Synthesis Of Methyl Oleate Research Articles

Optimization of Methyl Oleate Synthesis with Sulfonated Pyrrolidonium Ionic Liquids as Catalysts Using the Response Surface Methodology

In order to improve the efficiency of biodiesel production from esterification of free fatty acids, an alternative to sulfuric acid has been explored in this study. These catalysts including three pyrrolidonium ionic liquids (ILs), 1-methyl-2-pyrrolidonium hydrogen sulfate ([Hnmp]HSO4), 2-pyrrolidonium hydrogen sulfate ([Hnhp]HSO4), and 1-(3-sulfonic acid) propyl-2-pyrrolidonium hydrogen sulfate ([C3SO3Hnhp]HSO4), were applied as catalysts to produce biodiesel through the esterification reaction of oleic acid with methanol. The catalytic performances of the synthesized ILs for the esterification of oleic acid were evaluated, and [C3SO3Hnhp]HSO4 exhibited the best catalytic activity among all tested acidic ILs. Moreover, the esterification of oleic acid with methanol by the [C3SO3Hnhp]HSO4-catalyzed was systematically explored, and the reaction conditions were further optimized through a single-factor experiment, the Plackett-Burman design, and a response surface methodology. It was found that optimum response for oleic acid conversion was 97.4% under reaction condition of using catalyst dosage of 12.5%, methanol/oleic acid molar ratio of 9:1, reaction time at 4 h and reaction temperature at 70 °C. In addition, the catalytic activity of [C3SO3Hnhp]HSO4 still remained high level after 5 cycles. In a conclusion, the IL [C3SO3Hnhp]HSO4 has great potential as a catalyst for producing fatty acid methyl esters via the esterification reaction.

Intensification of autocatalytic methyl oleate synthesis in continuous flow rotating recycle reactor under hybrid radiation: Process optimization and Scale-up

Intensification of the autocatalytic esterification of methanol with oleic acid for producing methyl oleate (biodiesel) was accomplished using a continuous flow rotating reactor under recycle mode. To exaggerate the biodiesel yield, highly efficient hybrid electromagnetic radiation (near-infrared and microwave irradiation) was used as an energy source. Spherical-shaped nano-zinc-titanate photocatalyst (low band-gap energy: 2.01 eV and low recombination rate) was prepared and utilized in the aforementioned novel reactor. Box-Behnken statistical optimization technique was applied to attain the optimum condition (catalyst concentration 30 wt%, reaction temperature 333 K, methanol: oleic acid mole ratio 11:1, LHSV: 0.20 min−1) resulting in maximum biodiesel yield. Moreover, at optimum rotating speed (∼235 rpm), high external and internal mass transfer coefficients were achieved which rendered a remarkably augmented reaction rate under ideal reactor behavior (Dispersion number: 6.42 × 10−7). A geometric-based COMSOL model was simulated which confirmed uniformity of hybrid irradiation and temperature distribution within the rotating catalytic packed bed; which was applied for the development of a parallel-autocatalytic reaction kinetic model. Langmuir Hinshelwood kinetics of the parallel autocatalytic esterification is well represented in the experimental data (RSSQ=1.52×10-7). Without recycle stream, the reaction exhibited a non-autocatalytic reaction with a lower yield of 79.04 % biodiesel within 0.20 min−1 LHSV, whereas, under recycle mode, the biodiesel yield was increased up to 93.55 % even at a higher LHSV of 0.25 min−1. For larger-scale production of the methyl oleate, the ASPEN PLUS simulator has been deployed for a throughput scale-up factor of 1000 (geometric similarity), which corroborates well with lab-scale yield/reactor performance.

Methyl Oleate Synthesis by TiO2Photocatalytic Esterification of Oleic Acid: Optimisation by Response Surface Quadratic Methodology, Reaction Kinetics and Thermodynamics

AbstractMethyl oleate, an example of a FAME (fatty acid methyl ester), was produced by oleic acid (OA) photoesterification with TiO2and UVA light. Different parameters were evaluated and optimised: catalyst pretreatment, temperature (25–65 °C), catalyst loading (1–30 % w/wOA) and oleic acid : alcohol molar ratio (1 : 3–1 : 55). Response surface quadratic methodology obtained by central composite rotational design (RSM‐CCRD) was used to evaluate the main operational conditions of the photoesterification process. A high conversion of 98 % (±0.8) at 55 °C, 20 % TiO2(w/wOA), and 1(OA) : 55(methanol) molar ratio was achieved. The photoesterification mechanism is furthermore proposed. The Langmuir‐Hinshelwood kinetic model considered the forward and backward reaction as first‐order fits with the best accuracy (R2of 0.997). The thermodynamic results (ΔG338.15K=−20.75 kJ/mol, ΔH=13.75 kJ/mol, and ΔS=0.47 kJ/mol.K) indicate that the operating conditions are important, both to supply the energy requirement of the reaction, but also to increase the miscibility of the reactants.

Purification, Characterization and Immobilization of Lipase from Proteus vulgaris OR34 for Synthesis of Methyl Oleate

A newly isolated strain, Proteus vulgaris OR34, from olive mill waste was found to secrete an alkaline extracellular lipase at 11 U·ml-1 when cultivated on an optimized liquid medium. This lipase was purified 94.64- fold with a total yield of 9.11% and its maximal specific activity was shown to be 3232.58 and 1777.92 U·mg-1 when evaluated using the pH-stat technique at 55℃ and pH 9 and Tributyrin TC4 or olive oil as the substrate. The molecular mass of the pure OR34 lipase was estimated to be around 31 kDa, as revealed by SDSPAGE and its substrate specificity was investigated using a variety of triglycerides. This assay revealed that OR34 lipase preferred short and medium chain fatty acids. In addition, this lipase was stable in the presence of high concentrations of bile salt (NaDC) and calcium ions appear not to be necessary for its activity. This lipase was inhibited by THL (Orlistat) which confirmed its identity as a serine enzyme. In addition, the immobilization of OR34 lipase by adsorption onto calcium carbonate increased its stability at higher temperatures and within a larger pH range. The immobilized lipase exhibited a high tolerance to organic solvents and retained 60% of its activity after 10 months of storage at 4℃. Finally, the OR34 lipase was applied in biodiesel synthesis via oleic acid mediated esterification of methanol when using hexane as solvent. The best conversion yield (67%) was obtained at 12 h and 40℃ using the immobilized enzyme and this enzyme could be reused for six cycles with the same efficiency.

Application of water treatment sludge as a low-cost and eco-friendly catalyst in the biodiesel production via fatty acids esterification: Process optimization

One of the ways to produce biodiesel is through fatty acid esterification via heterogeneous catalysis. The water treatment plants in Manaus - Amazonas/Brazil produce about 20 tons of sludge per day. In order to establish an application to this abundant waste as a new heterogeneous catalyst, acid and heat treatments were performed and characterized by X-ray diffraction, X-ray fluorescence, infrared spectroscopy, thermogravimetric analysis, surface area, and scanning electron microscopy. The sludge is mainly composed of Si, Al, and Fe. Only the sludge without heat treatment showed S levels after acid treatment, proving the sulfation in these materials. The obtained materials were applied as catalysts, where the activity was evaluated by fatty acid esterification with methanol. The process was optimized using the best catalyst (WTS3M) and oleic acid, where under the following reaction conditions: 15:1 methanol:acid molar ratio, 5 wt% of catalyst, 100 °C and 3 h of reaction, resulted in conversions higher than 97%. The application of water treatment sludge as a catalyst with high catalytic activity for methyl oleate synthesis and the possibility of regeneration were demonstrated. This study will thus aid in the cost-effective reduction of water treatment sludge and increase the potential for additional biofuel production.

Production of methyl oleate by direct addition of fermented solid Penicillium sumatrense and Aspergillus fumigatus

Abstract This work objective was to use different lipases in the methyl oleate synthesis. Endophytic fungi strains of Penicillium sumatrense and Aspergillus fumigatus were isolated from castor leaves (Ricinus communis L.) in order to acquire lipases through solid-state fermentation, using sunflower seeds as substrate. Following this, the fermented solid went through the process of obtaining the crude extract, drying or immobilization. From the enzymatic preparations, esterification reactions were performed, using oleic acid as a substrate. The enzyme immobilization and extraction resulted in loss of hydrolytic activity and reduction of esterification efficiency, showing about 70–80% of maximum conversion in 12 h of reaction. The fermented solid showed 90% conversion after 8 h reaction and after conditions optimization, it resulted in 100% conversion. The produced enzymes presented themselves to be suitable for reutilization, the A. fumigatus enzyme showed a half-life of 14 reuse cycles. The fermented solid addition have some advantages when compared to others enzymatic preparations such as lower activity loss, reduced obtainment costs and possibility for reutilization.

Hydrogen Bonds in Disulfonic-Functionalized Acid Ionic Liquids for Efficient Biodiesel Synthesis.

Regulating the states of hydrogen bonds in ionic liquids (ILs) is an effective way to improve their catalytic performance. In this paper, disulfonic-functionalized acidic ionic liquids (DSFAILs) were synthesized successfully, including novel SO3H-functionalized binuclear IL (bis[3-(CH2)3SO3H-1-(CH2)2-Im][HSO4]2). For the biodiesel synthesis, compared with the traditional ILs catalysts, DSFAILs bis[(3-(CH2)3SO3H-1-(CH2)2-Im][HSO4]2, [Im(N (CH2)3SO3H)2][HSO4]) had higher catalytic activity even under mild reaction conditions. Using the density functional theory (DFT) method, the role of hydrogen bonds in different SO3H-functionalized acidic ionic liquids (SFAILs) was explored. The forms of hydrogen bonds existing in different ILs directly determine their acidity. It suggested that the forming status of the active sites (hydrogen bonds) were diverse in different SFAILs. Also, deep ionization of the hydrogen atoms from the cation–anion strong interaction could increase the acidity and catalytic performance of SFAILs. From this, the structure–activity relationship between the SFAILs structures and the catalytic activity of methyl oleate synthesis was proposed. Besides, the experimental results also showed that bis[3-(CH2)3SO3H-1-(CH2)2-Im][HSO4]2 catalyst had a high catalytic activity to obtain methyl oleate and the catalyst could be separated easily owing to its larger molecular weight. However, [Im(N(CH2)3SO3H)2][HSO4] had a stronger acidity and a lower steric hindrance and thus a higher catalytic activity and was the optimal catalyst for the methyl oleate synthesis. In the presence of a small amount of catalyst (6 wt %) and at low reaction temperature (353 K), the methyl oleate yield could reach up to 93%. After six recycles of the catalyst, the methyl oleate yield remained at 90%.

Water-Retaining Polymers in Organic Solvent Increase Lipase Activity for Biodiesel Synthesis

Background: Biocatalyzed esterification reactions in non-aqueous media require water removal materials and optimized enzyme formulations to improve reaction rate and conversion. We have tested a lipase biocatalysis process using anionic polymeric chains of polyacrylate as super-absorbent of water in the conversion of methyl oleate from oleic acid and methanol and in toluene as reaction medium. The water removal material that we used also for the enzyme immobilization is commercially named Aquasorb 3005K2 (herein called Aquasorb). Methods and findings: The synthesis of methyl oleate was catalyzed by Candida rugosa lipase or lipase G from Penicillium camemberti in the presence or absence of Aquasorb. The simple addition of Aquasorb to the reaction media of the lipase (commercial sample) catalyzed reaction allowed an enzyme activity 20% and 40% higher than that in the absence of Aquasorb for lipase from C. rugosa and lipase G, respectively. Furthermore, for the commercial form of lipase G, when used in the presence of Aquasorb, it was obtained a higher conversion of esterification (93% instead of 60%). Aquasorb was used also as support for the adsorption of the enzyme (via hydrogel formation followed by lyophilization) producing a lipase that was 100% and 60% more active than the enzyme dissolved in buffer in the absence of Aquasorb and lyophilized. However, these lipase formulations showed only about 20 % activity compared to when dry Aquasorb was simply added to the non-aqueous reaction medium. Conclusions: The use of Aquasorb appears beneficial as additive in esterification reactions (e.g., for biodiesel production) catalyzed by lipases in non-aqueous reaction media.

Modelling and optimization of Candida rugosa nanobioconjugates catalysed synthesis of methyl oleate by response surface methodology

Esters, such as methyl oleate, are functionally important compounds in many industrial sectors, mainly as components for manufacturing of emulsifiers, detergents, intermediate stabilizers and wetting agents. Acid functionalization of multi-walled carbon nanotubes (F-MWCNTs) by using a mixture of HNO3 and H2SO4 (1:3, v:v) was employed as the matrix for the adsorption of Candida rugosa lipase (CRL) as nanobioconjugates (CRL-MWCNTs) for the production of methyl oleate. Structural information of the developed CRL-MWCNTs was confirmed using Fourier Transform Infrared spectroscopy, thermogravimetric analysis and transmission electron microscopy, which revealed a successful attachment of CRL onto the F-MWCNTs. Process parameters (reaction time, temperature and alcohol:acid molar ratio) were optimized for high percent conversion of methyl oleate. Structural analysis established that CRL was successfully attached to the surface of the F-MWCNTs. Under the optimized conditions, which were 13.87 h, 51 °C, molar ratio oleic acid:methanol (1:3.80), a high ester yield of 90.90% was attained. Also, under conditions of the shortest reaction time of 6 h, 47.07 °C and acid:methanol ratio of 1:2.54, the CRL-MWCNTs catalysed a 74.51% ester yield. Hence, we established that response surface methodology (RSM) can be a practical technique for the prediction of the conditions that favour the high yield production of methyl oleate. Under optimized conditions, the CRL-MWCNTs nanobioconjugates are potentially good and economical biocatalysts for the production of methyl oleate, as well as other types of commercially important fatty-acid methyl esters.

Sustainable production of the emulsifier methyl oleate by Candida rugosa lipase nanoconjugates

Acid functionalization of multi-walled carbon nanotubes (F-MWCNTs) using a mixture of HNO3 and H2SO4 (1:3, v:v) was used as support materials for the adsorption of Candida rugosa lipase (CRL) as nanoconjugates (CRL-MWCNTs) for producing methyl oleate. To evaluate the competency of the CRL-MWCNTs nanoconjugates, parameters viz. reaction time, surfactant as well as thermostability and reusability were investigated. The characterization of CRL-MWCNTs nanoconjugates using Fourier transform infrared spectroscopy, Field Scanning Electron Microscopy and Transmission Electron Microscopy revealed successful attachment of CRL onto the F-MWCNTs. Utilization of CRL-MWCNTs nanoconjugates resulted in a higher acid conversion in the synthesis of methyl oleate (79.85% at 11h of reaction time) when compared with the free CRL i.e. an approximately 1.5-fold improvement over the free CRL. The highest percentage of esterification (83.62%) was observed following the use of nonionic surfactant when compared with the anionic and cationic ones. The CRL-MWCNTs nanoconjugates could be used up to 5 cycles, retaining 50% of its residual activity. Since the preparation of the CRL-MWCNTs nanoconjugates was facile and cheap while producing reasonable yield, the CRL-MWCNTs nanoconjugates developed here were found as promising biocatalysts for the production of methyl oleate.

PERFORMANCE OF LOOFA-IMMOBILIZED Rhizopus oryzae IN THE ENZYMATIC PRODUCTION OF BIODIESEL WITH USE OF OLEIC ACID IN n-HEXANE MEDIUM

The performance of loofa-immobilized Rhizopus oryzae (as a whole-cell biocatalyst) in the synthesis of methyl oleate was evaluated using oleic acid as a model substrate. The activities of the cell-bound lipase in terms of the esterification and hydrolysis reactions were found to be higher for the immobilized cells as compared with those of the free cells. The time to reach equilibrium for methyl oleate synthesis was 12 h in the presence of n-hexane (hexane:oleic acid ratio 9:1(v/v)), and the yield was 80%. In the absence of solvent, equilibrium was reached after 48 h and the yield was only 30%. The moisture repellency and the hydrophilic properties of loofa sponge make this natural fiber a good candidate for cell-enzyme immobilization, especially for lipases as the interfacial enzyme.

Study of the Catalytic Activity of Acidic Ionic Liquid in the Synthesis of Methyl Oleate

Four kinds of Brønsted-acidic ionic liquids were synthesized with netrogen-contained chemical groups and different anions,and were characterized by nuclear magnetic resonance (NMR) and infrared spectrum (IR). On this basic, when the mole ratio of catalyst quantity to oleic acid was 0.019, that of alcohol to acid was 2, the reaction temperature was 150°C and the reaction time was 5 hours,the esterification of oleic and methanol were studied and the catalytic activities of ionic liquids for the esterification were investigated. The results showed their catalytic activities were associated with the structures of nitrogen-contained chemical groups, anionic acid strength and acid volume. Under the coaction of anions and cations, ionic liquids ([MPy]HSO4) had the best catalysis activity. Meanwhile the conversion rate of oleic acid could reach 88.21% .

Magnetic and Stable H3PW12O40‐Based Core@shell Nanomaterial towards the Esterification of Oleic Acid with Methanol

AbstractA magnetically retrievable and stable composite, Fe3O4@SiO2–NH2/HPW@CS/HPW, in which H3PW12O40 (abbreviated as HPW hereafter) was successfully anchored onto the surface of a cross‐linked chitosan coating on magnetic Fe3O4 cores, has been prepared by means of chemical bonding between the amino and HPW components. The resultant composites were characterized by different physicochemical techniques, such as TEM, SEM, FTIR, and vibrating sample magnetometry (VSM). An improved synthesis of methyl oleate from oleic acid and methanol was observed with the as‐prepared material as catalyst with easy recovery by simply using an external magnet. A yield of 93.2 % of methyl oleate was achieved under the optimal reaction conditions, that is, a 20:1 molar ratio of methanol to oleic acid and 0.4 g catalyst at 60 °C for 4 h. It was demonstrated that improved catalytic performance and facilitated separation were simultaneously achieved in the esterification reactions as a result of the core@shell structures in which stabilized HPW and magnetic cores are integrated into one body.

Optimization of biological-hydroxyapatite supported iron catalyzed methyl oleate synthesis using response surface methodology

Innovative biological-hydroxyapatite (BHAp) derived from Catla catla (abundantly aqua-cultured freshwater species in South Asia) bone was employed to prepare cost-effective, reusable supported iron solid acid catalyst using Fe2 (SO4)3·H2O through wet impregnation method employing infrared (IR) irradiation assisted freeze-drying protocol. The catalytic effectiveness was assessed and optimized through response surface methodology (RSM) in synthesis of methyl oleate through esterification of oleic acid with methanol. Catalyst characterization involved TGA, FESEM, EDX, XRD, BET–BJH and FTIR analyses. The catalyst that rendered optimal performance possessed 14.9m2/g specific surface area, 0.0335cm3/g pore volume and 33.13nm modal pore size with an acidity of 10.336mmolKOH/g catalyst. Esterification attained a maximum 93.0% conversion at 70°C freeze-drying temperature, 1.85 weight ratio of ferric sulphate to BHAp and 2.0wt.% catalyst concentration within 60min batch time. Application of recyclable solid desiccant during esterification could further significantly augment methyl oleate yield at the derived optimal conditions. The novel catalyst exhibited appreciable reusability and rejuvenation attributes. The present research demonstrates successful application of C. catla bone as a potential support for economical preparation of solid iron acid catalyst, creating an innovative avenue for recycling of this municipal solid waste.

Production of methyl oleate with a lipase from an endophytic yeast isolated from castor leaves

Abstract This work aims to optimize lipase production through experimental design and to immobilize these biocatalysts for methyl oleate synthesis. For that, it was applied a 26−3 experimental design to optimize the lipase production, reaching the production of 25 U mL−1. The enzymes produced by submerged fermentation were obtained from an endophytic yeast Candida guillermondi isolated from castor leaves (Ricinus communis L.). The obtained enzyme was partially purified and freeze-dried before the immobilization process using agarose and silica gel supports. The distribution of the enzyme on the silica gel was homogeneous and verified by atomic force microscopy. The free and the immobilized enzymes were evaluated by the methyl oleate synthesis in order to compare the efficiencies of the reaction processes. The immobilization process increased the conversion rates for the synthesis of methyl oleate in all immobilized enzymes experiments. In addition to the immobilization process ensuring greater efficiency, the immobilized enzyme could also be reused. Therefore, the enzyme used in this work is expected to be a good biocatalyst to be applied in ester synthesis in the food and biofuel industry or laboratorial applications.

The Synthesis of Methyl Oleate Catalyzed by Phosphotungstic Acid Immobilized on the Functionalized Palygorskite

Esterification of oleic acid with methanol was investigated using tungstophosphoric acid (H3PW12O40) immobilized on the 3-aminopropyltriethoxysilane (H2N(CH2)3Si(OC2H5)3) functionalized palygorskite. Among different loading catalysts, 15% (w/w) H3PW12O40 immobilized onto functionalized palygorskite showed stable and substantially high activity with about 90% oleic acid conversion. Immobilized catalysts were characterized by X-ray photoelectron spectroscopy, X-ray diffraction, and temperature programmed desorption of NH3 for their surface element compositions and chemical states, crystallization, and acid strength, respectively. Characterization results indicated that H3PW12O40 was chemically and uniformly dispersed on modified palygorskite.

Towards continuous sustainable processes for enzymatic synthesis of biodiesel in hydrophobic ionic liquids/supercritical carbon dioxide biphasic systems

The excellent suitability of immobilized Candida antarctica lipase B (Novozym 435) catalyst to carry out the synthesis of methyl oleate (biodiesel) by methanolysis of triolein in ILs based on imidazolium cations with large alkyl side chain (from C12 to C18) has been demonstrated at 60 and 85°C. The phase behaviour of IL/triolein/methanol and IL/methyl oleate mixtures were studied at different concentrations and temperatures, the best results (up to 98.6% biodiesel yield after 6h) being obtained for ILs able to provide monophasic reaction systems, i.e. 1-methyl-3-octadecylimidazolium bis(trifluoromethylsulfonyl)imide). A continuous enzymatic reactor, based on biocatalysts particles coated with hydrophobic ILs, for biodiesel synthesis in supercritical carbon dioxide was studied at 60°C and 180bar. The operational stability of the immobilized lipase was improved by its coating with ILs, i.e. 1-methyl-3-octadecylimidazolium hexafluorophosphate, leading to a two-phase systems with respect to the biodiesel product, which showed an excellent catalytic behaviour in continuous operation under supercritical conditions (up to 82% biodiesel yield after 12 cycles of 4h).

Combined strategy for preparation of a bioimprinted Geotrichum sp. lipase biocatalyst effective in non-aqueous media

Geotrichum sp. lipase with enhanced activity and operational stability was prepared for use in non-aqueous media. A combined strategy comprising bioimprinting with dual imprint molecules and a co-solvent coupled to pH tuning, KCl salt activation, lecithin coating and immobilization on macroporous resin effectively enhanced the activity and operational stability of Geotrichum sp. lipase. The modified lipase exhibited 18.4-fold enhanced esterification activity towards methyl oleate synthesis, and retained 90% activity following repeated use in 10 cycles. The combined strategy exhibited a significant synergistic effect and was suitable for lipase modification, dramatically enhancing the enzyme activity and operational stability. This approach is applicable to the preparation of other enzyme biocatalysts, since the methods are effective for upgrading crude enzyme to a refined product with high activity and stability for use in non-aqueous media.

Optimization for producing cell-bound lipase from Geotrichum sp. and synthesis of methyl oleate in microaqueous solvent

An integrated optimization strategy involving a combination of different designs was employed to optimize producing conditions of cell-bound lipase (CBL) from Geotrichum sp. Firstly, it was obtained by a single factorial design that the most suitable carbon source was a mixture of olive oil and citric acid and the most suitable nitrogen source was a mixture of corn steep liquor and NH4NO3. Then, the Plackett-Burman design was used to evaluate the effects of 13 variables related to CBL production, and three statistically significant variables namely, temperature, olive oil concentration, and NH4NO3 concentration, were selected. Subsequently, the levels of the three variables for maximum CBL production were determined by response surface analysis as follows: 1.64% (v/v) olive oil, 1.49% (w/v) NH4NO3, and temperature 33.00 degrees C. Such optimization resulted in a high yield of CBL at 23.15 U/ml, an enhanced 4.45-fold increase relative to the initial result (5.2 U/ml) in shake flasks. The dried CBL was used to synthesize methyl oleate in microaqueous hexane, resulting in 94% conversion after 24 h, and showed reusability with 70% residual activity and 69% conversion after eight cycles of batch operation, which indicating that CBL, as a novel and natural form of immobilized enzyme, can be effectively applied in repeated synthesis of methyl oleate in a microaqueous solvent.

A novel hydrophilic support, CoFoam, for enzyme immobilization.

Lipases from different sources (porcine pancreas, Mucor miehei and Candida antarctica B) were covalently immobilized on a hydrophilic polyurethane composite (CoFoam). Their hydrolytic activities assayed with tributyrin were 0.55, 2.1 and 447 U g(-1), respectively. The activity of the C. antarctica B composite in the synthesis of methyl oleate in hexane was 8.8 U g(-1) compared to 60.6 U g(-1) for commercial Novozyme 435. The advantage of the CoFoam composite lies in the low pressure drop in a packed-bed reactor at fairly large flow rates. For example, at flow rates of 10-12 l min(-1), the pressure drop over 15 cm is typically 3 kPa.