Esterification Reaction Of Fatty Acids Research Articles

Mechanism of the effect of temperature on the characteristics of microwave hydrothermal products of dead pig model compounds

Microwave hydrothermal treatment is a promising technology for the environmentally friendly disposal and resource utilization of dead pigs. However, the hydrothermal transformation mechanism of animal-based biomass is unclear, impeding the regulated conversion of target products. To address this, bovine serum albumin, glycerol-oleic acid, and glucose were selected as model compounds for protein (P), lipid (L), and carbohydrate (C), respectively. In this paper, the product distribution and related properties of single, binary, and ternary model compounds at different microwave hydrothermal temperatures (120–240 °C) were investigated, and the essential reaction pathway of the dead pig model compounds during microwave hydrothermal treatment was proposed. The results showed that lipids dominated the formation of bio-oil. L&C and L&P showed a slight synergistic effect on bio-oil yield at 240 ℃, while exhibited antagonistic effects at other temperatures. L&P&C showed antagonistic effects on bio-oil yield at all temperatures. The participation of glucose was more conducive to the formation of carbonized solid products. The model compounds of dead pigs underwent a series of reactions such as dehydration, decarboxylation, deamination and condensation during microwave hydrothermal treatment. To a certain extent, lipids promoted the Maillard reaction of protein and carbohydrate, while glucose promoted the esterification reaction of fatty acids.

Preparation of highly dispersed SnO/TiO2 catalysts and their performances in catalyzing polyol ester.

A series of stannous oxide supported on rutile titanium dioxide (SnO/TiO2) were prepared by a conventional incipient wetness impregnation method, and their performance as catalysts for fatty acid esterification reactions was investigated. The effects of Sn precursors (SnCl2·2H2O or SnC2O4), loading amounts (5-15%), and treating ambiences (air and N2) were explored. The optimized 10% SnO/TiO2-Cl with SnCl2·2H2O as the Sn precursor and thermal treatment in N2 showed the best esterification performance. Specifically, 10% SnO/TiO2-Cl catalyzed the esterification process of trimethylolpropane and n-octanoic acid with a conversion of 99.6% over 5 h at 160 °C, and 10% SnO/TiO2-Cl was efficient for six catalytic cycles. Based on the results of X-ray diffraction (XRD), Raman spectra, high-resolution transmission electron microscopy (HRTEM), infrared spectra of pyridine adsorption (Py-IR), and ammonia temperature programmed desorption (NH3-TPD), the improved catalytic performance is supposed to be attributable to the high dispersion of the Sn species on 10% SnO/TiO2-Cl as the moderate Lewis acid sites.

Understanding the Biocatalytic Potential of Lipase from Rhizopus chinensis

Lipases occupy the third position in the world market for the sale of the most industrially used enzymes, being one of the most versatile and promising classes, highlighting the genus Rhizopus chinensis, which is exceptionally useful as biocatalysts for short-chain fatty acid esterification reactions with ethanol, biodiesel, and n-heptane when used directly in the solvent-free system and in potential critical applications. In this context, the present work presents the first complete general review of the lipases of the genus Rhizopus chinensis focusing on their industrial applications, in addition to the different immobilization techniques and the main reactions as biocatalysts, since these are an excellent alternative due to their advantages in economic accessibility and respect for the environment. In addition, they have high specificity catalytic activity for esterification and transesterification reactions in the presence or absence of organic solvents; they can also have great thermophilicity and moderate pressure resistance, with their catalytic behavior modulated by changes in these conditions. This review showed that Rhizopus chinensis lipase has ample potential for many other biotechnological applications with the appropriate chemical modifications and immobilization strategy.

Production of Sustainable Biochemicals by Means of Esterification Reaction and Heterogeneous Acid Catalysts

In recent years, the use of renewable raw materials for the production of chemicals has been the subject of different studies. In particular, the interest of the present study was the use of oleins, mixtures of free fatty acids (FFAs), and oleic acid to produce bio-based components for lubricants formulations and the investigation of the performance of a styrene-divinylbenzene acid resin (sPSB-SA) in the esterification reaction of fatty acids. This resin has shown good activity as a heterogeneous catalyst and high stability at elevated temperatures (180 °C). It was tested in the esterification reaction of oleic acid with 1,3-propanediol and of oleic acid with glycerol. In particular, the esterification reactions were performed in a steel stirred batch reactor and a PBR loop reactor. Tests were conducted varying the reaction conditions, such as alcohol type, temperature, reaction time, and catalysts, both homogeneous and heterogeneous ones. From the obtained results, acid resin (both in reticulated and not-reticulated form) showed high activity in esterification reaction of oleic acid with 1,3-propanediol and of oleic acid with glycerol and good resistance to the deactivation; thus, they can be considered promising candidates for future applications in continuous devices. Viscosity tests were performed, underlining the good properties of the obtained products as lubricant bases.

Preparation of sulfonated carbon-based catalysts from murumuru kernel shell and their performance in the esterification reaction.

In the present study, heterogeneous acid catalysts for fatty acid esterification reactions were synthesized using agro-industrial waste from murumuru kernel shells. The waste was carbonized and functionalized with concentrated sulfuric acid under different sulfonation conditions, obtaining the sulfonated biochar. The results indicate that the best sulfonation conditions were obtained with a contact time of 4 h, the temperature of 200 °C, and a solid-acid ratio of 1 : 10 (w/v). The best catalyst was characterized by acid–base titration for the determination of total acid density, X-ray diffraction, scanning electron microscopy, X-ray energy dispersion spectroscopy, Fourier transform infrared spectroscopy and thermal analysis. Reaction conditions of oleic acid with methanol and the viability of catalyst reuse were also investigated. A conversion of 97.2% was achieved under optimum esterification reaction conditions, employing 5% catalyst, 10 : 1 molar ratio of methanol to oleic acid, during 1.5 h at a temperature of 90 °C. After 4 reaction cycles, the catalyst preserved its efficiency at 66.3% conversion. The catalyst activity was evaluated in reactions using palmitic acid, soybean fatty acid distillate, palm fatty acid distillate, and coconut fatty acid distillate. The results demonstrate that the catalyst is applicable and efficient in esterification reactions of raw materials, containing different fatty acid compositions since different carbonized materials have varying abilities to combine acid groups. This work reveals the promising feasibility of using biomass generated in large quantities by the agroindustry for the development of a new heterogeneous acid catalyst for biodiesel production.

Benzenesulfonic acid functionalized hydrophobic mesoporous biochar as an efficient catalyst for the production of biofuel

Catalytic esterification of fatty acid with methanol, alkylation of 4-ethylphenol with benzyl alcohol as well as 2-methylfuran with cyclopentanone are of great significant for the production of biofuels. However, the in-situ produced water decreases the acidity of catalyst and induces side reaction, leading to an unsatisfactory catalytic activity and selectivity. Herein, a novel biochar-based hydrophobic benzenesulfonic acid is prepared for the first time by one-pot sulfonation method of biochar with 4-chlorobenzenesulfonic acid. It has a large specific surface area of 100-400 m2/g, a hydrophobicity with H2O contact angle higher than 110° and a high concentration of sulfonic acid over 1.0 mmol/g. In the esterification reaction of fatty acid with methanol for synthesis of biodiesel, it shows a higher conversion of 96.0% than sulfonic acid resin amberlyst-15 (86.7%) and traditional sulfonated biochar-SO3H (28.0%). In the alkylation reaction of 4-ethylphenol with phenylmethanol/2-methylfuran with cyclopentanone for high-density bicyclic/monocyclic biofuel, its catalytic efficiency with target product yields are 69.4% and 70.5% respectively, which are also higher than that of amberlyst-15 (74.3%, 49.4%) and biochar-SO3H (14.7%, 13.0%). Furthermore, the catalyst is more stable than biochar-SO3H. The preparation of hydrophobic biochar-based sulfonic acid catalysts not only opens a new way for high-value utilization of biochar, but also provides a novel efficient catalyst in many acid-catalyzed transformation reactions that the product H2O causes deleterious effects.

Sulfonic acid functionalized hydrophobic mesoporous biochar: Design, preparation and acid-catalytic properties

Sulfonic acid functional strong acidic catalysts are largely used in various chemical reactions. However, in many reactions with water as product, the catalytic activity and selectivity are unsatisfactory, because hydrophilic acid sites of SO3H would suffer from acidity decreasing and some hydrolysis side reactions would occur via water adsorption. Herein, a novel hydrophobic arenesulfonic acid functionalized biochar was successfully prepared for the first time by one-pot diazo reduction method of biochar with amino-arenesulfonic acid (such as, 4-aminbenzenesulfonic acid, 4-amino-1-naphthalenesulfonic acid, 8-amino-1-naphthalenesulfonic acid, 4-amino-3-hydroxy-1-naphthalenesulphonic acid). It has a large specific surface area of 200–400 m2/g, a hydrophobic network with water contact angle higher than 120° and a higher concentration of sulfonic acid over 1.0 mmol/g. Moreover, the hydrophobicity-oleophilicity and acidity are increased with the arene length and grafting amount of arenesulfonic acid. In the esterification reaction of fatty acid with methanol as well as the transesterification reaction of glycerol trioleate with methanol for the production of biodiesel, the sulfonated biochar shows a higher conversion of 96.7% for esterification and 86.3% for transesterification compared with amberlyst-15 (86.7%, 39.9%) and traditional sulfonation biochar-SO3H (27.4%, 32.6%). In the alkylation reaction of 2-methylfuran with cyclopentanone for the production of high-density biofuel, its catalytic efficiency with target product yield of 76.1% is higher than that of amberlyst-15 (50.2%) and traditional sulfonation biochar-SO3H (13.2%), because of its hydrophobicity and strong acidity. Furthermore, the catalyst is stable and shows an excellent cycle performance after 6 runs. The successful preparation of hydrophobic biochar-based acidic catalysts not only provides a new way for high-value utilization of biochar, but also eliminates the negative effect of water on many catalytic reactions.

Natural and Modified Montmorillonite Clays as Catalysts for Synthesis of Biolubricants.

In this study, natural and modified clays were evaluated as catalysts in an esterification reaction to obtain bio-based lubricants. The biolubricants are environmentally preferred to petroleum-based lubricants because they are biodegradable and non-toxic. Other advantages include very low volatility due to the high molecular weight and excellent viscosity properties with temperature variations. Modifications in natural clay were performed intending to obtain materials with different textural properties that could improve the reaction under study. The modified clays were obtained in two ways: by pillarization using Al13 Keggin polyoxocations or by acid treatments with H2SO4, HCl and HNO3. All samples were evaluated for the esterification reaction of fatty acids from castor oil (FACO) using 2-ethyl-hexanol. During the reaction step, a zeolite-based adsorbent was used for water removal to increase the reaction equilibrium conversion. Gas chromatography and nuclear magnetic resonance were performed to ensure the formation of the products. The highest conversion of fatty acids to esters was obtained using pillared clays. Adding adsorbent in the reaction medium (10 g of 3A zeolite to 100 g of FACO), the conversion improved from 74–88 wt % after 6 h at 50 °C.

In-situ FTIR study on the mechanism of both steps of zeolite-catalysed hydroesterification reaction in the context of biodiesel manufacturing

While biodiesel manufacturing using transesterification is a mature process, a number of key issues need to be addressed for widespread application. These include amongst others feedstock availability and waste products. In this paper, we report on a different approach to synthesize biodiesel, namely a two-stage process which alleviates the need to utilise purified oils and only contains relatively pure glycerol as by-product. We investigated a route for waste cooking oil hydroesterification (hydrolysis/esterification) over zeolites. We tried to understand the mechanism of both steps of zeolite-catalysed hydroesterification and investigate the adsorption of probe molecules, along with the compounds formed by ester hydrolysis and fatty acid esterification reactions over the ZSM-5 zeolite surface by employing in-situ FTIR. The 40% conversion level of waste oil hydrolysis into fatty acid mixture and 63% conversion level of the synthesised fatty acids esterification to biodiesel was observed over ZSM-5 (Si/Al ratio = 15) after 4 h. The results from FTIR spectroscopy evident the protonation of the carbonyl groups of ester and fatty acid via hydrogen bonding with bridging OsbndH in SisbndOHsbndAl group (Brønsted acid sites) of the zeolite. The electrophilic reaction of protonated fatty acid, adsorbed on the surface of zeolite, with alcohol was observed from FTIR spectroscopy of esterification reaction.

Free Fatty Acid Removal on Palm Oil Sludge using Heterogeneous Solid Catalyst derived from Palm Empty Fruit Bunch

The present research investigated the activity of catalysts from biomass waste derived from Palm Empty Fruit Bunch (PEFB). An important factor for assessing the feasibility of biodiesel production is related to its economic evaluation. The sludge of Palm Oil (SPO) is generated from palm oil processing industry. SPO was potentially as biodiesel feedstocks due to its low price. The investigation of free fatty acid esterification reactions on SPO with methanol was conducted in this research. Recently, a new strategy of preparing a heterogeneous solid catalyst from biomass wastes has been developed. The parametric investigation was carried out by varying the molar ratio of methanol to SPO catalyst to oil (8:1 - 14:1), the amounts of catalyst (0.5 - 5 wt. % SPO), and the reaction temperatures (40 - 60 °C). It is concluded that the optimum conditions of esterification reactions were acquired at molar ratio of methanol to SPO catalyst to oil 12:1, the amounts of catalyst 5 wt. % of SPO, and the reaction temperature of 60 °C.

Kinetics evaluation of the ethyl esterification of long chain fatty acids using commercial montmorillonite K10 as catalyst

This study reports an assessment of free fatty acid esterification reactions with ethanol using montmorillonite K10 as catalyst, a commercial solid catalyst known for having high performance in several catalytic processes. Therefore, the main objective of this work is to perform reactions of FFA (lauric, stearic and oleic acids) ethyl esterification, checking how different chain lengths and unsaturation presence affect the reaction kinetics. The catalyst was characterized by different techniques, in which the structure and acidic properties were evaluated. Esterification reactions were systematically evaluated by a factorial design (effects of temperature, molar ratio and catalyst content) to determine optimal conditions to be used in the reaction kinetics study. In addition, kinetics reactions without montmorillonite K10 were also carried out in order to evaluate the autocatalytic (or thermal) reaction contribution. The kinetic data obtained for all FFAs was used to adjust kinetic parameters and the model was capable to correlate the experimental data, providing values of the root mean square deviation (rmsd) around 3.5% in terms of fatty acid conversions. The low values obtained for the rmsd indicate the possibility to achieve a reactor design to process complex fatty matrices using data generated for a pure FFA without quality loss. Furthermore, due to the high activity presented in the free fatty acid esterification under the studied conditions, montmorillonite K10 proves to be a suitable catalyst for industrial-scale biodiesel obtention from raw materials with high content of free fatty acids.

Micro-reactor for Non-catalyzed Esterification Reaction: Performance and Modeling

Abstract Y-shape micro-reactor is designed, developed and implemented to investigate the effect of reactor miniaturization on chemical engineering kinetics, where, an esterification reaction of fatty acid (2- ethyl hexanoic acid) is considered as a case study. In order to investigate the differential change of micro-reaction conversion along the channel axis; a micro-reactor with multi-channel is designed in a manner that enables collecting the samples. The kinetics of esterification reaction of ethanol and fatty acid was explored under various operating conditions; Molar Ratio (MR) of ethanol to fatty acid at temperatures 25–65 °C. The conversion reached almost 99.3 % after 30 s at MR 4:1 and 25 °C. Steady and unsteady state axial dispersion mathematical models were developed; the latter approach resulted in fair agreement with the experimental results.

Efficient production of biodiesel from low-cost feedstock using zinc oleate as catalyst

In this study, the synthesis of fatty acid methyl esters (FAME) by the transesterification of low-cost feedstock containing 10 and 22 wt.% free fatty acid (FFA), using zinc oleate (ZnOl) as catalyst, was investigated. The performance of the ZnOl salt in the reaction medium was evaluated in terms of activity and stability in the presence of free fatty acids. At 140°C and 2h of reaction time, triglyceride conversion was 100%, FAME yield was close to 95%, and fatty acid conversion was 75.9% and 82.6% for feedstock with 10 and 22 wt.% FFA, respectively. The zinc carboxylic salt was able to catalyze simultaneously the triglyceride transesterification and the fatty acid esterification reactions with high activity and selectivity under moderate operating conditions and slight FAME and triglycerides hydrolysis.

BIODIESEL PRODUCTION FROM FATTY ACIDS OF REFINED VEGETABLE OILS BY HETEROGENEOUS ACID CATALYSIS AND MICROWAVE IRRADIATION

This work presents the biofuel production results of the esterification of fatty acids (C12-C18) and high-acid-content waste vegetable oils from different soap stocks (soybean, palm, and coconut) with methanol, ethanol, and butanol by acid catalysis. We used Amberlyst-35 (A35) sulfonic resin as a heterogeneous acid catalyst and p-toluenesulfonic acid as a homogeneous catalyst for comparison. Both the heterogeneous (A35) and homogeneous (p-toluenesulfonic acid) reactions were performed with 5% w/w of catalyst. The final products were analyzed by proton nuclear magnetic resonance (1H NMR). The homogeneous catalyzed esterification of fatty acids with methanol, ethanol, and butanol produced esters with yields higher than 90%. In the reaction with fatty acids and methanol catalyzed by A35, the best results were achieved with lauric acid and methanol, with a yield of 97%. An increase in the hydrocarbon chain decreased the rate of conversion and yield for stearic acid with methanol, which was 90%. Maximum biodiesel production was achieved from coconut and soybean soap stocks and methanol (96%-98%), which showed conversions very close to those obtained from their respective fatty acids. Microwave irradiation reduced the reaction time from 6 to 1 h in the esterification reaction of fatty acids with butanol.

Effects of the addition of dimer acid alkyl esters on the properties of ethyl cellulose.

In this study, we synthesized dimer acid (DA) esters, having short to long alkyl chains, (DA-Cn) by the Diels-Alder reaction and subsequent esterification reaction of fatty acids that were prepared by the hydrolysis of waste vegetable oil. It was found that the DA-Cn were thermally more stable than common petroleum-based plasticizer DOP. When the DOP, DA, or DA-Cn with short alkyl chains were added to ethyl cellulose (EC), the optical clarity and SEM images of the samples showed their good miscibility with those additives in a micro-scale. It was also found that the rubbery modulus of the EC decreased with increasing amount of additives; the type of the additives did not affect the rates of the decrease in the rubbery modulus. The main transition temperatures of the EC containing either DA or DA-C1 or DA-C4 decreased with increasing amounts of those additives and were comparable to that of the DOP-containing EC. The above findings suggested that the DA and its esters with short alkyl chains could act as effective plasticizer and, thus, could be used instead of the DOP. In addition, the results obtained from tensile testing and leaching experiments implied that the DA might be better plasticizer than the DA-C1 and DA-C4, at least in some cases, because of hydrogen-bonding with the EC.

An unprecedented (3,4,24)-connected heteropolyoxozincate organic framework as heterogeneous crystalline Lewis acid catalyst for biodiesel production

A novel 3D hexadecanuclear heteropolyoxozincate organic framework, IFMC-200, has been successfully synthesized based on a late transition metal-oxygen cluster. IFMC-200 not only represents the first example of (3,4,24)-connected framework but also contains the first 24-connected single metal cluster in a crystal structure. It exhibits superior thermal stability, good water-stability, and even insensitivity to the existence of acid and base within a certain range of pH values. Furthermore, it performs as a heterogeneous crystalline Lewis acid catalyst with good activity for the conversion of long-chain fatty acids rather than short-chain ones, and high recycling efficiency for esterification reaction of fatty acids with alcohols to produce biodiesel.

Novel and Highly Efficient SnBr2-Catalyzed Esterification Reactions of Fatty Acids: The Notable Anion Ligand Effect

In this work, the efficiency of Lewis acid catalysts, SnX2 (X = F−, Cl−, Br−, or −OAc), was investigated on the esterification reactions of fatty acids (i.e., myristic, palmitic, stearic, oleic, linoleic, and linoleic) with different alcohols (i.e., methyl, ethyl, propyl, isopropyl, and butyl alcohol). Tin(II) bromide was the most active catalyst in all reactions studied. We investigated the effects of main reaction parameters, such as catalyst concentration, temperature, and nature of alcohol and fatty acid. The highest activity of SnBr2 catalyst was discussed in terms of its lower activation energy, higher Lewis acid strength, and higher softness of anionic ligand. Finally, the SnBr2 catalyst can be easily recovered and reused without loss of catalytic activity. Effect of the tin catalyst nature on the oleic acid esterification with ethyl alcohol.

Application of Heteropolyacid-Based Heterogeneous Catalysts for Conversion of Oleochemicals into Renewable Fuels and other Value-Added Products

Oleochemicals offer viable choices to replace petrochemicals in a wide range of applications such as fuels, lubricants and surfactants. Many of the conversions require the use of suitable solid acids as the catalysts. The chemical and physical properties of the feedstock in oleochemical processes often result in difficulties and challenges that limit the success. Large amount of free fatty acids and high water content create barriers towards the successful use of broad range of oleochemicals as raw materials. To overcome this problem, efforts have been dedicated to the development of new technologies involving new types of catalyst. Solid acid catalysts based on heteropolyacids (HPAs) for various oleochemical conversions especially esterification reaction of fatty acids and transesterification of vegetable oils have been successfully developed. This type of catalyst already secured a tangible success in solving some problems associated with the earlier types of catalyst leading to higher productivity in the process while satisfying the needs of sustainable and environmental friendly industrial processes. Incorporation of HPAs active component into mesoporous supports can produce heterogeneous catalysts with high acid sites dispersion, stability to high temperature, recyclable and they usually demonstrate low leaching of active components in the reaction medium. This article reviews common oleochemical processes where various HPA catalysts already found successful application with some insight into the specific characteristics of the catalysts. Their advantages and drawbacks as well as specific process behaviors in few important oleochemical conversions of industrial importance will be discussed.

Investigation of a molybdenum-containing silica catalyst synthesized by the sol–gel process in heterogeneous catalytic esterification reactions using methanol and ethanol

Molybdenum-containing silica easily synthesized by the sol–gel process was evaluated as catalyst for heterogeneous esterification reaction of fatty acids using methanol and ethanol. The molybdenum content depended on the conditions employed during the synthesis. The solids were characterized by X-ray powder diffraction, textural analysis, X-ray photoelectronic spectroscopy, and inductively coupled plasma optical emission spectroscopy. The strength and distribution of the acid sites were assessed by the adsorption–desorption of n-butylamine as monitored by Fourier transform infrared spectroscopy and thermogravimetric analysis. Kinetic studies revealed high fatty acid conversion for both alcohols and diminished activity upon decreasing concentration of acid sites. Monitoring of the acid sites during the recycling experiments indicated association of the catalytic activity with Mo oxide species on the surface and with the availability of molybdenum-active sites displaying Brønsted–Lowry acidity in the silica structure.

Esterification of fatty acids with alcohols over niobium phosphate

The aim of this study is the evaluation of niobium catalysts (niobic acid, niobium phosphate) in the esterification reactions of fatty acids (C12–C18) with alcohols (methanol, ethanol, butanol). The catalysts were characterized by different techniques (N2 adsorption/desorption, XRD, FTIR, FTIR of adsorbed pyridine). The niobium phosphate was the most active in esterification of lauric acid with butanol and can be reutilized three times without loss of activity.