Esterification Of Oleic Acid Research Articles

Microwave‐Assisted Esterification of Oleic Acid Using an Ionic Liquid Catalyst

AbstractThe combination of 1‐butyl‐3‐methylimidazolium hydrogen sulfate ([Bmim]HSO4) ionic liquid (IL) and microwave heating was used to esterify oleic acid as a green approach in biodiesel synthesis. To compare the heating systems, conventional heating and the ultrasonic method were employed but the microwave method was found to be more effective. H2SO4 and 1‐methyl imidazole hydrogen sulfate ([Hmim]HSO4) were also used in the esterification of oleic acid and their catalytic activities were compared to that of [Bmim]HSO4. ILs provided some advantages such as reusability, easy recyclability, and very stable activity. There was only a small decrease in the catalytic activity of [Bmim]HSO4 after four successive applications, which means that ILs can be reused, contrary to homogeneous catalysts. The combination of IL catalysts and microwave irradiation proved to be a potential alternative method for biodiesel production.

MAGNETIC MESOPOROUS SILICA NANOCOMPOSITE DECORATED WITH HETEROPOLY TUNGSTIC ACID AS HIGHLY EFFICIENT AND STABLE CATALYST FOR BIODIESEL PRODUCTION

A multifunctional heterogeneous acid catalyst named as spFe3O4@SBA-15@HPW was prepared, which consists of versatile properties such as magnetic separability, high conversion efficiency and reusability. This catalyst was characterized by XRD, FT-IR, VSM, TEM and SEM/EDX techniques with respect to structural, morphological and magnetic properties. The catalyst showed higher catalytic activity than the commercial catalysts such as Amberlyst-15 and Dowex 50Wx4 and also heteropoly tungstic acid (HPW) alone in terms of conversion of oleic acid for biodiesel production by the esterification of oleic acid with methanol. The experimental data were correlated by pseudo-first-order homogeneous and Eley-Rideal heterogeneous models, and the results demonstrate the suitability of Eley-Rideal mechanism.

Influence of non-ideal behavior on esterification kinetics modeling

The well-known kinetics of Fischer esterification has already been reported for various systems. Despite this fact, the kinetic model of esterification of oleic acid and methanol under catalysis with sulfuric acid is still debated in the literature. The main reason is the two-phase character of the reaction mixture being neglected in kinetic studies. Contrary to this, the kinetics of autocatalytic esterification of cyclic alcohols with formic acid have not been published so far. Here, we present a kinetic study of both systems to assess the influence of the non-ideal (multi-phase) behavior on kinetic modeling. For the system of autocatalytic esterification of cyclic alcohols, we have found that a simple kinetic model without activity coefficients provides a good description of the experimental data. However, the same model is insufficient for the system of oleic acid and methanol. Therefore, we have developed a new approach based on kinetic modeling, including activity coefficients. Consequently, we have been able to describe for the first time the kinetics of oleic acid esterification in a homogeneous reaction mixture. Moreover, we provide a novel explanation for the commonly observed inhibition of this reaction by water as a result of phase equilibria in the reaction mixture.

An Improved Nanoemulsion Formulation Containing Kojic Monooleate: Optimization, Characterization and In Vitro Studies.

Tyrosinase inhibitors have become increasingly important targets for hyperpigmentation disease treatment. Kojic monooleate (KMO), synthesized from the esterification of kojic acid and oleic acid, has shown a better depigmenting effect than kojic acid. In this study, the process parameters include the speed of high shear, the time of high shear and the speed of the stirrer in the production of nanoemulsion containing KMO was optimized using Response Surface Methodology (RSM), as well as evaluated in terms of its physicochemical properties, safety and efficacy. The optimized condition for the formulation of KMO nanoemulsion was 8.04 min (time of high shear), 4905.42 rpm (speed of high shear), and 271.77 rpm (speed of stirrer), which resulted in a droplet size of 103.97 nm. An analysis of variance (ANOVA) showed that the fitness of the quadratic polynomial fit the experimental data with large F-values (148.79) and small p-values (p < 0.0001) and an insignificant lack of fit. The optimized nanoemulsion containing KMO with a pH value of 5.75, showed a high conductivity value (3.98 mS/cm), which indicated that the nanoemulsion containing KMO was identified as an oil-in-water type of nanoemulsion. The nanoemulsion remains stable (no phase separation) under a centrifugation test and displays accelerated stability during storage at 4, 25 and 45 °C over 90 days. The cytotoxicity assay showed that the optimized nanoemulsion was less toxic, with a 50% inhibition of cell viability (IC50) > 500 μg/mL, and that it can inhibit 67.12% of tyrosinase activity. This study reveals that KMO is a promising candidate for the development of a safe cosmetic agent to prevent hyperpigmentation.

Hule de llanta sulfonada utilizada como catalizador sólido para la producción de biodiésel con ácido oleico y optimizada por el método box-Behnken

Esterification of oleic acid was carried out to obtain methyl esters at temperatures below the critical point of methanol in the presence of sulfonated carbon. That was obtained by pyrolysis from tire rubber and use as catalytic support after sulfonated. The sulfonated carbonaceous material in the laboratory was analyzed by spectroscopy and microscopic techniques: IR spectroscopy, X-ray diffractometry, programmed desorption at a temperature (TG-DTG), X-ray photoelectron spectroscopy and scanning electron microscopy. The physicochemical properties of catalyst favor high performance in the production of biodiesel from oleic acid, are easily separated from the liquid mixture at the end of the reaction. At the temperature of 200 °C, with a reaction time of 20 min and a catalyst amount of 0.03% by weight, was the optimal experimental conditions for the esterification of oleic acid with methanol, giving a conversion of 97.9% of free fatty acids according to the response surface method. The Box-Behnken experiments were applied in order to evaluate the effects of the production parameters of biodiesel and find out the optimal conditions to obtain the maximum yield. Interestingly, stable catalytic activity in several reaction cycles was found.

Synthesis of polymer based catalyst: Optimization and kinetics modeling of the transesterification of Pistacia chinensis oil with diethyl carbonate using acidic ionic liquids

A novel solid acidic polymeric ionic liquid catalyst was synthesized for ethyl esters production via the esterification of oleic acid with ethanol, normally transesterification of Pistacia chinensis oil with diethyl carbonate. Gas chromatography-mass spectroscopy analysis was used to characterize the products and optimize the reaction conditions to provide P. chinensis oil derived ethyl esters in 93% yield. Kinetic studies performed at different temperatures revealed that the conversion of P. chinensis oil to an ethyl ester follows first order reaction kinetics. The properties of ethyl esters were determined, found to meet the ASTM D6751-02. Results revealed that the catalyst had perfect utility after several runs without much loss in activity. The mild conditions (1:5) P. chinensis oil:diethyl carbonate molar ratio, 300 wt% PIL loading, 120 °C, 400 rpm, 6 h, recyclability of the catalyst make the proposed synthesis a sustainable method for the development of ecofriendly, cost-effective biofuels.

Novel multi–SO3H functionalized ionic liquids as highly efficient catalyst for synthesis of biodiesel

Biodiesel is an attractive alternative to fossil fuels due to the energy and environmental concerns. In this paper, seven different multi –SO3H functionalized ILs based on the low-cost less-substituted amines, which contained massive sites for functionalization of sulfonic acid groups and further treatment of sulfonate-based anions, were prepared as catalysts with high acidity and desirable catalytic activity for the synthesis of biodiesel from the esterification of oleic acid with methanol. The physicochemical properties of these acidic ILs were characterized by a variety of analytical techniques such as FT-IR, EA, TGA, and the Brønsted acidity was well determined by UV–vis. Among the ILs prepared, [EDA-PS][P-TSA] showed the highest catalytic activity for esterification due to its high acidity and appropriate miscibility with reactants, with an ultrahigh 97.58% conversion of oleic acid under the optimum conditions (i.e. reaction time, 1.8 h; catalyst amount, 3 wt%; alcohol/acid molar ratio, 13:1, temperature 70 °C) acquired from the Box–Behnken response surface methodology. With the novel strategy of multi –SO3H modification on ILs, our catalyst had an approaching or even superior oleic acid conversion rate compared to other reported catalysts with considerably lower catalyst dosage and shorter reaction time. More importantly, it also exhibited high generality for converting various FFA feedstocks into biodiesel with considerable conversion within 93.59–94.33% under a rather lower catalyst dosage, which showed the valuable potential for converting low-cost oils into biodiesel from an economic and environmental perspective.

Heterogeneous acid catalyst based on sulfated iron ore tailings for oleic acid esterification

In this work, heterogeneous acid catalysts based on sulfated iron oxide produced from mining tailings were prepared by different processes, i.e. ammonium sulfate by simple grinding, (NH4)2SO4 aqueous impregnation and sulfuric acid impregnation, all treated at 500 °C. The materials were characterized by Mössbauer and Raman spectroscopies, FTIR, XRD, SEM, pyridine adsorption FTIR and potentiometric titration. The main mineral phases found were hematite and quartz and it was observed a great increase in the acidity of the materials produced due to the presence of sulfate groups. The synthesis with sulfuric acid was the most efficient process due to the formation of a greater amount of dispersed acid sites (density 0.1211 mmol g−1). The materials were used in esterification reactions. Ester production using 5 wt% of catalyst based on acid synthesis, 1:15 oleic acid:methanol molar ratio, 120 °C and 4 h led to conversions of 100%.

Microwave-Assisted Noncatalytic Esterification of Fatty Acid for Biodiesel Production: A Kinetic Study

This study developed a microwave-mediated noncatalytic esterification of oleic acid for producing ethyl biodiesel. The microwave irradiation process outperformed conventional heating methods for the reaction. A highest reaction conversion, 97.62%, was achieved by performing esterification with microwave irradiation at a microwave power of 150 W, 2:1 ethanol:oleic acid molar ratio, reaction time of 6 h, and temperature of 473 K. A second-order reaction model (R2 of up to 0.997) was established to describe esterification. The reaction rate constants were promoted with increasing microwave power and temperature. A strong linear relation of microwave power to pre-exponential factors was also established, and microwave power greatly influenced the reaction due to nonthermal effects. This study suggested that microwave-assisted noncatalytic esterification is an efficient approach for biodiesel synthesis.

Formulation of pH and temperature dual-responsive Pickering emulsion stabilized by chitosan-based microgel for recyclable biocatalysis

Developing green and smart emulsifier for multiple responsive Pickering emulsion has been a great significance to many industries. Therefore, a novel emulsifier, poly (N-isopropylacrylamide) (PNIPAM) grafted chitosan (CS) microgel (CS-g-PNIPAM), was obtained, which exhibited swelling and deswelling behaviors in response to abrupt changes of pH and temperature. The resulting O/W Pickering emulsion was also sensitive to pH and temperature, and adjusting either the pH from 5.0 to 9.0 or temperature from 25 to 45 ℃ could effectively trigger oil-water separation and emulsification on demand. Based on it, a biphasic biocatalysis was applied to evaluate the catalytic capacity of this approach. The hydrolysis of fish oil and esterification of oleic acid with n-octanol were performed successfully. Meanwhile, the easy separation of products and good recyclability could be realized by reversibly increasing or decreasing temperature. The green system provides a great potential for the application of biopolymers in biphasic interfacial biocatalysis.

Kinetic modeling of oleic acid esterification with UiO-66: from intrinsic experimental data to kinetics via elementary reaction steps

This work reports the experimental conversion of oleic acid (OA) into methyl oleate via UiO-66 MOF catalyst. Strong focus is on the kinetic modeling: 67 models, based on elementary reaction steps for Eley-Rideal, Langmuir-Hinshelwood and Hattori kinetic mechanisms, are proposed. Via the application of initial reaction rate theory and nonisothermal kinetic modeling, one model adequately describes the experimental data. It is a variant on the Eley-Rideal type of model, such that the surface reaction includes the oleic acid adsorbate, methanol reacts from the liquid phase and one additional active site is considered to make the ester and water as surface reaction products, so that overall two active sites are used in the surface reaction. An activation energy of 54.9 ± 1.8 kJ mol−1 is reported and the desorption of the ester was found to be irreversible. In addition, NH3 TPD revealed at least two types of acid sites (#) on the UiO-66 MOF, from which turnover rates were calculated in the range of 2.54 ± 0.33 to 8.82 ± 0.87 mmolOA mol#−1 s−1. Since the catalyst is recyclable and no additional acids have to be used, this system can be considered as a green alternative for the well-known homogeneously catalyzed esterification reaction.

Fabrication of sulfated spinel nickel aluminate for biofuel production: influence of Ni/Al ratio on its activity

Fabrication of active, stable, and regenerable catalysts is the main purpose of researchers in which spinel-type catalysts can provide some excellent properties to utilize in chemical processes. However, some effective parameters on their properties and performance must be deeply evaluated. Therefore, in this study, the effect of Ni/Al ratio on the properties and performance of Ni-NiAl2O4 catalyst synthesized by solution combustion method was investigated. The sulfated structure of the samples was used as solid acid catalysts for the esterification of oleic acid. Various characterization techniques were carried out on SO42−/Ni-NiAl2O4 composites, and the results revealed that the increase of nickel concentration led to the formation of NiO and metal Ni which bonded strongly with sulfate groups during the impregnation process. The strong bands between Ni cations and sulfate group increase sharply the surface area (from 28.6 m2 s−1 for Ni/Al ratio = 1 to 35.4 m2 s−1 for Ni/Al ratio = 1.75) and the activity of the samples, consequently. However, higher amounts of Ni cations (Ni/Al ratio of 2) led to agglomerated particles that were detected on the surface which filled the porosities. It can cause to reduce the surface area and activity of SO4/Ni-NiAl2O4 nanocatalyst. The sample fabricated by 1.75 times of Ni/Al ratio presented the highest surface area, pore diameter (the most of pores are greater than 8 nm), less roughness and uniform particle size that converted more than 95% of oleic acid to ester at the conditions of 120 °C, 9 molar ratio of methanol to oleic acid, 3 wt% of catalyst and 4 h of reaction time. It was also remained active for four uses and was successfully regenerated after deactivation by re-loading the sulfate group.

Heterogeneous catalytic esterification of oleic acid under sub/supercritical methanol over γ-Al2O3

A continuous pack-bed reactor experimental system was employed to investigate the heterogeneous catalytic esterification of oleic acid and sub/supercritical methanol with γ-Al2O3 as the catalyst. The experiment conditions were pressure of 10–20 MPa, temperature of 175–325 °C, residence time of 0.2–7 min and methanol/oil molar ratio of 20:1. A global one-step second order reversible kinetic model and a three-step Eley-Rideal mechanism model were proposed. The influence of impurity water and reaction pressure on the supercritical heterogeneous catalytic reaction were examined, and the stability of γ-Al2O3 under supercritical conditions was also evaluated. It was found that γ-Al2O3 showed excellent catalytic performance in both subcritical and supercritical processes, promoting theoretical maximum biodiesel yield at 20 MPa, 275 °C in 1 min. The impurity water hindered the conversion of biodiesel due to its negative influence on both the esterification reaction and the catalyst. Finally, the stability of γ-Al2O3 was tested under supercritical condition for 30 h.

Efficient production of biodiesel from ionic liquid catalyzed esterification using ultrasonic-microwave combined intensification

A novel approach was developed for producing biodiesel by acid ionic liquid catalyzed esterification of oleic acid and methanol under ultrasonic-microwave combined intensification. Four kinds of acid ionic liquids were synthesized as suitable catalysts. Some key parameters affecting oleic acid conversion were investigated using single factor experiments. Moreover, the production process was optimized via response surface methodology. The results indicated that the ionic liquid 1-(4-sulfobutyl)-3-methylmidazolium hydrosulfate exhibits good catalytic performance because of its double acid sites. The ultrasonic-microwave combined assistance can intensify the process to significantly shorten the reaction time from about 180 min to 15 min, thereby affording good industrial application potential. The specified regression model is accurate, reliable, and adequate for simulating actual production; the oleic acid conversion was 97.85 %, which is close to that achieved with conventional methods.

A Highly Active, Readily Synthesized and Easily Separated Graphene Oxide (GO)/Polyethersulfone (PES) Catalytic Membrane for Biodiesel Production

AbstractHeterogeneous acidic catalysts offer many advantages such as lower corrosion, easier separation and lower production cost compared with homogeneous sulfuric acid. Graphene oxide (GO) containing trace amount of oxygen‐containing functional groups have been demonstrated to be effective carbon‐based solid acid catalyst. However, GO are difficult to be recovered from liquid reaction system for further utilization. Graphene oxide/Polyethersulfone (PES) catalytic membranes were prepared and employed as heterogeneous acid catalysts in the esterification of oleic acid with methanol for biodiesel production. The membrane was annealed at different temperatures to promote the catalytic activity and reusability. As predicted, the OA conversion increased greatly with the increase of GO content in the membrane. Both internal and external diffusion have no influence on the catalytic activity. The catalytic membrane dosage, reaction temperature and methanol/oleic acid molar ratio affected its catalytic performance significantly. Among all the prepared membranes, the membrane annealed at 150 °C exhibited the best catalytic performance, with a conversion of over 85 % even after six cycles.

Effect of biodiesel ester structure optimization on low temperature performance and oxidation stability

The main shortcomings of biodiesel are related to the low-temperature performance and oxidation stability. Hence, this study proposes to investigate the influence of the oleic acid-based esters with various linear and branched chain alcohols on these two properties of biodiesel. The economic impact of biodiesel with various compositions is also evaluated by means of a mathematical model. The results showed that the longer the carbon chain length of the alcohol component, the better the low-temperature performance of the biodiesel. Hence, the cold filter plugging point and solidifying point of methyl oleate were −19 and −24°C, respectively, whereas the cold filter plugging point and solidifying point of amyl oleate were −36 and −41°C, respectively. The more irregular the molecular structure, the better the low-temperature performance of oleic acid-based lipids. For instance, the condensate point and solidifying point of oleic acid-based esters with branched chain alcohols should be lower than oleic acid-based esters with linear chain alcohols. On the other hand, for the linear esters of oleic acid, the oxidation stability is better as the carbon chain is longer. For instance, the induction period of methyl oleate is 0.07h while for amyl oleate, it is 0.36h, which corresponds to an increase of about 5 times. For the branched esters, although they are sensitive to oxidation, the induction period is higher than that of methyl oleate. Finally, the DEA evaluation model was used to analyze the economic aspects of the resulted biodiesel. The results showed that the addition of ethyl oleate to biodiesel significantly improved the low-temperature performance and oxidation stability of biodiesel with good economic benefits.

Biofuel Production With Sulfonated High Surface Area Carbons Derived From Glucose

AbstractSolid acid carbon catalysts were prepared by activating hydrothermal carbon with potassium hydroxide (KOH) to form high surface area carbon and using an environmentally benign L‐cysteine method for subsequent sulfonation. The textural and physical properties of the solid acid catalysts were characterized by different techniques including Powder X‐ray diffraction (PXRD), Thermogravimetric analysis (TGA), Brunauer‐Emmett‐Teller (BET) surface area, Scanning electron microscopy (SEM), and X‐ray photoelectron spectroscopy (XPS) in order to understand the functionalization of sulfonic acids on the carbon support. The catalytic activity of the carbon‐based materials towards biofuel production was studied by using the esterification of oleic acid as a prime example. A quantitative yield of 95 % fatty acid methyl ester was achieved using the high surface area sulfonated catalyst (HSC‐SO3H with SA=1751 m2/g) at 80 °C for 4 hours at 1 atm with 10 wt. % of catalyst loading and at a 10 : 1 molar ratio of methanol/oleic acid. Sulfonation of carbon with L‐cysteine represents a promising technique to obtain solid acid catalysts, which are expected to be useful for other applications in Lewis‐acid catalysis, separations, and beyond.

Dilute sulfonic acid post functionalized metal organic framework as a heterogeneous acid catalyst for esterification to produce biodiesel

In order to synthesize the efficient heterogeneous acid catalyst for biodiesel production, concentrated sulfuric acid (>18.4 mol/L) is commonly used as sulfonated reagent to anchor sulfonic acid group (SO3H) on a support. However, large amount of wastewater is generated while the concentrated sulfuric acid removed by washing. In this study, a green and highly stable sulfonated catalyst is prepared by using MIL-100(Fe), which is functionalized by the dilute sulfonic acid. The obtained catalyst is adopted to catalyze the esterification of methanol and oleic acid. Meanwhile, it is characterized by thermogravimetry analysis (TG), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), pyridine FTIR spectroscopy (Py-FTIR), scanning electron microscope (SEM), Hammett indicator titration and nitrogen adsorption-desorption. The maximum esterification conversion of 95.86% is achieved at molar ratio of methanol to oleic acid of 10, catalyst amount of 8 wt% (referred to oleic acid mass) at 70 °C within 2 h. More importantly, the catalyst could be repeatedly used for six cycles without significant activity loss.

Regulatory norms driving the demand for bio-based lubricants & increasing adoption in the automotive industry: Global bio-lubricants market to 2024

The application of three-dimensional, mesoporous titanosilicates, Ti-SBA-12 and Ti-SBA-16, as reusable solid acid catalysts for producing biodiesel and biolubricants is reported for the first time. Biodiesel was prepared by esterification of oleic acid with monohydric methanol and biolubricants by esterification with polyhydric alcohols (glycerol, trimethylolpropane, neopentyl glycol and pentaerythritol). High catalytic activity of these catalysts is attributed to the presence of dispersed Lewis acidic Ti sites and mesoporosity in the structure. Biodiesel yields as high as 90 mol% were obtained at 443 K. Surface hydrophobicity of the catalyst has also a predominant role, especially, in reactions involving polyhydric alcohols. In those reactions, Ti-SBA-16 showed higher catalytic activity than Ti-SBA-12.

Direct sulfonation of cacao shell to synthesize a solid acid catalyst for the esterification of oleic acid with methanol

Solid acid catalyst (SAC) was synthesized via direct treatment of cacao shells (CS) with concentrated sulfuric acid at varying temperature (80, 100, 120 °C) and time (4, 6, 8 h) settings. The synthesized catalysts were found to have sulfonic acid density ranging from 0.6326 to 0.8500 mmol SO3H/g dry CS-SAC and total acid density from 6.0509 to 7.1165 mmol H+/g dry CS-SAC. The catalytic activity is dependent on the sulfonic acid density of the catalyst. Catalyst synthesized at 120 °C for 6 h showed the highest sulfonic acid density (0.85 mmol SO3H/g catalyst) corresponding to highest catalytic activity (5.73 mmol OA converted/mmol SO3H·h) and a conversion of ∼39% after a fixed reaction time of 4 h and carried out at 65 °C. Conversions of up to 76% could be achieved after 24 h. The catalyst was reused for 4 cycles and was able to retain 78% of its catalytic activity from the 2nd to the 4th cycle. Direct sulfonation may be an alternative to conventional synthesis process.