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H3PW12O40 (HPA), an efficient and reusable catalyst for biodiesel production related reactions: esterification of oleic acid and etherification of glycerol
Sepúlveda, Jorge H.;Vera, Carlos R.;Yori, Juan C.;Badano, Juan M.;Santarosa, Daniel;Mandelli, Dalmo;
Química Nova , 2011, DOI: 10.1590/S0100-40422011000400009
Abstract: in esterification of oleic acid with methanol at 25 °c hpa displayed the highest activity. moreover the hpa could be reused after being transformed into its cesium salt. in the reaction of etherification of glycerol hpa and amberlyst 35w showed similar initial activity levels. the results of acid properties demonstrate that hpa is a strong protonic acid and that both surface and bulk protons contribute to the acidity. because of its strong affinity for polar compounds, hpa is also seemingly dissolved in both oleic acid and methanol. the reaction in this case proceeds with the catalyst in the homogenous phase.
Esterification of Oleic Acid for Biodiesel Production Catalyzed by SnCl2: A Kinetic Investigation  [PDF]
Abiney L. Cardoso,Soraia Cristina Gonzaga Neves,Marcio J. Da Silva
Energies , 2008, DOI: 10.3390/en1020079
Abstract: The production of biodiesel from low-cost raw materials which generally contain high amounts of free fatty acids (FFAs) is a valuable alternative that would make their production costs more competitive than petroleum-derived fuel. Currently, the production of biodiesel from this kind of raw materials comprises a two-stage process, which requires an initial acid-catalyzed esterification of the FFA, followed by a basecatalyzed transesterification of the triglycerides. Commonly, the acid H 2SO 4 is the catalyst on the first step of this process. It must be said, however, that major drawbacks such as substantial reactor corrosion and the great generation of wastes, including the salts formed due to neutralization of the mineral acid, are negative and virtually unsurmountable aspects of this protocol. In this paper, tin(II) chloride dihydrate (SnCl 2·2H 2O), an inexpensive Lewis acid, was evaluated as catalyst on the ethanolysis of oleic acid, which is the major component of several fat and vegetable oils feedstocks. Tin chloride efficiently promoted the conversion of oleic acid into ethyl oleate in ethanol solution and in soybean oil samples, under mild reaction conditions. The SnCl 2 catalyst was shown to be as active as the mineral acid H 2SO 4. Its use has relevant advantages in comparison to mineral acids catalysts, such as less corrosion of the reactors and as well as avoiding the unnecessary neutralization of products. Herein, the effect of the principal parameters of reaction on the yield and rate of ethyl oleate production has been investigated. Kinetic measurements revealed that the esterification of oleic acid catalyzed by SnCl 2·2H 2O is first-order in relation to both FFAs and catalyst concentration. Experimentally, it was verified that the energy of activation of the esterification reaction of oleic acid catalyzed by SnCl 2 was very close those reported for H 2SO 4.
Ethyl oleate production by means of pervaporation-assisted esterification using heterogeneous catalysis
Figueiredo, K. C. S.;Salim, V. M. M.;Borges, C. P.;
Brazilian Journal of Chemical Engineering , 2010, DOI: 10.1590/S0104-66322010000400013
Abstract: pervaporation-assisted esterification of oleic acid and ethanol was investigated by means of heterogeneous acid catalysis with the aim of increasing the ethyl oleate yield. the experimental strategy comprised kinetic tests with amberlyst 15 wet (rohm & haas), the characterization of hydrophilic pervap 1000 membrane (sulzer) and the evaluation of the membrane-assisted reactor. kinetic tests were carried out to study the effect of temperature, catalyst loading and ethanol/organic acid molar ratio for the esterification of oleic acid and ethanol. the ester yield and initial reaction rate were used as response. the hydrophilic poly(vinyl alcohol) membrane was able to remove water from the reaction medium and, hence, the ester yield was increased. the potential of coupling esterification and pervaporation was demonstrated, with a two-fold increase in the reaction yield of ethyl oleate.
Esterification of Fatty Acids with Short-Chain Alcohols over Commercial Acid Clays in a Semi-Continuous Reactor  [PDF]
Soumaya Bouguerra Neji,Mahmoud Trabelsi,Mohamed H. Frikha
Energies , 2009, DOI: 10.3390/en20401107
Abstract: Production of fatty acid esters from stearic, oleic, and palmitic acids and short-chain alcohols (methanol, ethanol, propanol, and butanol) for the production of biodiesel was investigated in this work. A series of montmorillonite-based clays catalysts (KSF, KSF/0, KP10, and K10) were used as acidic catalysts. The influence of the specific surface area and the acidity of the catalysts on the esterification rate were investigated. The best catalytic activities were obtained with KSF/0 catalyst. The esterification reaction has been carried out efficiently in a semi-continuous reactor at 150°C temperature higher than the boiling points of water and alcohol. The reactor used enabled the continuous removal of water and esterification with hydrated alcohol (ethanol 95%) without affecting the original activity of the clay.
Synthesis of High-Stability Acidic β/Al-MCM-41 and the Catalytic Performance for the Esterification of Oleic Acid  [PDF]
Zhiping Wang, Shitao Yu
Advances in Chemical Engineering and Science (ACES) , 2016, DOI: 10.4236/aces.2016.64031
Abstract: β/Al-MCM-41 molecular sieve was synthesized and used to catalyze the esterification of oleic acid with short chain alcohols such as methanol, ethanol, isopropanol and isobutanol to obtain biodiesel. The results indicated that β/Al-MCM-41 exhibited the excellent catalytic activity and stability, which was obviously superior to traditional Al-MCM-41. The relationship between acidity and catalytic activity was in detail examined by NH3-TPD and Py-FTIR. Moreover, the kinetics of esterification of oleic acid with methanol showed that the average reaction order n was 1.97 and that activation energy was 50.01 kJ/mol.
Soybean oil transesterification: Study of using Nb2O5.xH2O as catalyst in biodiesel production  [cached]
Deborah A. dos Santos,Valdemar Lacerda Júnior,Sandro José Greco,Reginaldo B. Santos
Orbital : the Electronic Journal of Chemistry , 2012,
Abstract: Economic and environmental reasons show a trend towards replacing fossil fuels with biofuels such as those from triglycerides. Biodiesel can be obtained from vegetable oils and animal fat through several processes such as transesterification, esterification, usually with methanol, ethanol or through pyrolysis, all of them in the presence of an acid or basis catalyst. The use of solid catalysts in biodiesel production has the following advantages: easy recovery and reuse, thus decreasing process costs and amount of waste generated.1 Some of the problems in the use of solid catalysts are: low concentration of active sites, microporosity, and leaching of active sites.2 Studies aiming at developing methodologies involving hydrated niobium oxide as catalyst in biodiesel production have been carried out by our research group.3,4 Parameters such as the use of assistant solvent to increase the boiling point of the mixture (toluene, ethylene glycol, and DMSO), pre-thermal treatment (calcinations) and catalyst molar concentration were initially assessed in esterification, oleic acid, and methanol reactions. From these studies we could observe that high temperatures and excessive alcohol favor esterification reactions. The best reaction conditions were then used as models and employed in transesterification reactions of soybean oil. DMSO (Dimethyl sulfoxide) was the solvent used to increase the reaction medium temperature without evaporating all the methanol. Transesterification reactions were carried out with soybean oil (0.5 g), methanol (0.85 g), DMSO (2.50 ml), and hydrated niobium oxide as catalyst in ratios of 20% and 100% (in relation to oil mass). Catalyst was employed without pretreatment and after pretreatment at 115 °C, 300 °C, and 500 °C. The reactions occurred at 170 °C, under reflux for 48 hours. A reaction without a catalyst was also carried out. All the reactions have shown conversion using CCD and they have been determined by 1H NMR spectroscopy.
Determination of critical conditions for the esterification of acetic acid with ethanol in the presence of carbon dioxide
Platt, G. M.;Henderson, N.;de Medeiros, J. L.;
Brazilian Journal of Chemical Engineering , 2006, DOI: 10.1590/S0104-66322006000300009
Abstract: in this work, we present the calculation of critical coordinates for the esterification of acetic acid with ethanol in compressed carbon dioxide. determination of the critical pressure for this system is useful, since the conversion of this reaction increases with pressure in the two-phase region, reaching a maximum at the critical point. we used a calculation framework based on a coordinate transformation for molar fractions, producing a new compositional domain. for a system with five components (acetic acid + ethanol + ethyl acetate + water + carbon dioxide) and one equilibrium reaction, the compositional domain is entirely described by three independent transformed coordinates. the results obtained were compared with experimental observations presented in the literature. the results illustrate the capability of the framework used to determine critical coordinates for reactive systems, and thus its usefulness as a tool for pressure tuning for this esterification reaction in compressed carbon dioxide.
Kinetics of Modified Zirconia-catalyzed Heterogeneous Esterification Reaction for Biodiesel Production  [PDF]
M.I. Zubir,S.Y. Chin
Journal of Applied Sciences , 2010,
Abstract: Biodiesel is one of the new possible substitutes of regular fuel for engines and is produced from different vegetable oils or animal fats. The main reaction involved is the transesterification of triglycerides into esters. The employment of low quality or waste raw materials has been considered to strongly improve the economic competitiveness of this biofuel with respect to the petroleum-derived diesel. In the case of waste raw materials characterized by a high content of Free Fatty Acids (FFAs), direct esterification of the FFAs is the primary route for producing biodiesel. The novel sustainable esterification process based on catalytic Reactive Distillation Column (RDC) has been proposed to overcome the shortcomings in the conventional process. A reliable kinetic model which would be applicable in a wide range of operating conditions is an important data for the RDC design. In the present study, kinetics of heterogeneous catalyzed direct fatty acid esterification was studied with a tungstated zirconia catalyst in a stirred batch reactor to synthesis biodiesel. The waste cooking oil with high content of FFAs was simulated by mixing pure oleic acid with refined palm oil. Ethanol was used in the experiments instead of methanol because it is less toxic and safer to handle. The effects of the main variables involved in the process such as reaction temperature, amount of catalyst, amount of triglyceride and the molar ratio of alcohol/free fatty acid were analyzed. The experimental data were interpreted with a second order, pseudo homogeneous kinetic model and a good agreement between experimental data and the model is obtained.
Kinetic Study of Catalytic Esterification of Butyric Acid and Ethanol over Amberlyst 15  [PDF]
Nisha Singh,Raj kumar,Pravin Kumar Sachan
ISRN Chemical Engineering , 2013, DOI: 10.1155/2013/520293
Abstract: The esterification reaction of butyric acid with ethanol has been studied in the presence of ion exchange resin (Amberlyst 15). Ethyl butyrate was obtained as the only product which is used in flavours and fragrances. Industrially speaking, it is also one of the cheapest chemicals, which only adds to its popularity. The influences of certain parameters such as temperature, catalyst loading, initial concentration of acid and alcohols, initial concentration of water, and molar ratio were studied. Conversions were found to increase with an increase in both molar ratio and temperature. The experiments were carried out in a batch reactor in the temperature range of 328.15–348.15?K. Variation of parameters on rate of reaction demonstrated that the reaction was intrinsically controlled. Experiment kinetic data were correlated by using pseudo-homogeneous model. The activation energy for the esterification of butyric acid with ethanol is found to be 30?k?J/mol. 1. Introduction Organic esters are important fine chemicals used widely in the manufacturing of flavors, pharmaceuticals, plasticizers, and polymerization monomers. They are also used as emulsifiers in the food and cosmetic industries. Several synthetic routes are available for obtaining organic esters, most of which have been briefly reviewed by Yeramian et al. [1]. Several synthetic routes have been used to make organic ester, but the most-used methodology for ester synthesis is direct esterification of carboxylic acids with alcohols in the presence of acid/base catalysts. Esterification is used. The most acceptable method is to react the acid with an alcohol catalyzed by mineral acids, and the reaction is reversible [2]. Esterification of carboxylic acid with alcohol in the presence of acid catalyst has been the subject of investigation of many research workers [3]. The traditional industrial process of synthesizing esters using homogeneous acid catalyst is conveniently replaced by solid acid catalyst, ion exchange resins, clay, and so forth [4]. The ion exchange resin is a promising material for replacement of homogeneous acid catalysts. The use of ion exchange resins as solid catalyst has many advantages over homogeneous acid catalysts. They eliminate the corrosive environment; they can separate from liquid reaction mixture by filtration and have high selectivity [5]. They can also be used repeatedly over a prolonged period without any difficulty in handling and storing them. And the purity of the products is higher since the side reactions can be completely eliminated [6]. Fatty acid esters are used
The oleic acid esterification of policosanol increases its bioavailability and hypocholesterolemic action in rats  [cached]
Haim, D.,Valenzuela, A.,Bra?es, M. C.,Fuenzalida, M.
Grasas y Aceites , 2012, DOI: 10.3989/gya.010612
Abstract: Policosanol comprises a mixture of long-chain aliphatic alcohols from sugarcane wax. More than 50 studies indicate that policosanol decreases serum cholesterol, while others failed to reproduce this effect. The objective of this investigation was to assess the bioavailability of esterified policosanol and non-esterified policosanol (NEP), in relation to their hypocholesterolemic effects. Sprague Dawley rats were given a daily oral dose of 100 mg/kg of NEP, 117 mg kg–1 of butyric acid esterified policosanol (BAEP), or 164 mg kg–1 of oleic acid esterified policosanol (OAEP). Policosanol absorption was evaluated in plasma between 0 and 3 hours after ingestion. To assess changes in total cholesterol, LDL-cholesterol, HDLcholesterol and triacylglycerols in plasma and liver 3-hydroxy- 3-methylglutaryl coenzyme A reductase (HMG- CoA red) phosphorylation, the rats were supplemented with nonesterified or esterified policosanol for 5 weeks. The results indicate that policosanol absorption was significantly greater in OAEP-treated rats than in those subjected to NEP or BAEP administration. OAEP significantly reduced plasma total and LDL-cholesterol in rats, in addition to a 5.6-fold increase (P < 0.05) in the hepatic content of phosphorylated HMG-CoA red over the control values. In conclusion, esterification of policosanol with oleic acid enhances policosanol bioavailability, and significantly improves the serum lipid profile in normocholesterolemic rats in association with the inactivation of HMG-CoA red controlling cholesterogenesis. Los Policosanoles están formados por una mezcla de alcoholes alifáticos de cadena larga y se obtienen de las ceras de la ca a de azúcar. Más de cincuenta estudios indican que los policosanoles reducen el colesterol sérico, mientras que otros no logran reproducir este efecto. El objetivo de esta investigación fue evaluar la biodisponibilidad de policosanoles esterificados y no esterificados (NEP), en relación con sus efectos hipocolesterolémicos. Para ello, a ratas Sprague Dawley se les administró una dosis oral diaria de 100 mg kg–1 de NEP, 117 mg kg–1 de policosanoles esterificados con ácido butírico (BAEP), ó 164 mg kg–1 de policosanoles esterificados con ácido oleico (OAEP). La absorción de los policosanoles se evaluó en el plasma entre 0 y 3 horas después de la ingestión. Para evaluar los cambios en el colesterol total, colesterol-LDL, colesterol-HDL y triglicéridos en el plasma y en la fosforilación de la hígado 3-hidroxi-3-metilglutaril coenzima A reductasa (HMG-CoA red), la ingesta de las ratas fue suplementada con policosano
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