Structural and acidity analysis of heteropolyacids supported on faujasite zeolite and its effect in the esterification of oleic acid and n-butanol

Facial synthesis of ferric molybdate (Fe2(MoO4)3) nanoparticle and its efficiency for biodiesel synthesis via oleic acid esterification

The esterification reaction of oleic acid using heterogeneous catalysts can be a promising alternative for the production of biodiesel. This study proposed to obtain biodiesel from the esterification of oleic acid with the Zr-SBA-15 and SO 4 2− /Zr-SBA-15 catalysts obtained by inserting Zr and subsequent sulphation of SBA-15 synthesized by the hydrothermal method. Zr-SBA-15 and SO 4 2− /Zr-SBA-15 catalysts were initially synthesized by the wet impregnation method, followed by the sulphation process. The characterization of the catalysts was performed by: X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, nitrogen adsorption/desorption, scanning electron microscopy, energy-dispersive X-ray spectroscopy and acidity test, with the aim of identifying the structure, composition and verification of the presence of acidic sites. The characterization results indicated that SBA-15 preserved the ordered hexagonal structure, after the incorporation of Zr, with the presence of nanoparticles of this metal dispersed on the surface and inside the microporous and mesoporous channels of the Zr-SBA-15 catalyst. After sulphation, the amount of acid sites increased and the ordered structure was maintained. For the Zr-SBA-15 and SO 4 2− /Zr-SBA-15 catalysts, there was the formation of tetragonal and monoclinic structures of ZrO 2 . The catalytic activity was evaluated by the esterification reaction of oleic acid via the methyl route. Biodiesel obtained with SO 4 2− /Zr-SBA-15 presented physico-chemical properties within the standards specified by ANP Resolution N° 798/2019 and a better yield of 80.7%. SBA-15 did not show catalytic activity for the oleic acid esterification reaction under the reaction conditions of this study.

Comparison of different heterogeneous catalysts and different alcohols for the esterification reaction of oleic acid

In this study, a Brönsted–Lewis bifunctional acidic catalyst PW/UiO/CNTs-OH was synthesized via the hydrothermal method. The parameters for the esterification reaction of oleic acid with methanol catalyzed by PW/UiO/CNTs-OH were optimized using central composite design-response surface methodology (CCD-RSM). A biodiesel yield of 92.9% was achieved under the optimized conditions, retaining 82.3% biodiesel yield after four catalytic cycles. The enhanced catalytic performance of PW/UiO/CNTs-OH can be attributed as follows: the [Zr6O4(OH)4]12+ anchored on the surface of multi-walled carbon nanotubes (MWCNTs) can serve as nucleation sites for UiO-66, not only encapsulating H3[P(W3O10)4] (HPW) but also reversing the quadrupole moment of MWCNTs to generate Lewis acid sites. In addition, introduction of HPW during synthesis of UiO-66 decreases the solution pH, inducing the protonation of p-phthalic acid (PTA) to disrupt the coordination with the [Zr6O4(OH)4] cluster, thereby creating an unsaturated Zr4+ site with electron pair-accepting capability, which generates Lewis acid sites. EIS analysis revealed that PW/UiO/CNTs-OH has higher electron migration efficiency than UiO-66 and PW/UiO. Furthermore, NH3-TPD and Py-IR analyses showed that PW/UiO/CNTs-OH possessed high densities of Lewis acidic sites of 83.69 μmol/g and Brönsted acidic sites of 9.98 μmol/g.

Biodiesel is currently getting great attention because it can reduce carbon dioxide emissions by 78.5% compared to petroleum-based diesel. The reaction that can produce biodiesel is the esterification reaction with the addition of a heterogeneous catalyst, one of which is SnO2 which can be used as Lewis acid for the esterification reaction. In our study, SnO2 has been successfully synthesized and then succeeded in reducing the level of oleic acid FFA (Free Fatty Acid) through an esterification reaction. SnO2 was synthesized from SnCl2.2H2O using the hydrothermal method with the addition of CTAB (Cetyl Trimethyl Ammonium Bromide) as a capping agent which was then analyzed using XRD (X-Ray Diffraction) and SEM (Scanning Electron Microscopy). The catalytic activity of the SnO2 sample was carried out through the esterification reaction of oleic acid in ethanol at 65 °C for 6 hours with variations in catalyst weight and variations in the ethanol mole ratio. From XRD analysis, SnO2 sample consists of cassiterite minerals and has typical peaks at 2θ = 26.56°; 33.84°; 37.92°; 38.90°; 42.53°; 51.64°; 54.66°; 57.76°; 61.68°; 62.34°; 64.60°; and 65.88° with the highest intensity at 2θ = 33.84°. During condition optimization of esterification reaction of oleic acid, variations in the weight of SnO2 catalyst resulting from the optimum FFA level could be reduced by 75.05%, whereas to variations in the mole ratio of ethanol, the optimum FFA level could be reduced by 85.53%. In our study, SnO2 has been successfully synthesized and then succeeded in reducing the level of oleic acid FFA through esterification reaction until 85.53%.

Investigation of the catalytic efficiency of a new mesoporous catalyst SnO 2/WO 3 towards oleic acid esterification

In this work, biodiesel was produced from esterification of oleic acid and short chain alcohols (methanol, ethanol, propanol, and butanol) catalyzed by Novozym 435 in a batch system at conditions: 45°C, oleic to alcohol molar ratio of 1:2, Novozym 435 loading at 5% (w/w of oleic acid), 250 rpm and 8 h of reaction time. Novozym 435 exhibited the best catalytic activity in the production of methyl oleate (FFA conversion of 94.82%). At 45°C, the rate constants (k values) for the production of methyl oleate, ethyl oleate, propyl oleate, and butyl oleate by Novozym 435 were 0.78, 0.52, 0.69 and 0.17 m3∙h-1∙kmol-1, respectively. The activation energies for the production of methyl oleate and ethyl oleate over the temperature range of 40 °C to 55 °C were 4.7 and 39.1 kJ/mol, respectively. The effect of thermal deactivation on the reusability of Novozym 435 in the esterification of oleic acid with ethanol at 50°C was greater than that with methanol. Novozym 435 could be reused in the production of methyl oleate and ethyl oleate for 13 cycles with FFA conversions of > 90%. When 96.0% ethanol and 95.0% ethanol were used, the numbers of Novozym 435 reuse cycles were not greater than 10 cycles and 8 cycles, respectively. The effective development of esterification from FFAs (oleic acids and PFAD) and methanol catalyzed by Novozym 435 was studied. The optimal operating condition was obtained in the single expanded bed circulation reactor at; FFA to methanol molar ratio of 1:2, 45oC, rotation speed of 600 rpm, feed volumetric flow rate of 5 mL/min, the bed to catalyst volumetric ratio of 2:1, Novozym 435 of 10% w/w of FFA and 5h. Novozym 435 could be reused 22 cycles with FFA conversion>90%. The continuous process in four expanded bed reactors in series was also investigated. FAME yields of esterification from FFAs (oleic acid and PFAD) and methanol were 93.46% and 88.50%, respectively. The productivity of biodiesel production using oleic acid and PFAD were 5.24 and 4.68 g FAME•h-1•g enzyme-1, respectively.

In this study, the esterification of oleic acid with a fraction of fusel oil was investigated. The variables that affect ester yield, such as temperature, molar ratio of oleic acid to alcohol, and amount of catalyst, were determined. Powdered silica gel was chosen to remove water instead of granular silica gel, magnesium sulfate, or benzene. The behavior of amyl alcohols and the fusel oil fraction was compared. The esterification reaction was carried out under the reaction conditions selected as optimal, and the ester conversion of the reaction was 97.3%. The product mixture compressed products, excess reactants, catalyst, and desiccant. Oleate ester and oleic acid (2.7%) were obtained using the refinement steps of filtration, evaportation, washing with distilled water, and drying over sodium sulfate.

In order to improve the efficiency of biodiesel production from esterification of free fatty acids, an alternative to sulfuric acid has been explored in this study. These catalysts including three pyrrolidonium ionic liquids (ILs), 1-methyl-2-pyrrolidonium hydrogen sulfate ([Hnmp]HSO4), 2-pyrrolidonium hydrogen sulfate ([Hnhp]HSO4), and 1-(3-sulfonic acid) propyl-2-pyrrolidonium hydrogen sulfate ([C3SO3Hnhp]HSO4), were applied as catalysts to produce biodiesel through the esterification reaction of oleic acid with methanol. The catalytic performances of the synthesized ILs for the esterification of oleic acid were evaluated, and [C3SO3Hnhp]HSO4 exhibited the best catalytic activity among all tested acidic ILs. Moreover, the esterification of oleic acid with methanol by the [C3SO3Hnhp]HSO4-catalyzed was systematically explored, and the reaction conditions were further optimized through a single-factor experiment, the Plackett-Burman design, and a response surface methodology. It was found that optimum response for oleic acid conversion was 97.4% under reaction condition of using catalyst dosage of 12.5%, methanol/oleic acid molar ratio of 9:1, reaction time at 4 h and reaction temperature at 70 °C. In addition, the catalytic activity of [C3SO3Hnhp]HSO4 still remained high level after 5 cycles. In a conclusion, the IL [C3SO3Hnhp]HSO4 has great potential as a catalyst for producing fatty acid methyl esters via the esterification reaction.

Surface functionalization of polymers is an alternative way to modify the hydrophilic/ hydrophobic character of a material. As a result of this process, it is possible to develop commercial polymers with new thermal, chemical and mechanical properties, increasing their applicability and with the possibility of using disposable materials. In this work, the chemical modification of pristine polypropylene (PP) was carried out through sulfonation reactions with concentrated sulfuric acid (98%), producing sulfonated polypropylene (PPS1), and with fuming sulfuric acid with 65% free SO3, producing the PPS2, which were used as heterogeneous catalysts in esterification reactions of oleic acid with methanol. For in relation to the synthesis of sulfonated polypropylene, a 3k factorial design was outlined, to maximize the efficiency of the reaction and to investigate the contributions of the variables of synthesis, time and polymer:sulfonating agent. The modified materials and the PP were characterized by spectroscopy in the infrared region (FTIR), elementary analysis (EA), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and ion exchange capacity measurements (IEC). The results showed that the two sulfonation agents were effective to promote the functionalization of PP, with the fuming sulfuric acid capable of promoting a greater chemical modification in the polymer. The evaluation of the modified materials as solid catalysts showed that both PPS1 and PPS2 have satisfactory catalytic activity in esterification reactions of oleic acid with methanol, showing even greater catalytic efficiency than the commercial ion exchange resin, Amberlyst 15. Under optimized conditions, the esterification catalyzed by PPS2, carried out at 100 °C, using 4% (w/w) of catalyst and alcohol:oleic acid molar ratio of 19.5:1, a conversion of 96.56% was obtained in 5 hours of reaction, while the process catalyzed by PPS1 provided a conversion of 84.86% in a reaction time of 3 hours, with alcohol:oleic acid molar ratio of 10:1, at 90 °C and a catalyst mass of 5% the starting oil. The reuse tests revealed that the materials, after acid regeneration, are structurally and catalytically stable even after 10 reaction cycles and can be recycled and reused without significantly reducing their activities. The kinetic study of the reactions catalyzed by PPS1 and PPS2 showed that the pseudo first order model fitted better to the experimental data, with an increase in reaction rate, in relation to the non-catalyzed process, of 58.51 and 44.91 times, respectively. Therefore, the results of this work showed that the conditions employed for the sulfonation of PP were satisfactory to produce materials with acidic characteristics necessary to catalyze the methyl esterification reaction of oleic acid, aiming at the production of biodiesel.

Preparation of the F−-SO42-/MWCNTs catalyst and kinetic studies of the biodiesel production via esterification reaction of oleic acid and methanol

Esterification of oleic acid and high acid content palm oil over an acid-activated bentonite catalyst

The esterification reaction of oleic acid with methanol practically does not occur at the temperature of most current industrial processes. If you raise the temperature, significant conversion occurs only above 200°C and after several hours. For the above reasons, all of today's industrial oleic acid esterification technologies are based on catalyzed esterification. Catalysts based on silicates are often used as catalysts in the mentioned reactions because they are cheap, easy to synthesize, insoluble in most organic solvents, and recyclable. In this work, modified mesopo-rous silica SBA-15 was used, which is suitable for a wide range of organic reactions. The effect of the amount of this catalyst on the yield of the esterification reaction was studied. It has been shown that with an increase in the amount of catalyst, the degree of conversion, i.e. the yield of methyl oleate, increases.

Bentonite pillarization using sonication in a solid acid catalyst preparation for the oleic acid esterification reaction

Solid acid catalysts based on sulfonated carbon nanostructures embedded in an amorphous matrix produced from bio-oil: esterification of oleic acid with methanol