Acetalization Of Glycerol Research Articles

High-efficacy glycerol acetalization with silica gel immobilized Brønsted acid ionic liquid catalysts—preparation and comprehending the counter-anion effect on the catalytic activity

Imidazolium sulfonate zwitterions (ZIs) with unconventional counter-anions were used to fabricate a series of mesoporous silica-gel-immobilized Brønsted acid ionic liquid (SG@BAIL) nanocatalysts.

HMF–glycerol acetals as additives for the debonding of polyurethane adhesives

Diols prepared via acetalisation of HMF with glycerol were incorporated into polyurethanes. This additive enables the selective debonding by acid-catalysed hydrolysis of PU-based adhesives to facilitate the recycling of components at the end of life of the product.

Chemically recyclable bio-based polyester composed of bifuran and glycerol acetal

Bio-based polymer alternatives to general-purpose polymers require new bio-based building blocks. The bifuran structure can be prepared from inedible biomass, and glycerol is manufactured as a byproduct. In this study, we constructed bifurylidene bis(glycerol acetal) (BFG)—composed of the bifuran and glycerol acetal structures—as a fully bio-based building block. Because the glycerol acetal formed five- and six-membered rings, with optical isomers and stereoisomers, BFG is a mixture of 22 isomers. BFG was polymerized with succinic anhydride to form poly[bifurylidene bis(glycerol acetal) succinate] (PBFGS). Td5% and Tg values for PBFGS were higher than those for poly(bifurfurylene succinate) (PBFS), in which the acetal structure is replaced with CH2, indicating that the acetal structure enhances the thermal properties of the polyester. Furthermore, the acetal-exchange reaction of PBFGS, to recover BFG, and the acid hydrolysis of poly[bifurylidene bis(glycerol acetal) dicarboxylate] (PBFGD), to recover bifurfural, a reactant of BFG, were successful, indicating that the introduction of the glycerol acetal structures endowed the bifuran-containing polymer with recyclability.

Synthesis of acetins from ethyl acetate via transesterification with glycerol using a sulphonic acid type ion-exchange resin

Demand for biodiesel has increased over the years as a substitute to petrol and diesel due to its environmental-friendly nature and lower cost. Glycerol being major by-product of the process constitutes 10 wt.% of the products hence conversion of glycerol to value added products such as acetins in the plant reduces the production cost of biodiesel. The present work focuses on the transesterification reaction between glycerol and ethyl acetate over heterogeneous catalyst, Amberlyst-15(wet). The batch studies were carried out and the effect of reaction parameters such as reaction time (1-7 h), glycerol to ethyl acetate molar ratio (1:3-1:12), temperature (50-70 o C), catalyst loading (2-5 w/w%) have been studied. The maximum conversion of glycerol obtained at (G : EA) molar ratio 1:6, reaction temperature of 70 ˚C and 4 w/w% catalyst loading for 7 h was 97.71 % and the selectivity of mono-, di- and triacetins were 36.7, 60.7 and 2.51 %, respectively. This provides an eco-friendly and sustainable path for valorisation of biodiesel derived glycerol.

Selective synthesis of dioxolane biofuel additive via acetalization of glycerol and furfural enhanced by MCM-41-alanine bifunctional catalyst

Highly active and selective acetalization catalyst, viz. alanine functionalized MCM-41 (MCM-41-16Alanine), synthesized using post-grafting method is reported. The mesoporous solid is first reacted with (3-chloropropyl)triethoxysilane (CPTES) before alanine is covalently bonded onto the hybrid support as confirmed by TGA/DTG, IR and UV-Raman spectroscopy analyses. Furthermore, the meso-ordered structure of MCM-41 is also retained after surface modification as revealed by the X-ray powder diffraction (XRD) and transmission electron microscopy (TEM) studies. The resulting bifunctional catalyst bearing both acidity and basicity exhibits good catalytic performance in the acetalization of glycerol with furfural reaction where 90% conversion with 78% selective to (2-(furan-2-yl)-1,3-dioxolan-4-yl)methanol-a valuable dioxolane biofuel additive-are achieved under optimized reaction conditions. Furthermore, the excellent catalytic performance of MCM-41-16Alanine is demonstrated when it is compared to other reported catalysts thanks to its large surface area, acid-base bifunctionality and mesopore confinement that induce synergistic effects. The catalyst also displays high catalyst reusability and no significant deterioration in catalytic activity is shown after six consecutive runs, thus offering a green pathway for synthesizing dioxolane biofuel additive with high selectivity.

Density and viscosity of mixtures of glycerol acetates saturated with CO2 for the design of a supercritical fractionation column

Supercritical CO2 technology has a great potential for the fractionation of glycerol acetates (mono, di, and triacetyl glycerol) according to the quality standards of the food and cosmeceutical sectors. The design of fractionation columns requires a robust thermodynamic model for phase-equilibrium and PVT predictions, as well as proper correlations for physical properties like viscosity. In this work, we measure volumetric and rheological properties of mixtures of glycerol acetates saturated with CO2 (up to 70 mol%) in the temperature range 298−323 K. The mixture molar volumes are between 75 mL/mol and 135 mL/mol, while the viscosities between 0.9 mPa.s and 20 mPa.s. Results show that assuming ideal solution behaviour to estimate the physical properties has a major impact on the design of the fractionation.

Catalytic acetalization of glycerol to biofuel additives over NiO and Co3O4 supported oxide catalysts: experimental results and theoretical calculations

A series of NiO and Co3O4 supported oxide catalysts was synthesized and investigated in the acetalization of glycerol with butyraldehyde to biofuels production. The catalysts were characterized by XRD, N2 sorption, FTIR and Raman spectroscopy, SEM-EDS and HRTEM techniques. The influence of the catalysts mass, glycerol to butyraldehyde molar ratios, reaction temperature and presence of solvent were deeply investigated. The dispersion of Ni and Co oxides gave distinct effects on the catalytic performances of the solids with AlTi and CeMn being actives in all conditions tested. The mechanistic aspect of the reaction was investigated by density functional theory (DFT). Among the catalysts, the high acidity of the Co/CeMn and Ni/CeMn promoted the acetalization of glycerol more efficiently to produce 4-methanol-2-propyl-1,3-dioxolane, in spite of the glycerol oligomers formation. The correlation of the structure, acidity, morphology and texture of the solids with the catalytic performance was illustrated for solventless acetalization of glycerol with butyraldehyde reaction. The theoretical calculations by DFT studies revealed a more favorable route to 1,3-dioxolane production.

An efficient process to synthesize solketal from glycerol over tin (II) silicotungstate catalyst

In this work, Sn(II)-exchanged silicotungstic acid salt (i.e., Sn2SiW12O40) was synthesized and evaluated as the catalyst on the acetalization of glycerol with acetone to produce solketal, a versatile bioadditive of fuel. The Sn2SiW12O40 salt was compared to the other solid Keggin heteropoly salts (i.e., Sn3/4PMo12O40, Sn3/4PW12O40), and liquid (i.e., HCl, H2SO4 and p-toluenesulfonic acid) catalysts. Amongst the catalysts assessed, it was the most active, achieving a high conversion (ca. > 99%, after 1 h reaction at room temperature) and selective (ca. 97%) toward the formation of solketal. Moreover, the Sn2SiW12O40 salt demonstrated to be more active than acid and precursor Tin (II) chloride salt, as well as other heteropoly salts and solid supported catalysts. The effects of the main reaction variables were assessed. The Sn(II) cation, as well as the silicotungstate anion, showed being essential to convert glycerol to solketal. Insights on the reaction mechanism were performed. In a simple recycle procedure, the solketal was purified, the acetone excess recycled, and the catalyst was reused without loss activity.

A continuous-flow process for the acetalization of crude glycerol with acetone on zeolite catalysts

A continuous flow process using heterogeneous catalysts like zeolites (BEA, MFI, FAU) was developed for the conversion of crude glycerol with acetone to solketal (2,2-dimethyl-1,3-dioxolane-4-methanol). It was found that BEA zeolite and the hierarchical zeolite of MFI structure exhibit a high catalytic activity in solketal production for 3 hr on stream. Almost 85% of glycerol conversion and 98% selectivity to solketal was achieved after 1 h of the reaction. The regeneration of spent catalysts by means of calcination with following ionic exchange restored the initial activity of the applied samples. The effect of particular impurities (alkaline cations, water, and MONG (matter organic non glycerol)) present in crude glycerol, on the deactivation process of catalysts, was also explored. Analysis of carbon balance and low-temperature nitrogen adsorption/desorption measurements, as well as FT-IR spectra of applied materials (pure and crude glycerol and spent catalysts) evidenced that the concurrent presence of MONG and alkaline cations reduce the zeolite catalysts activity.Considering the alteration of selectivity toward five and six membered isomers with declining acidity of spent catalyst, some tentative reaction paths of both isomers formation have been proposed.

Influence of moisture and acids on the chemical interesterification of rapeseed oil and ability of the catalyst to promote the glycerol as an undesirable by-product

In this study, the influence of moisture and acids on the content of fatty acid methyl esters and triacetin in the interesterification reaction by using 1M potassium tert-butoxide in tetrahydrofuran as a homogeneous catalyst was investigated. During the interesterification reaction, the presence of moisture causes a larger negative effect than free fatty acids or acetic acid. The highest content of fatty acid methyl esters (77.6 wt%) and triacetin (17.4 wt%) was achieved at methyl acetate to oil molar ratio (MAOMR) 60 and catalyst to oil molar ratio (COMR) 0.05 by using raw materials with moisture and acids content no larger than 0.005% and 0.08%, respectively.During the interesterification reaction, the excess of the catalyst caused the formation of two-layer and its proceeds only by using high-quality raw materials. This fact has never been mentioned in the literature. The upper layer is biodiesel, the lower layer consists of glycerol and glycerol acetates (mono-, di-, and triacetin). The COMR has a more significant effect on the formation of the biodiesel and glycerol acetates layers than MAOMR. The highest yield of glycerol acetates layer (19.4%) has been formed by using MAOMR 60 and COMR 0.3.

Acetalization of glycerol with acetone over appropriately-hydrophobic zirconium organophosphonates

The acetalization of glycerol with acetone is an effective way to obtain high value-added solketal. In this work, a series of zirconium organophosphonate with special flower-like outline were prepared via a facile hydrothermal method and used in the acetalization of glycerol with acetone. The structure and the property of the synthesized catalysts were characterized. It was found that these appropriately-hydrophobic zirconium organophosphonates were highly active and selective in the acetalization of glycerol with acetone under mild conditions. The characterization results indicated that an appropriate hydrophobic surface might retard the deactivation from adsorbed condensation water, which ensured an inconspicuous decrease of adsorption of the substrate. The prominent performance of ZrPP-20 mainly depended on the synergistic effect of acidity and hydrophilia/hydrophobicity balance of the framework.

Modelling sugarcane vinasse processing in an acidogenic reactor to produce hydrogen with an ADM1-based model

Biohydrogen can be produced by dark fermentation of sugarcane vinasse, wastewater from the sugar-alcohol industry, in acidogenic anaerobic bioreactors. In this work, a model based on ADM1 was constructed to model anaerobic processing of sugarcane vinasse in an acidogenic batch reactor. Based on experimental data, hypotheses were put forward. Two new pathways were assumed: Acetate+Lactate→Butyrate+Hydrogen and Glycerol→Butyrate+Hydrogen. A sensitivity analysis was carried out to reduce the number of free parameters, after which the model was calibrated with the experimental data. The proposed model was able to adequately describe sugar and glycerol consumption, acetate and lactate production and consumption and hydrogen and butyrate production over the operational time at an initial concentration of vinasse of 30kgCODm−3. Nevertheless more improvements can be carried out to make the model more realistic and to cover intermediate metabolic pathways under conditions of lower vinasse concentration, such as 15kgCODm−3 and 20kgCODm−3.

Hydrophobic functionalization of HY zeolites for efficient conversion of glycerol to solketal

Production of solketal by glycerol acetalization is a promising pathway to add values to glycerol. Our evidence indicated that, initially, the reaction was limited by poor interfacial mass transfer. Acetone slowly diffused and solubilized in the glycerol phase, where it reached the catalyst’s active sites to form solketal. We describe a strategy that overcomes this interfacial mass transfer limitation by grafting an organosilane surfactant (n-octadecyltrichlorosilane (OTS)) onto the surface of an HY catalyst. The OTS-grafted HY catalyst became hydrophobic and assisted in emulsion formation between the two immiscible reactants, minimizing the interfacial mass transfer limitation. As a result, the OTS-HY catalyst produced high catalytic activity (89% conversion) compared with that of HY (28% conversion) at 30 °C after 60 min. The high catalytic activity of organosilane-modified HY catalyst at low temperature makes it a promising candidate for other acid-catalysed two-phase reactions.

A green approach for the preparation of a surfactant embedded sulfonated carbon catalyst towards glycerol acetalization reactions

A surfactant embedded carbon-based acid catalyst was preparedviasimple physical mixing and thermal treatment to establish the relationship between hydrophobicity and acidic site density for efficient glycerol acetalization reaction.

Glycerol acetylation with acetic acid over Purolite CT-275. Product yields and process kinetics

An important category of glycerol derivatives, having multiple practical applications, are its esters with acetic acid (acetates or acetins). The most common preparation method of glycerol acetates is the direct esterification of glycerol with acetic acid in presence of acid catalysts. In this work is investigated the liquid phase glycerol esterification with acetic acid, catalyzed by the commercial Purolite CT-275 ion exchange resin. In this aim, there were performed batch experiments, in a stirred autoclave reactor, at initial acetic acid to glycerol molar ratios between 4 and 9 and temperatures between 70 and 110 °C. The experimental data were used to develop a kinetic model, based on the Langmuir Hinshelwood theory. The components activities, involved in the calculation of the reaction rates, were evaluated by the UNIFAC Dortmund method. The proposed kinetic model predicts with good accuracy the products distribution dependencies on the reactants molar ratio and reaction temperature. The calculated values of the Weisz-Prater criteria evidenced influences of the internal diffusion on the esterification process kinetics, over an initial reaction time interval. The proposed kinetic model is directly utilizable in the commercial process analysis and design calculations.

Acetalization of glycerol with ketones and aldehydes catalyzed by high silica Hβ zeolite

In this work, proton-exchanged *BEA zeolite with a high Si/Al ratio of 75 (Hβ-75), was demonstrated as an effective catalyst for the acetalization of glycerol with carbonyl compounds. This catalyst system was applicable to various substrates and reusable for at least 4 times with slight decrease in activity. The turnover frequency, based on acid site concentration, increased as a function of Hβ Si/Al ratio, indicating the importance of the zeolite hydrophobic surface properties. The origin of the high efficiency exhibited by Hβ-75 is quantitatively discussed based on kinetic studies, hydrophobicity, and acid site concentration.

Saccharomyces uvarum isolated from patagonian ciders shows excellent fermentative performance for low temperature cidermaking.

Saccharomyces uvarum has been recovered from natural habitats and traditionally fermented beverages (apple chicha) in Patagonia. However, this species has never been obtained from industrially relevant beverages like wine or cider in the same region. In this work, different strains belonging to the cryotolerant species S. uvarum were recovered from spontaneous cider fermentations carried out at low temperature in Red Delicious apple must. The strain S. uvarum NPCC1420 obtained from this cider and selected for its physiological and technological features, evidenced a better adaptation to the cidermaking process than a previously selected strain obtained from a less industrialized product called apple chicha. Some differences, like a higher ethanol and sulphite tolerance, seemed to be associated with differential domestication pressures suffered by each different strain. Moreover, the most important fermentative features of the strain NPCC1420 were a higher competition capacity than the strain NPCC1314 in non-sterile apple must, as well as significantly higher amounts of glycerol, 2-phenylethanol and 2-phenylethyl acetate than the strain isolated from apple chicha.

Ordered mesoporous titanium phosphate material: A highly efficient, robust and reusable solid acid catalyst for acetalization of glycerol

In the present work, a series of ordered mesoporous titanium phosphate (M-TiPO) materials with controllable composition are prepared by a simple one-pot method. The introduced Ti and P species are homogeneously dispersed in the skeleton of M-TiPO. Moreover, the influence of P content in mesoporous structure and existing states of Ti species is detailedly discussed. The result shows that the mesoporous structure is successfully improved by the introduction of P species. The M-TiPO-0.5 material (P/Ti = 0.5) exhibits outstanding textural properties (specific surface area (215 m2·g−1), pore size (6.6 nm) and volume (0.34 cm3·g−1)). Also, with the increasing of P species, the crystalline structure of mesoporous skeleton gradually changes from anatase TiO2 to amorphous phase, and the bonds in the materials transfer from Ti–O–Ti to Ti–O–P. The electron density of Ti decreases, and the acidic property is gradually enhanced. The gotten M-TiPO samples are utilized as catalyst for acetalization of glycerol with acetone. The M-TiPO-0.75 with excellent textural and acidic properties exhibits the best catalytic effect (the glycerol conversion is 91.3% and the acetal selectivity is 94.7%). More importantly, the M-TiPO-0.75 solid acid catalyst shows attractive reusability, and there is no decline in catalytic activity even after ten cycles. Consequently, M-TiPO material is a promising catalyst for the acetalization of glycerol.

SiO2 supported niobium oxides with active acid sites for the catalytic acetalization of glycerol

The silica supported niobium oxide catalysts with abundant acid active sites were successfully fabricated and demonstrated catalytic activity in the acetalization of glycerol with acetone to produce solketal. Although Niobium pentachloride which was used as the niobium precursor preferred to aggregate on the surface, the chemical vapor deposition method was introduced to remove the surface chloride. The synthesis parameter of the material affects the structure and the type of the supported niobium oxide on the carrier, and directly changes the amounts of catalytic sites. The effect of calcination temperature/time and loading amount of hydrated niobium oxide on the catalytic performance was investigated. The properties of acid sites on catalysts were characterized, and the catalytic process was directly observed by operando Raman. These in-situ experimental trials could provide deep insight to understand the catalytic mechanism.

A Kinetic Study of Glycerol Esterification with Acetic Acid Over a Commercial Amberlyst-35 Ion Exchange Resin

The increased quantities of glycerol available on the market initiated research efforts oriented to new valorization technologies, particularly by its conversion into medium tonnage chemicals, replacing petroleum derivatives. In this work it was investigated the valorization of glycerol by its transformation in glycerol acetates, by direct esterification with acetic acid, over a commercial Amberlyst-35 resin. Experiments were carried out batch-wise, in an autoclave reactor under controlled working conditions, at temperatures between 95 and 112 oC and initial acetic acid to glycerol molar ratios between 4 and 9. The experimental data evidenced that the glycerol conversion to monoacetate is faster than the next esterification steps. A relatively simple kinetic model was proposed and its parameters were evaluated from the experimental measurements. It proved reasonable predicting capacity for products distribution dependencies on the reactants molar ratio and reaction temperature.