Recent Approaches in the Catalytic Transformation of Biomass-Derived 5-Hydroxymethylfurfural into 2,5-Diformylfuran

The conversion of biomass into a great variety of valuable chemicals, polymers, and fuels gives a sustainable alternative for the insufficiency of non-renewable fossil fuel resources and reduces environmental pollution. 5-Hydroxymethylfurfural (HMF), converted from sustainable carbohydrates, is a significant building block chemical, and the selective oxidation of HMF into 2,5-diformylfuran (DFF) presents an ongoing challenge. DFF is a versatile platform molecule derived from biomass and has promising application in pharmaceuticals and polymers. This Review provides an overview of the latest developments of efficient catalytic systems for the sustainable conversion of HMF to DFF.

Imidazole-Functionalized Polyoxometalate Catalysts for the Oxidation of 5-Hydroxymethylfurfural to 2,5-Diformylfuran Using Atmospheric O2

Biomass as a sustainable and abundant carbon source has attracted considerable attention as a potential alternative to petroleum resources. The selective oxidation of 5-hydroxymethylfurfural (HMF), a versatile platform molecule, to value-added 2,5-diformylfuran (DFF) provides an efficient pathway for biomass valorization. Herein, three discrete imidazole-functionalized polyoxometalates (POMs), HPMo₈V^VI₄O₄₀(V^VO)₂[(V^IVO)(IM)₄]₂·nH₂O·(IM)_m (IM = 1-methylimidazole, n = 4, m = 8 for 1; IM = 1-ethylimidazole, n = 4, m = 9 for 2; IM = 1-propylimidazole, n = 0, m = 4 for 3), have been successfully synthesized by a facile solvothermal method and thoroughly characterized by routine techniques. Compounds 1-3 contain a bi-capped pseudo-Keggin {HPMo₈V₄O₄₀(VO)₂} and two imidazole-functionalized {(VO)(IM)₄} groups, which, to our knowledge, represent the first examples of organic-functionalized Mo-V clusters. Compounds 1-3 as heterogeneous catalysts can effectively promote the transformation of HMF to DFF using atmospheric O₂ as oxidant. Under minimally optimized conditions, 95% of HMF was converted by 1 with 95% selectivity for DFF and its catalytic activity was basically maintained after five cycles. Moreover, the important roles of the bi-capped pseudo-Keggin cluster and the functionalized V groups in the selective oxidation of HMF have been explored. According to experimental and spectroscopic results, a three-step oxidation mechanism of HMF to DFF has been proposed.

Theoretical study on molecular mechanism of aerobic oxidation of 5-hydroxymethylfurfural to 2,5-diformyfuran catalyzed by VO2+ with counterpart anion in N,N-dimethylacetamide solution

Vanadium-containing catalysts exhibit good catalytic activity toward the aerobic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-diformyfuran (DFF). The aerobic oxidation mechanism of HMF to DFF catalyzed by VO₂⁺ with counterpart anion in N,N-dimethylacetamide (DMA) solution have been theoretically investigated. In DMA solution, the stable VO₂⁺-containing complex is the four-coordinated [V(O)₂(DMA)₂]⁺ species. For the gross reaction of 2HMF + O₂ → 2DFF + 2H₂O, there are three main reaction stages, i.e., the oxidation of the first HMF to DFF with the reduction of [V(O)₂(DMA)₂]⁺ to [V(OH)₂(DMA)]⁺, the aerobic oxidation of [V(OH)₂(DMA)]⁺ to the peroxide [V(O)₃(DMA)]⁺, and the oxidation of the second HMF to DFF with the reduction of [V(O)₃(DMA)]⁺ to [V(O)₂(DMA)₂]⁺. The rate-determining reaction step is associated with the C–H bond cleavage of –CH₂ group of the first HMF molecule. The peroxide [V(O)₃(DMA)]⁺ species exhibits better oxidative activity than the initial [V(O)₂(DMA)₂]⁺ species, which originates from its narrower HOMO–LUMO gap. The counteranion Cl⁻ exerts promotive effect on the aerobic oxidation of HMF to DFF catalyzed by [V(O)₂(DMA)₂]⁺ species.

The rate-determining reaction step is associated with the C–H bond cleavage of –CH₂ group of the first HMF molecule oxidized by [V(O)₂(DMA)₂]⁺ species, while counteranion Cl⁻ exhibits catalytically promotive effect.

Phosphorus-Doped Carbon Supported Vanadium Phosphate Oxides for Catalytic Oxidation of 5-Hydroxymethylfurfural to 2,5-Diformylfuran

2,5-diformylfuran (DFF) is an important downstream product obtained by selective oxidation of the biomass-based platform compound 5-hydroxymethylfurfural (HMF). In this study, a phosphorus-doped carbon (P-C) supported vanadium phosphate oxide (VPO) catalyst was successfully prepared and showed remarkably high catalytic activity in the selective oxidation of HMF to produce DFF with air as an oxidant. The effects of the reaction temperature, reaction time, solvent, catalyst amount, and VPO loading amount were investigated. The results showed that an HMF conversion rate of 100% and a DFF yield of 97.0% were obtained under suitable conditions, and DMSO was found to be the most suitable solvent under an air atmosphere.

Recent advances in zeolite-encapsulated metal catalysts: A suitable catalyst design for catalytic biomass conversion

Metal clusters and nanoparticles, which have been used to tune the acidity of zeolite support, are beneficial for promoting the catalytic performance of various reaction processes, including biomass conversion. However, catalytic instabilities resulting from metal coalescence, sintering and leaching are major problems that need to be resolved. Therefore, metal encapsulation within the zeolite structure has been proposed as a feasible solution for this issue, particularly for biomass conversions that require high temperatures. In this current review, recent developments in metal confinement techniques are described along with experimental examples of biomass upgrading reactions. The present and future perspectives of zeolite-encapsulated metal catalysts in biomass conversions are also given.

Catalytic mechanisms of oxygen-containing groups over vanadium active sites in an Al-MCM-41 framework for production of 2,5-diformylfuran from 5-hydroxymethylfurfural

In the V-doped Al-MCM-41 framework, the [V-1] active site with a hydroxyl group displays better catalytic activity than the [V-0] active site without a hydroxyl group toward the oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran.

Oxidation of lignocellulosic platform molecules to value-added chemicals using heterogeneous catalytic technologies

This minireview gives an overview about heterogeneous catalytic technologies for the oxidation of key platform molecules (glucose, 5-hydroxymethylfurfural, furfural and levulinic acid) into valuable chemicals.

Fabrication of Trifunctional Polyoxometalate-Decorated Chitosan Nanofibers for Selective Production of 2,5-Diformylfuran

Trifunctional catalysts based on polyoxometalate (POM) decorating chitosan nanofibers (H₅ PMo₁₀ V₂ O₄₀ /chitosan nanofibers, abbreviated as HPMoV/CS-f), synthesized by using the electrospinning method, realized highly efficient oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF). Decorating chitosan nanofibers with POMs generated enhanced catalytic activity by merging their unique individual properties of redox ability, Brønsted acidity, basicity, and nanofiber structure with higher surface area. As a result, HPMoV/CS-f(25) (with 25 representing the POM amount) was found to be the most active catalyst in the aerobic oxidation of HMF, resulting in 94.1 % DFF yield at 96.2 % conversion in DMSO at 120 °C for 6 h, whereas 56.2 % DFF yield at 95.0 % conversion was obtained in water at 140 °C for 8 h. Importantly, DFF could be produced in one pot in one step to give 61.9 and 31.4 % yield, respectively, directly from fructose and glucose under the reaction conditions of 140 °C, 6 h in DMSO, which was owing to the suitable balance of Brønsted acidity and basicity of the trifunctional HPMoV/CS-f(25). Moreover, HPMoV/CS-f showed good stability and ability to be reused at least ten times without leaching of the POMs from the chitosan nanofibers.

Metal Nitrate Catalysis for Selective Oxidation of 5-Hydroxymethylfurfural into 2,5-Diformylfuran under Oxygen Atmosphere

Selective synthesis of various versatile compounds from biomass is of great importance to displace traditional fossil fuel resources. Here, homogeneous metal nitrate (M(NO3) x )/(2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) and M(NO3) x /TEMPO/NaNO2 catalyst systems in glacial acetic acid and acetonitrile, respectively, have been found to be highly active and practically sustainable for selective oxidation of 5-hydroxymethylfurfural (HMF) into 2,5-diformylfuran (DFF) using pure O2 or even O2 in air as the oxidant. The catalytic methods enable full HMF conversion with a nearly 100% DFF selectivity at 50 °C under atmospheric pressure using a very simple reaction setup and workup. Mechanistic aspects are discussed. The influences of reaction conditions such as different metal catalysts, catalyst loading, solvents, and reaction temperature on the promotion effect were studied. Meanwhile, the catalyst systems had also good performance for aerobic oxidation of other alcohols.

Recent Advances in the Development of 5-Hydroxymethylfurfural Oxidation with Base (Nonprecious)-Metal-Containing Catalysts

5-Hydroxymethylfurfural (HMF) is one of the versatile platform molecules that can be derived from biomass, and a promising starting substrate for producing 2,5-diformylfuran (DFF) and 2,5-furandicarboxylic acid (FDCA). DFF is a platform chemical with applications in pharmaceuticals, macrocyclic ligands, and functional polymeric materials. Importantly, FDCA is being considered as a potential alternative to replace terephthalic acid for producing the bioplastic polyethylene furanoate, instead of polyethylene terephthalate, by blending with ethylene glycol. A significant number of studies have focused on the oxidation of HMF to FDCA with metal-containing heterogeneous catalysts in both aqueous and organic media in the presence of peroxides/air/molecular oxygen as the oxidant. In this regard, articles have recently been published related to HMF oxidation with base (nonprecious)-metal-containing catalysts that exhibit appealing activity towards DFF or FDCA in terms of yield. Thus, this Minireview focuses on recent developments in efficient transformations of HMF to DFF and FDCA with base-metal-containing heterogeneous catalysts in aqueous and organic media. This review further focuses on the direct transformation of glucose/fructose to DFF and/or FDCA with nonprecious-metal-containing catalysts in various solvents. Photocatalytic approaches for HMF oxidation with nonprecious metal- containing catalysts are also briefly discussed.

The design and catalytic performance of molybdenum active sites on an MCM-41 framework for the aerobic oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran

The catalytic activity decreases as –(SiO)₃Mo(OH)(O) > –(SiO)₂Mo(O)₂ > –(O)₄–MoO.

Selective Oxidation of Biomass-Derived Alcohols and Aromatic and Aliphatic Alcohols to Aldehydes with O2/Air Using a RuO2-Supported Mn3O4 Catalyst

Selective catalytic oxidation of carbohydrate-derived 5-hydroxymethylfurfural, furfuryl alcohol, and various aromatic and aliphatic compounds to the corresponding aldehyde is a challenging task. The development of a sustainable heterogeneous catalyst is crucial in achieving high selectivity for the desired aldehyde, especially using O2 or air. In this study, a RuO2-supported Mn3O4 catalyst is reported for the selective oxidation reaction. Treatment of MnO2 molecular sieves with RuCl3 in aqueous formaldehyde solution gives a new type of RuO2-supported Mn3O4 catalyst. Detailed catalyst characterization using powder X-ray diffraction, N2 adsorption, scanning and transmission electron microscopes, diffuse reflectance UV-visible spectrometer, and X-ray photoelectron spectroscopy proves that the RuO2 species are dispersed on the highly crystalline Mn3O4 surface. This catalytic conversion process involves molecular oxygen or air (flow, 10 mL/min) as an oxidant. No external oxidizing reagent, additive, or cocatalyst is required to carry out this transformation. This oxidation protocol affords 2,5-diformylfuran, 2-formylfuran, and other aromatic and aliphatic aldehydes in good to excellent yield (70-99%). Moreover, the catalyst is easily recycled and reused without any loss in the catalytic activity.

One-pot tandem conversion of monosaccharides and disaccharides to 2,5-diformylfuran using a Ru nanoparticle-supported H-beta catalyst

Using a one-pot tandem approach, 2,5-diformylfuran is successfully synthesized in high yields from fructose, glucose and sucrose.

Catalytic oxidation of carbohydrates into organic acids and furan chemicals

A review on the development of new routes for the production of organic acids and furan compoundsviacatalytic oxidation reactions.

Aerobic oxidation of biomass-derived 5-hydroxymethylfurfural to 2,5-diformylfuran with cesium-doped manganese dioxide

Cesium-doped manganese dioxide (Cs/MnO_x) was prepared by a soft template method, and was found to be active for the selective oxidation of HMF to DFF with molecular oxygen.

Selective Electrogenerative Oxidation of 5-Hydroxymethylfurfural to 2,5-Furandialdehyde

2,5-furandialdehyde (DFF) was synthesized by electrogenerative oxidation of 5-hydroxymethylfurfural (HMF) over a PtRu catalyst with 89 % selectivity at 50 °C after 17 h. This approach opens an avenue for a selective, energy-efficient and green oxidation of biomass-derived platform alcohols to added-value chemicals.

Porous nitrogen-enriched carbonaceous material from marine waste: chitosan-derived carbon nitride catalyst for aerial oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid

Chitosan-derived, porous nitrogen-enriched carbonaceous carbon nitride catalyst (PCNx) has been synthesized from marine waste and its use demonstrated in a metal-free heterogeneous selective oxidation of 5-hydroxymethyl-furfural (HMF) to 2,5-furandicarboxylic acid (FDCA) using aerial oxygen under mild reaction conditions.

Polymers from biomass: one pot two-step synthesis of furilydenepropanenitrile derivatives with MIL-100(Fe) catalyst

Monomers from biomass have been prepared from HMF and methylene active compounds through a one pot process using MIL-100(Fe)/TEMPO/NaNO₂as the catalytic system.

Direct synthesis of V-containing all-silica beta-zeolite for efficient one-pot, one-step conversion of carbohydrates into 2,5-diformylfuran

V-containing all silica beta-zeolite exhibited high atom-efficiency in the direct synthesis of 2,5-diformylfuran from carbohydrates.

Cascade catalysis via dehydration and oxidation: one-pot synthesis of 2,5-diformylfuran from fructose using acid and V2O5/ceramic catalysts

A vanadium pentoxide/ceramic catalyst was synthesized and a one-pot method for the preparation of 2,5-DFF from fructose was developed.

One-Pot Template-Free Synthesis of Cu-MOR Zeolite toward Efficient Catalyst Support for Aerobic Oxidation of 5-Hydroxymethylfurfural under Ambient Pressure

Supported catalysts are widely studied, and exploring new promising supports is significant to access more applications. In this work, novel copper-containing MOR-type zeolites Cu-MOR were synthesized in a one-pot template-free route and served as efficient supports for vanadium oxide. In the heterogeneous oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) with molecular oxygen (O2) under ambient pressure, the obtained catalyst demonstrated high yield (91.5%) and good reusability. Even under the ambient air pressure, it gave a DFF yield of 72.1%. Structure-activity relationship analysis indicated that the strong interaction between the framework Cu species and the guest V sites accounted for the remarkable performance. This work reveals that the Cu-MOR zeolite uniquely acts as the robust support toward well-performed non-noble metal heterogeneous catalyst for biomass conversion.

One-Pot Conversion of Carbohydrates into Furan Derivatives via Furfural and 5-Hydroxylmethylfurfural as Intermediates

Recently, there has been growing interest in the transformation of renewable biomass into value-added fuels and chemicals. The catalytic conversion of naturally abundant carbohydrates can generate two-important furan chemicals: 5-hydroxymethylfurfural (HMF) from C6 carbohydrates and furfural from C5 carbohydrates. Both HMF and furfural have received great interest as precursors in the synthesis of commodity chemicals and liquid fuels. In recent years, a trend has emerged to integrate sequential catalytic processes involving multistep reactions for the direct one-pot transformation of carbohydrates into the aimed fuels and chemicals. One-pot reactions have remarkably unique and environmentally friendly benefits, including the fact that isolation and purification of intermediate compounds can be avoided. Herein, the present article aims to review recent advances in the one-pot conversion of carbohydrates into furan derivatives via furfural and HMF as intermediates. Special attention will be paid to the catalytic systems, mechanistic insight, reaction pathways, and catalyst stability. It is expected that this review will guide researchers to develop effective catalytic systems for the one-pot transformation of carbohydrates into furan derivatives.

One-pot synthesis of 2,5-diformylfuran from fructose using a magnetic bi-functional catalyst

A magnetic bi-functional WO₃HO-VO(salten)-SiO₂@Fe₃O₄nanocatalyst was prepared to directly synthesize 2,5-diformylfuran (2,5-DFF) from fructose.

Theoretical study of the catalytic oxidation mechanism of 5-hydroxymethylfurfural to 2,5-diformylfuran by PMo-containing Keggin heteropolyacid

The mechanism for the aerobic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) catalysed by PMo-containing Keggin heteropolyacid (H₃PMo₁₂O₄₀) has been systematically investigated at the M06/6-31++G(d,p), Lanl2dz level in dimethylsulfoxide.

Ionic self-assembly affords mesoporous ionic networks by crosslinking linear polyviologens with polyoxometalate clusters

Polyoxometalate-crosslinked mesoporous ionic networks were constructed by ionic self-assembly of linear cationic polyviologens with PMoV clusters, acting as highly efficient heterogeneous catalysts for the conversion of HMF to DFF with ambient O₂.