Heteropolyacid supported on ionic liquid decorated hierarchical faujasite zeolite as an efficient catalyst for glycerol acetalization to solketal

To handle huge amount of glycerol produced in biodiesel industry, glycerol is transformed to value-added products. In this regard, glycerol acetalization to solketal is industrially attractive. As in this process various by-products can be formed, designing highly selective catalysts is of great importance. In this line, we wish to report a novel catalyst that benefits from strong acidity, high specific surface area and thermal stability, which can selectively form solketal in glycerol acetalization. To prepare the catalyst, hierarchical zeolite was prepared via a novel method, in which partially dealuminated NaY was treated with PluronicF-127 and then reacted with NH4NO3 to furnish the H-form zeolite. Hierarchical faujasite was then achieved through calcination and template removal. Subsequently, it was functionalized with ionic liquid and used for the immobilization of heteropolyacid. The results indicated the importance of the mesoprosity of zeolite and the presense of ionic liquid functionality for achiveing high solketal yield. Moreover, among three investigated heteropolyacids, phosphomolybdic acid exhibited the highest catalytic activity. In fact, using 10 wt% catalyst at 55 °C and glycerol to acetone molar ratio of 1:20, solketal with yield of 98% was furnished under solvent-less condition. Besides, the catalyst was recyclable with low leaching of heteropolyacid.

Highly Active Nickel (II) Oxide-Supported Cerium Oxide Catalysts for Valorization of Glycerol into Oxygenated Fuel Additives

Acetylation of glycerol to yield monoacetin (MAT), diacetin (DAT), and triacetin (TAT) over NiO-supported CeO₂ (xNiO/CeO₂) catalysts is reported. The catalysts were synthesized utilizing a sol-gel technique, whereby different quantities of NiO (x = 9, 27, and 45 wt%) were supported onto the CeO₂ substrate, and hexadecyltrimethylammonium bromide (CTABr) served as a porogen. The utilization of EDX elemental mapping analysis confirmed the existence of evenly distributed Ni²⁺ ion and octahedral NiO nanoparticles on the CeO₂ surface through the DRS UV-Vis spectroscopy. The most active catalyst is 27NiO/CeO₂ based on TAT selectivity in the glycerol acetylation with ethanoic acid, attaining 97.6% glycerol conversion with 70.5% selectivity to TAT at 170 °C with a 1:10 glycerol/ethanoic acid molar ratio for 30 min using a non-microwave instant heating reactor. The 27NiO/CeO₂ is reusable without significant decline in catalytic performance after ten consecutive reaction cycles, indicating high structure stability with accessible active acidity.

Modified boehmite: a choice of catalyst for the selective conversion of glycerol to five-membered dioxolane

The catalytic activity of WO3@boehmite for the acetalization of glycerol with aromatic aldehydes is described in this article. The catalyst is selective towards dioxolane (up to 96%) with excellent conversion (up to 100%) in selective substrates.

Acetalization of glycerol and benzaldehyde to synthesize biofuel additives using SO4 2-/CeO2-ZrO2 catalyst

Synthesis of 1,3- dioxane and 1,3-dioxolane, using sulfated CeO₂–ZrO₂ catalyst for acetalization of glycerol with benzaldehyde, is the focus of present work. SO₄^2-/CeO₂–ZrO₂ catalyst was synthesized using combustion method. Experiments were carried out to analyze the effect of various solvents (n-hexane, toluene, tert-butyl alcohol, pentanol), molar ratios (1:3, 1:5, 1:7), catalyst loadings (3 wt%, 5 wt%, 9 wt %) and temperatures (80 °C, 90 °C, 100 °C) on glycerol conversion and selectivity of the products. Selectivity of 87.20% dioxolane and 12.80% dioxane was obtained at molar ratio of 1:3, 9 wt% catalyst loading and temperature of 100 °C.Strong NH₃ desorption peak from NH₃-TPD study indicated the high acidic strength of sulphated catalyst. Strong surface acidity and surface porosity (observed from TEM and SEM analysis) contributed to an enhanced activity of the catalyst for glycerol acetalization reaction. The kinetics of the reaction was studied using an elementary kinetic law. A correlation coefficient of 0.98 from the selected kinetic model proved that the rate of acetalization reaction was dependent on glycerol concentration and acetal formation was instantaneous. The study demonstrated the application of an environmentally benign, inexpensive, thermally stable, active SO₄^2-/CeO₂–ZrO₂ catalyst for glycerol acetalization reaction to synthesize 1,3-dioxolane as the desired product.

Versatile Coordination Polymer Catalyst for Acid Reactions Involving Biobased Heterocyclic Chemicals

The chemical valorization/repurposing of biomass-derived chemicals contributes to a biobased economy. Furfural (Fur) is a recognized platform chemical produced from renewable lignocellulosic biomass, and furfuryl alcohol (FA) is its most important application. The aromatic aldehydes Fur and benzaldehyde (Bza) are commonly found in the slate of compounds produced via biomass pyrolysis. On the other hand, glycerol (Gly) is a by-product of the industrial production of biodiesel, derived from fatty acid components of biomass. This work focuses on acid catalyzed routes of Fur, Bza, Gly and FA, using a versatile crystalline lamellar coordination polymer catalyst, namely [Gd(H4nmp)(H2O)2]Cl·2H2O (1) [H6nmp=nitrilotris(methylenephosphonic acid)] synthesized via an ecofriendly, relatively fast, mild microwave-assisted approach (in water, 70 °C/40 min). This is the first among crystalline coordination polymers or metal-organic framework type materials studied for the Fur/Gly and Bza/Gly reactions, giving heterobicyclic products of the type dioxolane and dioxane, and was also effective for the FA/ethanol reaction. 1 was stable and promoted the target catalytic reactions, selectively leading to heterobicyclic dioxane and dioxolane type products in the Fur/Gly and Bza/Gly reactions (up to 91% and 95% total yields respectively, at 90 °C/4 h), and, on the other hand, 2-(ethoxymethyl)furan and ethyl levulinate from heterocyclic FA.

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.

Glycerol Acetylation with Propionic Acid Using Iron and Cobalt Oxides in Al-MCM-41 Catalysts

In this work, Al-MCM-41 molecular sieves were synthesized, containing iron and/or cobalt oxides, impregnated by incipient wetness method, characterized and applied as catalysts in the acetylation reaction of glycerol with propionic acid to produce green glyceryl propionate molecules of high commercial value. According to this, X-ray Diffraction (XRD), X-ray Fluorescence (XRF), Fourier Transform Infra Red (FT-IR), adsorption/desorption N2 isotherms, textural analysis, and Scanning Electron Microscope (SEM) analysis were recorded to evaluate the main characteristics of materials. The presence of Lewis and Brønsted acidic sites and catalysts surface area were observed as important key points to functionalize acetylation reaction. Thus, time reaction, temperature, and glycerol / propionic acid ratio varied to improve the most suitable reaction conditions and behaviors. As a result, glycerol conversion was above 96%, followed by 68% of selectivity to glyceryl monopropionate as well as the formation of glyceryl di- and tri- propionate and a small amount of ethylene glycol dipropionate as an undesired product. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Influence of Heterogeneous Catalysts and Reaction Parameters on the Acetylation of Glycerol to Acetin: A Review

Glycerol, a polyhydric alcohol, is currently receiving greater attention worldwide in view of its glut in the market occasioned by the recent upsurge in biodiesel production. The acetylation of glycerol to acetin (acetyl glycerol) is one of the many pathways of upgrading glycerol to fine chemicals. Acetin, which could be mono, di, and or triacetin, has versatile applications in the cosmetics, medicines, food, polymer, and fuel industries as a humectant, emulsifier, plasticizer, and fuel additive and so it is of high economic value. Given the critical role of catalysts in green chemistry, this paper reports the influence of the different heterogeneous catalysts used in glycerol acetylation. It also reviewed the influence of catalyst load, temperature, molar ratio, and the time on the reaction.

Ammonium Salts Catalyzed Acetalization Reactions in Green Ethereal Solvents

Cyclopentyl methyl ether and 2-methyltetrahydrofuran, low impact ethereal solvents forming a positive azeotrope with water, were successfully employed as solvents in the synthesis of a variety of acetals carried out under Dean–Stark conditions in the presence of heterogeneous acidic catalysts. Under these conditions, ammonium salts, either as such or supported on SiO2, performed better or equally well than widely employed homogeneous and heterogeneous acidic catalysts such as p-toluenesulfonic acid, Amberlyst 15®, or Montmorillonite K10. Several examples highlight the advantage of tuning the relative acidities of ammonium salts by appropriately selecting the counterion. Within one of these examples, our protocol clearly outweighs the classic p-toluenesulfonic acid/toluene protocol in terms of chemoselectivity. Silica-supported catalysts were characterized by SEM, TEM, and FTIR spectroscopies, as well as by N2 physisorption. Such a characterization reveals an even distribution of ammonium salts on silica, thus confirming the formation of expected catalytic supports.

Iron(III) Complexes for Highly Efficient and Sustainable Ketalization of Glycerol: A Combined Experimental and Theoretical Study

The growing production of biodiesel as a promising alternative and renewable fuel led as the main problem the dramatic increase of its by-product: glycerol. Different strategies for glycerol derivatization have been reported so far, some more efficient or sustainable than others. Herein, we report a very promising and eco-friendly transformation of glycerol in nontoxic solvents and chemicals (i.e., solketal, ketals), proposing three new families of Fe(III) compounds capable of catalysing glycerol acetalization with unpublished turn over frequencies (TOFs), and adhering most of the principles of green chemistry. The comparison between the activity of complexes of formula [FeCl₃(1-R)] (1-R = substituted pyridinimine), [FeCl(2-R,R')] (2-R,R' = substituted O,O'-deprotonated salens) and their corresponding simple salts reveals that the former are extremely convenient because they are able to promote solketal formation with excellent TOFs, up to 10⁵ h^-1. Satisfactory performances were shown with respect to the entire range of substrates, with results being competitive to those reported in the literature so far. Moreover, the experimental activity was supported by an accurate and complete ab initio study, which disclosed the fundamental role of iron(III) as Lewis acid in promoting the catalytic activity. The unprecedented high activity and the low loading of the catalyst, combined with the great availability and the good eco-toxicological profile of iron, foster future applications of this catalytic process for the sustainable transformation of an abundant by-product in a variety of chemicals.

An Overview of Recent Research in the Conversion of Glycerol into Biofuels, Fuel Additives and other Bio-Based Chemicals

The depletion of fossil fuels has heightened research and utilization of renewable energy such as biodiesel. However, this has thrown up another challenge of significant increase in its byproduct, glycerol. In view of the characteristics and potentials of glycerol, efforts are on the increase to convert it to higher-value products, which will in turn improve the overall economics of biodiesel production. These high-value products include biofuels, oxygenated fuel additives, polymer precursors and other industrial bio-based chemicals. This review gives up-to-date research findings in the conversion of glycerol to the above high-value products, with a special focus on the performance of the catalysts used and their challenges. The specific products reviewed in this paper include hydrogen, ethanol, methanol, acetin, glycerol ethers, solketal, acetal, acrolein, glycerol carbonate, 1,3-propanediol, polyglycerol and olefins.

A Review on the Catalytic Acetalization of Bio-renewable Glycerol to Fuel Additives

The last 20 years have seen an unprecedented breakthrough in the biodiesel industry worldwide leads to abundance of glycerol. Therefore, the economic utilization of glycerol to various value-added chemicals is vital for the sustainability of the biodiesel industry. One of the promising processes is acetalization of glycerol to acetals and ketals for applications as fuel additives. These products could be obtained by acid-catalyzed reaction of glycerol with aldehydes and ketones. Application of different supported heterogeneous catalysts such as zeolites, heteropoly acids, metal-based and acid-exchange resins have been evaluated comprehensively in this field. In this review, the glycerol acetalization has been reported, focusing on innovative and potential technologies for sustainable production of solketal. In addition, the impacts of various parameters such as application of different reactants, reaction temperature, water removal, utilization of crude-glycerol on catalytic activity in both batch and continuous processes are discussed. The outcomes of this research will therefore significantly improve the technology required in tomorrow's bio-refineries. This review provides spectacular opportunities for us to use such renewables and will consequently benefit the industry, environment and economy.

Synthesis and cytotoxic activity of novel acyclic nucleoside analogues with functionality in click chemistry

We describe synthesis of novel acyclic nucleoside analogues which are building blocks for CuAAC reaction and their activity against two types of human cancer cell lines (HeLa, KB). Three of chosen compounds show promising cytotoxic activity. Synthesis pathway starting from simple and easily accessible substrates employing DMT or TBDPS protective groups is described. Adenosine and thymidine analogues containing alkyne moiety and adenosine analogue containing azido group were synthesized. The obtained units showed ability of forming triazole motif under the CuAAC reaction conditions.

Dealuminated BEA zeolite for selective synthesis of five-membered cyclic acetal from glycerol under ambient conditions

BEA zeolite is modified using phenoldisulfonic acid to change catalyst characteristics, which helps to form a single cyclic product. A new term called volume space acidity (VSA) provides volume space available for dioxane to dioxalane rearrangement.

POSS-derived solid acid catalysts with excellent hydrophobicity for highly efficient transformations of glycerol

New POSS-derived acid catalysts were synthesized, which proved to be highly efficient, and steadily reused for glycerol transformations.

Silica-immobilized Aquivion PFSA superacid: application to heterogeneous direct etherification of glycerol with n-butanol

Silica-immobilized Aquivion® resin with high mesoporosity and acid-site accessibility demonstrated good activity, selectivity and reusability for glycerol etherification withn-butanol.