•HMF can inhibit the production of hydrogen and change the community structure of microorganisms.•Low concentrations of HMF could be utilized to increase methane production.•HMF can interfere with ...the normal physiological functions of microorganisms.•The strategies of reducing the effects of HMF on fermentation were summarized.
Anaerobic fermentation is a clean production process for recycling of many agricultural and industrial wastes. During anaerobic fermentation, the existence of various inhibitors often leads to low efficiency or even failure of anaerobic digesters. 5-hydroxymethylfurfural (HMF) is such an inhibitor which can be produced in the pretreatment of biomass for subsequent anaerobic digestion. This paper provides a review of various production methods of HMF and its effects on hydrogen production, methane production and ethanol production through fermentation. The conversion and removal of HMF were summarized from the aspects of biomass pretreatment, non-biological treatment and biological treatment. This article aims to provide new ideas and methods for reducing the inhibition effect of HMF on anaerobic fermentation of biomass and restoring the performance of the anaerobic fermentation.
Vegetables are health-promoting foods due to their content on a wide range of phytochemicals, being involved in antioxidant protection. However, such bioactivity can be modified during cooking and ...also along the digestion-fermentation process. Thus, the aim of the paper is to establish a relation among the type of processing (raw, boiled, steamed, grilled, roasted, and fried), time of processing (raw, usual time and well-done), antioxidant capacity and the development of the Maillard reaction (measured though the analysis of furosine and HMF) of 23 widely consumed vegetables. Antioxidant capacity was measured with three methods (TEACABTS, TEACFRAP, TEACOH) after submitting vegetables to an in vitro digestion followed by and in vitro fermentation process. Furosine and HMF were useful indicators to control both cooking time and heat intensity of common vegetables, being correlated with antioxidant capacity. Those samples cooked with aggressive techniques (frying, grilling or breading) showed the higher antioxidant values.
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•Furosine/HMF are markers of thermal damage in processed/cooked vegetables.•Antioxidant capacity is highly dependent on the cooking technique.•The cooking technique modifies the substrates that reach the colon.•The cooking technique could modify microbial behavior towards digested vegetables.
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•SAPO-34 was found to be an effective and robust catalyst in GVL/water for 5-HMF production from glucose.•High 5-HMF yield of 93.6% from glucose was achieved.•The presence of water ...(5–15wt%) increased the yields of 5-HMF.
The production of 5-hydroxymethylfurfural (5-HMF) from carbohydrates is scientifically valuable but technologically challenging. In the present work, with the aim of developing an efficient and less harmful alternative to the Cr/ionic liquid system for 5-HMF production, SAPO-34 was prepared and used as the sole catalyst for the conversion of hexoses to 5-HMF in γ-valerolactone (GVL). This novel catalytic approach was quite selective for 5-HMF, affording 93.6% HMF yield from glucose at 443K. Peculiarly, contrary to results obtained with conventional systems, the presence of water in this reaction system exhibited a positive effect on the 5-HMF yield. Moreover, SAPO-34 proved to be a robust heterogeneous catalyst that can be recycled and reused for at least five runs without significant loss of catalytic activity. The catalytic route proposed in this paper shows great potential for optimizing the catalytic process for 5-HMF production.
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•Solvent polarity and basicity effect on fructose selective conversion was discussed.•High polarity-low basicity solvent was favorable for furfural formation.•High polarity-high ...basicity solvent promoted the HMF formation.•Solvents around fructose preferential arrangement caused the selective conversion.•High yields of furfural (76.2%, GBL-H2O) and HMF (90.5%, DMSO-H2O) were obtained.
Selective transformation of biomass-based feedstocks into value-added energy chemical is one of the most critical steps in biorefinery process. Herein, we gave insight into solvent effect on selective production of furfural or 5-hydroxymethylfurfural (HMF) from fructose with the combination of experiments, nuclear magnetic resonance (NMR) and molecular dynamics (MD) simulation. It was found that the selective formation of furfural and HMF was mainly dominated by solvent polarity and basicity, and solvent properties could change the reaction pathway of fructose. High polarity-high basicity solvent promoted HMF formation, while high polarity-low basicity solvent was conductive to furfural formation. The preferential arrangement of solvents around fructose tautomers, especially on different C-OH, consequently led to the different products. High yields of furfural (76.2%) and HMF (90.5%) were obtained in the solvents of γ-butyrolactone (GBL)–H2O and dimethyl sulfoxide (DMSO)–H2O.
For tandem reactions with several intermediate products, improving the reaction rate of each step is vital for accelerating the entire reaction. However, simultaneously enhancing the conversions of ...different intermediates using a single-active-site catalyst remains a challenge because the catalyst commonly promotes only one type of reaction. Herein, a Co-based double-active-site relay catalyst (denoted as (Co1→Cop)/N-CNTs) is reported. Due to the preferable catalytic activities of Co single atoms (Co1) and Co nanoparticles (Cop) for the oxidation of hydroxyls to aldehyde groups and aldehydes to carboxyl groups, respectively, the prepared (Co1→Cop)/N-CNTs exhibited good catalytic performance for the aerobic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). The catalyst achieved 100% HMF conversion efficiency and 96% FDCA yield under a 0.1 MPa O2 atmosphere at 100 °C for 8 h. The presented strategy offers prospects for the development of highly active catalysts for complex tandem reactions.
Developing highly efficient and cost-effective catalysts for electrochemically oxidizing biomass-derived 5-hydroxymethylfurfural (HMF) into value-added 2,5-furandicarboxylic acid (FDCA) is of great ...importance. Herein, we report a controllable nitrogen doping strategy to significantly improve the catalytic activity of Co3O4 nanowires for highly selective electro-oxidation of HMF into FDCA. The nitrogen doping leads to the generation of defects including nitrogen dopants and oxygen vacancies in Co3O4 nanowires, which is conducive to the formation of catalytically active sites. As a result, the electro-oxidation potential for HMF is only 1.38 V (vs. RHE) when the current density reaches 50 mA/cm2. More importantly, the conversion rate of HMF is as high as 99.5%, and the yield of FDCA is up to 96.4%.
In this work, we report a controllable N-doping strategy to significantly improve the electrocatalytic activity of Co3O4 nanowires for highly selective oxidation of HMF into FDCA. Display omitted
5-Hydroxymethylfurfural (HMF) is a biomass-based chemical platform that can undergo many feasible reactions. One of the most important reactions is the oxidation to 2,5-furandicarboxylic acid (FDCA), ...which is the monomer for bioplastic production. In this work, the radiation method was used to investigate the conversion of HMF in both aqueous (DI) and dimethyl sulfoxide (DMSO) solutions. The effects of media solvents, atmospheric gases, HMF concentrations, additive bases, and absorbed doses of gamma radiation were studied. The results showed that the media solvent played a crucial role in HMF conversion under gamma irradiation. At 30 kGy, the HMF conversions in DI and DMSO were 92.1 and 24.1%, respectively, and the oxidation products were only found in the irradiated samples under DMSO. The HMF conversion and oxidation product formation increased with the gamma radiation dose. Moreover, it was found that FDCA stability toward gamma irradiation is highly sensitive in aqueous solution but relatively stable in DMSO. The results implied the alternative promising choice of radiation method compared with traditional methods. To join the bridge, the use of a mixture solvent DI/DMSO seems considerable in the future.
Catalytic transformation of biomass‐derived compounds to different platform chemicals and liquid fuel is a prominent way to reduce the global dependence on fossil resources. In past few decades, ...biomass‐derived furans such as 2‐furfuraldehyde (furfural) and 5‐hydroxymethyl‐2‐furfural (HMF) have received outstanding attention because of their wide applications in the production of various industrially important value‐added chemicals and fuel components. Various catalytic systems and methodologies have been extensively explored for the transformation of these furans to a wide range of products including open ring diketones, ketoacids, alcohols and long chain alkanes. This Review is aimed to provide an extensive overview of the recent developments of several high‐performing heterogeneous catalysts for the catalytic upgradation of the key biomass‐derived furans (furfural and HMF) to value‐added chemicals. Moreover, the role of these catalysts in the catalytic transformations including hydrogenation, decarbonylation, oxidation, hydrogenolysis and ring opening reactions, and the mechanistic pathways are also highlighted in this Review.
Value rising: In this Review, we provided an up‐to‐date comprehensive overview on a wide collection of heterogeneous catalysts explored for the prominent catalytic transformations of biomass‐derived furans (furfural and HMF) to value‐added chemicals and fuel component following various processes such as hydrogenation, decarbonylation, oxidation, hydrogenolysis and furan ring opening. This Review elaborated in details the key role of catalysts in these diverse upgrading processes and the mechanistic pathways for biomass transformation.
Hydrolysis of lignocellulosic biomass is a crucial step for the production of sugars and biobased platform chemicals. Pretreatment experiments in a semi-continuous plant with diluted sulphuric acid ...as catalyst were carried out to measure the time-dependent formation of sugars (glucose, xylose, mannose), furfurals, and organic acids (acetic, formic, and levulinic acid) at different hydrolysis temperatures (180, 200, 220 °C) of one representative of each basic type of lignocellulose: hardwood, softwood, and grass. The addition of the acid catalyst is followed by a sharp increase in the sugar concentration. Xylose and mannose were mainly formed in the initial stages of the process, while glucose was released slowly. Increasing the reaction temperature had a positive effect on the formation of furfurals and organic acids, especially on hydroxymehtylfurfural (HMF) and levulinic acid, regardless of biomass type. In addition, large amounts of formic acid were released during the hydrolysis of miscanthus grass. Structural changes in the solid residue show a complete hydrolysis of hemicellulose at 180 °C and of cellulose at 200 °C after around 120 min reaction time. The results obtained in this study can be used for the optimisation of the hydrolysis conditions and reactor design to maximise the yields of desired products, which might be sugars or furfurals.
Microwave hot spots at strongly polarized solid/liquid interface drive energy-efficient dehydration reactions
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•TiO2 structure control maximizes the density of active center and ...degrees of interfacial polarization.•Strongly polarized solid/liquid interface promotes reaction energy efficiency under microwave.•10 times higher energy efficiency was achieved than commercial TiO2 in fructose dehydration reaction.•Surface sulfonic group polarizes surface water molecules and acts as “hot-spots” to accelerate reaction.
A strongly polarized solid/liquid interface is constructed to create a “micro-hydrothermal” environment under microwave and promote reaction energy efficiency. Specifically, TiO2 with open crystal structure was synthesized to maximize the density of surface-active centers and the degrees of interfacial polarization. Acidic groups were grafted on the catalyst surface, which served as catalytically active sites as well as heat-generation spots under microwave irradiation. Benefited by enhanced interfacial polarization, 10 times higher energy efficiency (6.8 mmol (kJ L)-1) than commercial TiO2 can be achieved in fructose dehydration reaction. MD simulation revealed that sulfonic group polarized surface water molecules and acted as “hot-spots” to accelerate fructose dehydration to HMF. Such alignment of site-specific heating and reaction by material design has great potential to shift the energy efficiency for a wide range of chemical reactions.
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