Efficient conversion of furfuryl alcohol into alkyl levulinates catalyzed by an organic-inorganic hybrid solid acid catalyst

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.

Synthesis of Silico-Phospho-Aluminum Nanosheets by Adding Amino Acid and its Catalysis in the Conversion of Furfuryl Alcohol to Fuel Additives

Self-assembled spheres of silico-phospho-aluminum nanosheets were synthesized with the addition of l-arginine and evaluated as catalysts for the valorization of furfuryl alcohol to fuel additives. Adding the amino acid, a bio-derived additive, contributed to higher external specific surface area and more active sites, featuring a simple, environmentally friendly, and feasible strategy to regulate the growth of nanosheets. Herein, in the reaction of furfuryl alcohol with ethanol, the performance of silico-phospho-aluminum nanosheets was significantly improved compared with typical silicon phosphorus aluminum catalyst SAPO-34. The yield of ethyl levulinate with the use of silico-phospho-aluminum nanosheets was 7.8 times higher than for SAPO-34, and meanwhile the amount of undesirable byproduct diethyl ether was decreased by two orders of magnitude and negligibly produced compared with SAPO-34. Moreover, replacing part of aluminum isopropoxide with aluminum sulfate as aluminum source could introduce sulfate in situ in the process of catalyst synthesis and increase the amount of acid sites on the catalyst.

Porous organic-inorganic hybrid materials for catalysis, energy and environmental applications

Introduction of organic functionalities into the porous inorganic materials make the resulting hybrid porous framework not only more flexible and hydrophobic, but also provide additional scope for further functionalization, which...

Conversion of furfuryl alcohol to ethyl levulinate in the presence of mesoporous aluminosilicate catalyst

The one-pot acid-catalyzed the conversion of furfuryl alcohol (FA) to ethyl levulinate (EL) was investigated in the presence of mesoporous aluminosilicate (TUD-1) with a high surface area (up to 579 m2 g−1) and well-interconnected mesospheres synthesized via a solvothermal process and characterized using scanning electron microscope, transmission electron microscope, X-ray diffraction, 27Al-NMR, and N2 sorption isotherm. The resulting solid acid catalyst was tested for the alcoholysis of FA with ethanol, affording 87.8% EL yield under the optimal reaction conditions of 120°C and 4 h. Moreover, the catalyst showed a good reusability with less loss of activity after a simple solvent washing and calcination procedure.

The selective conversion of furfuryl alcohol to ethyl levulinate over Zr-modified tungstophosphoric acid supported on β-zeolites

Catalysts of zirconium-exchanged proton-containing tungstophosphoric acid (TPA) supported on β-zeolites were prepared by an impregnation method for the selective alcoholysis of furfuryl alcohol into ethyl levulinate.

Recognizing soft templates as stimulators in multivariate modulation of tin phosphate and its application in catalysis for alkyl levulinate synthesis

Soft template tunes and controls explicitly both morphology and nature of active sites during the synthesis of tin phosphate catalyst. This synthesis strategy helped in producing alkyl levulinate in high yields from one-pot alcoholysis of furfuryl alcohol.

Current Approaches to Alkyl Levulinates via Efficient Valorization of Biomass Derivatives

Biomass is a potential non-food, carbon-neutral, and abundant resource, which can be used as an alternative to fossil fuels during the sustainable preparation of various platform chemicals. Alkyl levulinates (ALs) have found widespread application as flavorings, plasticizing agents, and fuel additives, as well as synthetic precursors to various building blocks. Several processes have been investigated to transform biomass and its derivatives into ALs, which mainly include: (i) direct esterification of levulinic acid (LA) with alkyl alcohols and (ii) alcoholysis reactions of renewable biomass feedstocks and their derivatives, including furfuryl alcohol (FAL), chloromethyl furfural (CMF), and saccharides. This review focuses on illustrating the effects of the biomass pretreatment step, catalyst texture, possible mechanisms, acidities, and intermediates on the synthesis of ALs from sustainable resources covering a wide range of intermediates, including diethyl ether (DEE), 4,5,5-triethoxypentan-2-one (TEP), ethoxymethylfuran (EMF), ethyl-D-fructofuranoside (EDFF), and ethyl-D-glucopyranoside (EDGP).

Simultaneous Conversion of C5 and C6 Sugars into Methyl Levulinate with the Addition of 1,3,5-Trioxane

The simultaneous conversion of C₅ and C₆ mixed sugars into methyl levulinate (MLE) has emerged as a versatile strategy to eliminate costly separation steps. However, the traditional upgrading of C₅ sugars into MLE is very complex as it requires both acid-catalyzed and hydrogenation processes. This study concerns the development of a one-pot, hydrogenation-free conversion of C₅ sugars into MLE over different acid catalysts at near-critical methanol conditions with the help of 1,3,5-trioxane. For the conversion of C₅ sugars over zeolites without the addition of 1,3,5-trioxane, the MLE yield is quite low, owing to low hydrogenation activity. The addition of 1,3,5-trioxane significantly boosts the MLE yield by providing an alternative conversion pathway that does not include the hydrogenation step. A direct comparison of the catalytic performance of five different zeolites reveals that Hβ zeolite, which has high densities of both Lewis and Brønsted acid sites, affords the highest MLE yield. With the addition of 1,3,5-trioxane, the hydroxymethylation of furfural derivative and formaldehyde is a key step. Notably, the simultaneous conversion of C₅ and C₆ sugars catalyzed by Hβ zeolite can attain an MLE yield as high as 50.4 % when the reaction conditions are fully optimized. Moreover, the Hβ zeolite catalyst can be reused at least five times without significant change in performance.

Lewis-Brønsted acid catalysed ethanolysis of the organic fraction of municipal solid waste for efficient production of biofuels

A combined Lewis-Brønsted acid ethanolysis of sugars was thoroughly investigated with the aim of producing ethyl levulinate (EL) in a single step. Ethanolysis carried out at 453 K for 4 h using H₂SO₄ (1 wt%) and AlCl₃·6H₂O (30 mol % with respect to sugars) produced a yield of 60 mol % of EL respect to glucose and starch. Such optimised conditions were positively applied directly on different food waste, preliminarily characterised and found to be mainly composed by simple (10-15%) and relatively complex sugars (20-60%), besides proteins (6-10%) and lipids (4-10%), even in their wet form. The catalytic system resulted robust enough to the point that the copresence of proteins, lignin, lipids and mineral salts not only did not negatively affect the overall reactivity, but resulted efficiently converted into soluble species, and specifically, into other liquid biofuels of different nature.

Heterogeneous catalysis by tungsten-based heteropoly compounds

In this review, the recent works on heterogeneous catalytic applications of polyoxotungstates in liquid-phase organic reactions are reviewed.

A metabolic pathway for catabolizing levulinic acid in bacteria

Microorganisms can catabolize a wide range of organic compounds and therefore have the potential to perform many industrially relevant bioconversions. One barrier to realizing the potential of biorefining strategies lies in our incomplete knowledge of metabolic pathways, including those that can be used to assimilate naturally abundant or easily generated feedstocks. For instance, levulinic acid (LA) is a carbon source that is readily obtainable as a dehydration product of lignocellulosic biomass and can serve as the sole carbon source for some bacteria. Yet, the genetics and structure of LA catabolism have remained unknown. Here, we report the identification and characterization of a seven-gene operon that enables LA catabolism in Pseudomonas putida KT2440. When the pathway was reconstituted with purified proteins, we observed the formation of four acyl-CoA intermediates, including a unique 4-phosphovaleryl-CoA and the previously observed 3-hydroxyvaleryl-CoA product. Using adaptive evolution, we obtained a mutant of Escherichia coli LS5218 with functional deletions of fadE and atoC that was capable of robust growth on LA when it expressed the five enzymes from the P. putida operon. This discovery will enable more efficient use of biomass hydrolysates and metabolic engineering to develop bioconversions using LA as a feedstock.

Alcoholysis: A Promising Technology for Conversion of Lignocellulose and Platform Chemicals

In the catalytic conversion of lignocellulose to valuable products, the first entry point is to break down these biopolymers to sugar units or aromatic monomers, which is conventionally achieved by hydrolysis in water medium. Recent years have seen tremendous progress in the alcoholysis process, which has remarkable advantages, such as the avoidance of treating waste water, suppression of humins or chars, and enhancement of reaction rate and product yield. Advances have been focused on the alcoholysis of cellulose, hemicellulose, and lignin to alkyl glucosides, xylosides, and aromatic monomers, respectively. Alcoholysis of the platform molecule furfuryl alcohol (FAL) to alkyl levulinate (AL) and integrated alcoholysis of cellulose and furfural into AL are also summarized. This Minireview highlights the comparisons between alcoholysis and hydrolysis, the reaction mechanism of alcoholysis, and future challenges for industrial applications.

Efficient synthesis of butyl levulinate from furfuryl alcohol over ordered mesoporous Ti-KIT-6 catalysts for green chemistry applications

Here we describe the synthesis of butyl levulinate by alcoholysis of furfuryl alcohol with n-butanol over a series of titanium incorporated mesoporous KIT-6 molecular sieve catalysts prepared by a simple sol–gel treatment.