固定化全细胞催化可再生油脂合成生物柴油的稳定性

酶法合成生物柴油具有反应条件温和、醇用量小、无污染物排放、产物易分离回收等优点,越来越得到关注。全细胞催化剂,无需酶的提取和纯化,减少了酶活损失,有望大幅降低生产成本;Rhizopus oryzae IFO4697全细胞可以有效催化植物油脂合成生物柴油,进一步提高全细胞在催化植物油脂甲醇解制备生物柴油过程中的稳定性,对于工业放大具有重要意义。本实验对固定化全细胞Rhizopus oryzae IFO4697催化植物油脂合成生物柴油的稳定性进行了系统地研究,结果表明:反应体系水含量对于全细胞催化剂的反应活性和催化稳定性有重要影响,5%～15%含水量适宜;研究范围内,载体粒度及干燥方式对稳定性影响不显著;经过戊二醛交联后,全细胞催化油脂甲醇解反应的稳定性显著提高,1200h反应后,仍然可以保持75%的生物柴油得率;真空抽滤直接回用的方式有利于稳定性的保持。在优化条件下,回用20个批次,生物柴油得率可维持在80%。     

复合脂肪酶催化生物柴油的初步研究

初步探讨了复合脂肪酶催化生物柴油的工艺。优化了复合酶配比条件和叔丁醇反应体系。在无溶剂体系中,Novozym435分别与Lipozyme TLIM和Lipozyme RMIM均以70／30质量比混合时,甲酯得率分别达到94．52％和96．25％,比Novozym435单独催化时的甲酯得率分别提高了9．52％和9．99％。在叔丁醇体系中,当Novozym435与Li-pozyme TLIM和Lipozyme RMIM分别以60／40和80／20的质量比混合时,其甲酯得率分别为85．06％和81．5％,比Novozym435单独催化的效率分别提高了9．89％和7．48％。优化叔丁醇体系中复合酶催化条件后,甲酯得率达92％。     

间歇及连续式固定化酶反应生产生物柴油

探讨了利用本实验室自制的Candida sp99．125脂肪酶转酯化合成生物柴油的过程。在利用间歇式反应得到最佳反应条件的情况下利用固定床反应器生产生物柴油,经过初步优化的试验结果表明,在采用分级流加甲醇下,生物柴油的转化率可以达到93％左右,并且固定化酶的使用寿命超过480h。     

脂肪酶催化制备生物柴油的研究进展

生物柴油作为一种可再生的清洁能源,以其良好的环境效应受到越来越多的关注。酶法生产生物柴油具有化学催化法不可比拟的优越性,是工业化生产的发展方向。本文综述了利用固定化脂肪酶、游离酶、全细胞生物催化剂制备生物柴油的研究与应用进展,并探讨了我国生物柴油产业化发展的困境和对策。     

超声波辅助下脂肪酶催化高酸值废油脂制备生物柴油

探讨了超声波辅助条件下脂肪酶催化高酸值废油脂转化为生物柴油的反应。来源于Aspergillus oryzae和Candida antarctica的固定化脂肪酶,在超声波辅助下,对高酸值废油脂转化为生物柴油具有高的催化活性。以来自于C.antarctica的固定化脂肪酶Novozym435为催化剂,以酸价为157mg KOH/g的高酸值废油脂为原料在超声波辅助下与丙醇反应,在脂肪酶用量为油质量的8%、初始醇油摩尔比为3∶1、反应温度控制在40~45℃、超声波频率和功率分别采用28kHz和100W的条件下,反应50min转化率达到94.86%。在此条件下,不同碳原子数(C1~C5)的直链和支链醇均有较高的转化率,在短链醇的选择上具有宽广的适应性。超声波还减少了反应产物和反应体系中其他黏性杂质在固定化脂肪酶表面的吸附,回收的Novozym435相较单纯机械搅拌条件下回收的外观干净、分散良好无结块现象、易于洗涤和再次利用,具有良好的操作稳定性。     

非水相中脂肪酶催化甘油三酯转酯反应动力学

本文研究了脂肪酶在己烷中催化甘油三丁酸酯与硬脂酸之间的转酯反应动力学。转酯反应分为二个连续的反应步骤:由酯生成的酰基酶复合物的水解和由酸生成的酰基酶复合物的醇解,整个反应符合乒乓反应机制,动力学参数为:K_m(酯)=3.2×10~(-2)mol/L,K_m(酸)=6.9×10~(-2)mol/L,V_m=1.7×10~(-4)mol/L·min。     

脂肪酶催化合成生物柴油的研究进展

环保型燃料生物柴油有望解决能源短缺的问题,脂肪酶催化动植物油脂合成生物柴油的方法具有反应条件温和、产物易分离和不污染环境等优点。综述了酶催化法在提高脂肪酸酯产率和减少生产成本等方面的研究进展。     

固定化脂肪酶催化毛棉籽油制备生物柴油

研究了固定化脂肪酶Lipozyme TL IM和Novozym435催化毛棉籽油和乙酸甲酯制备生物柴油的过程。通过向反应体系中添加甲醇,可减少乙酸的抑制,明显提高生物柴油得率,确定最佳反应条件为:正己烷作溶剂,乙酸甲酯与油摩尔比9:1,添加油重3%的甲醇、油重10%的LipozymeTLIM和5%的Novozym435复合使用,温度55°C,反应8h,生物柴油得率达到91.83%。最后探索了酶催化毛棉籽油合成生物柴油的动力学,得到动力学方程。     

微生物途径发展生物柴油产业

生物柴油实际上就是生物油脂与甲醇或乙醇在酸、碱催化剂的作用下进行脂交换反应而制造的脂肪酸甲酯或乙酯;也可以在常温下由微生物脂酶催化进行酯化反应,其产品是一种可再生燃料,能替代石油柴油。这些生物柴油主要来自植物油或其它生物油脂,也有用废弃食用油为原料通过甲醇的酯交换反应来制造生物柴油的。研发这些生物柴油也可以说是节能的一项重要措施。在我国,对石油的需求量越来越大,石油进口量也随之猛增,显示出我国的能源形势日益严峻。面对这种情况,发展可再生能源或替代能源是个必然趋势,生物柴油便是其中之一。目前我国生物柴油的…     

复合脂肪酶协同催化制备生物柴油的研究

【目的】探讨复合酶协同催化体系在含水量较高的体系中催化油脂制备生物柴油的工艺条件。【方法】通过基因工程手段在毕赤酵母中分别高效分泌表达南极假丝酵母脂肪酶(CALB)和米根霉脂肪酶(ROL),构建CALB和ROL复合酶协同催化体系制备生物柴油,利用单因素实验优化工艺条件,以甲酯化得率作为复合酶协同催化体系效能的评价标准。【结果】优化工艺条件为:CALB?ROL最佳复合酶配比为7?3,每克大豆油中加入16 U的复合脂肪酶,甲醇与大豆油摩尔比为4?1,并按0 h时2?1醇油摩尔比,12 h和24 h时以1?1醇油摩尔比分批加入甲醇,含水量为30%-60%之间,40°C反应29-34 h,甲酯得率达到93%。【结论】该复合酶协同催化体系对环境友好,与常规酶法制备生物柴油工艺相比对酶的使用量和催化时间减少幅度都在50%以上,本复合酶协同催化体系能有效降低生物柴油制备成本,具有较好的工业化应用前景。     

Enzymatic transesterification for biodiesel production

Biodiesel consists monoalkyl esters of long chain fatty acids. It is produced from vegetable oils or fats either by chemical transesterification or by lipase-catalyzed transesterification with methanol or ethanol. Biodiesel is a green fuel and can be used as a blend with diesel or alone. Either way, it does not require any modification in engine design or storage facilities. The enzymatic process offers several advantages over the chemical routes. The handicap of increase in process cost because of the cost of the enzyme can be overcome by using efficient production process for enzyme and using reusable derivatives of enzymes, such as immobilized enzyme. Numerous strategies available in the area of non-aqueous enzymology can be exploited during the enzymatic alcoholysis for biodiesel production. Some of the technical challenges and their possible solutions are also discussed.     

Optimisation of biodiesel production by sunflower oil transesterification

In this work the transformation process of sunflower oil in order to obtain biodiesel by means of transesterification was studied. Taguchi's methodology was chosen for the optimisation of the most important variables (temperature conditions, reactants proportion and methods of purification), with the purpose of obtaining a high quality biodiesel that fulfils the European pre-legislation with the maximum process yield. Finally, sunflower methyl esters were characterised to test their properties as fuels in diesel engines, such as viscosity, flash point, cold filter plugging point and acid value. Results showed that biodiesel obtained under the optimum conditions is an excellent substitute for fossil fuels.     

Advances in direct transesterification of microalgal biomass for biodiesel production

Microalgae biomass is becoming an interesting raw material to produce biodiesel, where several approaches in the transesterification process have been applied such as different catalysts, different acyl acceptors, incorporation of co-solvents and the different operational conditions. However there are some drawbacks that must be solved before any industrial application could be intended. The main problems are related with the high water content of the biomass (over 80 %) and the several process steps involved in biodiesel production such as: drying, cell disruption, oils extraction, transesterification and biodiesel refining. In comparison to other alternatives, the use of direct transesterification could be a suitable alternative since cell disruption, lipids extraction and transesterification are carried out in one step, with a direct reaction of oil-bearing biomass to biodiesel. This process could be applied even using biomass with high water content, and its efficiency could be improved by the incorporation of promising technologies such as microwave or ultrasonication that can enhance the mass transfer rate between immiscible phases, simultaneously diminishing the reaction time. However, it is still necessary to decrease the costs of these technologies so they can be suitable alternatives in future industrial applications.     

Membrane microreactor in biocatalytic transesterification of triolein for biodiesel production

Transesterification is a principal chemical reaction that occurs in biodiesel production. We developed a novel biocatalytic membrane microreactor (BMM) for continuous transesterification by utilizing an asymmetric membrane as an enzyme-carrier for immobilization. The BMM was developed by pressure driven filtration of lipase from Pseudomonas fluorescens, which is suitable for highly efficient biocatalytic transesterification. Lipase solution was allowed to permeate through an asymmetric membrane with NMWL 300 kDa composed of polyethersulfone. The performances of BMM were studied in biodiesel synthesis via transesterification of triolein with methanol. Transesterification was carried out by passing a solution of triolein and methanol through the asymmetric membrane. The degree of triolein conversion using this microreactor was ca. 80% with a reaction time of 19 min. The BMM system displayed good stability, with no activity decay over a period of 12 day with continuous operation. Results from triolein transesterification clearly demonstrate the potential of an asymmetric membrane as an enzyme carrier material. Enzyme activity (mmol/h·g_lipase) was approximately 3 fold higher than that of native free lipase.     

Factor analysis of transesterification reaction of waste oil for biodiesel production

In the present paper a factor analysis is presented for the enzymatic transesterification of waste oil for biodiesel production. The experimental data on batch reactor evidence two key variables: enzyme loading and mixing conditions. These variables were subjected to a factor analysis and their combined effect on the reaction performance was determined. Response surface methodology (RSM) was used based on a linear first order model (steepest ascent method) and on a second order one in proximity of the optimal solution. The result was a model able to predict reaction performance within the range of mixing rates and enzyme amount considered for model formulation and outside of it, as shown in the final validation. Best performances were obtained at high stirring and high enzyme loading.     

Development of heterogeneous base catalysts for biodiesel production

Investigations were conducted on heterogeneous base catalysts for the transesterification of oil aimed at effective production of biodiesel. Thirteen different kinds of metal oxides containing calcium, barium, magnesium, or lanthanum were prepared as catalysts. Their catalytic activities were tested for transesterification at 60 degrees C with a 6:1 molar ratio of methanol to oil and a reaction time of 10h. The calcium-containing catalysts - CaTiO3, CaMnO3, Ca2Fe2O5, CaZrO3, and CaO-CeO2 - showed high activities and approximately 90% yields of methyl ester. Furthermore, catalytic durability tests were performed by repeating the transesterification reaction several times with the calcium-containing catalysts recovered from the previous reaction mixture. It was found that CaZrO3 and CaO-CeO2 show high durability and have the potential to be used in biodiesel production processes as heterogeneous base catalysts.     

Optimization of alkali-catalyzed transesterification of Pongamia pinnata oil for production of biodiesel

Studies were carried out on transesterification of Karanja oil with methanol for the production of biodiesel. The reaction parameters such as catalyst concentration, alcohol/oil molar ratio, temperature, and rate of mixing were optimized for production of Karanja oil methyl ester (KOME). The fatty acid methyl esters content in the reaction mixture were quantified by HPLC and 1H NMR method. The yield of methyl esters from Karanja oil under the optimal condition was 97-98%.     

Integrated production for biodiesel and 1,3-propanediol with lipase-catalyzed transesterification and fermentation

Biodiesel, a renewable alternative to fossil energy, has shown great prospects for global proliferation in the past decade. Lipase catalyzed transesterification for biodiesel production, as a biological process with many advantages has drawn increasing attention. As a by-product, glycerol accounts for about 10% w/w of biodiesel during the process of biodiesel production. As a result, the conversion of glycerol has become a common problem which has to be resolved if considering large amount of biodiesel production. Glycerol can be fermented into 1,3-propanediol, a high value added chemical with a promising future in the polymers, for example, polytrimethylene terephthalate, and also fermentation approaches for 1,3-propanediol production which have drawn more and more attention due to advantages such as relatively low investment, mild reaction conditions and using renewable sources as the starting materials. Based on the latest technology advancements in lipase-mediated transformation for biodiesel production, the aerobic fermentation technology and genetic engineering for 1,3-propanediol production, and the integrated production of 1,3-propanediol from crude glycerol could be a promising way to improve the profit of the whole process during biodiesel production.     

Efficient solvothermal wet in situ transesterification of Nannochloropsis gaditana for biodiesel production

In situ transesterification of wet microalgae is a promising, simplified alternative biodiesel production process that replaces multiple operations of cell drying, extraction, and transesterification reaction. This study addresses enhanced biodiesel production from Nannochloropsis gaditana at elevated temperatures. Compared with the previously reported in situ transesterification process of conducting the reaction at a temperature ranging from 95 to 125 °C, the present work employs higher temperatures of at least 150 °C. This relatively harsh condition allows much less acid catalyst with or without co-solvent to be used during this single extraction-conversion process. Without any co-solvent, 0.58% (v/v) of H₂SO₄ in the reaction medium can achieve 90 wt% of the total lipid conversion to biodiesel at 170 °C when the moisture content of wet algal paste is 80 wt%. Here, the effects of temperature, acid catalyst, and co-solvent on the FAEE yield and specification were scrutinized, and the reaction kinetic was investigated to understand the solvothermal in situ transesterification reaction at the high temperature. Having a biphasic system (water/chloroform) during the reaction also helped to meet biodiesel quality standard EN 14214, as Na⁺, K⁺, Ca²⁺, Mg²⁺ cations and phosphorus were detected only below 5 ppm. With highlights on the economic feasibility, wet in situ transesterification at the high temperature can contribute to sustainable production of biodiesel from microalgae by reducing the chemical input and relieve the burden of extensive post purification process, therefore a step towards green process.

     

Microwave assisted alkali-catalyzed transesterification of Pongamia pinnata seed oil for biodiesel production

In this study, microwave assisted transesterification of Pongamia pinnata seed oil was carried out for the production of biodiesel. The experiments were carried out using methanol and two alkali catalysts i.e., sodium hydroxide (NaOH) and potassium hydroxide (KOH). The experiments were carried out at 6:1 alcohol/oil molar ratio and 60 °C reaction temperature. The effect of catalyst concentration and reaction time on the yield and quality of biodiesel was studied. The result of the study suggested that 0.5% sodium hydroxide and 1.0% potassium hydroxide catalyst concentration were optimum for biodiesel production from P. pinnata oil under microwave heating. There was a significant reduction in reaction time for microwave induced transesterification as compared to conventional heating.