reaction temperature, 160°C; reaction time, 4 h. After eight consecutive reaction cycles, the metakaolinite can be recovered and reused after being washed and dried. The biodiesel thus obtained exhibited a viscosity of 5.4?mm²?s^–1 and a density of 900.1 kg?m^–3. The results showed that metakaolinite is a prominent, inexpensive, reusable and thermally stable catalyst for the transesterification of waste cooking oil.     

Conversion of waste cooking oil to biodiesel using ferric sulfate and supercritical methanol processes

In this comparative study, conversion of waste cooking oil to methyl esters was carried out using the ferric sulfate and the supercritical methanol processes. A two-step transesterification process was used to remove the high free fatty acid contents in the waste cooking oil (WCO). This process resulted in a feedstock to biodiesel conversion yield of about 85-96% using a ferric sulfate catalyst. In the supercritical methanol transesterification method, the yield of biodiesel was about 50-65% in only 15 min of reaction time. The test results revealed that supercritical process method is probably a promising alternative method to the traditional two-step transesterification process using a ferric sulfate catalyst for waste cooking oil conversion. The important variables affecting the methyl ester yield during the transesterification reaction are the molar ratio of alcohol to oil, the catalyst amount and the reaction temperature. The analysis of oil properties, fuel properties and process parameter optimization for the waste cooking oil conversion are also presented.     

Lipase‐catalyzed ethanolysis of soybean oil in a solvent‐free system using central composite design and response surface methodology

BACKGROUND: In this work we describe the synthesis of ethyl esters, commonly known as biodiesel, using refined soybean oil and ethanol in a solvent‐free system catalyzed by lipase from Thermomyces lanuginosus. Central composite design and response surface methodology (RSM) were employed to optimize the biodiesel synthesis parameters, which were: reaction time, temperature, substrate molar ratio, enzyme content, and added water, measured as percentage of yield conversion. RESULTS: The optimal conditions obtained were: temperature, 31.5 °C; reaction time, 7 h; substrate molar ratio, 7.5:1 ethanol:soybean oil; enzyme content, 15% (g enzyme g⁻¹ oil); added water, 4% (g water g⁻¹ oil). The experimental yield conversion obtained under these conditions was 96%, which is very close to the maximum predicted value of 94.4%. The reaction time‐course at the optimal values indicated that 5 h was necessary to obtain high yield conversions. CONCLUSION: A high yield conversion was obtained under the optimized conditions, with relative low enzyme content and short time. Comparison of predicted and experimental values showed good correspondence, implying that the empirical model derived from RSM can be used to adequately describe the relationship between the reaction parameters and the response (yield conversion) in lipase‐catalyzed biodiesel synthesis. Copyright © 2008 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.     

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     

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.     

Biodiesel Synthesis in a Solvent-Free System by Recombinant Rhizopus oryzae Lipase. Study of the Catalytic Reaction Progress

The recombinant 1,3-positional selective Rhizopus oryzae lipase (rROL) was used to synthesize biodiesel and monoacylglycerols simultaneously. The reaction was carried out in a solvent-free system with the enzyme immobilized on octadecyl-Sepabeads. Using response surface methodology, the methyl ester yield was optimized by means of the study of the effect of water, substrate molar ratio (methanol:olive oil) and methanol stepwise addition. It was concluded that in order to prevent enzyme inactivation by methanol, alcohol should be added slowly; otherwise a large amount of water would be present. Taking the best conditions, a 50.3 % yield was achieved in 3 h, which corresponds to 75.4 % of the acyl groups at the 1,3-position undergoing transesterification. It was also concluded that methyl esters result from the esterification of the free fatty acid hydrolyzed by the enzyme and also from a direct transesterification of oil. In addition, the fatty acid selectivity of rROL was found not to favor one fatty acid in olive oil over another.     

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     

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.     

Production of mixed methyl/ethyl esters from waste fish oil through transesterification with mixed methanol/ethanol system

Biodiesel (mixed fatty acid methyl/ethyl esters) was prepared from waste fish oil through base-catalyzed transesterification with mixed methanol/ethanol system. Effect of methanol/ethanol (% v/v), type and concentration of the catalyst, mixed alcohols to oil molar ratio, the reaction temperature, and the reaction time on the biodiesel yield was optimized. Maximum biodiesel yield (97.30?wt%) was produced by implementing 1:1 methanol/ethanol (v/v), 1.0?wt% KOH, 6:1 mixed alcohols to oil molar ratio, 40°C reaction temperature, and 30?min of reaction time. Conversion of the waste fish oil to mixed methyl/ethyl esters was confirmed by ¹H NMR spectroscopy. Fuel properties of the resulting biodiesel in addition to its blends with petrodiesel were in good agreement with specifications of ASTM D6751 and ASTM D7467, respectively. Therefore, it was concluded that using mixed alcohol system for biodiesel production could reduce the production cost through reducing conditions required for maximum conversion.     

硅基MCF材料固载脂肪酶转化餐饮废油产生物柴油

引言"地沟油"重返餐桌现象日益成为关系民众身体健康、社会和谐发展的焦点,开发合理有效处置方式,挖掘餐饮废油的剩余经济价值,是解决"地沟油"问题的根本出路。长链脂肪酸和低碳醇经过酯化反应后生成的脂肪酸酯,可以替代石油炼制的柴油作为车用燃料[1-2],即生物柴油。研究表明餐     

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.     

Enzymatic transesterification of sunflower oil in an aqueous-oil biphasic system

A biphasic oil-aqueous system for FAME production by enzymatic catalysis was studied. The transesterification of sunflower oil with methanol was catalyzed by free or immobilized lipases from Rhizomucor miehei (Palatase 20 000 L) and Humicola insolens (Lipozyme TL 100 L). The effects of protein amount, temperature, pH, and molar ratio of methanol to sunflower oil on the enzymatic reaction using free lipase were evaluated; the best results were obtained with H. insolens, at pH 5, 40°C, and 36.8 mg of protein. By using this lipase immobilized in Hypol^® 2002 (64. 8 mg of protein) at a 6∶1 methanol/oil molar ratio and a 2∶1 volumetric oil/water phase ratio, an ester content of 96.1% and a conversion of 91.2% were achieved. The immobilized lipase could be reused, although a 30% reduction in conversion efficiency was observed after four uses.