Catalyst For Esterification Research Articles

Preparation and Characterization of Sulfonated Magnetic SiO2 Microspheres as the Solid Acid Catalysts for Esterification.

The sulfonated magnetic SiO2 microsphere solid acid catalysts were prepared by the impregnation and grafting methods with iron oxide magnetic nanoparticles (Fe3O4 MNPs) as the magnetic cores. The catalytic properties of the magnetic SiO2 solid acid catalyst were studied in detail. The characterization results showed that the SiO2 was successfully coated on the Fe3O4 MNPs. Compared with the grafting method, impregnated solid acid exhibits higher catalytic performance, which reached an esterification rate of up to 99.00% when the reaction temperature was 105 °C, the molar ratio of n-butanol/adipic acid was 3:1, and the ratio of the catalyst (the mass of magnetic solid acid) to liquids (the total volume of n-butanol and adipic acid) was 2.95%. The magnetic solid acid exhibited great separation ability and reusability. After six times of recycle, the conversion of the grafted magnetic solid acid still attained 85.61% compared with that of the impregnated magnetic solid acid, which reduced to 81.35%, holding great potential for green chemical processes.

Selective production of green solvent (isoamyl acetate) from fusel oil using a sulfonic acid-functionalized KIT-6 catalyst

Isoamyl acetate production from fusel oil was demonstrated in a heterogeneous system using sulfonated mesoporous silica KIT-6 catalysts. These were prepared by co-condensation at different 3-mercaptopropyl(methyl)dimethoxysilane (MPMDS):tetraethoxysilane (TEOS) ratios and subsequent oxidation (x-SO3H-KIT-6, where x is the molar ratio of MPMDS). Isoamyl acetate production was performed via esterification of fusel oil with acetic acid in a batch reactor at different reaction temperatures and reaction times. The optimal conditions were: 80 °C, 3 h, catalyst loading of 5 wt.%, and a 2:1 (v/v) acetic acid:fusel oil ratio. Under these conditions, a 95% yield of isoamyl acetate was achieved. The efficiency in terms of turnover frequency (TOF) was strongly affected by the number and accessibility of the acid sites, and therefore by the MPMDS:TEOS ratio. The highest yield was found for 0.3-SO3H-KIT-6, while 0.1-SO3H-KIT-6 had the highest TOF. The 0.3-SO3H-KIT-6 catalyst also exhibited excellent reusability over four cycles, with only a small reduction in isoamyl acetate yield in each cycle. Overall, the 0.3-SO3H-KIT-6 catalyst exhibited catalytic activity comparable to that of a commercial esterification catalyst. This novel catalyst has potential practical applications in selective production of isoamyl acetate.

Synthesis of Solid Acid Catalyst from Fly Ash for Eugenol Esterification

A series of fly ash-based heterogeneous acid catalysts were prepared by chemical and thermal treatment. Fly ash was chemically activated using sulfuric acid and followed by thermal activation. Characterization methods of XRD, BET, SEM-EDX, and the performance in esterification of eugenyl acetate production was carried out to reveal the physical and chemical characteristics of prepared catalysts. Activated catalyst showed high silica content (96.5%) and high BET surface area of 70 m2.g-1. The catalyst was proven to be highly active solid acid catalyst for liquid phase esterification of eugenol with acetic acid yielding eugenyl acetate. A yield of 43-48% was obtained with activated fly ash catalysts for 90 minutes reaction. These catalysts may replace beneficially the conventional homogenous liquid acid to the eco-friendly heterogeneous one.

Structure‐Activity Relationships of Au/Al2O3 Catalyst for the Selective Oxidative Esterification of 1,3‐Propanediol and Methanol

Abstract1.5 wt. % Au/Al2O3 catalysts were prepared using the deposition‐precipitation or colloid‐deposition method and calcined at different temperatures for the selective oxidative esterification reaction of 1,3‐propanediol and methanol to form methyl 3‐hydroxypropionate (3‐HPM). The catalysts were characterized by nitrogen adsorption, transmission electron microscopy (TEM), X‐ray diffraction (XRD), UV‐Vis diffuse reflectance spectroscopy, X‐ray photoelectron spectra (XPS), CO2 temperature‐programmed desorption (CO2‐TPD) and NH3 temperature‐programmed desorption (NH3‐TPD). The effect of the calcination temperature of the catalyst prepared by the deposition‐precipitation method on the catalytic performance for the selective oxidative esterification of 1,3‐propanediol was studied. The results showed that the conversion of 1,3‐propanediol and the selectivity of 3‐HPM increased at first and then decreased with the increase of the calcination temperature of catalyst. The highest conversion of 1,3‐propanediol and selectivity of 3‐HPM at the optimal calcination temperature of 350 °C were 92.0% and 88.5%, respectively. Considering the effects of preparation method and calcination temperature, it could be concluded that the metallic Au nanoparticles with appropriate particle size in coordination with the suitable amount of weak and middle acid and base sites, were favorable to the oxidative esterification of 1,3‐propanediol and methanol to 3‐HPM. Moreover, we found that the 1.5 wt. % Au/Al2O3 catalyst could be effectively recovered without obvious decline of the catalytic properties.

Propyl-SO3H functionalized graphene oxide as multipurpose solid acid catalyst for biodiesel synthesis and acid-catalyzed esterification and acetalization reactions

A graphene based acid catalyst, GO-PrSO3H, was prepared through a simple two-step process. Surface modification with (3-mercaptopropyl) trimethoxysilane followed by oxidation of sulfide groups led to the production of sulfonic acid sites on graphene oxide nanosheets. The results of various physicochemical techniques approved the synthesis of desired catalyst. The amount of acid sites was measured via the acid-base treatment with triethylamine which exhibited 1.07 mmol/g H+ in the catalyst structure. Two kinds of acid-catalyzed reactions i.e. esterification and acetalization were adopted to evaluate the catalytic performance of prepared catalyst. More than 90% conversion was achieved for butyl acetate production in acetic acid esterification with n-butanol. Moreover, methyl oleate as one of the main components of biodiesel was produced with good yield over the prepared catalyst via oleic acid esterification with methanol. The 1H NMR technique was also conducted to characterize and determine the amount of produced methyl oleate. Finally, the benzaldehyde acetalization with ethylene glycol was performed which high conversion (92%) was obtained at 3 h. The catalyst reusability for both esterification and acetalization reactions demonstrated the catalyst stability after five reaction cycles.

Tailoring the surface area and the acid\u2013base properties of ZrO2 for biodiesel production from Nannochloropsis sp.

Bifunctional heterogeneous catalysts have a great potential to overcome the shortcomings of homogeneous and enzymatic catalysts and simplify the biodiesel production processes using low-grade, high-free-fatty-acid feedstock. In this study, we developed ZrO2-based bifunctional heterogeneous catalysts for simultaneous esterification and transesterification of microalgae to biodiesel. To avoid the disadvantage of the low surface area of ZrO2, the catalysts were prepared via a surfactant-assisted sol-gel method, followed by hydrothermal treatments. The response surface methodology central composite design was employed to investigate various factors, like the surfactant/Zr molar ratio, pH, aging time, and temperature on the ZrO2 surface area. The data were statistically analyzed to predict the optimal combination of factors, and further experiments were conducted for verification. Bi2O3 was supported on ZrO2 via the incipient wetness impregnation method. The catalysts were characterized by a variety of techniques, which disclosed that the surfactant-assisted ZrO2 nanoparticles possess higher surface area, better acid–base properties, and well-formed pore structures than bare ZrO2. The highest yield of fatty acid methyl esters (73.21%) was achieved using Bi2O3/ZrO2(CTAB), and the catalytic activity of the developed catalysts was linearly correlated with the total densities of the acidic and basic sites. The mechanism of the simultaneous reactions was also discussed.

Excellent Properties of Dimer Fatty Acid Esters as Biolubricant Produced by Catalyst‐ and Solvent‐Free Esterification

AbstractCurrently most technologies available to produce esters require acid or base catalysts for esterification or transesterification reactions. Production of dimerate esters (DE) exhibiting potential as a biolubricant for low temperature applications using catalyst‐ and solvent‐free approaches is presented in this article. Hydrogenated C36dimer acid and alcohol are reacted under the following conditions: dimer acid/alcohol (1:4.5 molar ratio), 150–200 °C, 24 h, 3Å molecular sieve (15% w/w). The performances of four DE species—dibutyl, dihexyl, di‐(2‐ethylhexyl), and dioctyl dimerate—as lubricant base stocks are evaluated by kinematic viscosity, viscosity index, cloud and pour point (cold flow properties) as well as oxidative stability, and compared with commercial synthetic lubricant base stock and DE, Radialube 7121. High viscosity indexes ranging between 129 and 138 are observed for the synthesized DEs, which are comparable with two commercial base stock, polyalpha olefin (PAO), and polyolester (POE). Significantly low pour point, less than −42 °C, is observed for di‐(2‐ethylhexyl) dimerate attributed to the branching of the side chain. The DEs are categorized as ISO VG 68 based on their viscosity according to ISO 3448 classification and show potential as biolubricant with high viscosity index and excellent cold flow properties.Practical Applications: DFAE obtained have high potential to be used as lubricant base stock for equipment and machinery operating at extremely low temperature.

Nanostructured large-pore zeolite: The enhanced accessibility of active sites and its effect on the catalytic performance

Abstract Zeolites Y, ZSM-5, beta, mordenite and LTL were converted into hierarchical meso-microporous catalysts applying the surfactant templating strategy and the resulting materials were utilised as catalysts for esterification and aldol condensation reactions for the production of the second generation biofuels and platform chemicals from biomass derived molecules. The relationship between the catalytic performance and the accessibility of active sites in zeolites was examined using FTIR spectroscopy of adsorbed pyridine, 2,4,6-trimethylpyridine and 1,3,5-triisopropylbenzene. It was found that the esterification of oleic acid can be enhanced by the presence of strong acid sites in zeolites and their improved accessibility. In the aldol condensation reaction, furfural conversion over hierarchical catalysts also increased as compared to the parent zeolites. However, K-forms of the studied zeolites exhibited a higher conversion and selectivity toward the desired reaction products in comparison with their H-forms. Overall, mesostructured zeolites demonstrated an improved catalytic performance as a result of increasing accessibility of the zeolite active sites.

Expanding the Reaction Space of Linkage-Specific Sialic Acid Derivatization.

The human glycome is characterized by a high degree of sialylation, affecting, amongst others, cell–cell interactions and protein half-life. An established method for the linkage isomer-specific characterization of N-glycan sialylation is based on the linkage-specific derivatization of sialylated glycoconjugates, inducing ethyl esterification of α2,6-linked sialic acids and lactonization of α2,3-linked sialic acids. While the carboxylic acid activator and nucleophile used in this reaction received extensive investigation, the role of the catalyst was never thoroughly explored. A frequently used catalyst for the linkage-specific esterification of sialic acids is 1-hydroxybenzotriazole (HOBt). Here, a systematic evaluation was performed of five HOBt alternatives in combination with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) in ethanol for the linkage-specific derivatization of sialic acids. Derivatized glycans were analyzed by MALDI-TOF-MS and the catalyst performance was evaluated based on the completeness of the reactions and the linkage-specificity obtained. The use of both 6-Cl-HOBt and 6-CF3-HOBt resulted in high linkage-specificity and minimal byproduct formation, similar to the benchmark method using HOBt. Performing the reaction with these catalysts at neutral or acidic pH showed comparable efficiencies on both sialyllactose and complex-type N-glycans. The reported investigations resulted in an expansion of the reaction space for linkage-specific sialic acid derivatization.

Insight into the effect of Pd and Pd3Pb surface structure on activation of reactant O2 and product H2O in direct oxidative esterification

Density functional theory is performed to systematically study the effect of surface structure and facet of Pd and Pd3Pb catalysts on activity for O2, H2O activation, O diffusion and stability of resistance toward deactivation induced by H2O adsorption and aggregation. Our results show that flat (1 1 1) (Pd3Pb(1 1 1), Pd(1 1 1)) and (1 0 0) (Pd(1 0 0)) facets rather than stepped (2 1 1) facet (Pd(2 1 1), Pd3Pb(2 1 1)) are active surfaces, mathing well with our previous experimental result that Pd(1 1 1) and Pd3Pb(1 1 1) planes detected in Pd-Pb alloy, further confirm that main exposed Pd3Pb(1 1 1) surface of Pd3Pb promotes O2, H2O activation, O diffusion and inhibits H2O adsorption, aggregation. Moreover, preadsorbed O coverage and numbers of H2O on Pd3Pb have little effect on H2O adsorption and cluster forming. Therefore, Pd3Pb catalysts not only present better activity and stronger stability but also decrease cost than pure Pd. Firstly finding that surface average charge through Mulliken charge analysis serves as a indicator judging minimum active region. Higher activity and stability of Pd3Pb catalysts are attributed to exposed rhomboid active unit with Pb synergistic effect. Dependence of Pd and Pd3Pb catalyst’s activity and stability on surface structure and facet revealed may provide new way for designing better, stable Pd-Pb catalysts in direct oxidative esterification.

Nickel-Catalyzed Esterification of Amides Under Mild Conditions

The use of ligands to adjust the catalytic activity of the catalyst for esterification of amides is challenge in organic chemistry. In this paper, Nickel(II)-NHC-catalyzed the esterification reaction between N,N-di-Boc amide and alcohols at room temperature have been demonstrated. The imidazolium salt bearing a hydroxyl functionalized side arm showed high effective catalytic activity in the activation of the amide N–C bond in air atmosphere.

Catalytic Cleavage of Amide C-N Bond: Scandium, Manganese, and Zinc Catalysts for Esterification of Amides.

Amide C-N bonds are thermodynamically stable and their fission, such as by hydrolysis and alcoholysis, is considered a long-challenging organic reaction. In general, stoichiometric chemical transformations of amides into the corresponding esters and acids require harsh conditions, such as strong acids/bases at a high reaction temperature. Accordingly, the development of catalytic reactions that cleave not only primary and secondary amides, but also tertiary amides in mild conditions, is in high demand. Herein, we surveyed typical stoichiometric transformations of amides, and highlight our recent achievements in the catalytic esterification of amides using scandium, manganese, and zinc catalysts, together with some recent catalyst systems using late-transition metal reported by other groups.

Reusable Heterogeneous Tungstophosphoric Acid-Derived Catalyst for Green Esterification of Carboxylic Acids

Solid acid catalysts are environmentally friendly alternatives to the use of mineral acids in a range of applications, including the esterification of carboxylic acids. Here, a phosphorus- and nitrogen-doped, carbon-modified, fully heterogeneous solid acid catalyst was prepared by pyrolysis of a mixture of melamine and tungstophosphoric acid at 250, 500, and 750 °C under a nitrogen atmosphere provided. The structure of the different catalysts was evaluated by surface area measurements, XRD, XPS, Raman spectroscopy, elemental analysis, and electron microscopies. Pyrolysis at 500 °C created complex solid materials with larger surface area and significantly higher acidity, which can be attributed to WO3 formation on a heteroatomic (N,P)-carbon structure. The 500 °C-treated heterogeneous catalysts showed remarkably better activity for esterification of palmitic acid and were thus applied in the esterification of a broad range of carboxylic acids with good overall yields. Furthermore, the solid acid catalyst c...

Aluminum foil waste as catalyst for esterification of waste cooking oil

ABSTRACT In this study, aluminum chloride hexahydrate (AlCl3.6 H2O) was derived from aluminum foil waste as a heterogeneous acid catalyst in the esterification of waste cooking oil. The parameters of catalyst loading (2–8 wt%), ultrasonic frequency (12–40 kHz), and reaction time (15–60 min) were optimized for maximum biodiesel yield production. Under constant condition of methanol to oil molar ratio of 6:1 and temperature of 50°C, a biodiesel yield of 91% was obtained at 2 wt% catalyst loading, 26 kHz ultrasonic frequency, and 40 min reaction time.

Interplay of Lewis and Brønsted Acid Sites in Zr-Based Metal-Organic Frameworks for Efficient Esterification of Biomass-Derived Levulinic Acid.

We report the performance of UiO-66 and its Brønsted acid functionalized derivative, UiO-66-(COOH)2, as heterogeneous catalysts for levulinic acid esterification with ethanol. Importantly, compared with UiO-66, UiO-66-(COOH)2 displayed superior catalytic performance (up to 97.0 ± 1.1% yield of ethyl levulinate) attributed to the synergistic effect between Lewis acidic Zr clusters and Brønsted acidic -COOH groups. Furthermore, UiO-66-(COOH)2 was stable and reusable without an appreciable loss in catalytic activity for at least five consecutive cycles. This study demonstrates that the interplay of Brønsted and Lewis acid sites in zirconium metal-organic frameworks leads to more efficient catalytic conversion of a biomass feedstock to biofuel, and with further hypothesis driven research, additional materials that show promise as candidates for catalytic conversion of biomass feedstocks to biofuels and valuable chemicals can be developed.

Acidic Ionic Liquid as Both Solvent and Catalyst for Fast Chemical Esterification of Industrial Lignins: Performances and Regioselectivity.

Lignin can be considered an essential under-exploited polymer from lignocellulosic biomass representing a key for a profitable biorefinery. One method of lignin valorization could be the improvement of physico-chemical properties by esterification to enhance miscibility in apolar polyolefin matrices, thereby helping the production of bio-based composites. The present work describes for the first time a succeeded chemical esterification of industrial lignins with maleic anhydride in an acidic ionic liquid: 1-butyl-3-methyl imidazolium hydrogen sulfate without additional catalyst. This efficient strategy was applied to four industrial lignins: two softwood Kraft lignins (Indulin AT, Wayagamack), one hardwood Kraft lignin (Windsor), and one softwood organosolv lignin (Lignol), distinct in origin, extraction process and thus chemical structure. The chemical, structural, and thermal properties of modified lignins were characterized by 31P nuclear magnetic resonance, infrared spectroscopy and thermal analyses, then compared to those of unmodified lignins. After 4 h of reaction, between 30 to 52% of the constitutive hydroxyls were esterified depending on the type of lignin sample. The regioselectivity of the reaction was demonstrated to be preferentially orientated toward aliphatic hydroxyls for three out of four lignins (66.6, 65.5, and 83.6% for Indulin AT, Windsor and Lignol, respectively, vs. 51.7% for Wayagamack). The origin and the extraction process of the polymer would thus influence the efficiency and the regioselectivity of this reaction. Finally, we demonstrated that the covalent grafting of maleyl chain on lignins did not significantly affect thermal stability and increased significantly the solubility in polar and protic solvent probably due to additional exposed carboxylic groups resulted from mono-acylation independently of H/G/S ratio. Blending with polyolefins could then be considered in regard of compatibility with the obtained physico-chemical properties.

Organosulfonic acid functionalized montmorillonites as solid catalysts for (trans) esterification of free fatty acids and (waste) oils

Organosulfonic acid functionalized montemorillonite-MMT (K10 and cloisite Na+) were prepared by different methodologies: (a) one-pot organosilylation or sulfonation, and (b) two-step organosilylation followed by sulfonation or oxidation. The physicochemical characterization ensured the success of the selected methodologies to promote HSO3-functionalization including high S contents (2.84 mmol S/g) and acidities up to 6.03 mmol H+/g (K10_PhSO3H).All the organosulfonic acid functionalized MMT were tested as acid catalyst in the esterification of free fatty acids in a hybrid feedstock model. Conversions of 100% were obtained after 60 min for K10_PhTESO3H, K10_SO3H, Cloi_PhTESO3H and Cloi_H2SO4, in accordance with the acid character of these catalysts, prepared by one-pot and two-step methodologies involving a sulfonation step. The MMT catalysts obtained by direct sulfonation exhibited the highest TOF whereas those obtained by two-step organosilylation-sulfonation showed the highest stability and reusability. The increase of FFA carbon chain length led to higher conversions, showing the prevalence of inductive effect and absence of steric effects on the esterification mechanism using these organosulfonic acid functionalized catalysts. Moreover, K10-PhSO3H was applied as solid acid catalyst in a simultaneous (trans) esterification of different feedstock types for biodiesel production giving up to 100% of FAMEs under moderate conditions.

The SO3H-functionalized carbonaceous@montmorillonite efficient heterogeneous catalyst for synthesis of trimethylolpropane from long-chain fatty acid

Abstract As the increasing demand of bio-lubricants in industries, the new “green” synthetic method to polyolesters has attracted lots of attention. Herein, we report a novel efficient heterocatalyst contained sulfonic acid group, which was assembled through hydrothermal carbonization with the mixture carbon source of chitosan and furaldehyde, the hydroxyethylsulfonic acid aqueous solution was added as SO3H source. The obtained carbonaceous intercalated clay composites conserved regular layered and enlarged specific surface areas and pore volumes, which were proved by small-angle XRD, SEM and N2 sorption isotherms. The FT-IR, XPS, 13C CP/MAS NMR spectrum, Raman spectra and elemental analysis were employed to confirm the SO3H groups and its loading level. As an acidic heterogeneous catalyst for esterification between trimethylolpropane and oleic acid, synthesized SO3H-loaded carbonaceous intercalated montmorillonite composite exhibits high catalytic activity under the solvent-free conditions. The yield of the desired bio-lubricant is as high as 91% in 3 h. With little loss of catalytic activity after be reused five times, the SO3H-functionalized carbonaceous intercalated montmorillonite composite shows good reusability.

Acid functionalized coal fly ashes: New solid catalysts for levulinic acid esterification

Coal fly ash (CFA) from different sources (CFA 5, 10, 13) and different size fractions (> or < 75 μm) were characterized and used as inorganic supports for sulfonic acid functionalization by two methodologies including one-pot organosilylation (CFA_CSPTMS) and two-step benzyl alcohol condensation followed by sulfonation (CFA_BnSO3H). The as-prepared organosulfonic CFAs were characterized by solid-state 1H, 13C and 29Si NMR spectroscopy, XPS, S content was quantified by elemental analysis and the intrinsic acidity was determined by potentiometric titration; the highest –SO3H content was obtained for CFA13_BnSO3H. All the functionalized CFAs were tested for the first time as acid solid catalysts in the esterification of levulinic acid (LA) a biomass platform molecule, in the presence of n-butanol. n-Butyl levulinate was the only product with conversions of 100% after 40 min. reaction and using the CFA13_BnSO3H as catalyst. This catalyst also exhibited the highest TOFs (447 h−1) and showed to be the most stable and reusable for 5 consecutive catalytic cycles.

Assessment of niobium phosphate as heterogeneous catalyst in esterification with methyl acetate

AbstractBACKGROUNDThe aim of this work was to investigate the esterification reaction from oleic acid with methyl acetate (MeA) catalyzed by niobium phosphate to produce methyl esters. This catalyst has an amorphous structure and large surface area. Catalytic tests were performed according to an experimental design. The results were analyzed statistically and all of the variables were significant, especially the temperature.RESULTSA kinetic study of the reaction was carried out and the most suitable reaction conditions were 240 °C, 10% (m/m) of catalyst and MeA: oleic acid molar ratio 10:1. After 2 h, it was possible to obtain ≈80% (m/m) methyl oleate content. A noncatalytic test corroborated niobium phosphate activity in the reaction. A kinetic model fitted experimental data for the catalyzed and noncatalyzed reactions; kinetics parameters for Arrhenius equation were estimated. In a reuse test, the catalyst showed a gradual decrease in catalytic activity over five reaction cycles.CONCLUSIONNiobium phosphate can be considered as a promising heterogeneous catalyst for biodiesel synthesis. © 2019 Society of Chemical Industry