Transesterification Of Triolein Research Articles

Catalytic evaluation of Li and K supported on CaO in the transesterification of triolein, triestearin, and tributyrin

Catalytic evaluation of Li and K supported on CaO in the transesterification of triolein, triestearin, and tributyrin

Transesterification Using Ultrasonic Spray of Triolein Containing CaO Particles into Methanol Vapor in a 3-Phase Reactor

Ultrasonic spraying was used in a three-phase reactor to produce small droplets of triolein mixed with CaO as a solid catalyst at temperatures above the boiling point of methanol for enhancement of the transesterification of triolein. Droplets fell in the methanol countercurrent flow and were collected at the bottom of the reactor, followed by circulation to the ultrasonic spray system. The experimental parameters included triolein flow rates of 2.5–9.0 mL/min, reaction temperatures of 70–100 °C, and catalyst contents of 1.0–7.0 wt%. The methanol feed rate was set to be constant. The results suggested that the enhancement was successful after using the three-phase reactor by generating a high contact surface area for the droplets, which was a key factor for determining the performance. Comparing the results with conventional transesterification in the liquid phase using the same CaO at 60 °C, the three-phase reactor produced a methyl ester yield 2–5% higher during the 60 min trial period. However, the yield became lower after 60 min because the mass transfer of methanol to the droplets was limited. The transesterification kinetics were estimated based on the experimental data—assuming a first-order reaction—and the results indicated a range of the rate constant, an apparent activation energy, and a pre-exponential factor of 1.21–3.70 × 10−2 min−1, 36.1 kJ mol−1, and 64.9 min−1, respectively, suggesting that the three-phase reactor was effective for fast transesterification at the initial stage.

Transesterification of triolein and methanol with Novozym 435 using co-solvents

To enhance the reaction rate and yield during biodiesel synthesis with Novozym 435 (an immobilized lipase), a co-solvent method was applied, after which the relationships between reaction time and reaction yield during the single-phase enzymatic transesterification of triolein and methanol in the presence of co-solvents such as tetrahydrofuran, acetone, and hexane were investigated. The addition of hexane led to inactivation of Novozym 435, whereas in the presence of acetone or tetrahydrofuran, the reaction was accelerated and the yield was higher than with a conventional solvent-free enzymatic reaction. There was a clear difference in the dispersion of Novozym 435 particles between with and without co-solvents. The co-solvents prevented particle aggregation from occurring during the reaction without co-solvent. This is the likely reason for the enhanced reaction yield in the presence of co-solvents. To better understand the difference among the co-solvents employed, we estimated phase compositions during transesterification using the LLE (liquid-liquid equilibrium)-UNIFAC (UNIversal quasichemical Functional group Activity Coefficients) model, and examined the effect of these compositions on the reaction and dispersion of the glycerin by-product phase. Using the model, we also accounted for why hexane led to inactivation by estimating the transfer free energy of methanol, glycerin, and water between the initial bulk reaction solution and the water layer on the enzyme surface.

Aggregation of immobilized enzyme during transesterification of triolein and methanol, and the effect of two types of aggregates on reaction yield

During the transesterification of triglycerides with methanol catalyzed by immobilized lipase resin (Novozym 435 (N435)) in a glass vial, two types of aggregate of N435 particles were observed: a thin-layer aggregate on the glass surface inside the vial, and bulky aggregates. This prompted us to investigate the conditions under which only one type of aggregate could be formed, by changing the material from which the reaction vial was made and the feed ratio of N435 to the cross section of the reaction glass vial. When a polypropylene vial was used, only the bulky aggregates were formed, and reducing the feed ratio led to only the thin-layer aggregate being formed. We also examined the influence of morphological variation of the aggregates on the reaction yield. The thin-layer aggregate showed high activity, with a reaction yield of 0.932. In contrast, the bulky aggregate grew as the reaction time elapsed, resulting in a reduction in the surface area of the enzyme resin, consequently giving not only a reaction yield of about 0.454 but also low repeatability. These results show that the reactor material and feed ratio strongly affect the reaction yield as well as the aggregation form of enzyme resin. Finally, the durability of the thin-layer aggregate and the effect of accumulation of glycerin were investigated.

Supercritical CO2 Transesterification of Triolein to Methyl-Oleate in a Batch Reactor: Experimental and Simulation Results

In earlier work (Silva et al., 2016; Soh et al., 2014a; Soh et al., 2015), the supercritical CO2 transesterification of triolein to methyl-oleate using Nafion solid-acid catalyst and large methanol/triolein molar feed ratios was carried out. Herein, these ratios are adjusted (from 50–550) to evaluate the yield of fatty acid methyl esters in batch laboratory reactors as temperature is varied from 80–95 °C and pressure is varied from 8.0–9.65 MPa. Also, to better understand the effect of varying these operating parameters, batch reactor simulations using the Soave-Redlich-Kwong Equation of State (RK-ASPEN EOS) in ASPEN PLUS are carried-out. A single-reaction kinetic model is used and phase equilibrium is computed as the reactions proceed. Experimental data are compared with these results.

Binary interaction parameters from reacting mixture data. Supercritical biodiesel process with CO2 as cosolvent

A method is presented for the calculation of binary interaction parameters from reacting mixture data. The process studied is the supercritical methanol transesterification of triolein with CO2 as cosolvent. The reaction proceeds through 3 reversible reactions in series, on a solid catalyst (Nafion® SAC-13), for which the kinetics is known. To describe the reactor performance, the kinetic constants and the binary interaction parameters for the Peng-Robinson equation of state, are necessary, and were included in the reactor model. Previously published view-cell observations and thermodynamic calculations indicate that no condensation occurs in the reactor. Kinetic and thermodynamic parameters were determined by a global optimisation procedure. From the rate constants obtained, the process exhibits some reversibility, despite the excess of methanol used. Our methodology allows to obtain the binary interaction coefficients for the intermediate reaction species (dioleins and monooleins) that were unavailable so far. The method is sensitive to the errors in the measured concentrations.

CFD study of the supercritical transesterification of triolein: Wall-to-fluid/particle-to fluid transport effects

Transesterification of triglycerides is a process by which biodiesel is produced. Biodiesel is a sustainable alternative to petroleum diesel; hence, its efficient production is of significant importance. The transesterification of triolein with methanol under supercritical conditions in the presence of a solid catalyst structured as packed beds is of particular interest due to high yields at moderate temperatures and continuous operability. Fundamental understanding of the heat and mass transfer phenomena in a supercritical transesterification reaction is paramount for a better modelling of the reaction.Computational Fluid Dynamics (CFD) were used to study, by means of a simplified numerical model, heat and mass transport phenomena in a supercritical transesterification reactor. The CFD model was built replicating an experimental pilot plant reactor. Simulations were performed for a 3D geometrical model of a packed bed of cylindrical catalysts. Wall-to-fluid and particle-to-fluid heat and mass transfer were studied for a fluid mixture of methanol (CH3OH) and triolein (C57H104O6) along with co-solvent carbon dioxide (CO2), flown into the packed bed under supercritical conditions (25 MPa, 473.15 K). Detailed flow, temperature and concentration profiles in packed bed were obtained. Free and forced convection effects for different flow rates were analyzed. Large density gradients were observed near the packed bed inlet, generating hydrodynamic instabilities due to natural convection as observed in Metais-Eckert maps. Heat and mass transfer coefficients were estimated from CFD data, and the obtained values of Nuw, Nup, Shp were compared against empirical models for different flow rates for validation of the CFD data. The simulation data agreed well with empirical correlationsfor predicting transport coefficients.

Transesterification of triolein with ethanol using lipase-entrapped NIPA-co-PEGMEA gel beads

Monodisperse, millimeter-sized, lipase-entrapped NIPA-co-PEGMEA (N-isopropylacrylamide-co-poly(ethylene glycol) methyl ether acrylate) gel beads were prepared by sedimentation polymerization. The feasibility of the lipase-entrapped gel for use in biodiesel fuel (BDF) production was evaluated by studying its catalytic performance in transesterification of triolein with ethanol as the model. The reaction rate was expressed by the ping-pong bi-bi mechanism with ethanol inhibition; the parameters for the immobilized lipase were as follows; the maximum reaction rate, Vmax, was 0.405 mol/(min kg − Lipase PS); the Michaelis constants for triolein and ethanol, Km,T and Km,EtOH, were 481 and 1770 mol/m3, respectively; the ethanol inhibition constant, Ki, was 394 mol/m3. The NIPA-co-PEGMEA gel support improved the stability of the immobilized lipase. We developed a water-washing process wherein the by-product glycerol, which is absorbed and accumulated in the NIPA-co-PEGMEA gel, is removed, so that the lipase-entrapped gel could be reused for multiple cycles (10 cycles were confirmed). The glycerol absorbability of the NIPA-co-PEGMEA gel makes it promising for use in facile BDF production, as it allows for the simultaneous enzymatic reaction and glycerol removal.

Optimization of biodiesel production from transesterification of triolein using zeolite LTA catalysts synthesized from kaolin clay

Abstract Biodiesel was produced from transesterification of triolein with excess methanol using NaOH-treated kaolin clay as an active catalyst. The natural kaolin was first transformed into an efficacious catalyst under the conditions as (1) calcined kaolin/NaOH (aq ) = 1/2 (w/w), and (2) hydrothermal aging for 24 h at 90 °C prior to calcination at 400 °C for 6 h. Coincidently, these NaOH-treated kaolin catalysts possess characteristics of zeolite LTA. Subsequently, the Box–Behnken experimental design was applied to optimize the transesterification process of triolein in methanol. The optimal conditions are found as follows: (1) 36.6 as the mass ratio of methanol-to-triolein in the initial feed, (2) at 62.9 °C as the reaction temperature, (3) 146 min for reaction time, and (4) a catalyst loading at 72 wt. % of triolein used. Under this optimal condition, the conversion efficiency of triolein to biodiesel is (92.8 ± 4.0)%. Furthermore, these as-synthesized zeolite LTA-kaolin catalysts could be reused at least for three consecutive reaction cycles.

Transesterification of Triolein and Methanol by Novozym 435 with Dimethyl Ether

Transesterification of Triolein and Methanol by Novozym 435 with Dimethyl Ether

Evaluation of hydrolysis–esterification biodiesel production from wet microalgae

Wet microalgae hydrolysis–esterification route has the advantage to avoid the energy-intensive units (e.g. drying and lipid extraction) in the biodiesel production process. In this study, techno-economic evaluation of hydrolysis–esterification biodiesel production process was carried out and compared with conventional (usually including drying, lipid extraction, esterification and transesterification) biodiesel production process. Energy and material balance of the conventional and hydrolysis–esterification processes was evaluated by Aspen Plus. The simulation results indicated that drying (2.36MJ/L biodiesel) and triolein transesterification (1.89MJ/L biodiesel) are the dominant energy-intensive stages in the conventional route (5.42MJ/L biodiesel). By contrast, the total energy consumption of hydrolysis–esterification route can be reduced to 1.81MJ/L biodiesel, and approximately 3.61MJ can be saved to produce per liter biodiesel.

High-silica zeolite beta as a heterogeneous catalyst in transesterification of triolein for biodiesel production

Zeolite beta with a high Si/Al ratio as a heterogeneous catalyst in the transesterification of triolein for biodiesel production was synthesized hydrothermally in fluoride media. The prepared zeolite beta was subsequently treated with dilute NaOH solutions to render better catalysis in the transesterification reaction. Effects of heating procedures, namely reflux and microwave heating, to the reaction system and sizes of the zeolite beta particles on the conversion of triolein to biodiesel were investigated as well. A conversion efficiency over 90% could be attained within an hour of the reflux reaction. Moreover, these Na-treated zeolite catalysts still exhibit acceptable endurability and good catalysis in the transesterification reaction after nine consecutive cycles. It is inferred that sodium cations existing in the cages and the defect sites of the NaOH-treated zeolite beta can be supplied to the surface of the catalysts during the transesterification reaction and, thus, to enhance the catalysis.

Carbon-based acid catalyst from waste seed shells: preparation and characterization

Abstract A carbon-based solid acid catalyst was prepared by the sulfonation of carbonized seed shells of Jatropha curcas (J. curcas L.). The structure of amorphous carbon consisting of polycyclic aromatic carbon sheets attached a high density of acidic SO3H groups (2.0 mmol · g−1) was identified with scanning electron microscopy (SEM), fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The performance of the solid acid catalyst was evaluated for biodiesel production in the esterification of oleic acid with methanol. 95.7% yield of biodiesel was obtained after 2 h reaction and the conversions with reused catalyst varied in the range of 95.7% to 95.1%, showing better activity and stability than commercial catalyst amberlyst-46. It was also observed that the prepared catalyst showed enhanced activity in the transesterification of triolein with methanol when compared with other solid acid catalysts. A synergistic effect results from the high density of SO3H groups and the good access of reactants to the acidic sites can be used to explain the excellent catalytic activity, as well as the strong affinity between the hydrophilic reactants and the neutral OH groups bonded to the polycyclic aromatic carbon rings.

Role of CO2 in Mass Transfer, Reaction Kinetics, and Interphase Partitioning for the Transesterification of Triolein in an Expanded Methanol System with Heterogeneous Acid Catalyst

Fatty acid methyl ester (FAME) production via transesterification of triglycerides (TGs) over a heterogeneous acid catalyst is mediated by carbon dioxide in an expanded methanol system. A representative TG, triolein, is used to determine the mechanisms and interactions responsible for the improved yields over Nafion-NR50 in these system conditions. Namely, the system mass transfer limitations, reaction kinetics, and interphase partitioning behavior are explored by varying mixing conditions and catalyst characteristics over a time series of 4 h. It is found that CO2 enhances mass transfer leading to improved reaction yields and product profiles due to increased substrate transport to and from the catalyst surface. CO2 also contributes to catalyst expansion, leading to greater exposure of active sites and faster reaction kinetics. Initial reaction rate constants using methanol-soaked Nafion reflect pseudo-first-order kinetics. Finally, the substrate-reagent mediating properties of CO2 are discussed in refer...

Transesterification of Triolein over Hydrophobic Microporous Carbon with SO3H Groups

AbstractSO3H‐bearing microporous amorphous carbon with a large BET surface area (≈2000 m2 g−1) and a high density of SO3H groups (0.5 mmol g−1) was investigated as a solid acid catalyst for the transesterification of triolein and esterification of oleic acid with methanol. The separable and reusable carbon catalyst exhibits higher catalytic performance for both reactions than conventional homogeneous and heterogeneous acid catalysts, including sulfuric acid, at 353 K. This carbon catalyst can provide methyl oleate yields over 99 %, even in a triolein–oleic acid mixture that resembles a crude vegetable oil, owing to efficient transesterification and esterification reactions. The carbon material is sufficiently hydrophobic to be distributed throughout the hydrophobic triolein phase, resulting in high catalytic performance for both reactions.

Methyl Oleate Production in a Supported Sol–Gel Immobilized Lipase Packed Bed Reactor

A supported immobilized lipase was investigated as a suitable biocatalyst for the transesterification of triolein to methyl oleate in a packed bed reactor (PBR). The packing material for the bioreactor was comprised of lipase immobilized in sol–gel and supported on Celite (CSG). A kinetic- and mass transfer-based model was developed, incorporating a novel efficiency correlation to account for the effect of glycerol on the immobilized enzyme. Comparing the CSG PBR performance to that using a commercial lipase preparation (Novozym 435 (N435)), higher product conversion was achievable using CSG over a shorter time period, indicating the superior performance of CSG for enzymatic transesterification. A rate equation accounting for alcohol inhibition was used to compare the kinetics of the CSG and N435 PBRs. It was found that CSG exhibited a higher maximum reaction rate and was less prone to inhibition by methanol relative to N435. The resulting model showed good agreement with the experimental data, and CSG exhibited good stability without loss of activity over a five day period. This biocatalyst shows significant potential for the efficient production of biodiesel, and the mechanistic model developed has broader applications for similar enzyme and reaction systems.

Fast and economic immobilization methods described for non-commercial Pseudomonas lipases.

BackgroundThere is an increasing interest to seek new enzyme preparations for the development of new products derived from bioprocesses to obtain alternative bio-based materials. In this context, four non-commercial lipases from Pseudomonas species were prepared, immobilized on different low-cost supports, and examined for potential biotechnological applications.ResultsTo reduce costs of eventual scaling-up, the new lipases were obtained directly from crude cell extracts or from growth culture supernatants, and immobilized by simple adsorption on Accurel EP100, Accurel MP1000 and Celite®545. The enzymes evaluated were LipA and LipC from Pseudomonas sp. 42A2, a thermostable mutant of LipC, and LipI.3 from Pseudomonas CR611, which were produced in either homologous or heterologous hosts. Best immobilization results were obtained on Accurel EP100 for LipA and on Accurel MP1000 for LipC and its thermostable variant. Lip I.3, requiring a refolding step, was poorly immobilized on all supports tested (best results for Accurel MP1000). To test the behavior of immobilized lipases, they were assayed in triolein transesterification, where the best results were observed for lipases immobilized on Accurel MP1000.ConclusionsThe suggested protocol does not require protein purification and uses crude enzymes immobilized by a fast adsorption technique on low-cost supports, which makes the method suitable for an eventual scaling up aimed at biotechnological applications. Therefore, a fast, simple and economic method for lipase preparation and immobilization has been set up. The low price of the supports tested and the simplicity of the procedure, skipping the tedious and expensive purification steps, will contribute to cost reduction in biotechnological lipase-catalyzed processes.

Calculating the Thermodynamic Characteristics and Chemical Equilibrium of the Stepwise Transesterification of Triolein Using Supercritical Lower Alcohols

A comparative study of triolein transesterification using three individual supercritical alcohols (methanol, ethanol, and isopropanol) was performed using thermodynamic analysis. The correlative properties were calculated for all components, including boiling point, critical parameters, acentric factor, enthalpy, entropy, and constant-pressure heat capacity. Chemical equilibria of the three reaction systems were discussed and diagrams of reaction enthalpy, Gibbs free energy and the chemical equilibrium constant as a function of temperature were constructed for the temperature range from 300 to 700 K. The results illustrated that, in the supercritical state, the triolein transesterification reaction proceeds primarily with methanol under the proper reaction conditions, but rarely occurs with ethanol or isopropanol. This observation was consistent with the experimental results reported in literature. This study provides a reliable method for analyzing analogous reaction systems for biodiesel synthesis with supercritical fluids.

Kinetic modelling of the production of methyl oleate by Celite® supported lipase sol–gels

This study illustrates the benefits of Celite® supported lipase sol–gels for the transesterification of triolein to produce methyl oleate. A ping–pong bi–bi kinetic model was developed and validated taking into account the inhibition effects of methanol and glycerol as well as the effect of temperature. Although initial reaction rate models are useful for predicting the kinetics in the absence of products, a kinetic model beyond the initial conditions that considers glycerol inhibition is important. The model developed was consistent with the experimental data (R2=0.95) predicting an increase in methyl oleate production with increasing methanol concentration up to an optimal range of 1.3M to 2.0M depending on the temperature. In general, increasing the temperature increased the initial reaction rate for the immobilized lipase over the temperature range of 40–60°C. Based on the kinetic constants, the maximum velocity of the reverse reaction is about 25% slower than that of the forward reaction and glycerol inhibition has a more significant effect on the reaction kinetics than methanol inhibition. The model developed would be useful for understanding the effects of methanol and glycerol inhibition as well as temperature on the production of methyl oleate using lipase-mediated enzymatic transesterification.

Low-Al Zeolite Beta as a Heterogeneous Catalyst in Biodiesel Production from Microwave-assisted Transesterification of Triglycerides

In this work microwave and reflux-assisted transesterification of triolein in methanol was carried out with alkali-loaded low-Al Zeolite Beta as catalyst. The results show that the alkali-treated Zeolite Beta can effectively catalyze transesterification reaction of triglycerides to produce fatty acid ethyl esters (biodiesel), if Zeolite Beta has been properly modified with the alkali ion-exchange process. As a result, the final conversion yield over 90% could be obtained within an hour of reflux reaction. However, the durability of this Na-modified Zeolite Beta still has much room to be improved. In this work, this inferior catalytic durability is overcome by using the low-Al Zeolite Beta with a smaller particle size near 0.5μm. Consequently, for at least eight cycles, cyclic tests of these zeolite catalysts do not result in any significant decrease in catalysis in transesterification reaction. It is inferred that alkali cations existing in defect-sites of low-Al Zeolite Beta can be supplied to the surface of the catalysts during transesterification and enhance the catalysis.