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•In-depth analyses clarify the different selectivity over Ni and Cu catalysts.•DHMF desorption and further hydrogenation influence HMF hydrogenation selectivity.•High dielectric ...solvents enhance DHMF desorption and change selectivity over Ni.•Hydrogenation is less favorable at high temperatures due to thermodynamic nature.
The development of heterogeneous catalysts for converting abundant biomass feedstocks to higher value products is one of the most challenges these days. 2,5-dihydroxymethylfuran (DHMF) and 2,5-dihydroxymethyltetrahydrofuran (DHMTHF), synthesized from HMF hydrogenation, serve as crucial precursors in various applications. Non-noble metal catalysts are particularly attractive for this reaction, given their affordability and impressive catalytic efficiency. This work unveils the origin of the unique selectivity over Ni and Cu through mechanistic investigation using density functional theory (DFT), thermodynamic and kinetic analyses. The results emphasize that temperature and solvent play a crucial role in altering the energetic stabilities of intermediates, thereby influencing the energetic span (δG), turnover frequency (TOF), and selectivity of the reaction. The theoretical results align well with experimental observations. At 373.15 K, the highest TOF values over Ni and Cu are predicted in the HMF-to-DHMTHF path (1.79 × 103h−1) and the HMF-to-DHMF path (4.01 × 105h−1), respectively, in gas phase—under low dielectric constant ε condition. In contrast, the highest TOF value for Ni is observed in the HMF-to-DHMF path under implicit water condition (ε = 78.4) at 298.15 K. Competitive DHMF desorption and further hydrogenation influence the reaction’s selectivity. These insightful fundamental findings reveal key descriptors essential for designing new heterogeneous catalysts or enhancing existing ones, with the aim of potentially impacting biomass upgrading and other hydrogenation reactions.
Electrocatalytic oxidation of 5‐hydroxymethylfurfural (HMF) provides an efficient way to obtain high‐value‐added biomass‐derived chemicals. Compared with other transition metal oxides, CuO exhibits ...poor oxygen evolution reaction performance, leading to high Faraday efficiency for HMF oxidation. However, the weak adsorption and activation ability of CuO to OH− species restricts its further development. Herein, the CuO–PdO heterogeneous interface is successfully constructed, resulting in an advanced onset‐potential of the HMF oxidation reaction (HMFOR), a higher current density than CuO. The results of open‐circuit potential, in situ infrared spectroscopy, and theoretical calculations indicate that the introduction of PdO enhances the adsorption capacity of the organic molecule. Meanwhile, the CuO–PdO heterogeneous interface promotes the adsorption and activation of OH− species, as demonstrated by zeta potential and electrochemical measurements. This work elucidates the adsorption enhancement mechanism of heterogeneous interfaces and provides constructive guidance for designing efficient multicomponent electrocatalysts in organic electrocatalytic reactions.
A CuO–PdO heterogeneous interface, which exhibits a low onset potential of 5‐hydroxymethylfurfural oxidation reaction and high current density, is successfully synthesized. The analytical results show that the CuO–PdO heterogeneous interface can strengthen the adsorption and activation capacity of organic molecules and OH− species, and promote the dehydrogenation and electron transfer in the process of 5‐formyl‐2‐furancarboxylic acid→2,5‐furandicarboxylic acid.
Electrochemical oxidation of biomass-derived platform molecules can enable the production of value-added oxygenated commodity chemicals under mild conditions in a distributed fashion using renewable ...electricity; however, very few efficient, robust, and inexpensive electrocatalysts are available for such electrochemical oxidation. Here we demonstrate that earth-abundant NiFe layered double hydroxide (LDH) nanosheets grown on carbon fiber paper can efficiently catalyze the oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) at the anode of an electrochemical cell. A near-quantitative yield of FDCA and 99.4% Faradaic efficiency of HMF conversion under ambient conditions can be achieved in the electrochemical process. HMF has a higher rate of oxidation than water and can act as an alternative anodic reaction for alkaline H2 evolution in water-splitting cells. As the first report on using bimetallic metal hydroxide/oxide catalysts for electrochemical oxidation of HMF, this work opens up opportunities in electrochemical devices to simultaneously produce building-block chemicals from biomass-derived molecules and clean H2 fuels under ambient conditions with earth-abundant materials.
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•Mo-doped NF@Ni0.85Se nanosheet arrays were synthesized by two-step hydrothermal process.•The obtained material shows excellent hydrogen evolution and HMF oxidation ...performance.•Boosting hydrogen generation via coupling electrocatalytic HMF oxidation.•Mo doping could refine the d-band center in Ni0.85Se to reduce the adsorption energy of H*.
Electrochemical oxidation of biomass convert into worthy production is considered to be a prospective alternative to slow kinetic oxygen evolution reaction (OER) in order to facilitate H2 generation. Herein, Mo-doped Ni0.85Se on the Ni foam (denoted as NF@Mo-Ni0.85Se) was prepared as effective bifunctional catalyst to boost H2 production and translate 5-hydroxymethylfurfural (HMF) into 2, 5-furfuran carboxylic acid (FDCA) simultaneously. Operando electrochemical impedance spectroscopy (EIS) and theoretical calculations confirm that the Mo doping could speed the electron transmission within the catalyst and downshift the d-band center of Ni in NF@Ni0.85Se, which is not only conducive to abating H* adsorption energy, but further promotes the hydrogen evolution reaction (HER) and organic hydrogen adsorption process. The as-synthesized electrocatalysts have shown outstanding hydrogen evolution property in acid, neutral, alkaline and seawater. When the NF@Mo-Ni0.85Se||NF@Mo-Ni0.85Se catalyst couple was employed for HER as well as HMF oxidation in basic electrolytes, the potential only required a potential of 1.50 V to obtain the current density of 50 mA cm−2, lower than that of overall water splitting (1.68 V). This present work especially emphasizes the significance of doping transition metals to improve material properties for constructing bifunctional electrocatalysts towards highly efficient energy utilization.
Levoglucosan (LGA), as the main primary anhydrosugar of cellulose pyrolysis, is of great significance for future value-added chemicals production. In this study, effective conversion of LGA to ...5-hydroxymethylfurfural (HMF) was investigated in a NaCl–H2O/acetone biphasic system over sulfonated resin and AlCl3. The results show that the biphasic system could efficiently inhibit the overreaction of HMF compared with pure water, leading to a significant enhancement of HMF production. HMF was obtained with the highest yield of 68.5 % at 96.5 % of LGA conversion at the optimized conditions. The use of cellobiose as substrate produced 61 % of HMF while LGA-rich bio-oil led to a sharp decease of HMF yield to 33 %. Through the respective experiments using LGA, glucose and fructose as the substrates, the reaction network was constructed for kinetic analysis, and satisfactory fitting results are observed in agreement with the experimental results, providing the best conditions for producing glucose and HMF, respectively. In addition, the mechanism of LGA conversion to HMF was calculated by DFT, which needs to overcome the highest free energy barrier of 121 kJ/mol.
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•LGA conversion to HMF is employed in a NaCl–H2O/acetone biphasic system.•The reaction pathway is clarified by the synergistic effect of sulfonated resin and AlCl3.•HMF was obtained with the highest yield of 68.5 % at 96.5 % of LGA conversion.•Results predicted by the kinetics are well consistent with the experimental results.•LGA conversion to HMF has an energy barrier of 121 kJ/mol by DFT calculations.
In this study, we developed a spectrophotometry method for the analysis of 5-hydroxymethylfurfuraldehyde (HMF) in pharmaceutical formulations using citrate@Fe3O4 adsorbent. As bare magnetite (Fe3O4) ...has certain limitations, such as aggregation and oxidation, surface modifications are commonly used to improve its properties. We successfully coated Fe3O4 with sodium citrate to create a magnetic adsorbent for isolating HMF from samples. We confirmed the successful surface coating of Fe3O4 with citrate using Fourier Transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Zeta potential, and scanning electron microscopy (SEM). The high adsorption capacity of citrate@Fe3O4 is due to the abundance of carboxyl and hydroxyl groups on the surface of the adsorbent, making it ideal for HMF extraction. The HMF concentration was then quantified using spectrophotometry.
Citrate@Fe3O4 exhibited a high surface area and strong interaction with HMF. We analyzed the individual influential factors affecting the magnetic solid phase extraction (MSPE) setup. Validation parameters were also provided to confirm the reliability of the method. Under optimal parameters, the method exhibited excellent linearity in the range of 0.05–30.00 μg/ml with the lower limit of quantification (LLOQ) of 0.05 μg/ml. Relative standard deviations (RSD) values for precision were better than 10% and the method's trueness were better than 10%. Recoveries were found to be in the range of 85% to 106%, indicating excellent accuracy and reliability. We used this method to identify and measure HMF in six different dextrose pharmaceutical dosage forms as intravenous injectable solutions and three honey samples.
•Synthesis and characterization of a citrate@Fe3O4 nanoadsorbent for selective HMF extraction.•Optimization of a magnetic solid phase extraction method for HMF.•Accurate HMF quantification in pharmaceutical formulations via spectrophotometric analysis.
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•Adsorbed OH– ions on the Au surface behave as active sites for HMF oxidation.•Aldehyde oxidation on Au catalysts is favorable at high OH– ions surface coverage.•Alcohol oxidation is ...kinetically slow on Au catalysts.•Au catalysts become inactive for aldehyde and alcohol oxidation when oxidized.
Au nanoparticle catalysts are promising electrocatalysts for biomass upgrading. Starting from a pristine Au electrode, herein we demonstrate a simple route for the electrochemical preparation of Au NPs supported on thin layers of humin (Au/H). Utilizing an oxidized Au surface as a precursor, these electrocatalytic structures are formed upon reduction of 5-hydroxymethylfurfural (HMF) in alkaline media while performing a potential sweep. We subsequently utilize this Au/H structure for the electrochemical oxidation of ethanol and HMF in a rotating disk electrode (RDE) configuration and perform additional analysis via electrochemical surface-enhanced Raman Scattering (SERS). The RDE test reveals Au/H has different reaction kinetics towards alcohol and aldehyde functional groups, enabling a mechanistic understanding of the reaction pathway for HMF oxidation. The SERS experiment identifies the favorable reduction pathway from Au2O3 to gold, suggesting the possible active site on this catalyst for HMF oxidation.
The catalytic upgrading of biomass-derived feedstocks to valuable chemicals generally requires catalysts with integrated active sites and tuned structures for selective activation of their ...multifunctional groups. Herein, we fabricated different Cu-based catalysts with multiple interfaces by facile reduction of layered double hydroxides (LDHs), aimed at controlling the reaction pathway and product selectivity in the hydrogenation of 5-(hydroxymethyl)furfural (HMF), an important biomass-based platform molecule. These Cu catalysts were characterized by XRD, Raman, TPR, HAADF-STEM, and in situ XAFS. For Cu/MgAlO x , derived from CuMg5Al2-LDHs, Cu particles were partially encapsulated by a MgAlO x support, thus forming highly intimate Cu–MgAlO x interfaces. On Co@Cu/CoAlO x , derived from CuCo x Al2-LDHs, together with a Cu–CoAlO x interface, partially reduced ultrasmall Co clusters were mounted around Cu particles to form a metallic Co–Cu interface, which is tunable by varying the Cu/Co ratio. As expected, Cu/MgAlO x was only active in CO hydrogenation to produce 2,5-bis(hydroxymethyl)furan (DHMF) in a 92.7% yield, while Co@Cu/3CoAlO x sequentially catalyzed the CO hydrogenation and C–OH hydrogenolysis to yield as high as 98.5% 2,5-dimethylfuran (DMF), in sharp contrast to Co@Cu/5CoAlO x , which further broke the CC bonds of DMF to yield 83.6% 2,5-dimethyltetrahydrofuran (DMTHF). The dependence of the reaction pathway and product selectivity on the composition and properties of the interface was revealed by identifying various intermediates using in situ IR. Specifically, HMF transformed into an O-bound intermediate on the Cu sites over the Cu–MgAlO x , while the unsaturated interfacial Cu–CoAlO x structure served as dual active sites to form a C,O-bound intermediate, thus leading to different products. In addition, the tunable Cu–Co interfacial sites remarkably influenced the adsorption modes of CC bonds in the furan ring. This work provides a rationale for controlling the reaction pathway and product selectivity for complicated biomass reactions via the controllable construction of multiple interfaces.
A series of porphyrin-based porous organic polymer-supported Ag nanoparticle, Ag(0)@POP-x were prepared by the reaction pathway of ion coordination followed by hydrogen reduction. The resulting ...composite Ag(0)@POP-6.52 shows excellent catalytic performance toward the selective oxidation of HMF to HMFCA, and an impressive HMFCA yield of 97.2% (Na2CO3 2 eq, O2 2.0 MPa 90 min, 100 °C). Analysis techniques such as ICP-OES, XRD, TEM, SEM, N2 adsorption-desorption, and XPS was employed to characterize the structure and properties of Ag(0)@POP-6.52. The reaction conditions including the type of base and solvent, base and catalyst dosage, oxygen pressure, reaction temperature and time were studied in detail to improve the yield of HMFCA. Furthermore, the catalytic stability of the Ag(0)@POP-6.52 was evaluated by leaching and reusing tests, the results shows that the catalyst has good stability and robustness structure. Finally, the other aldehydes oxidation over Ag(0)@POP-6.52 was tested for investigation the substrate scope of Ag(0)@POP-6.52.
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•A novel heterogeneous silver catalysts, Ag(0)@POP-6.52 was prepared.•An impressive HMFCA yield of 97.2% can be achieved over the catalysis of Ag(0)@POP-6.52•Over-oxidation of HMF is unfavoured over Ag(0)@POP-6.52.•High reusability and structural stability are observed during synthesis of HMFCA.•Ag(0)@POP-6.52 shows high activity in the oxidation of other aromatic aldehydes.
We report the catalytic conversion of glucose in high yields (62%) to 5-hydroxymethylfurfural (HMF), a versatile platform chemical. The reaction system consists of a Lewis acid metal chloride (e.g., ...AlCl3) and a Brønsted acid (HCl) in a biphasic reactor consisting of water and an alkylphenol compound (2-sec-butylphenol) as the organic phase. The conversion of glucose in the presence of Lewis and Brønsted acidity proceeds through a tandem pathway involving isomerization of glucose to fructose, followed by dehydration of fructose to HMF. The organic phase extracts 97% of the HMF produced, while both acid catalysts remain in the aqueous phase.
