Improved high-pressure enzymatic biodiesel batch synthesis in near-critical carbon dioxide (original) (raw)
Related papers
Enzymatic Biodiesel Synthesis in Semi-Pilot Continuous Process in Near-Critical Carbon Dioxide
Applied Biochemistry and Biotechnology, 2013
A semi-pilot continuous process (SPCP) for enzymatic biodiesel synthesis utilizing near-critical carbon dioxide (NcCO 2 ) as the reaction medium was developed with the aim of reducing the reaction time and alleviating the catalyst inhibition by methanol. Biodiesel synthesis was evaluated in both lab-scale and semi-pilot scale reactors (batch and continuous reactors). In a SPCP, the highest conversion (∼99.9 %) in four and a half hours was observed when three-step substrate (methanol) addition (molar ratio [oil/methanol]=1:1.3) was used and the reaction mixture containing enzyme (Lipozyme TL IM, 20 wt.% of oil) was continuously mixed (agitation speed=300 rpm) at 30°C and 100 bar in a CO 2 environment. The biodiesel produced from canola oil conformed to the fuel standard (EU) even without additional downstream processing, other than glycerol separation and drying.
Journal of Supercritical Fluids, 2011
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%.
BMC Biotechnology, 2017
Background: Waste animal fat is a promising feedstock to replace vegetable oil that widely used in commercial biodiesel process, however the high content of free fatty acid in waste fat makes it unfeasible to be processed with commercial base-catalytic process. Enzymatic process is preferable to convert waste fat into biodiesel since enzyme can catalyze both esterification of free fatty acid and transesterification of triglyceride. However, enzymatic reaction still has some drawbacks such as lower reaction rates than base-catalyzed transesterification and the limitation of reactant concentration due to the enzyme inhibition of methanol. Supercritical CO 2 is a promising reaction media for enzyme-catalyzed transesterification to overcome those drawbacks. Result: The transesterification of waste animal fat was carried out in supercritical CO 2 with varied concentration of feedstock and methanol in CO 2. The CO 2 to feedstock mass ratio of 10:1 showed the highest yield compared to other ratios, and the highest FAME yield obtained from waste animal fat was 78%. The methanol concentration effect was also observed with variation 12%, 14%, and 16% of methanol to feedstock ratio. The best yield was 87% obtained at the CO 2 to feedstock ratio of 10: 1 and at the methanol to feedstock ratio of 14% after 6 h of reaction. Conclusion: Enzymatic transesterification to produce biodiesel from waste animal fat in supercritical fluid media is a potential method for commercialization since it could enhance enzyme activity due to supercritical fluid properties to remove mass transfer limitation. The high yield of FAME when using high mass ratio of CO 2 to oil showed that supercritical CO 2 could increase the reaction and mass transfer rate while reducing methanol toxicity to enzyme activity. The increase of methanol concentration also increased the FAME yield because it might shift the reaction equilibrium to FAME production. This finding describes that the application of supercritical CO 2 in the enzymatic reaction enables the application of simple process such as a packed-bed reactor.
Enzymatic production of biodiesel from canola oil using immobilized lipase
Biomass and Bioenergy, 2008
In the present work, a novel method for immobilization of lipase within hydrophilic polyurethane foams using polyglutaraldehyde was developed for the immobilization of Thermomyces lanuginosus lipase to produce biodiesel with canola oil and methanol. The enzyme optimum conditions were not affected by immobilization and the optimum pH for free and immobilized enzyme were 6, resulting in 80% immobilization yield. Using the immobilized lipase T. lanuginosus, the effects of enzyme loading, oil/alcohol molar ratio, water concentration, and temperature in the transesterification reaction were investigated. The optimal conditions for processing 20g of refined canola oil were: 430μg lipase, 1:6 oil/methanol molar ratio, 0.1g water and 40°C for the reactions with methanol. Maximum methyl esters yield was 90% of which enzymatic activity remained after 10 batches, when tert-butanol was adopted to remove by-product glycerol during repeated use of the lipase. The immobilized lipase proved to be stable and lost little activity when was subjected to repeated uses.
Continuous production of biodiesel from fat extracted from lamb meat in supercritical CO2 media
Biochemical Engineering Journal, 2012
Waste animal fat is considered a promising cheap alternative feedstock for biodiesel production that does not compete with food stock. In addition, using waste animal fat as a feedstock is considered a waste management process. In this work, an integrated process for a continuous fat extraction from lamb meat followed by enzymatic production of biodiesel in supercritical CO 2 has been developed and tested. The system simultaneously produces two valuable products, namely biodiesel and healthy low-fat lean lamb meat (HLFLM). For the enzymatic process to be feasible, lipase is preferred to be used in immobilized form, which allows easy reuse. The continuous system was operated at 200 bar and a SC-CO 2 flow of 0.5 ml min −1 , with extraction and transesterification temperatures of 45 • C and 50 • C, respectively. The effects of methanol:fat (M:F) molar ratio and enzyme stability were investigated. It was found that with fresh enzyme, a M:F molar ratio of 10:1 gave the highest biodiesel production rate of 0.37 mg min −1 genzyme −1 compared to only 0.09 mg min −1 g-enzyme −1 using a M:F molar ratio of 5:1. However, when a M:F molar ratio of 10:1 was used, the activity of the enzyme in the third meat replacement cycle drastically dropped to 18% of its original value, compared to 79% using a M:F molar ratio of 5:1.
Current Biochemical Engineering, 2017
Biodiesel represents an interesting alternative to fossil fuels. Traditionally the standard method for biodiesel production from oils is alkaline-catalyzed transesterification. Chemical catalysis can be replaced by enzymatic catalysis using lipases (EC 3.1.1.3, triacylglycerol acyl hydrolases), obtained from plants, animals or microorganisms. These biocatalysts act at milder temperature and normal pressure conditions, resulting in lower energy consumption. Also, undesirable side-reactions do not occur, originating pure products. Refined vegetable oils are the most common feedstocks for biodiesel production, accounting for 70-80% of the overall biodiesel production costs. The search for low-cost feedstocks, i.e. non-edible oils and high acidic waste oils/greases, is an alternative to make biodiesel competitive. Non-regioselective and sn-1,3regioselective lipases can catalyze esterification of free fatty acids and transesterification of triacylglycerols with good yields. The lipases used as catalysts for biodiesel production must present alcohol resistance, thermo-tolerance, high stability and activity. Recently, enzymatic processes for biodiesel production have been implemented at industrial scale. Despite this trend, the conventional chemical process still remains the most popular, mainly due to the high cost of commercial lipases. This review consists of an update of the state of the art of enzymatic biodiesel production, including legislation, feedstocks, lipases used for biodiesel synthesis, the role of acyl acceptors and strategies to avoid lipase inactivation, the mechanisms proposed for biocatalysis and the enzymatic bioreactors used. In addition, the economics of the bioprocess is also presented.
Applied Biochemistry and Biotechnology, 2009
In this study, we evaluate the effects of various reaction factors, including pressure, temperature, agitation speed, enzyme concentration, and water content to increase biodiesel production. In addition, biodiesel was produced from various oils to establish the optimal enzymatic process of biodiesel production. Optimal conditions were determined to be as follows: pressure 130 bar, temperature 45°C, agitation speed 200 rpm, enzyme concentration 20%, and water contents 10%. Among the various oils used for production, olive oil showed the highest yield (65.18%) upon transesterification. However, when biodiesel was produced using a batch system, biodiesel conversion yield was not increased over 65%; therefore, a stepwise reaction was conducted to increase biodiesel production. When a reaction medium with an initial concentration of methanol of 60 mmol was used and adjusted to maintain this concentration of methanol every 1.5 h during biodiesel production, the conversion yield of biodiesel was 98.92% at 6 h. Finally, reusability was evaluated using immobilized lipase to determine if this method was applicable for industrial biodiesel production. When biodiesel was produced repeatedly, the conversion rate was maintained at over 85% after eight reuses.
Optimized synthesis of lipase-catalyzed biodiesel by Novozym 435
Journal of Chemical Technology & Biotechnology, 2005
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.
Process Safety and Environmental Protection, 2019
The enzymatic conversion of vegetable oils is a cleaner alternative to the chemically catalysed transesterification processes. The present study describes the development of heterogeneous enzyme catalyst by immobilising lipase onto waste derived activated carbon (AC) support and its application in enzymatic transesterification. The study includes optimisation of enzymatic transesterification using indigenously prepared biocatalyst by considering four parameters. The main parameters affecting the biodiesel yield were recognized by statistical analysis using analysis of variance (ANOVA) and contribution factor. The obtained optimised conditions for maximum biodiesel yield were: catalyst loading 3 wt%, M/O ratio 6:1, time 5 h and temperature 20 • C. The ANOVA revealed that catalyst loading and temperature are the two most dominant parameters affecting the biodiesel yield significantly with contribution factor 68.99 and 27.95% respectively. The produced rubber seed oil methyl esters (RSOME) were characterised for estimating fuel properties and found to be comparable with conventional diesel. The catalyst is reused at the optimised condition and observed that 6-7% decay in catalytic activity after 7 cycles. Thus, AC supported lipase as a biocatalyst is highly effective in conversion of rubber seed oil (RSO) to biodiesel at optimised conditions derived using Taguchi approach.
Enzymatic biodiesel synthesis � Key factors affecting efficiency of the process
Renewable Energy, 2009
Chemical processes of biodiesel production are energy-consuming and generate undesirable by-products such as soaps and polymeric pigments that retard separation of pure methyl or ethyl esters of fatty acids from glycerol and di-and monoacylglycerols. Enzymatic, lipase-catalyzed biodiesel synthesis has no such drawbacks. Comprehension of the latter process and an appreciable progress in production of robust preparations of lipases may soon result in the replacement of chemical catalysts with enzymes in biodiesel synthesis. Engineering of enzymatic biodiesel synthesis processes requires optimization of such factors as: molar ratio of substrates (triacylglycerols: alcohol), temperature, type of organic solvent (if any) and water activity. All of them are correlated with properties of lipase preparation. This paper reports on the interplay between the crucial parameters of the lipase-catalyzed reactions carried out in non-aqueous systems and the yield of biodiesel synthesis.