Transesterification Activity Research Articles

Investigation of Lipozyme TL IM-catalyzed transesterification using ultraviolet spectrophotometric assay

A novel ultraviolet (UV) spectrophotometric method for evaluating lipase transesterification activity in organic solvents is described. The model reaction was lipase-catalyzed transesterification between p -nitrophenyl palmitate (pNPP) and n -butanol in n -hexane at 30 °C. The conversion of pNPP to p -nitrophenol was monitored by measuring UV absorbance changes at 310 nm. Seven commercial lipases were tested using this method, and the results were similar to those obtained using gas chromatography. The UV spectrophotometric method was used to investigate the kinetics of the Lipozyme TL IM-catalyzed reaction of pNPP, and the correlation between synthetic activity and biocatalyst concentration was determined. The method was also used to investigate the Lipozyme TL IM-catalyzed transesterification properties, namely solvent effect, acyl acceptor specificity, alcohol tolerance, optimum reaction temperature, and thermostability. A modified p -nitrophenyl palmitate assay for lipase transesterification activity determination in organic solvents was described. On the basis of the method, the transesterification properties of Lipozyme TL IM were determined.

Enzyme‐catalyzed transesterification of lipids in methyl acetate using a methanol tolerant lipase from Proteus mirabilis (583.5)

Recombinant lipase catalyzed biodiesel production has the potential to be more economically efficient than traditional acid and/or base catalyzed methods. Enzyme catalysis may require smaller loads, lower temperatures, less time and can be repeated if immobilized enzymes are utilized. However, many lipases expressed in E.coli are found in inclusion bodies, making recombinant production difficult. Further, often they are denatured in the methanol, the most common acyl acceptor. Lipase from Proteus mirabilis is naturally soluble in E.coli and has previously been mutated for methanol tolerance. These “dieselzymes” have not been previously characterized or optimized in reactions using alternate acyl acceptors. Mutated “dieselzymes” have been expressed in E.coli using the pET28 bacterial expression vector, purified using immobilized metal affinity chromatography and characterized for transesterification activity in reactions using methyl acetate, p‐nitrophenyl palmitate, and synthetic triacylglycerides at varying pHs and temperatures

Immobilized lipase of reconstructed oil bodies and its potential application in biodiesel production

Signal peptide-deleted lipase, Lipd25A, with transesterification activity from Pseudomonas aeruginosa B10 was overexpressed in Escherichia coli (E. coli) as a fusion with Jatropha curcas oleosin 2 (Jco2). The fusion protein Jco2-Lipd25A which coexpressed with molecular chaperone LipB was named Jco2-Lipd25AB. J. curcas seed oil bodies and Jco2-Lipd25AB were used to prepare reconstructed oil bodies (ROBs) for biodiesel production as immobilized lipase (ROBs-Jco2-Lipd25AB). Results indicated that Jco2-Lipd25AB could be immobilized on ROBs efficiently. The lytic cycle of ROBs was 30d, meaning that it could be reused three times in series, as evidenced by the stability and reusability analysis. Interestingly, methanol toxicity test suggested that ROBs-Jco2-Lipd25AB presented transesterification activity in a high methanol concentration (300mmol/L) environment without significant change of transesterification rate. The orthogonal L25(56) test design showed that the amount of ROBs-Jco2-Lipd25AB and solvent reaction system are the two most important factors in the transesterification reaction. The highest transesterification rate (75.19%) reached under the following optimal conditions: 2mL ROBs-Jco2-Lipd25AB with a 3/1 ratio of methanol to oil (n/n), water content (%) 1 at 33°C, with shaking at 180rpm in a petroleum ether reaction system. Due to low cost, easy operation and friendly to environmental, natural oil body mediated immobilized lipase presents great prospects for biodiesel production.

Basicity–FAME yield correlations in metal cation modified MgAl mixed oxides for biodiesel synthesis

In this paper Zn2+, Co2+, Fe3+ and La3+ were respectively introduced into Mg3Al1 mixed oxides to prepare Mg1Zn2Al1, Mg1Co2Al1, Mg3Al0.6Fe0.4 and Mg3Al0.6La0.4 oxides by calcinations at 773K. The XRD, XPS, BET, ICP-AES and CO2-TPD characterizations of samples exhibited that the effects of the substitution of trivalent cations (Fe3+, La3+) for Al3+ on the basicity of samples were stronger than the substitution of divalent cations (Zn2+, Co2+) for Mg2+ because of high O2− concentration which were coincident with the FAME yield for these catalysts. La3+ modified catalyst exhibited highest activity in transesterification.

Aspects of Mg–Al mixed oxide activity in transesterification of rapeseed oil in a fixed-bed reactor

The performance of Mg–Al mixed oxides prepared from different types of precursors in transesterification of rapeseed oil was studied in a fixed-bed reactor. The structure and basicity of Mg–Al–K and Mg–Al–Na mixed oxides with 3.6Mg/Al molar ratio were compared before and after the catalytic tests carried out at various reaction temperatures (115 and 140°C) and residence times (0.7, 1.54 and 1.79h). The maximum ester yield of 77% was obtained at 140°C and residence time of 1.54h. The ester yield was stable during 50h of the experiment. It was associated with the negligible magnesium leaching from the solid catalyst into the liquid phases and the minimum change in the composition, structure and basicity of Mg–Al mixed oxides after the catalytic test.

Trans-Esterification of Triglycerides with Methanol on Sulfated Zirconia Prepared with Different Concentration of Sulfuric Acid

Biodiesel derived from vegetable oils is renewable and environmentally friendly than those of petroleum diesel. Currently most of the biodiesel is produced using homogeneous catalysts which are corrosive and non-reusable, leading to an increased cost and causing environmental problems. Alternatively, heterogeneous catalysts are being considered over homogeneous catalysts. Trans-esterification of triacetin with methanol was studied over sulfated zirconia which was prepared with different concentrations of sulfuric acid. Liquid-phase reaction was performed at 60°C for 8 hours using a stirred batch reactor. IR-pyridine was used to characterize the acid sites concentration and strength of the solid catalyst. Conversion of triacetin was about 69% on sulfated zirconia modified with 2M sulfuric acid. The conversion of triacetin was improved due to an increased in the amount of acid sites. The acidity of the sulfated zirconia has significantly affected the catalytic activity in the trans-esterification of triacetin.

Basicities and transesterification activities of Zn–Al hydrotalcites-derived solid bases

Upon calcination, as-prepared Zn–Al hydrotalcites are converted into dehydrated Zn–Al hydrotalcites and oxides, which show catalytic activities in the transesterification.

Biodiesel production from waste cooking oil using a heterogeneous catalyst from pyrolyzed rice husk

A solid acid catalyst was prepared by sulfonating pyrolyzed rice husk with concentrated sulfuric acid, and the physical and chemical properties of the catalyst were characterized in detail. The catalyst was then used to simultaneously catalyze esterification and transesterification to produce biodiesel from waste cooking oil (WCO). In the presence of the as-prepared catalyst, the free fatty acid (FFA) conversion reached 98.17% after 3h, and the fatty acid methyl ester (FAME) yield reached 87.57% after 15 h. By contrast, the typical solid acid catalyst Amberlyst-15 obtained only 95.25% and 45.17% FFA conversion and FAME yield, respectively. Thus, the prepared catalyst had a high catalytic activity for simultaneous esterification and transesterification. In addition, the catalyst had excellent stability, thereby having potential use as a heterogeneous catalyst for biodiesel production from WCO with a high FFA content.

Transesterification of a series of 12 parabens by liver and small-intestinal microsomes of rats and humans

Hydrolytic transformation of parabens (4-hydroxybenzoic acid esters; used as antibacterial agents) to 4-hydroxybenzoic acid and alcohols by tissue microsomes is well-known both in vitro and in vivo. Here, we investigated transesterification reactions of parabens catalyzed by rat and human microsomes, using a series of 12 parabens with C1–C12 alcohol side chains. Transesterification of parabens by rat liver and small-intestinal microsomes occurred in the presence of alcohols in the microsomal incubation mixture. Among the 12 parabens, propylparaben was most effectively transesterified by rat liver microsomes with methanol or ethanol, followed by butylparaben. Relatively low activity was observed with longer-side-chain parabens. In contrast, small-intestinal microsomes exhibited higher activity towards moderately long side-chain parabens, and showed the highest activity toward octylparaben. When parabens were incubated with liver or small-intestinal microsomes in the presence of C1–C12 alcohols, ethanol and decanol were most effectively transferred to parabens by rat liver microsomes and small-intestinal microsomes, respectively. Human liver and small-intestinal microsomes also exhibited significant transesterification activities with different substrate specificities, like rat microsomes. Carboxylesterase isoforms, CES1b and CES1c, and CES2, exhibited significant transesterification activity toward parabens, and showed similar substrate specificity to human liver and small-intestinal microsomes, respectively.

Activity of supported MoO3 catalysts for the transesterification of sunflower oil

Investigations on the transesterification of sunflower oil over MoO3 (8 %) supported on SiO2, SiO2–Al2O3, TiO2 and Al2O3, carried out in order to elucidate the effects of the support on the nature of the supported MoO3 species and transesterification activity, are reported. The supported MoO3 samples were calcined at two temperatures (800 and 950 K). The samples were characterized by physicochemical and spectroscopic methods to identify the different MoO3 species present at the surface. The catalytic activities of the samples were evaluated in the transesterification of sunflower oil with methanol at different temperatures and at different run times in a batch reactor. The support is found to have major influence on the effect of calcination temperature on the nature of the supported MoO3 species and catalytic activity. Besides, the support influences the stability of the MoO3 during the reaction.

Ti-incorporated SBA-15 mesoporous silica as an efficient and robust Lewis solid acid catalyst for the production of high-quality biodiesel fuels

One-pot synthesized Ti-SBA-15 mesoporous materials with various Ti loadings of 0.808–6.78mol% were applied as heterogeneous solid acid catalysts for simultaneous esterification and transesterification of vegetable oils with methanol into high-quality biodiesel fuel (BDF) at 200°C under autogeneous pressure. According to the diffuse-reflectance (DR) UV–vis spectra, diffuse-reflectance infrared Fourier transform (DRIFT) spectra and pulsed ammonia (NH3) chemisorption studies combined with other conventional characterizations, the catalytically active site for high-quality BDF synthesis was mostly related to the tetrahedral Ti4+ species with weak Lewis acid character, which differential heat of NH3 adsorption was lower than 90kJmol−1. Due to that the tetrahedral Ti4+ species were accessible on largely mesoporous framework, the Ti-SBA-15 catalyst gave much higher activity in transesterification of crude Jatropha oil (CJO) with methanol than microporous titanosilicate of TS-1 and commercial TiO2 nanocrystallites. Among them, the 3Ti-SBA-15 catalyst with a Ti loading of 2.46mol% showed a highest fatty acid methyl ester (FAME) content of 90mass% at 200°C for 3h using a methanol-to-oil molar ratio of 27. When the reaction period and methanol-to-oil molar ratio were increased to 3–6h and 108, respectively, a great variety of edible and non-edible vegetable oils with various acid values (0.06–190mgKOHg−l), including refined soybean oil (RSO), refined rapeseed oil (RRO), waste cooking oil (WCO), crude palm oil (CPO), CJO and palm fatty acid distillates (PFAD), was directly transformed into high-quality BDFs, which met with a European standard (EN 14214:2009), over 3Ti-SBA-15 catalyst at 200°C. The used 3Ti-SBA-15 catalyst was easily regenerated by calcination and its high activity was maintained. Most importantly, the 3Ti-SBA-15 catalysts could resist 5wt% of water or 30wt% of free fatty acid (FFA), which tolerance levels were several ten times better than those of homogeneous and heterogeneous catalysts in the current BDF production technology.

Biofuel production from green seed canola oil using zeolites

Solid acid catalysts are of interests for various organic reactions. Among the solid acids, heteropoly acids (HPA) show strong and Brønsted acidity. Especially, 12-tungstophosphoric acid (TPA) (H3PW12O40) possesses super acidity (Brønsted acidity) and higher thermal stability compared to other HPAs. The major disadvantages of using this heteropoly acid are lower surface area (1–10m2/g) and solubility in polar media. These problems can be avoided by supporting TPA on various carriers. In this work, tungsten oxide (WO3) and TPA was supported on H-Y, H-β and H-ZSM-5 zeolite catalysts. The catalysts were characterized extensively using BET, XRD, FTIR, Raman, XPS and NH3-TPD. Their catalytic activity was tested by esterification of the free fatty acid (FFA) present in the green seed canola (GSC) oil, and transesterification of the GSC oil, using a stirred tank reactor for biodiesel production. In this study, TPA impregnated H-Y zeolite showed higher catalytic activity for esterification, and TPA impregnated H-β zeolite showed higher catalytic activity for the transesterification reaction compared to other catalysts. A 55% TPA/H-β showed optimum catalytic activity for both esterification and transesterification. It yielded 99.3wt% ester, when 3.3wt% catalyst (based on green seed canola oil) and 21.3:1 methanol to green seed canola oil molar ratio were used at 200°C, reaction pressure of 4.14MPa and reaction time of 6.5h. Glycerol is the major by-product during transesterification reaction of vegetable oils. This catalyst (55% TPA/H-β) was experimented for etherification of pure glycerol, and maximum conversion of glycerol (100%) was achieved in 5h at 120°C, 1MPa, 1:5 molar ratio (glycerol:TBA), 2.5% (w/v) catalyst loading. Later, these conditions were used to produce glycerol ether successfully from the glycerol derived after transesterification of green seed canola oil. A mixture of GSC derived biodiesel and glycerol ether was defined as biofuels. The properties of biofuels were evaluated and compared to those reported with ASTM standard for pure biodiesel. The reaction kinetics and reaction mechanism of the esterification–transesterification and etherification reactions were also analyzed.

Catalytic properties of spinel-type mixed oxides in transesterification of vegetable oils

Crystalline mixed oxides of AB2O4 composition, where A=Co, Ni, Cu and Zn and B=Al, Fe and Co, were prepared by co-precipitation of hydroxides and calcination at 873K. The catalytic activity of these materials in the transesterification of sunflower oil with methanol to produce fatty acid mono esters (FAME; biodiesel) was investigated. The transesterification activity was found to depend on element A, the order of activity being: Zn>Cu>Ni>Co. The Zn containing spinels were more active than the others and their activity was found to go through a maximum with Sanderson's intermediate electronegativity. Detailed investigations carried out on ZnFe2O4 revealed it to be a suitable solid catalyst for the transesterification of used cooking oil and Jatropha oil. The catalyst was reusable many times. The performance of this spinel was also investigated in a bench-scale (30g catalyst loading) fixed-bed reactor.

Pentynyl dextran as a support matrix for immobilization of serine protease subtilisin Carlsberg and its use for transesterification of N-acetyl-l-phenylalanine ethyl ester in organic media

In this study, serine protease (subtilisin Carlsberg) was immobilized on pentynyl dextran (PyD, O-alkynyl ether of dextran, 1) and used for the transesterification of N-acetyl-L-phenylalanine ethyl ester (2) with different aliphatic (1-propanol, 1-butanol, 1-pentanol, 1-hexanol) and aromatic (benzyl alcohol, 2-phenyl ethanol, 4-phenyl-1-butanol) alcohols in tetrahydrofuran (THF). The effect of carbon chain length in aliphatic and aromatic alcohols on initial and average transesterification rate, transesterification activity of immobilized enzyme and yield of the reaction under selected reaction conditions was investigated. The transesterification reactivity of the enzyme and yield of the reaction increased as the chain length of the alcohols decreased. Furthermore, almost no change in yield was observed when the immobilized enzyme was repeatedly used for selected alcohols over six cycles. Intrinsic fluorescence analysis showed that the catalytic activity of the immobilized enzyme in THF was maintained due to retention of the tertiary structure of the enzyme after immobilization on PyD (1).

Isocyanate-mediated covalent immobilization of Mucor miehei lipase onto SBA-15 for transesterification reaction

Mucor miehei lipase (Mm-L) covalently bind on a hexagonally ordered silica SBA-15 (Santa Barbara Amorphous), previously functionalized with isocyanate moieties, was examined as biocatalyst for transesterification of colza oil with methanol. The isocyanate-mesoporous silica (NCO-SBA-15) was obtained by condensation of silanol with triethoxysilane propyl isocyanate (TPI). The efficiency of the functionalization has been evidenced by infrared, 29Si and 13C NMR spectroscopies. The substrate provided a moderate hydrophobic microenvironment together with reactive sites for chemical immobilization of the enzyme. The biocatalyst containing 0.28 g of Mm-L per gram of support afforded a high level of transesterification activity (yield up to 80%) while using 1:1 molar ratio of methanol/colza oil and small amount of water. The biocatalyst showed higher operational stability than the corresponding physisorbed enzyme since it can be reused 6 times against 2 consecutive runs for the physisorbed enzyme.

TBD-functionalized mesoporous silica: Synthesis and catalytic activity in corn oil transesterification

Mesoporous silica has been functionalized with a strong organic base, 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD). The obtained high loading guanidine functionalized mesoporous SBA-16 and KIT-6 samples showed high activity in the transesterification of vegetable oil.

Biodiesel production from waste cooking oil using bifunctional heterogeneous solid catalysts

Abstract In the present work, bifunctional heterogeneous catalysts were studied to develop an effective catalyst for biodiesel production from waste cooking oil with improved catalytic activity and stability. The catalysts were characterized by various analytical techniques to explore their physicochemical properties. The catalytic activity was evaluated in the transesterification of waste cooking oil for low cost biodiesel production. The bifunctional heterogeneous catalysts show improved transesterification activities. Among the different catalysts tested, the Mo–Mn/γ-Al 2 O 3 -15 wt% MgO catalyst provides the maximum biodiesel yield of 91.4% in reaction time of 4 h at reaction temperature of 100 °C, methanol to oil molar ratio of 27:1 and an agitation speed of 500 rpm. Moreover, the bifunctional heterogeneous catalyst shows substantial chemical stability and could be reused for at least eight times without major loss in its catalytic activity. The physicochemical properties of the biodiesel produced from waste cooking oil were further studied and compared with the ASTM and the EN biodiesel specifications. The results show that the properties of the biodiesel produced comply with the international standard specifications.

Comparison of the salt-induced activation of Pseudomonas cepacia lipase in organic media by phosphate buffer and sodium sulfate

The effects of a kosmotropic phosphate buffer (PB) or sodium sulfate (SS) on the enzymatic activity of crude Pseudomonas cepacia lipase (PCL) in organic media were explored. Previously, it was believed that SS acts as an effective enzyme activator, and PB was only used to adjust the solution pH. The present work showed PB-induced activation of PCL in the transesterification activity, where an increase of nearly 10-fold was achieved by carefully controlling the lyophilization condition. This activation, which gave about one-half of the native catalytic efficiency of PCL in aqueous media, was even more effective than the SS-induced activation. Thermogravimetric analysis of PCL preparations showed that different local environments surrounded PCL due to the presence of PB or SS. The local polarity of PCL preparations suspended in n -hexane was investigated by fluorescence spectroscopy using 2-(4'-amino-2'-hydroxy phenyl)benzoxazole as the probe. SS-incorporated PCL showed a much stronger local polarity than PB-incorporated and salt-free PCL. A correlation was found between the transesterification activity and local polarity of the enzyme preparation as a function of salt content. The data confirmed that the salt-induced activation of PCL in organic media can be attributed in part to the polar environment constituted by the salt-bonded water surrounding the PCL. 系统研究了Al掺杂TS-1 (Al-TS-1)分子筛的合成及其催化氧化性能, 采用X射线衍射/紫外-可见光谱/电感耦合等离子体发射光谱/扫描电镜/ 27 Al和 29 Si固体核磁共振等手段对Al-TS-1样品进行了表征. 结果表明, 在合成过程中, Al的引入会影响TS-1中骨架Ti的形成, 但当Al含量低于一定值(Al/Si ≤ 0.005)时, 其影响很小. Al-TS-1中骨架Al和骨架Ti均不对其相应的酸催化和催化氧化作用产生影响. 骨架Al抑制了Al-TS-1在碱性应用体系中的与Ti相邻Si的溶脱, 从而保护了骨架Ti活性中心. The catalytic activity of Pseudomonas cepacia lipase (PCL) in organic media was drastically enhanced by the addition of a kosmotropic phosphate buffer or sodium sulfate. This activation is probably due to the polar environment formed by the salt-bound water surrounding the PCL.

Immobilized Burkholderia cepacia lipase for biodiesel production from crude Jatropha curcas L. oil

The present world is in a dilemma with fast depletion of fossil fuels. So there arises a drastic need for development of biofuels to power the earth. From an environmental point of view, biodiesel has great potential as an alternative diesel fuel. In this study, lipase from Burkholderia cepacia was first cross linked with glutaraldehyde followed by entrapment in a hybrid matrix of equal proportions of alginate and κ-carrageenan. Later, this biocatalyst was employed for biodiesel production from crude Jatropha curcas L. oil. The optimal conditions for processing 10 g crude Jatropha oil were: 35 °C, 1:10 mol ratio of oil to ethanol, 1 g water, 5.25 g immobilized lipase, 6 g RCF and 24 h reaction time. At the optimal conditions, 100% yield of fatty acid ethyl esters could be achieved. The immobilized lipase was stable and retained 73% relative transesterification activity after six cycles of reuse. This shows that the immobilized lipase in alginate/κ-carrageenan matrix is a potential environmental friendly biocatalyst for biodiesel industry.

Production and activity of extracellular lipase from Luteibacter sp.

Microbial lipases are widely used in industrial applications due to their versatility, and the characterization of new lipase-producing microorganisms could provide new sources of these enzymes, with different specificities and better activities. In this context, we have improved lipase production by Luteibacter sp. by using basal medium supplemented with 2 % olive oil, a pH of 6 and a growth temperature of 37 °C. The enzyme extraction process with the addition of 0.25 % Tween 80 increased lipase activity. Implementation of these modifications increased lipase activity by approximately 430 %. The lipase activities produced in the culture supernatant (LCS) and extracted with Tween 80 (LCST80) were characterized. Both extracts hydrolyzed ρ-nitrophenyl (ρNP) esters with different acyl chain lengths, with a preference for short acyl lengths, and had optimum activity at 45 °C. The LCS was stable at acidic and alkaline pH, but LCST80 was only stable at alkaline pH. Methanol, SDS, Triton X-100, EDTA, and EGTA did not affect lipase activity, while divalent cations (Ca2+, Zn2+, Mg2+) - with the exception of Co2+— increased lipase activity. Both extracts showed transesterification activity on ρNP ester substrates, and both were able to hydrolyze different natural lipids. The characterization of lipase produced by Luteibacter sp. introduces this recently described genus as a new source of lipases with great biotechnological potential.