Synthesis of 5-ethoxymethylfurfural from 5-hydroxymethylfurfural and fructose in ethanol catalyzed by MCM-41 supported phosphotungstic acid

5-Hydroxymethylfurfural and its Downstream Chemicals: A Review of Catalytic Routes

Biomass assumes an increasingly vital role in the realm of renewable energy and sustainable development due to its abundant availability, renewability, and minimal environmental impact. Within this context, 5-hydroxymethylfurfural (HMF), derived from sugar dehydration, stands out as a critical bio-derived product. It serves as a pivotal multifunctional platform compound, integral in synthesizing various vital chemicals, including furan-based polymers, fine chemicals, and biofuels. The high reactivity of HMF, attributed to its highly active aldehyde, hydroxyl, and furan ring, underscores the challenge of selectively regulating its conversion to obtain the desired products. This review highlights the research progress on efficient catalytic systems for HMF synthesis, oxidation, reduction, and etherification. Additionally, it outlines the techno-economic analysis (TEA) and prospective research directions for the production of furan-based chemicals. Despite significant progress in catalysis research, and certain process routes demonstrating substantial economics, with key indicators surpassing petroleum-based products, a gap persists between fundamental research and large-scale industrialization. This is due to the lack of comprehensive engineering research on bio-based chemicals, making the commercialization process a distant goal. These findings provide valuable insights for further development of this field.

Efficient Diesel Desulfurization by Novel Amphiphilic Polyoxometalate-Based Hybrid Catalyst at Room Temperature

Amphiphilic hybrid catalysts were prepared by modifying [SMo12O40]2− with tetrabutylammonium bromide (TBAB), 1-butyl-3-methylimidazole bromide (BMIMBr) and octadecyl trimethyl ammonium bromide (ODAB), respectively. The prepared catalysts were characterized by IR, XRD, SEM, TG and XPS. The desulfurization performance of the catalysts was investigated in model oil and actual diesel using hydrogen peroxide (H2O2) as an oxidant and acetonitrile as an extractant. All catalysts exhibited favorable activity for removing sulfur compounds at room temperature. Dibenzothiophene (DBT) can be nearly completely removed using SMo12O402−-organic catalysts within a short reaction time. For different sulfur compounds, the [TBA]2SMo12O40 catalyst showed a better removal effect than the [BMIM]2SMo12O40 and [ODA]2SMo12O40 catalyst. The [TBA]2SMo12O40 dissolved in extraction solvent could be reused up to five times in an oxidative desulfurization (ODS) cycle with no significant loss of activity. The [BMIM]2SMo12O40 performed as a heterogeneous catalyst able to be recycled from the ODS system and maintained excellent catalytic activity. The catalysts showed a positive desulfurization effect in real diesel treatment. Finally, we described the ODS desulfurization mechanism of DBT using SMo12O402−-organic hybrid catalysts. The amphiphilic hybrid catalyst cation captures DBT, while SMo12O402− reacts with the oxidant H2O2 to produce peroxy-active species. DBT can be oxidized to its sulfone by the action of peroxy-active species to achieve ODS desulfurization.

Systematic Data-Driven Modeling of Bimetallic Catalyst Performance for the Hydrogenation of 5-Ethoxymethylfurfural with Variable Selection and Regularization

Catalyst development for biorefining applications involves many challenges. Mathematical modeling can be seen as an essential tool in assisting to explain catalyst performance. This paper presents studies on several machine learning (ML) methods that can model the performance of heterogeneous catalysts with relevant descriptors. A systematic approach for selecting the most appropriate ML method is taken with focus on the variable selection. Regularization algorithms were applied to variable selection. Several different candidate model structures were compared in modeling with interpretation of results. The systematic modeling approach presented aims to highlight the necessary tools and aspects to unexperienced users of ML. Literature datasets for the hydrogenation of 5-ethoxymethylfurfural with simple bimetal catalysts, including main metals and promoters, were studied with the addition of catalyst descriptors found in the literature. Good results were obtained with the best models for estimating conversion, selectivity, and yield with correlations between 0.90 and 0.98. The best identified model structures were support vector regression, Gaussian process regression, and decision tree methods. In general, the use of variable selection procedures was found to improve the performance of models. The modeling methods applied thus seem to exhibit a strong potential in aiding catalyst development based mainly on the information content of descriptor datasets.

Catalytic Synthesis of the Biofuel 5-Ethoxymethylfurfural (EMF) from Biomass Sugars

A new generation of bioplatform molecule 5-ethoxymethylfurfural (EMF) has excellent energy density and combustion performance, which makes it a potential fuel additive. This article reviews the factors that affect the production of EMF from different feedstocks, including platform compounds, monosaccharides, polysaccharides, and raw lignocellulosic biomass. Focus is placed on discussing the catalytic efficiency with pros and cons of different acid catalysts, including homogeneous catalysts (i.e., liquid acids and metal salts), heterogeneous catalysts (i.e., zeolites, heteropolyacid-based hybrids, and SO3H-based catalysts), ionic liquids, mixed acid catalysts, and deep eutectic solvents (DESs). Except for the commonly used ethanol solvent, this review also summarizes the influence of the cosolvent system (e.g., ethanol/dimethylsulfoxide (DMSO), ethanol/tetrahydrofuran (THF), and ethanol/γ-valerolactone (GVL)) on the EMF yield.

Sulfonic acid-functionalized PCP(Cr) catalysts with Cr3+ and -SO3H sites for 5-ethoxymethylfurfural production from glucose

5-Ethoxymethylfurfural (EMF) has been identified as a potential biofuel and fuel additive, for which the production from glucose (the most abundant and inexpensive monosaccharide) in a one-step process would be highly desirable. Here, the synthesis of sulfonic acid-functionalized porous coordination polymers (PCPs) and their application as catalysts for EMF synthesis are reported. PCP(Cr)-BA (PCP material with Cr³⁺ ions and H₂BDC-SO₃H linkers) and PCP(Cr)-NA (PCP material with Cr³⁺ ions and H₂NDC(SO₃H)₂ linkers) materials containing both Cr³⁺ sites and Brønsted-acidic –SO₃H sites were prepared. The morphology, pore structure, acidity, chemical composition, and thermal stability of the two functionalized PCP(Cr) catalysts were analyzed by systematic characterization. The catalysts featured a porous morphology and dual Cr³⁺ and –SO₃H sites, which enabled the cascade conversion of glucose to EMF. PCP(Cr)-BA exhibited higher performance than PCP(Cr)-NA with an EMF yield of 23.1% in the conversion of glucose at 140 °C after 22 h in an ethanol/water system. In addition, the as-prepared catalyst exhibited a high stability in the current catalytic system for EMF production from glucose with a constant catalytic activity in a four-run recycling test without an intermediate regeneration step.

The PCP(Cr)-BA catalysts featured porous morphology and dual Cr³⁺ and –SO₃H sites, which enabled the cascade conversion of glucose to EMF. In addition, the as-prepared catalyst exhibited a high stability in the current catalytic system.

Experimental and theoretical studies on glucose conversion in ethanol solution to 5-ethoxymethylfurfural and ethyl levulinate catalyzed by a Brønsted acid

The fundamental understanding of glucose conversion to 5-ethoxymethylfurfural (EMF) and ethyl levulinate (EL) (value-added chemicals from biomass) in ethanol solution catalyzed by a Brønsted acid is limited at present. Consequently, here, the reaction pathways and mechanism of glucose conversion to EMF and EL catalyzed by a Brønsted acid were studied, using an experimental method and quantum chemical calculations at the B3LYP/6-31G(D) and B2PLYPD3/Def2TZVP level under a polarized continuum model (PCM-SMD). By further verification through GC/MS tests, the mechanism and reaction pathways of glucose conversion in ethanol solution catalyzed by a Brønsted acid were revealed, showing that glucose is catalyzed by proton and ethanol, and ethanol plays a bridging role in the process of proton transfer. There are three main reaction pathways: through glucose and ethyl glucoside (G/EG), through fructose, 5-hydroxymethylfurfural (HMF), levulinic acid (LA), and EL (G/F/H/L/EL), and through fructose, HMF, EMF, and EL (G/F/H/E/EL). The G/F/H/E/EL pathway with an energy barrier of 20.8 kcal mol^-1 is considered as the thermodynamic and kinetics primary way, in which the reaction rate of this is highly related to the proton transfer in the isomerization of glucose to fructose. The intermediate HMF was formed from O5 via a ring-opening reaction and by the dehydration of fructose, and was further converted to the main product of EMF by etherification or by LA through hydrolysis. EMF and LA are both unstable, and can partially be transformed to EL. This study is beneficial for the insights aiding the understanding of the process and products controlling biomass conversion in ethanol solution.

Recent progress in the development of advanced biofuel 5-ethoxymethylfurfural

Biomass-derived 5-ethoxymethylfurfural (EMF) with excellent energy density and satisfactory combustion performance holds great promise to meet the growing demands for transportation fuels and fuel additives to a certain extent. In this review, we summarized the relative merits of the EMF preparation from different feedstocks, such as platform chemicals, biomass sugars and lignocellulosic biomass. Advances for EMF synthesis over homogeneous (i.e. inorganic acids and soluble metal salts), heterogeneous catalysts (i.e. zeolites, heteropolyacid-based hybrids, sulfonic acid-functionalized catalysts, and others) or mixed-acid catalysts were performed as well. Additionally, the emerging development for the EMF production was also evaluated in terms of the different solvents system (i.e. single-phase solvents, biphasic solvents, ionic liquids, and deep eutectic solvents). It is concluded with current challenges and prospects for advanced biofuel EMF preparation in the future.

Efficient and controllable ultrasound-assisted depolymerization of organosolv lignin catalyzed to liquid fuels by MCM-41 supported phosphotungstic acid

In this study, effects of catalyst types, reaction temperatures, reaction times, reaction solvents and ultrasound frequencies were carefully investigated to improve the yields and characteristics of various depolymerization products of organosolv lignin. Generally, both catalyst types and ultrasound frequencies played important roles in promoting lignin depolymerization and reducing char yield. In particular, the yield and distribution of phenolic monomer (PM) products were greatly influenced by pore structure and acidity of the catalyst. The optimal reaction condition was got in isopropanol at 310 °C for 6 h with 30% ultrasound frequency and 50% phosphotungstic acid (PTA)/MCM-41 catalyst. The highest yields of PM, bio-oil, liquid fuels and lignin conversion were reached as 8.63 wt%, 86.89 wt%, 95.52 wt% and 98.54 wt%, respectively. The results showed that ultrasound acoustic cavitation could enhance the depolymerization of lignin, thus greatly enhancing production of liquid fuels. Simultaneously, the hydrogen composition and high heating value of various lignin depolymerization products improved, and the oxygen content decreased, indicating that hydrogenation and/or hydrodeoxygenation happened during the depolymerization process. Finally, we also found that the 50% PTA/MCM-41 catalyst had high stability; it could be reused for up to five cycles without loss of catalytic activity.

Lignin was subjected to different contents of PTA/MCM-41-catalyzed ultrasound-assisted depolymerization for efficient β-O-4 aryl ether bond cleavage to achieve efficient liquid fuel yields.

Hierarchical porous HPW/titania–silica material with superior adsorption-catalytic oxidation activity for multi-ring thiophenic sulfur compounds

HPW/titania–silica catalysts with micro-meso-macroporous structures and high specific surface areas are prepared and applied as oxidative desulfurization catalysts.

Adjusting the acidity of sulfonated organocatalyst for the one-pot production of 5-ethoxymethylfurfural from fructose

A novel sulfonated organocatalyst bearing stable double H-bonds shows high catalytic performance and good reusability for the tandem production of 5-ethoxymethylfurfural (EMF), a biofuel candidate, from biomass-derived fructose.

Upgrading of Carbohydrates to the Biofuel Candidate 5-Ethoxymethylfurfural (EMF)

5-Ethoxymethylfurfural (EMF), one of the significant platform molecular derivatives, is regarded as a promising biofuel and additive for diesel, owing to its high energy density (8.7 kWh·L−1). Several catalytic materials have been developed for the synthesis of EMF derived from different feedstocks under relatively mild reaction conditions. Although a great quantity of research has been conducted over the past decades, the unsatisfactory production selectivity mostly limited to the range 50%–70%, and the classic fructose used as the substrate restricted its application for fuel manufacture in large scale. To address these production improvements, this review pays attention to evaluate the activity of various catalysts (e.g., mineral salts, zeolites, heteropolyacid-based hybrids, sulfonic acid-functionalized materials, and ionic liquids), providing potential research directions for the design of novel catalysts for the achievement of further improved EMF yields.

Functionalized Ordered Mesoporous Silicas (MCM-41): Synthesis and Applications in Catalysis

Mesoporous silica sieves are among the most studied nano-objects due to their stable pore structure and easy preparation. In particular, MCM-41 have attracted increasing research attention due to their chemical versatility. This review focuses on the synthesis and regioselective functionalization of MCM-41 to prepare catalytic systems. The topics covered are: mono and di-functionalized MCM-41 as basic and acid catalysts, catalysts based on metallic complexes and heteropolyacids supported onto MCM-41, metallic nanoparticles embed onto functionalized MCM-41 and magnetic MCM-41 for catalytic purposes.

Variations of Major Product Derived from Conversion of 5-Hydroxymethylfurfural over a Modified MOFs-Derived Carbon Material in Response to Reaction Conditions

In recent years, the conversion of 5-hydroxymethylfurfural (HMF) into 5-ethoxymethylfurfural (EMF) and ethyl levulinate (EL) has become an attractive biomass transformation route due to their potential applications in the energy and chemical industries. In this study, we have developed an effective method to prepare a catalyst for this reaction. Sulfonic-acid-functionalized carbon nanomaterials (C-SO₃H), prepared from the direct pyrolysis of Metal-Organic Frameworks (MOFs) precursor Cu-benzene-1,3,5-tricarboxylate (Cu-BTC) followed by acidification with sulfuric acid, show excellent catalytic activity with a total yield higher than 90%. It is interesting that, different from the previous catalysts, a different major product—EMF or EL—can be selectively obtained by controlling the reaction temperature and time.

A Bioactive Trypanosoma cruzi Bromodomain Inhibitor from Chemically Engineered Extracts

A set of chemically engineered extracts enriched in compounds including N-N and N-O fragments in their structures was prepared. Bromodomain binding screening and bioguided fractionation led to the identification of one oxime hit that interacts with TcBDF3 with affinity in the submicromolar range and that shows interesting antiparasitic properties against the different life cycle stages of T. cruzi.

One-step fabrication of carbonaceous solid acid derived from lignosulfonate for the synthesis of biobased furan derivatives

An eco-friendly and low-cost lignosulfonate-based acidic carbonaceous catalyst (LS-SO₃H) was effectively fabricated using the sulfite pulping by-product of sodium lignosulfonate as a precursor by facile one-step simultaneous carbonization and sulfonation, and employed for the synthesis of promising biofuel furan derivatives from biorenewable feedstocks. The catalyst preparation conditions significantly affected the preparation and properties of LS-SO₃H. A relatively high catalyst preparation yield (40.4%) with strong –SO₃H density (1.33 mmol g⁻¹) were achieved when the lignosulfonate was treated in concentrated H₂SO₄ solution at 120 °C for 6 h. The preparation yield of LS-SO₃H was nearly twice as much as that of one-step prepared catalyst using alkaline lignin (another technical lignin from pulping) as a precursor. The as-prepared LS-SO₃H had similar textural characteristics to the frequently-used two-step prepared carbonaceous catalyst involving pyrolysis carbonization and sulfonation. LS-SO₃H was found to show good catalytic activity for the synthesis of 5-ethoxymethylfurfural (EMF) in ethanol medium, affording around 86%, 57% and 47% yields from 5-hydroxymethylfurfural (HMF), fructose and inulin, respectively. Also, a high HMF yield of 83% could be obtained from fructose when DMSO was replaced as reaction medium. The used LS-SO₃H was readily recovered by filtration, and remained active in recycle runs.

An easy-prepared and bio-supported lignosulfonate-based acidic carbonaceous catalyst was developed for the synthesis of promising furan biofuels from biorenewable feedstocks.

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.