Biodiesel production and optimization from Calophyllum inophyllum linn oil (honne oil) – A three stage method

The present work examines the production of a biodiesel from a non-edible oil namely honne oil (Calophyllum inophyllum linn). A three stage process viz., pre-treatment, alkali catalyzed transesterification and post treatment adopted for the production is discussed. The reaction parameters such as methanol to oil molar ratio, catalyst concentration, temperature and time have been optimized for the production of biodiesel. The yield of biodiesel from the honne oil under the optimized conditions is found to be 89%.     

脂肪酶协同催化猪油合成生物柴油工艺研究

探讨了以乙酸甲酯为酰基受体两种脂肪酶协同催化猪油转酯合成生物柴油的工艺条件。首先利用单因子试验确定2种固定化脂肪酶Novozym435、Lipozyme TLIM单独作为催化剂时的最佳酶用量为40％,反应温度为50℃,乙酸甲酯用量为14（相对于油的摩尔比）。在此基础上,采用3因素5水平和3个中心点的中心组分旋转设计法研究了上述2种脂肪酶协同使用时脂肪酶用量（g/g）、混合酶的配比（%/%）以及乙酸甲酯用量诸因素共同作用对转酯反应转化率的影响。优化后的反应条件为：总酶用量为40％,混合酶配比为50/50,乙酸甲酯用量为14,在该条件下甲酯得率可达97.6％,比同质量的Novozym435、Lipozyme TLIM的催化活性分别高出7.6％、22.3％。表明脂肪酶协同催化猪油合成生物柴油工艺可以较好地提高甲酯得率,并且节约生产成本。     

Transesterification of soybean oil using combusted oyster shell waste as a catalyst

Transesterification of soybean oil catalyzed by combusted oyster shell, which is waste material from shellfish farms, was examined. Powdered oyster shell combusted at a temperature above 700 degrees C, at which point the calcium carbonate of oyster shell transformed to calcium oxide, acted as a catalyst in the transesterification of soybean oil. On the basis of factorial design, the reaction conditions of catalyst concentration and reaction time were optimized in terms of the fatty acid methyl ester concentration expressed as biodiesel purity. Under the optimized reaction conditions of a catalyst concentration and reaction time of 25wt.%. and 5h, respectively, the biodiesel yield, expressed relative to the amount of soybean oil poured into the reaction vial, was more than 70% with high biodiesel purity. These results indicate oyster shell waste combusted at high temperature can be reused in biodiesel production as a catalyst.     

Selection of lipase producing yeasts for methanol-tolerant biocatalyst as whole cell application for palm-oil transesterification

Methanol-tolerant lipase producing yeast was successfully isolated and selected thorough ecological screening using palm oil-rhodamine B agar as one step-approach. All 49 lipase-producing yeasts exhibited the ability to catalyze esterification reaction of oleic acid and methanol at 3 molar equivalents. However, only 16 isolates catalyzed transesterification reaction of refined palm oil and methanol. Rhodotorula mucilagenosa P11I89 isolated from oil contaminated soil showed the strongest hydrolytic lipase activity of 1.2U/ml against palm oil. The production of oleic methyl ester and fatty acid methyl ester (FAME) of 64.123 and 51.260% was obtained from esterification and transesterification reaction catalyzed by whole cell of R. mucilagenosa P11I89 in the presence of methanol at 3 molar equivalents against the substrates, respectively. FAME content increased dramatically to 83.29% when 6 molar equivalents of methanol were added. Application of the methanol-tolerant-lipase producing yeast as a whole cell biocatalyst was effectively resolved major technical obstacles in term of enzyme stability and high cost of lipase, leading to the feasibility of green biodiesel industrialization.     

Homogeneous,heterogeneous and enzymatic catalysis for transesterification of high free fatty acid oil (waste cooking oil) to biodiesel: A review

In the last few years, biodiesel has emerged as one of the most potential renewable energy to replace current petrol-derived diesel. It is a renewable, biodegradable and non-toxic fuel which can be easily produced through transesterification reaction. However, current commercial usage of refined vegetable oils for biodiesel production is impractical and uneconomical due to high feedstock cost and priority as food resources. Low-grade oil, typically waste cooking oil can be a better alternative; however, the high free fatty acids (FFA) content in waste cooking oil has become the main drawback for this potential feedstock. Therefore, this review paper is aimed to give an overview on the current status of biodiesel production and the potential of waste cooking oil as an alternative feedstock. Advantages and limitations of using homogeneous, heterogeneous and enzymatic transesterification on oil with high FFA (mostly waste cooking oil) are discussed in detail. It was found that using heterogeneous acid catalyst and enzyme are the best option to produce biodiesel from oil with high FFA as compared to the current commercial homogeneous base-catalyzed process. However, these heterogeneous acid and enzyme catalyze system still suffers from serious mass transfer limitation problems and therefore are not favorable for industrial application. Nevertheless, towards the end of this review paper, a few latest technological developments that have the potential to overcome the mass transfer limitation problem such as oscillatory flow reactor (OFR), ultrasonication, microwave reactor and co-solvent are reviewed. With proper research focus and development, waste cooking oil can indeed become the next ideal feedstock for biodiesel.     

Biodiesel production—current state of the art and challenges

Biodiesel is a clean-burning fuel produced from grease, vegetable oils, or animal fats. Biodiesel is produced by transesterification of oils with short-chain alcohols or by the esterification of fatty acids. The transesterification reaction consists of transforming triglycerides into fatty acid alkyl esters, in the presence of an alcohol, such as methanol or ethanol, and a catalyst, such as an alkali or acid, with glycerol as a byproduct. Because of diminishing petroleum reserves and the deleterious environmental consequences of exhaust gases from petroleum diesel, biodiesel has attracted attention during the past few years as a renewable and environmentally friendly fuel. Since biodiesel is made entirely from vegetable oil or animal fats, it is renewable and biodegradable. The majority of biodiesel today is produced by alkali-catalyzed transesterification with methanol, which results in a relatively short reaction time. However, the vegetable oil and alcohol must be substantially anhydrous and have a low free fatty acid content, because the presence of water or free fatty acid or both promotes soap formation. In this article, we examine different biodiesel sources (edible and nonedible), virgin oil versus waste oil, algae-based biodiesel that is gaining increasing importance, role of different catalysts including enzyme catalysts, and the current state-of-the-art in biodiesel production. JIMB 2008: BioEnergy—special issue.     

Biodiesel production by transesterification using immobilized lipase

Biodiesel can be produced by transesterification of vegetable or waste oil catalysed by lipases. Biodiesel is an alternative energy source to conventional fuel. It combines environmental friendliness with biodegradability, low toxicity and renewability. Biodiesel transesterification reactions can be broadly classified into two categories: chemical and enzymatic. The production of biodiesel using the enzymatic route eliminates the reactions catalysed under acid or alkali conditions by yielding product of very high purity. The modification of lipases can improve their stability, activity and tolerance to alcohol. The cost of lipases and the relatively slower reaction rate remain the major obstacles for enzymatic production of biodiesel. However, this problem can be solved by immobilizing the enzyme on a suitable matrix or support, which increases the chances of re-usability. The main factors affecting biodiesel production are composition of fatty acids, catalyst, solvents, molar ratio of alcohol and oil, temperature, water content, type of alcohol and reactor configuration. Optimization of these parameters is necessary to reduce the cost of biodiesel production.     

Lipase-catalyzed biodiesel production with methyl acetate as acyl acceptor

Biodiesel is an alternative diesel fuel made from renewable biological resources. During the process of biodiesel production, lipase-catalyzed transesterification is a crucial step. However, current techniques using methanol as acyl acceptor have lower enzymatic activity; this limits the application of such techniques in large-scale biodiesel production. Furthermore, the lipid feedstock of currently available techniques is limited. In this paper, the technique of lipase-catalyzed transesterification of five different oils for biodiesel production with methyl acetate as acyl acceptor was investigated, and the transesterification reaction conditions were optimized. The operation stability of lipase under the obtained optimal conditions was further examined. The results showed that under optimal transesterification conditions, both plant oils and animal fats led to high yields of methyl ester: cotton-seed oil, 98%; rapeseed oil, 95%; soybean oil, 91%; tea-seed oil, 92%; and lard, 95%. Crude and refined cottonseed oil or lard made no significant difference in yields of methyl ester. No loss of enzymatic activity was detected for lipase after being repeatedly used for 40 cycles (ca. 800 h), which indicates that the operational stability of lipase was fairly good under these conditions. Our results suggest that cotton-seed oil, rape-seed oil and lard might substitute soybean oil as suitable lipid feedstock for biodiesel production. Our results also show that our technique is fit for various lipid feedstocks both from plants and animals, and presents a very promising way for the large-scale biodiesel production.     

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.     

Study of lipase immobilization on zeolitic support and transesterification reaction in a solvent free-system

In order to understand the role of the acid–base, electrostatic and covalent interactions between enzyme and support, the catalytic behavior of the Rhizomucor miehei lipase (RML) immobilized on zeolite materials has been studied. The highest lipase activities were obtained when this enzyme, immobilized by adsorption, interacts through acid–base binding forces with the support surface, resulting in activation of the enzyme catalytic center. Due to the interest in biodiesel production by mild enzymatic transesterification, this heterogeneous biocatalyst has been used in transesterification of fatty acids contained in olive oil. The results show a high oleic acid conversion for several reaction cycles with a higher total biodiesel productivity compared to that using the free enzyme.     

Production of biodiesel by Burkholderia cepacia lipase as a function of process parameters

Despite the already established route of chemically catalyzed transesterification reaction in biodiesel production, due to some of its shortcomings, biocatalysts such as lipases present a vital alternative. Namely, it was noticed that one of the key shortcomings for the optimization of the enzyme catalyzed biodiesel synthesis process is the information on the lipase activity in the reaction mixture. In addition to making optimization difficult, it also makes it impossible to compare the results of the independent research. This article shows how lipase intended for use in biodiesel synthesis can be easily and accurately characterized and what is the enzyme concentration that enables achievement of the desired level of fatty acid methyl esters (FAME) in the final product mixture. Therefore, this study investigated the effect of two different activity loads of Burkholderia cepacia lipase on the biodiesel synthesis varying the pH and temperature optimal for lipase activity. The optimal lipase pH and temperature were determined by two different enzyme assays: spectrophotometric and titrimetric. The B. cepacia lipase pH optimum differentiated between assays, while the lipase optimally hydrolyzed substrates at 50°C. The analysis of FAME during 24 hr of biodiesel synthesis, at two different enzyme concentrations, pH 7, 8, and 10, and using two different buffers, revealed that the transesterification reaction at optimal pH, 1 hr reaction time and lipase activity load of 250 U per gram of reaction mixture was sufficient to produce more than 99% FAME.     

Biotechnological production of biodiesel fuel using biocatalysed transesterification: A review

Biotechnological production of biodiesel has attracted considerable attention during the past decade compared to chemical-catalysed production since biocatalysis-mediated transesterification has many advantages. Currently, there are extensive reports on enzyme-catalysed transesterification for biodiesel production; the related research can be classified into immobilised-extracellular and immobilised-intracellular biocatalysis and this review focusses on these forms of biocatalyst for biodiesel production. The optimisation of the most important operating conditions affecting lipase-catalysed transesterification and the yield of alkyl esters, such as the type and form of lipase, the type of alcohol, the presence of organic solvents, the content of water in the oil, temperature and the presence of glycerol, are discussed. However, there is still a need to optimise lipase-catalysed transesterification and reduce the cost of lipase production before it is applied commercially. Optimisation research of lipase-catalysed transesterification could include development of new reactor systems with immobilised biocatalysts, the use of lipases tolerant to organic solvents, intracellular lipases (whole microbial cells) and genetically modified microorganisms (intelligent yeasts). Biodiesel fuel is expensive in comparison with petroleum-based fuel and 60–70% of the cost is associated with feedstock oil and enzyme. Therefore ways of reducing the cost of biodiesel with respect to enzyme and substrate oils reported in literature are also presented.     

高含游离脂肪酸的香果树籽油制备生物柴油的方法

目前生物柴油因其环保和可再生利用资源的特性备受关注。多数生物柴油是通过甲醇和碱催化食用油得到的,而大量非食用油也可以制备生物柴油。本文报道用高含游离酸脂肪油快速高效低成本制备成其单酯的二步法工艺。先用1% H2SO4以少于1.5%量对甲醇和云南特产香果树（Lindera communis）籽的粗原料油以10∶1摩尔比组成的混合液酸催化酯化游离脂肪酸;之后再对醇和得到的油脂产品按摩尔比15∶1的混合液碱催化转化为单甲酯和甘油。本方法是一个直接甲脂化制备生物柴油的工艺简洁、降低成本的新技术。文中还讨论了该工艺影响转化效率的主要因素,如摩尔比,催化量,温度,反应时间和酸度。香果树生物柴油不重蒸,而其生物柴油的主要特性,如粘度、热值、比重、闪点、冷滤点等与生物柴油标准的匹配度,也做了报道,研究结果将为香果树生物柴油以非重蒸油料制备生物柴油产品,作为潜在的柴油燃料替代产品提供技术支撑。     

Technical difficulties and solutions of direct transesterification process of microbial oil for biodiesel synthesis

Microbial oils are considered as alternative to vegetable oils or animal fats as biodiesel feedstock. Microalgae and oleaginous yeast are the main candidates of microbial oil producers’ community. However, biodiesel synthesis from these sources is associated with high cost and process complexity. The traditional transesterification method includes several steps such as biomass drying, cell disruption, oil extraction and solvent recovery. Therefore, direct transesterification or in situ transesterification, which combines all the steps in a single reactor, has been suggested to make the process cost effective. Nevertheless, the process is not applicable for large-scale biodiesel production having some difficulties such as high water content of biomass that makes the reaction rate slower and hurdles of cell disruption makes the efficiency of oil extraction lower. Additionally, it requires high heating energy in the solvent extraction and recovery stage. To resolve these difficulties, this review suggests the application of antimicrobial peptides and high electric fields to foster the microbial cell wall disruption.     

Production of Biodiesel Using Immobilized Lipase—A Critical Review

Increase in volume of biodiesel production in the world scenario proves that biodiesel is accepted as an alternative to conventional fuel. Production of biodiesel using alkaline catalyst has been commercially implemented due to its high conversion and low production time. For the product and process development of biodiesel, enzymatic transesterification has been suggested to produce a high purity product with an economic, environment friendly process at mild reaction conditions. The enzyme cost being the main hurdle can be overcome by immobilization. Immobilized enzyme, which has been successfully used in various fields over the soluble counterpart, could be employed in biodiesel production with the aim of reducing the production cost by reusing the enzyme. This review attempts to provide an updated compilation of the studies reported on biodiesel production by using lipase immobilized through various techniques and the parameters, which affect their functionality.     

An overview on the recent advances in the transesterification of vegetable oils for biodiesel production using chemical and biocatalysts

Biodiesel, chemically defined as monoalkyl esters of long chain fatty acids, are derived from renewable feed stocks like vegetable oils and animal fats. It is produced by both batch and continuous transesterification processes in which, oil or fat is reacted with a monohydric alcohol in the presence of a catalyst. The conventional method of producing biodiesel involves acid and base catalysts to form fatty acid alkyl esters. Downstream processing costs and environmental problems associated with biodiesel production and byproducts recovery have led to the search for alternative production methods and alternative substrates. Enzymatic reactions involving lipases can be an excellent alternative to produce biodiesel through a process commonly referred to as alcoholysis, a form of transesterification reaction or through an interesterification reaction. In order to increase the cost effectiveness of the process, the enzymes are immobilized using a suitable matrix. The use of immobilized lipases and whole cells may lower the overall cost, while presenting less downstream processing problems. Main focus of this paper is to discuss the important parameters that affect the biodiesel yield, various immobilization techniques employed, mechanisms and kinetics of transesterification reaction and the recent advances in continuous transesterification processes.     

Direct preparation of biodiesel from rapeseed oil leached by two-phase solvent extraction

A new method which coupled the two-phase solvent extraction (TSE) with the synthesis of biodiesel was studied. Investigations were carried out on transesterification of methanol with oil-hexane solution coming from TSE process in the presence of sodium hydroxide as the catalyst. Biodiesel (fatty acid methyl esters) were the products of transesterification. The influential factors of transesterification, such as reaction time, catalyst concentration, mole ratio of methanol to oil and reaction temperature were optimized. The results showed that the optimal reaction parameters were sodium hydroxide concentration 1.1% by weight of rapeseed oil, mole ratio of methanol to oil 9:1, reaction time 120 min, and reaction temperature 55-60 degrees C. Under these conditions, the TG conversion would rise up to 98.2%. Based on the new method, biodiesel production process could be simplified and the biodiesel cost could be reduced.     

Biodiesel production from heterotrophic microalgal oil

The present study introduced an integrated method for the production of biodiesel from microalgal oil. Heterotrophic growth of Chlorella protothecoides resulted in the accumulation of high lipid content (55%) in cells. Large amount of microalgal oil was efficiently extracted from these heterotrophic cells by using n-hexane. Biodiesel comparable to conventional diesel was obtained from heterotrophic microalgal oil by acidic transesterification. The best process combination was 100% catalyst quantity (based on oil weight) with 56:1 molar ratio of methanol to oil at temperature of 30 degrees C, which reduced product specific gravity from an initial value of 0.912 to a final value of 0.8637 in about 4h of reaction time. The results suggested that the new process, which combined bioengineering and transesterification, was a feasible and effective method for the production of high quality biodiesel from microalgal oil.     

Biodiesel production using a membrane reactor

The immiscibility of canola oil in methanol provides a mass-transfer challenge in the early stages of the transesterification of canola oil in the production of fatty acid methyl esters (FAME or biodiesel). To overcome or rather, exploit this situation, a two-phase membrane reactor was developed to produce FAME from canola oil and methanol. The transesterification of canola oil was performed via both acid- or base-catalysis. Runs were performed in the membrane reactor in semi-batch mode at 60, 65 and 70 degrees C and at different catalyst concentrations and feed flow rates. Increases in temperature, catalyst concentration and feedstock (methanol/oil) flow rate significantly increased the conversion of oil to biodiesel. The novel reactor enabled the separation of reaction products (FAME/glycerol in methanol) from the original canola oil feed. The two-phase membrane reactor was particularly useful in removing unreacted canola oil from the FAME product yielding high purity biodiesel and shifting the reaction equilibrium to the product side.     

Transesterification of oil mixtures catalyzed by microencapsulated cutinase in reversed micelles

Recombinant cutinase from Fusarium solani pisi was used to catalyze the transesterification reaction between a mixture of triglycerides (oils) and methanol in reversed micelles of bis(2-ethylhexyl) sodium sulfosuccinate (AOT) in isooctane for the purposes of producing biodiesel. The use of a bi-phase lipase-catalyzed system brings advantages in terms of catalyst re-use and the control of water activity in the medium and around the enzyme micro-environment. Small-scale batch studies were performed to study the influence of the initial enzyme and alcohol concentrations, and the substrates molar ratio. Conversions in excess of 75 were obtained with reaction times under 24?h, which makes this enzymatic process highly competitive when compared to similar lipase catalyzed reactions for biodiesel production using methanol.