Application In Esterification Research Articles

Characteristics of surface modified sugarcane bagasse cellulose: application of esterification and oxidation reactions

Research on polymer matrix composites has become increasingly important in both the academic and industrial sectors. The study of polymer-natural fiber composites, known for their eco-friendly properties, has gained significance. Sugarcane bagasse fibers, abundant as discarded agricultural byproducts, offer improved properties such as density, rigidity, strength, and cost-effectiveness, enhancing sustainability. As a result, experiments were performed on cellulose fibers pre-treated from sugarcane bagasse using 5% NaOH solution by simply soaking them for 4–5 h followed by washing with water. Further modifications involved esterification using phthalic anhydride and phthaloyl chloride via steam baths at 90 °C and oxidation using sodium percarbonate with a phase transfer catalyst (Adogen) at 80 °C. These chemically altered cellulose fibers exhibited significant peak changes in the FTIR spectra, a reduced crystallinity index in the XRD pattern, increased thermal stability as evidenced by TGA curve, and improved surface roughness in the SEM analysis. This paper emphasizes successful pretreatment procedures for isolating cellulose fibers from sugarcane bagasse and introduces three chemical treatments for surface functionalization which might find applications in the preparation of biocomposites.

Surface Modification of Magnetic ZIF-90 Nanoparticles Improves the Microenvironment of Immobilized Lipase and Its Application in Esterification.

Interactions of enzymes with supports significantly affect the activity and stability of immobilized enzymes. Herein, amino-functionalized ionic liquid (IL)-grafted magnetic zeolitic imidazolate framework-90 (MZIF-90) was prepared and used to immobilize porcine pancreatic lipase (PPL). The nanocomposites were fully characterized; meanwhile, the interactions between ILs and ZIF-90 were calculated based on density functional theory. The prepared biocatalyst (PPL-ILs/MZIF-90) had a lipase loading of 178.3 mg/g and hydrolysis activity up to 287.5 U/g. When the biocatalyst was used to synthesize isoamyl acetate, the reaction media, molar ratio of alcohol/acid, temperature, and reaction time were optimized. Under the optimized reaction conditions (in hexane, alcohol/acid = 3:1, under 45 °C, reacted for 9 h), the ester yield reached 85.5%. The results of the stability test showed that PPL-ILs/MZIF-90 retained 88.7% of the initial activity after storing for 35 days and 92.5% of the initial activity after reusing for seven cycles for synthesizing isoamyl acetate. Moreover, the secondary structure analysis showed that the synthesized supports protected the active conformation of immobilized lipase, which lead to the enhanced catalytic performance. Additionally, the biocatalyst can be easily separated with a magnet, which facilitated the reusability. This study provides insights regarding the application of metal organic framework composites in the field of enzyme catalysis.

Characterization of rare earths obtained from monazite concentrate processing and their application in esterification for biodiesel production

Rare earths namely lanthanum (La), neodymium (Nd) and cerium (Ce) obtained from the monazite concentrate processing were comprehensively characterized using XRF, XRD, FTIR, N2 adsorption–desorption, CO2/NH3-TPD and SEM to reveal their catalytic performance in esterification of oleic acid for biodiesel production. The effect of calcination temperatures (500–1000 °C) on the catalyst properties and biodiesel conversion was also investigated. The catalytic performances of the catalysts were tested under the conditions of catalyst loading 3 wt%, molar ratio of oil to methanol 1:20, reaction temperature 200 °C, stirring rate 600 rpm for 5 h. It is interesting that the Ce catalyst calcined at 1000 °C showed the best performance and the highest FAME content of 78.54% could be achieved, even its acid sites was very low, which is probably associated to the availability of oxygen vacancies at high calcination temperature. The La catalysts calcined at 600 °C exhibited the balancing of strong Lewis acid and Lewis basic sites, which is related to the catalytic activity with FAME content of 74.44%. For the catalytic performance of Nd catalysts, the FAME content of 63.60% was obtained at calcination temperature of 500 °C, which was lower than those La and Ce catalysts.

On the modelling and surface response analysis of a non-conventional wall-cooled solid/gas bioreactor with application in esterification

Solid/gas biocatalysis is, nowadays, an attractive discipline in biotechnology for applying synthesis reactions. The design of the solid/gas bioreactor is, nevertheless, the main engineering challenge for its application at full scale. Although modeling is the most reliable engineering tool to design a reaction technology and guide the experimental work, as far as the authors know, there is not, today, a mathematical model for the solid/gas bioreactor. To this end, this work is aimed at developing a pseudo-continuous model for a wall-cooled packed-bed reactor for solid/gas biocatalysis. Esterification of propionic acid and isobutyl alcohol on supported lipases extracted from Candida antarctica is implemented as the case study because of the importance of isobutyl propionate in the commodities market. The proposal and construction of the mathematical model are based on reactor engineering principles. Thus, the pseudo-continuous model is applied for carrying out parametric sensitivity and surface response analyses. The former contributes to understanding the complex microscopic interaction between thermodynamics, kinetics, and transport phenomena at the studied operating conditions and selected geometrical settings; while the latter allows the identification of the operational window where the biocatalyst meets its optimal macroscopic performance without having the well-known computational cost due to the time required to solve pseudo-continuous models accounting for the bioreactor heterogeneity and fluid dynamics. The pseudo-continuous model constitutes a valuable tool for future studies focused on either providing a deeper understanding of the solid/gas biocatalytic esterification or carrying out the conceptual design and operation of the solid/gas bioreactor.

Characterization of Rare Earths Obtained from Monazite Concentrate Processing and Their Application in Esterification for Biodiesel Production

Characterization of Rare Earths Obtained from Monazite Concentrate Processing and Their Application in Esterification for Biodiesel Production

Metal–organic framework-derived nanoporous titanium dioxide–heteropoly acid composites and its application in esterification

Abstract MIL-125(Ti) metal–organic framework-derived nanoporous titanium dioxide–heteropoly acid (PW–TiO2) have been synthesized by a facile hydrothermal approach and subsequent calcination, and the PW–TiO2 catalysts were investigated using various characterization technologies including FTIR, XRD, SEM, TEM, N2-physisorption, and NH3-TPD. Further, we investigated the use of PW–TiO2 composites as heterogeneous acid catalysts for the catalytic esterification of oleic acid. Among all series of catalysts, the calcined PW–TiO2 at a temperature of 350°C showed excellent activity with a high conversion of 90.5% at 160°C for 4 h. More importantly, the catalyst could be simply separated via centrifugation and reused for six cycles and shows a relatively high conversion of 74.8%.

Carbon-based solid acid catalyst derived from Undaria pinnatifida and its application in esterification

In this study, solid acid catalysts were prepared from a marine biomass, Undaria pinnatifida, also known as wakame, which is one of the hundred most invasive species worldwide. Carbonaceous materials from U. pinnatifida were prepared using sequential carbonization methods of pyrolysis and hydrothermal carbonization. The influence of these two carbonization methods on the characteristics of the solid acid catalysts was investigated. Catalysts prepared with a sequential carbonization method, pyro-hydrochar, exhibited the highest specific surface area while its sulfonated form showed good acidity of 2.14H+ mmol g−1. The catalytic performance of the prepared catalysts was evaluated through the esterification of acetic acid and ethanol. The catalyst derived from the sulfonated pyro-hydrochar presented higher catalytic activity than sulfonated pyrochar or hydrochar on its own. This study indicates that the sequential carbonization method is effective in producing carbonaceous material with great potential from U. pinnatifida that could be converted into highly efficient solid acid catalysts upon sulfonation.

Preparation of sulfonated carbon derived from orange peel and its application in esterification

Sulfonated carbon derived from orange peel (SAC-OP-x) was prepared by hydrothermal partially carbonization. Their catalytic performances for the esterification of oleic acid with methanol and citric acid with n-butanol were investigated. The prepared catalysts were characterized by XRD, FT-IR, N2 physisorption, elemental analysis, Raman and FT-IR of adsorbed pyridine. The FT-IR of adsorbed pyridine showed the existence of Brönsted acid sites and Lewis acid sites in the SAC-OP-x samples. Moreover, the SAC-OP-x sample with sulfonation time of 2 h exhibited the maximum conversion of oleic acid and citric acid with 92.8% and 81.3% under the optimum conditions, respectively.

Preparation of heterogeneous interfacial catalyst benzimidazole-based acid ILs@MIL-100(Fe) and its application in esterification

A functionalized heterogeneous interfacial catalyst (BIMAILs@MIL-100(Fe)) is fabricated by encapsulating benzimidazole-based acidic ionic liquids (ILs:[BIMAILs]HSO4) into the cages of MIL-100(Fe) framework. The characterization of the target heterogeneous catalyst is represented by SEM, FT-IR, XRD, N2 adsorption-desorption and EA techniques, and its catalytic activity is assessed by the esterification on the interface between heterogeneous catalyst and oleic acid/methanol. The effect of esterification temperature, esterification time, molar ratio of methanol/oleic acid, and catalyst dosage is elaborated to obtain its optical reaction condition, respectively. The results show that [BIMAILs]HSO4 ILs are effectively encapsulated in the cages of MIL-100(Fe) framework, and the prepared heterogeneous interfacial catalyst displays the excellent catalytic activity by the esterification of oleic acid, resulting in a maximum conversion of oleic acid 92.3% under the optimized situation, and the conversion is only reduced from 92.3–84.1% when the catalyst is reused for 6 cycles, which indicates that the prepared heterogeneous catalyst has good reusability.

Synthesis and characterization of lactic acid esterified starch by an in-situ solid phase method

To improve the hydrophobicity and thermoplastic processability of starch, lactic acid esterified starch (LA-e-starch) was prepared by in-situ solid phase esterification with corn starch as the raw material and LA as the esterifying agent. Fourier transform infrared spectroscopy confirmed that the esterification reaction was successful. The optimal esterification efficiency of LA-e-starch was obtained when the LA proportion was 20% by mass, catalyst ratio at 3%, reaction temperature 80 °C and reaction time 2.5 h. LA-e-starch was characterized by scanning electron microscopy (SEM), contact angle (CA) analysis, X-ray diffractometry (XRD), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) as well as its water absorption rate evaluated. Results showed that in-situ solid phase esterification mainly occurred on starch granule surfaces and did not destroy the starch granularity. LA-e-starch surfaces were covered with a layer of polylactic acid resin, which caused starch granules to stick together. The initial contact angle of LA-e-starch was clearly larger than that of native starch and the water absorption rate lower than native starch in a 168 h test time, which showed that esterification effectively improved the hydrophobicity of starch. This esterification destroyed the crystalline structure of starch to some extent, resulting in a crystallinity reduction to 25.16%. In addition, the gelatinization temperature and enthalpy were lower than those of native starch. XRD and DSC analyses indicated that esterification modification increased starch thermoplasticity. Also, LA-e-starch exhibited better thermal stability than native starch, from which it was inferred that this application of esterification could improve the thermoplastic processability of starch modify the interfacial compatibility between starch and polymer resins.

Synthesis of Polyionic Liquid by Phenolic Condensation and Its Application in Esterification

A novel polyionic liquid for esterification was synthesized by phenolic condensation. Different characterization techniques were applied, and the result showed that the catalyst had high acidity am...

Facile one-pot synthesis of Cu-BTC metal-organic frameworks supported Keggin phosphomolybdic acid for esterification reactions

ABSTRACT In the present study, phosphomolybdic acid (HPMo) supported on Cu-BTC Metal-organic frameworks (MOFs) were prepared and utilized as a solid acid catalyst. The structure of the synthesized materials was characterized by using powder XRD, FT-IR, N2 adsorption-desorption, SEM, TEM, TG, and NH3-TPD techniques. These results exposed that HPMo was successfully encapsulated in the Cu-BTC cage and the Keggin structure of HPMo was maintained in the composite catalyst. In addition, the catalytic activity and recovery properties of the HPMo/Cu-BTC catalyst for the esterification of oleic acid with methanol into biodiesel were evaluated. These results showed that the HPMo/Cu-BTC catalyst exhibited high conversion (93.7%) and excellent reusability due to its mesoporous structure, excellent acidic activity, high BET surface area, large pore volume, and good thermal stability. Meanwhile, the kinetic studies of the esterification reaction revealed that it follows pseudo-first-order kinetics with a low activation energy of 37.5 KJ/mol. More interestingly, it shows potential application for esterification of free fatty acids (FFAs) or pretreatment of low-cost feedstocks contain high FFAs content for the green production of biodiesel.

Pore-expanded SBA-15 for the immobilization of a recombinant Candida antarctica lipase B: Application in esterification and hydrolysis as model reactions

A pore-expanded mesoporous silica (SBA-15) was investigated for the immobilization of a recombinant Candida antarctica lipase B (LIPB). The influence of contact time and medium pH during adsorption, as well as thermal and solvent stability of the immobilized enzyme were evaluated. The best prepared biocatalyst was then evaluated in a model esterification reaction, the production of two flavour esters (e.g. methyl and ethyl butyrate) and in a model hydrolysis reaction, the ethyl hexanoate hydrolysis. The biocatalyst maintained high activity and operational stability even after five successive cycles of synthesis. A commercial C. antarctica lipase B was also immobilized on SBA-15 and evaluated under the same conditions, achieving similar volumetric productivities. In addition, the biocatalyst SBA-15-LIPB was tested in ethyl hexanoate hydrolysis. The influence of reactional medium pH was conducted (pH 5, 7 and 9.2) and the highest biocatalyst activity was at pH 5 (about 636.3U/genzyme). SBA-15-LIPB and SBA-15-LIPB-GA (crosslinked biocatalyst) were reused for 5 cycles, retaining, after the third cycle, 56.6 and 76.80%, respectively, of its initial activity. The prepared biocatalysts were able to catalyze the model reactions (esterification and hydrolysis) with high activity and reasonable stability.

Superacidic porous polymer catalyst and its application in esterification of carboxylic acid

Two solid acid catalysts, SAC1 and SAC2, with porous structure obtained from mesoporous hard template were synthesized and characterized by Fourier transform infrared spectroscopy, acid-base titration, nitrogen adsorption/desorption, scanning electron microscopy, and their catalytic activity in esterification of carboxylic acid. Acid-base titration showed that these catalysts have acidic concentration of 1.02–1.10 mmol/g. The catalytic test in esterification of 6-bromohexanoic acid with methanol showed that SAC1 with perfluorinated sulfonic acid is catalytically more active than SAC2 with aryl sulfonic acid. In spite of lower acid loading, SAC1 showed a comparable catalytic activity with commercially available solid acid catalyst Amberlyst 15 with higher acid capacity (4.80 mmol/g) due to high acidity and well-defined pore structure. SAC1 could be recycled up to three times without significant loss in activity.

ZrO2-modified TiO2 nanorod composite: Hydrothermal synthesis, characterization and application in esterification of organic acid

ZrO2-modified TiO2 nanorod composites were synthesized by using the hydrothermal synthesis approach. The synthesized materials were characterized by XRD, SEM, TEM, Raman, IR, and XPS. It was found that both sizes and morphologies of ZrO2 particles significantly depended on the reaction temperatures and hydrothermal synthesis time. TEM results exhibited that large sized particles of ZrO2 of 50 nm were achieved at low hydrothermal synthesis temperature of 110 °C, while small sized particles of ZrO2 of 20 nm stably deposited on the surface of TiO2 nanorods are generated at high temperature of 200 °C. The ZrO2–TiO2 nanorod composite was further functionalized by sulfate groups and utilized as the solid superacid catalyst for upgrading of bio-oil model compound organic acid by esterification. Both IR and XPS approved the presence of sulfate groups on Zr and Ti adsorption sites. HPLC results for the conversion of model compound levulinic acid to ester showed that 81.2% of levulinic acid converted to ethyl levulinate at 110 °C in 2 h over a 20 wt% ZrO2–TiO2 nanorod composite. GC–MS result displayed that ester was produced as the only product.

Application of a statistically enhanced, novel, organic solvent stable lipase from Bacillus safensis DVL-43

This paper presents the molecular identification of a newly isolated bacterial strain producing a novel and organic solvent stable lipase, statistical optimization of fermentation medium, and its application in the synthesis of ethyl laurate. On the basis of nucleotide homology and phylogenetic analysis of 16S rDNA sequence, the strain was identified as Bacillus safensis DVL-43 (Gen-bank accession number KC156603). Optimization of fermentation medium using Plackett–Burman design and response surface methodology led to 11.4-fold increase in lipase production. The lipase from B. safensis DVL-43 exhibited excellent stability in various organic solvents. The enzyme retained 100% activity after 24h incubation in xylene, DMSO and toluene, each solvent being used at a concentration of 25% (v/v). The use of partially purified DVL-43 lipase as catalyst in the synthesis of ethyl laurate, an esterification product of lauric acid and ethanol, resulted in 80% esterification in 12h under optimized conditions. The formation of ethyl laurate was confirmed using TLC and 1H NMR. Organic solvent stable lipases exhibiting potential application in enzymatic esterification are in great demand in flavor, fine chemicals and pharma industries. We could not find any report on lipase production from B. safensis strain and its application in esterification.

Facile synthesis of mesoporous sulfated Ce/TiO2nanofiber solid superacid with nanocrystalline frameworks by using collagen fibers as a biotemplate and its application in esterification

Collagen fibers, one of the most abundant biomass in the natural world, were used as the biomass template to synthesize cerium-doped mesoporous TiO2 nanofiber (SO42−–Cex/TiO2) solid acid catalysts. The physiochemical properties of the as-prepared catalysts were well characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), N2 adsorption–desorption isotherms, X-ray photoelectron spectroscopy (XPS). The fibrous morphology of native collagen fibers were found to be well preserved in SO42−–Cex/TiO2, and the acid strength and textural property of the SO42−–Cex/TiO2 were adjustable by changing the doping amount of Ce and the curing temperature. The catalytic properties of as-prepared catalysts were evaluated in the esterification reactions. It was found that the SO42−–Cex/TiO2 exhibited high activity under mild reaction conditions. When reacted at 90 °C for 45 min with a catalyst amount of 2 wt%, the conversion yields of ethyl acetate, butyl acetate, hexyl acetate and ethyl caproate were 99.9%, 97.06%, 94.29% and 86.75%, respectively. Additionally, the SO42−–Cex/TiO2 solid acid catalyst could be reused at least 6 times without significant loss of activity, exhibiting much better reusability as compared with the SO42−–TiO2* catalyst prepared by conventional approach.

Spinnability of SPPESK and its application in esterification

The electrospinning of sulfonated poly(phthalazinone ether sulfone ketone) (SPPESK) and its blend with polyether sulfone (PES) were investigated and the blend nanofibers were applied as a catalyst in esterification. Attempts to electrospin pure SPPESK resulted in electrospraying rather than electrospinning. However, a blend polymer solution of SPPESK and PES resulted in smooth electrospinning when SPPESK content was lower than 9 wt%. The geometrical properties such as fiber diameter and distribution, surface chemical properties such as inter-molecular interaction and crystalline, mechanical properties were investigated by SEM, FTIR, XRD, etc. The catalytic activities of SPPESK-PES nanofibers were measured by esterification of ethanol with acetic acid. A pseudo-homogeneous model was established to describe the kinetics of esterification with nanofiber as a catalyst. The results showed that the SPPESK-PES blend nanofiber had a high specific surface area (46.7–58.9 m2/g), good mechanical properties, good catalytic properties (ethanol conversion up to 80 % when reacted 8 h), and good forward rate constants (10.0 × 10−3–14.6 × 10−3 L/(mol∙min)).

Preparation of sulfated alumina supported on mesoporous MCM-41 silica and its application in esterification

Abstract New types of mesoporous SA/MCM-41 solid acid catalysts were prepared by loading sulfated alumina (SA) on MCM-41. The prepared catalysts were characterized by XRD, IR, N 2 physisorption, elemental analysis, FT-IR of adsorbed pyridine and NH 3 -TPD. The esterification of acetic acid with n -butanol and citric acid with n -butanol were used as model reactions to test the catalytic activities and reusability of the SA/MCM-41 solid acid catalysts. Compared with SA catalyst, SA/MCM-41 catalysts exhibited higher catalytic performances, which were attributed to their high BET surface area and large pore volume. Moreover, 20SA/MCM-41 solid acid catalyst showed excellent reusability in both esterifications.

Synthesis, characterization, and properties of imidazole dicationic ionic liquids and their application in esterification

Three kinds of imidazole based dicationic [C2(Mim)2], [C3(Mim)2], [C4(Mim)2] with traditional counter anion HSO4- ionic liquids (ILs) were synthesized. Key physicochemical properties, such as thermal stability, solubility in common solvents, acidic property and corrosion of ILs for Austenitic stainless steel 316 were determined. Esterification of alcohols by carboxylic acids has been carried out at room temperature in a group of imidazole dicationic ionic liquid. The catalytic performance was found to be much better than that of conventional non-cation functionalized ionic liquids and the corrosion was five times weaker than sulfuric acid. The esters were easily recovered due to immiscibility with the ionic liquid and reported imidazole dicationic ionic liquids were a promising catalyst for esterification reaction.