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Homogeneous metal salt catalysts play a pivotal role in industrial production of 5‐hydroxymethylfurfural (HMF). Herein, we first proposed the anion effect on steerable production of HMF using metal salts with different anions as catalyst in a biphasic system of tetrahydrofuran (THF)/NaCl aqueous solution (NaCl aq). Notably, the anions affected the catalytic activity of the metal salts, leading to an order of magnitude difference in the HMF yields, i.e. AlBr3 (74.0 mol %)>AlCl3 (60.8 mol %)>Al2(SO4)3 (35.2 mol %)>Al(NO3)3 (14.9 mol %). The anion effect on steerable production of HMF could be attributed to the proximity effect and electron tension. Anions form close‐range interactions with glucose molecules by proximity effect to promote electron transfer, facilitating the isomerization of glucose to fructose. Besides, anions induce a reduction of the electron cloud density of glucose carbon atoms, generating electron tension that rapidly transforms glucose from the ground state to the transition state, thereby increasing the HMF yield. Based on the revelation of anions effect and evaluation of techno‐economic process, we expect to provides theoretical guidance for high‐throughput screening of metal salt catalysts in industrial biorefinery. [ABSTRACT FROM AUTHOR]

2,5‐Furandicarboxylic acid (FDCA) is a biomass‐derived monomer for the production of poly(ethylene 2,5‐furandicarboxylate) (PEF), which is a novel polyester that can serve as a sustainable alternative to traditional petroleum‐based poly(ethylene terephthalate) (PET). Currently, the industrial production of FDCA depends on the thermo catalytic aerobic oxidation of 5‐hydroxymethylfurfural (HMF) using heterogeneous catalysts in aqueous solution, in which process equivalent homogeneous bases are usually needed to promote the oxidation of hydroxymethyl and aldehyde groups and simultaneously improve the solubility of oxidative products via forming carboxylate. The involvement of massive base causes risks of equipment corrosion and necessitates subsequent product separation and purification with a large amount acid. In this context, the base‐free aerobic oxidation of HMF to FDCA has attracted much concern. Nowadays, by developing supported catalysts with multiple catalytic sites, using diluted substrate and finding good solvent for FDCA, much progress has been achieved in this field. This review provides the state of the art of the heterogeneous catalysis for aerobic oxidation of HMF to FDCA under base‐free conditions, highlighting the catalytic mechanism to shed light on the catalyst design principles. [ABSTRACT FROM AUTHOR]

Electrocatalytic oxidation of biomass‐derived 5‐hydroxymethylfurfural (HMF) presents a promising pathway for synthesizing the value‐added chemical, 2,5‐furandicarboxylic acid (FDCA). However, it is still lack of scalable strategies to fabricate electrocatalysts with high activity and selectivity. Herein, a bayberry‐like Ni@Ni3S2 core–shell catalyst is prepared via a spontaneous corrosion strategy for HMF electro‐oxidation. The Ni3S2 shells with abundant electron‐deficient Ni sites facilitate the generation of high‐valence Ni3+OOH active species. Additionally, the in situ oxidation of S2− to SO42− enhances the electron and proton transport capacity. Both high‐performance liquid chromatography (HPLC) and density functional theory (DFT) analyses reveal that Ni@Ni3S2 preferentially selects the 2,5‐dicarboxyfurylfuran (DFF) pathway due to the lower reaction energy barrier from HMF to DFF, and the rate‐determining step of DFF oxidation to generate 5‐formylfuran‐2‐carboxylic acid (FFCA) is significantly accelerated. Consequently, the yield of FDCA and Faraday efficiency are found to be 99.20% and 99.35%, respectively, and they still reach 88.79% and 90.33% after ten cycles, showing excellent stability. Moreover, a mass production of 13.97 g Ni@Ni3S2 is successfully synthesized using the spontaneous corrosion strategy. This work offers a valuable reference for designing scalable and high‐performance catalysts by manipulating reaction routes to achieve efficient biomass conversion. [ABSTRACT FROM AUTHOR]

The synthesis of supported multielement transition metal phosphides (TMPs) to exploit the synergistic interplay between electronic and geometric effects resulting from the presence of different metals in the material and the arrangement of heterogeneous atoms is pivotal for reducing metal content while offering multiple active sites. However, the integration of Ni, Co, and P, for example, into a nanostructured carbon network to develop self‐supporting NixCoyP bimetallic phosphides is limited by several factors, including the synthesis and the discrepancy between the crystal structure of the respective monometallic phosphides. Moreover, conventional synthesis of supported TMPs often separates nanoparticles, support and phosphidation steps, which do not allow tailoring of physical and catalytic properties via particle support, electronic and geometric interactions. Herein, an innovative solid‐state, ex situ phosphidation‐free approach tailored to synthesize a library of self‐supporting NixCoyP TMPs in N,S,P‐modified nanostructured carbon networks generated together with NixCoyP particles is presented. Extensive multivariate characterization validates the unique properties of NixCoyP bimetallic materials with enhanced electrocatalytic performance for the hydrogen evolution reaction and the selective electroconversion of biomass‐derived 5‐hydroxymethylfurfural (5‐HMF) to value‐added 2,5‐furandicarboxylic acid (FDCA) with 90–100% Faradaic efficiency. Overall, the synthesis expands the possibilities for tailoring the microstructure of supported TMPs for improved physical/catalytic properties. [ABSTRACT FROM AUTHOR]

Mesoporous niobium‐based solid acid catalysts were successfully synthesized using the soft template method with sodium lignosulfonate (SLS) as the template. In most studies the template is calcined to form mesopores after hydrothermal synthesis; however, in this study SLS was retained to produce niobium‐carbon composite catalysts. The catalysts obtained were characterized by X‐ray diffraction, nitrogen adsorption–desorption, Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and static contact angle measurements. The catalytic activity of the solids was also investigated in the conversion of glucose to 5‐hydroxymethylfurfural (HMF) using pure water as the solvent. Under optimal conditions, niobium‐carbon composite catalyst achieved a glucose conversion yield of 65.1% and an HMF yield of 42.1%. The enhanced catalytic activity was attributed to the timely extraction of the HMF by the carbonized SLS. [ABSTRACT FROM AUTHOR]

In an attempt to expand the utility of natural compounds in catalysis, a novel heterogeneous catalyst derived from Gum Arabic, a natural polysaccharide, was synthesized by its modification with chlorosulfuric acid and subsequent magnetization. Material characterization confirmed the successful modification and magnetization of GA. Hammet method also approved increase of acidity of gum upon functionalization with chlorosulfuric acid. According to Response Surface Methodology optimization, this catalyst exhibited high activity for the conversion of fructose to 5-hydroxymethylfurfural under mild conditions, achieving a 96% yield at 85 °C within 73 min using 30 wt% catalyst loading. The kinetic study indicated an activation energy of 89 kJ/mol. Thermodynamic parameters were determined, with enthalpy, entropy, and Gibbs free energy values of 86.11 kJ/mol, − 29.45 J/mol, and 96.65 kJ/mol, respectively. Furthermore, the catalyst displayed excellent recyclability, retaining over 87% activity for five consecutive cycles, and a heterogenous nature as confirmed by hot filtration test. This study demonstrates the potential of the as-prepared catalyst for sustainable 5-hydroxymethylfurfural production, highlighting its high activity, recyclability, and environmentally friendly nature. [ABSTRACT FROM AUTHOR]

This research presents the Mn partial substitution in perovskite oxide LaNiO3 to provoke its catalytic activities for the 5-hydroxymethylfurfural (5-HMF) oxidation — a chemical transformation producing higher-value products. The benefit of different B-cation incorporation is to induce the reactive oxygen sites — it plays an essential role in catalysis. Hence, the research aims to study the effect of the Mn element partially replacing Ni-cation in the LaNiO3 structure, so-called double perovskite oxide with LaMnxNi1-xO3-δ (0 ≤ x ≤ 1). The catalysts were synthesized by the sol–gel method. In addition, comprehensive characterizations such as SEM–EDX, XRD, and XPS were used to study catalyst properties, especially oxygen surface sites. The 5-HMF oxidation reaction was performed in TBHP oxidant and acetonitrile solvent. Besides, crucial operating parameters, i.e., temperature (80–120 °C), pressure (1–5 bar), base addition (0–6 mmol), and time (2–24 h), were studied to predict the optimal reaction conditions. The results show that the variation of the Mn element incorporated with LaNiO3-δ solid affected 5-HMF conversion and the intermediate distribution. The LaMn0.5Ni0.5O3-δ, a high relative O2−latt/Oads ratio catalyst, shows 100% HMF conversion with as much as 61% FDCA yield. The appropriated value of 0.04 mmol Na2CO3 addition, 120 °C operating temperature, and 2-h reaction time suggested for the highly catalyzed 5-HMF oxidation over the alternative LaMnxNi1-xO3-δ catalyst. [ABSTRACT FROM AUTHOR]

The field of biocatalysis is envisioned as an important contributor to the development of bioprocesses producing molecules that can replace those derived from oil, while maintaining the durability and resistance characteristics offered by petroleum-based materials. In the search for substitutes for petroleum derivatives, the compounds belonging to the furan platform appear among the best known due to their reactivity, as they present a mono- (Furfural) or disubstituted (5-HMF) furan ring in their structure, identifying them among the molecules with the greatest applications in the synthesis of new fuels and polymer precursors. In this context, taking advantage of the metabolic diversity of microorganisms, biocatalytic and fermentative methods for the bioconversion of furans have been explored, proposing processes of lower cost and low environmental impact. This review presents the oxidation and reduction products of furfural and 5-HMF obtained by biological processes, using cells or enzymes. [ABSTRACT FROM AUTHOR]

A series of CuCo bimetallic catalysts were prepared via the co‐precipitation method for the catalytic transformation of biomass‐derived 5‐hydroxymethylfurfural (HMF) into 2,5‐furandicarboxylic acid (FDCA). FDCA acts as a precursor for biodegradable biopolymer polyethylene furanoate production, thereby achieving a carbon‐neutral approach. Out of all the synthesized catalysts, CuCo(1 : 1) showed remarkable catalytic activity and yielded 70.67 % FDCA while achieving 100 % HMF conversion in 5 minutes at 50 °C temperature in the presence of tert‐butyl hydroperoxide as an oxidant. Synergistic effects of the catalyst, such as adsorbed oxygen, relative oxygen vacancy, lesser pore size, and pore volume, were key factors attributed to the catalyst's excellent activity. The synthesized catalyst showed good recyclability with a minimal decrease in FDCA yield up to 5 cycles. Pre and post‐characterization of catalysts such as BET, TEM, FE‐SEM, XRD, H2‐TPR, CO2 TPD, ICP‐OES, and XPS were done to correlate the catalyst's properties with its activity. In addition, the effect of reaction parameters such as stirring speed, temperature reaction time, catalyst weight, base, and oxidant were studied to achieve optimum reaction conditions. The reaction products were analyzed quantitatively and qualitatively using HPLC and HR‐MS. [ABSTRACT FROM AUTHOR]

The selective hydrogenation of 5‐hydroxymethylfurfural (HMF) to 2,5‐bishydroxymethyltetrahydrofuran (BHMTHF), a vital fuel precursor and solvent, is crucial for biomass refining. Herein, we report highly selective and stable PdNi nanoalloy catalysts for this deep hydrogenation process. A CO2‐assisted green method was developed for the controllable synthesis of various bimetallic and monometallic catalysts. The PdNi/SBA‐15 catalysts with various Pd/Ni ratios exhibited a volcano‐like trend between BHMTHF yield and Pd/Ni ratio. Among all catalysts tested, Pd2Ni1/SBA‐15 achieved the best performance, converting 99.0 % of HMF to BHMTHF with 96.0 % selectivity, surpassing previously reported catalysts. Additionally, the Pd2Ni1/SBA‐15 catalyst maintained excellent stability even after five recycling runs. Catalyst characterizations (e. g., HAADF‐STEM) and density functional theory (DFT) calculations confirmed the successful formation of the alloy structure with electron transfer between Ni and Pd, which accounts for the remarkable performance and stability of the catalyst. This work paves the way for developing highly selective and stable alloy catalysts for biomass valorization. [ABSTRACT FROM AUTHOR]

The present study reports the synthesis, characterization, and application of NiCo bimetallic catalysts to produce 2,5‐furandicarboxylic acid (FDCA) via the oxidation of bio‐renewable 5‐hydroxymethylfurfural (HMF). FDCA is a biopolymer precursor and a potential replacement for terephthalic acid (TPA). The catalysts were synthesized via the co‐precipitation method in different molar ratios of NiCo, followed by calcination in a muffle furnace. As a result, the complete conversion of HMF and a maximum 84.89 % FDCA yield was measured at 50 °C in 50 minutes in the presence of NiCo(3 : 1) catalyst. In addition, effect reaction parameters, including catalyst amount, temperature, time, base, and oxidant amount on the FDCA yield, were studied, and the process was optimized. The NiCo(3 : 1) catalyst showed a negligible loss in activity for at least five cycles. The higher catalytic activity and stability are attributed to the synergistic effect of bimetallic catalysts, such as higher lattice oxygen. Accordingly, the catalyst was characterized using BET, XRD, H2‐TPR, CO2‐TPD, HR‐TEM, and XPS to correlate their properties and activity. The reaction products were analyzed quantitatively using HPLC and qualitatively using HR‐MS. [ABSTRACT FROM AUTHOR]

In the past decade, organic electrosynthesis has emerged as an atom‐ and energy‐efficient strategy for harvesting renewable electricity that provides exceptional control over the reaction parameters. A profound and fundamental understanding of electrochemical interfaces becomes imperative to advance the knowledge‐based development of electrochemical processes. The major strategy toward an efficient electrochemical system is based on the advancement in material science for electrocatalysis. Studies on the complex interplay among electrode surface, electrolyte, and transformation intermediates have only recently started to emerge. It involves acquiring atomic‐scale insights into the electrochemical double layer, for which the identity and concentration of composing ions play a crucial role. In this study, we present how the identity and concentration of alkali cations impact the selectivity of aldehyde functionality electroreduction. As a case‐study transformation, we set the electrochemical conversion of 5‐hydroxymethylfurfural (HMF), a promising biomass‐derived feedstock for the sustainable production of polymer or fuel precursors. Our findings reveal a consistent trend of the selectivity shift towards 2,5‐bis(hydroxymethyl)furan (BHMF) as a function of cation size and concentration, rationalized by specific cation adsorption at the glassy carbon (GC), followed by the increase in the electrode surface charge density. [ABSTRACT FROM AUTHOR]

The efficient separation of photocarriers and facile generation of superoxide radicals are crucial for enhancing the performance of photocatalysts in the selectively photo‐oxidizing 5‐hydroxymethylfurfural (HMF) into 2,5‐diformylfuran (DFF). Herein, a ZnIn2S4/CeO2 composite with S‐scheme heterojunction and sulfur vacancies (SV) is successfully developed through a one‐step hydrothermal method. The optimal catalyst (SV‐ZnIn2S4/CeO2) exhibits excellent catalytic activity with 100% conversion of HMF and 96.1% selectivity of DFF in 80 min under ambient conditions, the production rate of DFF is up to 952.6 µmol g−1 h−1. Intriguingly, the performance remains significant even when the concentration of HMF is increased from 8 to 100 mм. Experimental and theoretical investigations discover that the synergistic effect of S‐scheme heterojunction and sulfur vacancies contribute to the separation of photocarriers and the activation of oxygen, which facilitate the generation of superoxide radicals, thus boosting the catalytic oxidation reactions. [ABSTRACT FROM AUTHOR]

5‐Hydroxymethylfurfural (HMF) is a versatile platform molecule that can be derived from biomass feedstocks and catalytically converted into various value‐added chemicals. In this work, selective hydrogenation of HMF is investigated to produce valuable furan‐based diols, namely 2,5‐bis‐hydroxymethylfuran (BHMF) and 2,5‐bis‐hydroxymethyltetrahydrofuran (BHMTHF), using TiO2 supported Ru catalysts. The catalyst performance was fine‐tuned to achieve over 98% yield to BHMF and BHMTHF under optimized reaction conditions with very good recyclability. We pointed out several key factors allowing to maximize the yield towards the respective diols. Features such as the Ru nanoparticle size, the strength of metal‐support interactions and the presence of residual chlorine were found to significantly influence the reaction. A characteristic volcano‐shaped relationship was obtained between the particle size and the catalytic activity giving the highest diol yield for an optimum Ru nanoparticle size of 1.6 nm. Further, metal‐support interactions were found to be responsible for providing optimum Ru‐TiOx interfacial surface sites and chlorine was affecting the electronic properties of Ru nanoparticles, potentially benefiting to the selective formation of BHMF. The reaction time was shown to control the hydrogenation of the furan ring and the selectivity of the reaction, that can be directed optimally towards BHMF or BHMTHF. [ABSTRACT FROM AUTHOR]

5‐Hydroxymethylfurfural (5‐HMF) derived from lignocellulose represents an important platform molecule that could be employed in the selective hydrogenation of the furan ring to prepare 5‑hydroxymethyltetrahydrofurfural (HMTHF). However, the reported catalytic systems for the synthesis of HMTHF using 5‐HMF still require additional hydrogen pressure. In this study, the Pd/ZrO2 catalyst with uniformly dispersed Pd nanoparticles was prepared via a simple impregnation reduction process. This catalyst exhibited excellent catalytic activity and selectivity for the hydrogenation of 5‐HMF to HMTHF. High HMTHF yields up to 92.3% were produced under mild reaction conditions of ambient hydrogen pressure and room temperature in methanol solvent. This result was superior to the most catalytic systems that had been reported so far. The mechanism study revealed that the active hydrogen species on the surface of the Pd nanoparticles and the reaction solvent in this study were the pivotal factors influencing the hydrogenation of furan rings in 5‐HMF. [ABSTRACT FROM AUTHOR]

We carried out a mechanistic investigation of the dehydration of fructose catalyzed by a series of proton‐exchanged faujasite zeolites. Using a combination of analytical tools (HPLC, GC, NMR), we could solve and quantify most of the variety of products formed, including (i) cyclic intermediates (ii) transient species (monomeric and dimeric) (iii) byproducts (oligomeric species and humins). The results prove that the reaction goes through a cyclic mechanism, and we could propose a kinetic model matching most of our experimental results and describing the interplay between the different categories of products. By comparing the performances of different catalysts with varying properties, we surprisingly find that increasing the concentration of Brønsted acid sites induces lower catalytic activity. Contrary to general expectations, the mesoporous volume seems to be the most determining parameter for the activity of the catalysts over the set of catalysts evaluated here, which may be explained by the importance of allowing the reactant a significant accessibility to the active sites. [ABSTRACT FROM AUTHOR]

Electrochemical dehydrogenation of hydroxides plays a crucial role in the formation of high‐valence metal active sites toward 5‐hydroxymethylfurfural oxidation reaction (HMFOR) to produce the value‐added chemical of 2,5‐furandicarboxylic (FDCA). Herein, we construct benzoic acid ligand‐hybridized NiCo(OH)x nanowires (BZ‐NiCo(OH)x) with ample electron‐deficient Ni/Co sites for HMFOR. The robust electron‐withdrawing capability of benzoic acid ligands in BZ‐NiCo(OH)x speeds up the electrochemical activation and dehydrogenation of lattice‐hydroxyl‐groups (M2+−O−H⇌M3+−O), boosting the formation of abundant electron‐deficient and high‐valence Ni/Co sites. DFT calculation reveals that the deintercalation proton is prone to establishing a hydrogen bridge with the carbonyl group in benzoic acid, facilitating the proton transfer. Coupled with the synergistic oxidation of Ni/Co sites on hydroxyl and aldehyde groups, BZ‐NiCo(OH)x delivers a remarkable current density of 111.20 mA cm−2 at 1.4 V for HMFOR, exceeding that of NiCo(OH)x by approximately fourfold. And the FDCA yield and Faraday efficiency are as high as 95.24 % and 95.39 %, respectively. The ligand‐hybridized strategy in this work introduces a novel perspective for designing high‐performance transition metal‐based electrocatalysts for biomass conversion. [ABSTRACT FROM AUTHOR]

5‐Hydroxymethylfurfural (5‐HMF) is an important biomass‐based platform compound that links biomass feedstocks with petrochemical refinery products. In this work, we developed a novel approach using triethylbenzylammonium chloride (TEBAC)‐based acidic deep eutectic solvents (ADESs) to synthesize 5‐HMF through the dehydration of fructose. Our approach demonstrates significant improvements in both 5‐HMF yield and process efficiency compared to conventional solvent systems. Under optimal experimental conditions (90 °C, 4.5 h), a maximum 5‐HMF yield of 97.77±3.20 % was achieved at a TEBAC:acetic acid ratio of 2 : 3 with 1 wt % fructose loading, which represents a notable advancement over other methods. Notably, our system inhibits the formation of by‐products such as levulinic acid (LA) and formic acid (FA), which are commonly detected in other dehydration processes. Additionally, higher 5‐HMF yields of 76.67±0.33 % and 73.51±1.14 % were achieved with 10 wt % and 20 wt % fructose loadings, respectively, further highlighting the scalability of the process. The acidity of ADESs was found to significantly affect the dehydration rate and yield, as demonstrated through Hammett's acidity function analysis. The key innovation of our study lies in the strategic selection of hydrogen bond donors and acceptors in the DES, enabling both high efficiency and selectivity in 5‐HMF production. These findings provide a promising pathway for large‐scale biomass conversion with reduced by‐product formation. [ABSTRACT FROM AUTHOR]

Using biomass oxidation reactions instead of water oxidation reactions is optimal for accomplishing biomass conversion and effective hydrogen generation. Here, we report that α‐Fe2O3 photoanodes with a NiOOH cocatalyst exhibit excellent performance for photoelectrochemical oxidation of 5‐hydroxymethylfurfural (HMF) to 2,5‐furandicarboxylic acid (FDCA). The conversion efficiency for HMF reaches 98.5 %, while the selectivity for FDCA is 94.2 %. We revealed that HMF is oxidized through a spontaneous proton‐coupled electron transfer (PCET) process with the high‐valent phase of the Ni‐based catalyst. The dangling oxygen and bridging oxygen of the high‐valent phase species serve as proton‐accepting sites. Furthermore, we pointed out that the deprotonated bond dissociation free energy difference between the catalysts and alcohols is the thermodynamic trigger for the PCET process. This study provides a reasonable explanation for the alcohol oxidation reaction, which is beneficial for designing biomass conversion systems. [ABSTRACT FROM AUTHOR]

Polyols such as 1,5-pentadiol, 1,6-hexanediol, and 1,2,6-hexanetriol are crucial chemicals, traditionally derived from non-renewable fossil sources. In the pursuit of sustainable development, exploring renewable and environmentally benign routes for their production becomes imperative. Furfural and 5-hydroxymethylfurfural are C5 and C6 biomass-derived platform molecules, which have potential in the synthesis of various polyols through hydrogenation and hydrogenolysis reactions. Currently, there is an extensive body of literature exploring the transformation of biomass-derived furan compounds. However, a comprehensive review of the transformation of furan compounds to polyols is lacking. We summarized the literature from recent years about the ring-opening reaction involved in converting furan compounds to polyols. This article reviews the research progress on the transformation of furfural, furfuryl alcohol, and 2-methylfuran to 1,2-pentadiol, 1,4-pentadiol, 1,5-pentadiol, and 1,2,5-pentanetriol, as well as the transformation of 5-hydroxymethylfurfural to 1,2-hexanediol, 1,6-hexanediol, and 1,2,6-hexanetriol. The effects of the supported Pd, Pt, Ru, Ni, Cu, Co, and bimetallic catalysts are discussed through examining the synergistic effects of the catalysts and the effects of metal sites, acidic/basic sites, hydrogen spillover, etc. Reaction parameters like temperature, hydrogen pressure, and solvent are considered. The ring opening catalytic reaction of furan rings is summarized, and the catalytic mechanisms of single-metal and bimetallic catalysts and their catalytic processes and reaction conditions are discussed and summarized. It is believed that this review will act as a key reference and inspiration for researchers in this field. [ABSTRACT FROM AUTHOR]

The effect of organic precursors on catalysts was studied and the preparation of catalyst and reaction conditions were optimized. A 91% selectivity of 2,5-dimethylfuran (DMF) from the hydrogenolysis of 5-hydroxymethylfurfural (HMF) was obtained on a Mo monometallic catalyst, in which nitrogen doping played a key role. Density functional theory (DFT) shows that Mo sites with N, O and C coordination have moderate adsorption strength of HMF and H2 and lower energy barrier of key steps compared with pure molybdenum nitride, molybdenum carbide and molybdenum oxide, which may be conducive to catalytic hydrogenolysis of HMF. [ABSTRACT FROM AUTHOR]

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Herein, we report a controllable and versatile strategy for the synthesis of highly dispersed Co nanoparticles embedded in open‐channel hierarchically porous N/O‐doped carbon skeleton. Moreover, the pore sizes of the hierarchical structures can be easily tuned by adjusting the size of precursors. The as‐obtained Co@NC‐2ST exhibits unprecedented activity and selectivity in the oxidative esterification of 5‐hydroxymethylfurfural (HMF) to dimethyl furan‐2,5‐dicarboxylate under base‐free and atmospheric conditions. In particular, the achieved turnover frequency value is an order of magnitude higher than that of the state‐of‐art heterogeneous catalysts reported to date. A combination of experimental and density function theory studies reveals that the unique features of Co@NC‐2ST enable a novel reaction route, that is, the CHO group of HMF is preferentially esterified instead of the OH group. This can be attributed to the nucleophilic addition reaction caused by the attack of methoxy anion on the CHO group of HMF. [ABSTRACT FROM AUTHOR]

A green corrosion inhibitor was prepared from the bio‐based platform compound 5‐hydroxymethylfurfural through a green synthetic route, which avoid the use of toxic reagent. The inhibition performance and mechanism of this compound for the corrosion of mild steel in 0.1 M HCl was investigated by using the weight loss experiments, polarization measurements, EIS measurements and quantum chemical calculations. The corrosion inhibition efficiency by weight loss measurement (ηWLM%) of this inhibitor can reach up to 90.3 % at 303 K with 1.2 mM concentration. Moreover, the electrochemical experiments revealed that this corrosion inhibitor acts as a mixed‐type inhibitor. Thermodynamic studies gave the values of the standard Gibbs free energy ΔGads0 ${{\rm \Delta }{G}_{ads}^{0}}$ , fall within the range of −20 kJ/mol to −40 kJ/mol, suggested the adsorption of this compound is a spontaneous process involving both physisorption and chemisorption. In addition, quantum chemical calculations were conducted to further validate the formation of an effective absorption layer by this inhibitor on metal surfaces, which showed that the electron density iso‐surfaces of HOMO was mainly distributed on chloride ions, while LUMO tended to be distributed on furan rings and aldehyde groups. Besides, the other quantum chemical parameters of this inhibitor were also calculated to explore the molecular activity, such as, the molecular volume (ν, 333.105 Å), global hardness (η, 4.706 eV), global softness (σ, 0.2125 eV), electronegativity (χ, 4.93 eV), dipolemoment (μ, 13.1429 D) and vertical ionization energy (VIE, 7.2646 eV). [ABSTRACT FROM AUTHOR]

AbstractDeep-fat frying gives food a desirable color and flavor but inevitably leads to oil deterioration and production of hazards. In this study, the simultaneous generation of multiple hazards under different frying conditions was investigated, the deterioration of frying oil was evaluated, and finally, their correlation was analyzed. The results showed that as the temperature of frying chicken wings increased from 150 to 190 °C, the levels of acrylamide (AA), heterocyclic amines (HCAs), and polycyclic aromatic hydrocarbons (PAHs) in the oil also increased proportionally. At 190 °C, the fried potato oil contained the highest AA content of 2.60 mg·kg−1, while the content of HCAs and PAHs was the highest in fried chicken wings oil, with values of 5.06 μg·kg−1 and 5.18 μg·kg−1, respectively. 5-Hydroxymethylfurfural was detected only in fried potato oil. Oil quality deteriorated gradually with increasing frying temperature and heating time, as indicated by increased acid value, carbonyl value, and levels of total polar compounds. Overall, the results indicated hazards were positively correlated with oil deterioration, suggesting that oil deterioration contributed to the generation of hazards. This work links hazards and oil deterioration, which is crucial for improving the quality and safety of fried foods, while reducing negative environmental impacts, and achieving clean production. [ABSTRACT FROM AUTHOR]

5‐Hydroxymethylfurfural (HMF) is a widely used biomass platform chemical that plays a crucial role in bridging biomass and fossil resources. Electrocatalytic oxidation of HMF provides an efficient way to obtain high‐value‐added biomass‐derived chemicals, among which the intermediate product 5‐formyl‐2‐furan carboxylic acid (FFCA) has attracted considerable attention. However, the weak adsorption ability of monometallic nickel oxide (NiOx) to HMF in neutral electrolyte restricts its further development, resulting in low HMF conversion and FFCA yield. In this study, we successfully constructed a novel nickel oxide‐platinum oxide hybrid catalyst supported on carbon felt (NiOx‐PtOx/CF), which exhibits an optimized adsorption ability of HMF, leading to the outstanding FFCA yield up to 77 % in the neutral media. The high activity of the NiOx‐PtOx/CF catalyst can be attributed to the redistribution of the electrons and the optimization of the electronic structure on the Ni active site due to the introduction of PtOx on NiOx nanosheets. This study offers valuable insights for the design of efficient multicomponent electrocatalysts for electrocatalytic biomass refinery systems. [ABSTRACT FROM AUTHOR]

Extremely limited research exploring the photocatalytic potential of main group metals, such as aluminum, gallium, and tin, has been undertaken due to their weak light harvesting properties. This study reports the efficient transformation of sugars to 5‐hydroxymethylfurfural (HMF) with high yield employing an original heterogeneous photocatalyst comprising a gallium(III) complex immobilized on an alumina support. Under visible light irradiation, the reaction rate of HMF formation is ~143 times higher than the equivalent thermal reaction performed in the absence of light. The turnover number (TON) of the heterogeneous gallium(III) photocatalyst was as high as 1500, which was ca. two orders of magnitude higher than the TON of the homogeneous gallium(III) system. It is proposed that photoirradiation significantly enhances the Lewis acidity of the catalyst by forming a semi‐coordination state between gallium(III) and N‐donor ligands, enabling the increased interaction of reactant sugar molecules with gallium(III) active sites. Consistent with this, the photoresponsive coordination of the gallium(III) complex and the abstraction of the hydroxy group by the metal under irradiation with visible light is observed by NMR spectroscopy for the first time. These findings demonstrate that efficient photocatalysts derived from the main group elements can facilitate biomass conversion using visible light. [ABSTRACT FROM AUTHOR]

The synthesis of 2,5‐diformylfuran (DFF) through photocatalytic oxidation of 5‐hydroxymethylfurfural (HMF) is an attractive approach. In this manuscript, a photocatalytic selective oxidation strategy for HMF was developed, using Ag/Ag3PO4 as the photocatalyst and O2 as the oxidizing agent. The prepared catalyst was characterized systematically by SEM, XRD, XPS, UV‐Vis, PL spectra, and so on. In contrast to previous photocatalytic oxidation strategies for HMF conversion, this catalytic system could efficiently generate 1O2 without other reactive oxygen species (ROS) under visible light irradiation. DFF would be obtained with about 90 % selectivity. Moreover, the exclusive formation of 1O2 was linked to the more positive conduction band potential (+0.90 eV) of Ag/Ag3PO4, confirmed by an array of characterization techniques. Additionally, the stability of the catalyst was assessed through cyclic testing and analyses including XRD, and XPS. Nonetheless, this catalytic system could potentially serve as a robust platform for various selective oxidation reactions in the future, due to its exclusive presence of 1O2 without the involvement of other ROS. [ABSTRACT FROM AUTHOR]

Ni-doped CoTe nanorods have been prepared for 5-hydroxymethylfurfural oxidation reaction. The doping of Ni facilitates the oxidation of Co2+ to high-valent CoO 2 to achieve efficient electrosynthesis of the valuable 2,5-furandicarboxylic acid. [Display omitted] • A crude nanorod structure CoNiTe was prepared by two-step hydrothermal reactions for HMFOR. • Ni doping modulates the electronic structure of Co and improves the electrocatalytic performance of CoNiTe. • The generation of high-valent cobalt is the key for excellent HMFOR. Replacing the anodic oxygen evolution reaction (OER) in water splitting with 5-hydroxymethylfurfural oxidation reaction (HMFOR) can not only reduce the energy required for hydrogen production but also yield the valuable chemical 2,5-furandicarboxylic acid (FDCA). Co-based catalysts are known to be efficient for HMFOR, with high-valent Co being recognized as the main active component. However, efficiently promoting the oxidation of Co2+ to produce high-valent reactive species remains a challenge. In this study, Ni-doped CoTe (CoNiTe) nanorods were prepared as efficient catalysts for HMFOR, achieving a high HMFOR current density of 65.3 mA cm−2 at 1.50 V. Even after undergoing five successive electrolysis processes, the Faradaic efficiency (FE) remained at approximately 90.7 %, showing robust electrochemical durability. Mechanistic studies indicated that Ni doping changes the electronic configuration of Co, enhancing its charge transfer rate and facilitating the oxidation of Co2+ to high-valent CoO 2 species. This work reveals the effect of Ni doping on the reconfiguration of the active phase during HMFOR. [ABSTRACT FROM AUTHOR]

Chitin biomass is the second largest biomass resource on Earth but under-utilized. In this study, pretreated shrimp shells were converted into value-added platform chemical 5-hydroxymethylfurfural (HMF) using microwave hydrothermal treatment. Under the combined pretreatment of acid decalcification at room temperature and microwave-assisted alkali deacetylation, the HMF yield could reach 1.8 wt%. The key process parameters, including the holding temperature, holding time, and pH value, were evaluated and optimised. The highest HMF yield of 6.5 wt% was obtained at 202.6°C at a holding time of 5.8 min and a pH value of 1.5. This result demonstrates the potential of synchronously treating waste and recycling it, thereby offering a highly promising valorisation strategy for chitin-biomass utilisation. [ABSTRACT FROM AUTHOR]

We developed a series of heteropolyacid-modified lignin-MOF derived bimetallic catalyst for the efficient in situ hydrogenation/hydrodeoxygenation of biomass-derived 5-hydroxymethylfurfural using isopropanol as hydrogen-donating solvent. [Display omitted] Catalytic conversion of biomass-derived value-added chemicals was of great significance for the utilization of renewable biomass resources to instead of fossil chemicals. Biomass-derived lignin was regarded as an important support and 5-hydroxymethylfurfural (HMF) was a vital platform chemical derived from cellulose. Herein, a series of lignin-MOF hybrid catalysts were prepared and modified with different heteropolyacids (HPAs), which were then successfully introduced into the selective conversion of HMF to 5-hydroxymethylfurfuryl alcohol (MFA). The effect of different HPA, calcination temperature, etc. were all studied, and all catalysts were well characterized. It was confirmed that silicotungstic acid modified catalyst (Ni 3 Co-MOF-LS@HSiW) exhibited the best catalytic performance, while the highest conversion of HMF was up to 100%, with the best MFA yield of 86.5%. The finding in this study could provide novel insights for the utilization of lignin and preparation of value-added biomass-derived chemicals. [ABSTRACT FROM AUTHOR]

Design of non-noble metal electrocatalysts for biomass conversion to high-value chemicals and understanding the related catalytic mechanisms are of profound significance but have remained a major challenge. Here, we developed a novel biomass-derived electrocatalyst (denoted as Cu/NC), featuring with electron-deficient copper nanoparticles anchored on N-doped carbon nanosheets, for the electrochemical reduction of 5-hydroxymethylfurfural (HMF) to 2,5-bis(hydroxymethyl)furan (BHMF, a vital precursor of functional polymers). The optimized Cu/NC electrocatalyst exhibited an excellent performance with high Faradaic efficiency (89.5%) and selectivity (90.8%) of BHMF at a low concentration of HMF (18.1 mM). Even at a very high HMF concentration (108.6 mM), the Faraday efficiency and selectivity of BHMF could still reach 74.8% and 81.1%, respectively. This performance approached those of the reported noble metal-based electrocatalysts. Mechanism study revealed that the N doping in the Cu/NC catalyst could regulate the electronic structure of Cu, strengthening the adsorption of the HMF carbonyl group, and thus boosting the selectivity of BHMF. Additionally, strong electronic metal-support interactions of Cu and the N-doped carbon support optimized the charge transfer rate, thus promoting the dissociation of water to the active hydrogen (H*) species and boosting the reaction kinetic rate of H* and HMF. [ABSTRACT FROM AUTHOR]

Renewable resources based polymers provides a sustainable alternative to petroleum derived polymeric materials. As a part of our series on synthesis of vanillin based renewable polymers, we report the synthesis of poly(hydrovanilloin-furfural) [poly(HVL-Fur)] and poly(hydrovanilloin–5-hydromethylfurfural) [poly(HVL-5-HMF)]. Vanillin was dimerized to a mixtures of meso/DL-hydrovanilloins with 94% meso product by electrochemical reductive coupling in aqueous sodium hydroxide using lead electrodes in quantitative yield. Then sodium hydroxide catalyzed condensation of hydrovanilloin with furfural in water at 80°C for 72 h was used to synthesize poly(HVL-Fur) with Mw = 8600 g mol−1, PDI = 1.28 in 78% yield. Similarly, condensation of hydrovanilloin with 5-hydroxymethylfurfural at 80°C for 48 h produced poly(HVL-5-HMF) with Mw = 12,100 g mol−1, PDI = 1.27 in 68% yield. poly(HVL-Fur) and poly(HVL-5-HMF) showed similar Tg values of 59°C and 60°C, respectively; whereas melting behaviors are dissimilar with Tm 171°C–173°C and 148°C–182°C, respectively. [ABSTRACT FROM AUTHOR]

The development of mild strategies to transform of fructose to prepare high-purity 5-hydroxymethylfurfural (HMF) is of great significance for biomass valorization, and the design of an efficient catalytic approach is crucial. Herein, a mild catalytic strategy was developed to achieve the preparation of high-purity HMF from fructose over Amberlyst-15 catalyst in a water-methyl isobutyl ketone (MIBK) biphasic system under atmospheric pressure and lower temperature (90 °C). The catalytic system was optimized and analyzed by response surface methodology and kinetics study. Results indicated that a 46.6% yield of HMF could be obtained under optimal conditions: 80 wt% Amberlyst-15 catalyst, the mass ratio of MIBK to H2O 10, and the reaction time of 7 h. Furthermore, a simple and efficient purification strategy of HMF was established. High purity (99.0%) and recovery rate (65.5%) of HMF were obtained. This work provides an efficient catalytic strategy to produce high-purity HMF from fructose under atmospheric pressure and lower temperature. [ABSTRACT FROM AUTHOR]

Converting carbohydrates into 5-hydroxymethylfurfural (5-HMF) is an attractive and promising route for value-added utilization of agricultural and forestry biomass resource. As an important platform compound, 5-HMF possesses high active furan structure with hydroxymethyl and aldehyde group for production of various bio-chemicals and materials, meanwhile, which suffer from low stability and poor yield during the industrial biorefinery process. Hence, selective production of 5-HMF with high-yield and low-cost has attracted extensive attention from scientific and industrial researchers. This review sorted and described the latest advanced research on solvent and catalyst system, as well as energy field effect for production of 5-HMF with different feedstock in detail, emphatically discussing the solvent effect and its synergistic effect with other aspects. Besides, the future prospects and challenges for production of 5-HMF from carbohydrates were also presented, which provide a profound insight into industrial 5-HMF process with economic and environmental feature. [ABSTRACT FROM AUTHOR]

Photoinduced chemical reactions and the development of new materials represent a current and significant topic. We present a sustainable and eco-friendly approach to the Knoevenagel condensation reaction involving carbonyl and active methylene compounds. Our method utilizes photo-activated carbon dots (CDs) derived from 5-hydroxymethylfurfural (5HMF) within an aqueous medium and does not require acidic, basic, or thermal conditions. This protocol operates effectively with aromatic, aliphatic, and heteroaromatic aldehydes and ketones. The 5HMF-derived-CDs can be reused four times without significant loss of activity. Moreover, this methodology is suitable for scaling up reactions, thereby highlighting its potential for industrial applications. [ABSTRACT FROM AUTHOR]

These days, a growing consumer demand and scientific interest can be observed for nutraceuticals of natural origin, including apiculture products. Due to the growing emphasis on environmental protection, extensive research has been conducted on the pesticide and heavy metal contamination of bee products; however, less attention is devoted on other food safety aspects. In our review, scientific information on the less‐researched food safety hazards of honey, bee bread, royal jelly, propolis, and beeswax are summarized. Bee products originating from certain plants may inherently contain phytotoxins, like pyrrolizidine alkaloids, tropane alkaloids, matrine alkaloids, grayanotoxins, gelsemium alkaloids, or tutin. Several case studies evidence that bee products can induce allergic responses to sensitive individuals, varying from mild to severe symptoms, including the potentially lethal anaphylaxis. Exposure to high temperature or long storage may lead to the formation of the potentially toxic 5‐hydroxymethylfurfural. Persistent organic pollutants, radionuclides, and microplastics can potentially be transferred to bee products from contaminated environmental sources. And lastly, inappropriate beekeeping practices can lead to the contamination of beekeeping products with harmful microorganisms and mycotoxins. Our review demonstrates the necessity of applying good beekeeping practices in order to protect honeybees and consumers of their products. An important aim of our work is to identify key knowledge gaps regarding the food safety of apiculture products. [ABSTRACT FROM AUTHOR]

To explore the formation pattern of 5-hydroxymethylfurfural (5-HMF) and the safety of dried longan during processing and storage, this study monitored the changes in 5-HMF content during drying and storage at different temperatures. The changes in the contents of reducing sugar, total acid and total free amino acid and browning degree during processing were determined and their correlation with 5-HMF content was analyzed. Moreover, the safety of dried longan was analyzed using in vitro simulated digestion experiments and a Caco-2 cell model. The results showed that as the drying temperature increased above 85 ℃, the 5-HMF content significantly increased (P < 0.05). The 5-HMF content was positively correlated with the total acid content and browning degree, but negatively correlated with the contents of total free amino acid and reducing sugar. During storage at different temperatures (4, 25, and 37 ℃), the 5-HMF level first increased and then decreased with storage time, and showed different increasing trends under different storage conditions. At 25 ℃, the 5-HMF content began to decline earliest and was lower overall. The 5-HMF content briefly increased during oral digestion, but significantly decreased during gastric and intestinal digestion. The water extract of dried longan inhibited the absorption of 5-HMF and counteracted the cytotoxicity of 5-HMF at 24 mmol/L to Caco-2 cells. These results indicated that optimizing the drying and storage conditions of dried longan can reduce the content of 5-HMF. In the case of normal consumption, the human digestive tract can reduce 5-HMF in dried longan, improving its safety for consumption.

Polyols such as 1,5-pentadiol, 1,6-hexanediol, and 1,2,6-hexanetriol are crucial chemicals, traditionally derived from non-renewable fossil sources. In the pursuit of sustainable development, exploring renewable and environmentally benign routes for their production becomes imperative. Furfural and 5-hydroxymethylfurfural are C5 and C6 biomass-derived platform molecules, which have potential in the synthesis of various polyols through hydrogenation and hydrogenolysis reactions. Currently, there is an extensive body of literature exploring the transformation of biomass-derived furan compounds. However, a comprehensive review of the transformation of furan compounds to polyols is lacking. We summarized the literature from recent years about the ring-opening reaction involved in converting furan compounds to polyols. This article reviews the research progress on the transformation of furfural, furfuryl alcohol, and 2-methylfuran to 1,2-pentadiol, 1,4-pentadiol, 1,5-pentadiol, and 1,2,5-pentanetriol, as well as the transformation of 5-hydroxymethylfurfural to 1,2-hexanediol, 1,6-hexanediol, and 1,2,6-hexanetriol. The effects of the supported Pd, Pt, Ru, Ni, Cu, Co, and bimetallic catalysts are discussed through examining the synergistic effects of the catalysts and the effects of metal sites, acidic/basic sites, hydrogen spillover, etc. Reaction parameters like temperature, hydrogen pressure, and solvent are considered. The ring opening catalytic reaction of furan rings is summarized, and the catalytic mechanisms of single-metal and bimetallic catalysts and their catalytic processes and reaction conditions are discussed and summarized. It is believed that this review will act as a key reference and inspiration for researchers in this field.

BACKGROUND: Roasting is an essential step in making roasted teas, and its role in producing flavors has been widely studied. However, the variation of potential hazardous compounds during the tea roasting process is still vague. The present study established an effective method based on liquid chromatography‐triple quadrupole‐tandem mass spectrometry to simultaneously determine the variation of acrylamide (AA), 5‐hydroxymethylfurfural (5‐HMF), and free amino acids during the tea roasting process. Meanwhile, the effects of several tea polyphenols on the formation of AA and 5‐HMF were investigated by a wet‐to‐dry thermal model reaction. RESULTS: Medium‐temperature roasted teas had the highest levels of AA and 5‐HMF, with ranges of 0.13–0.15 μg g−1 and 68.72–123.98 μg g−1, respectively. Quantitative results showed that the levels of monosaccharides and amino acids decreased during roasting, which might contribute to the formation of 5‐HMF and AA. Meanwhile, the decrease of epigallocatechin gallate (EGCG), epigallocatechin (EGC), and epicatechin (EC) might be related to their inhibitory effects on 5‐HMF and AA. Thermal model reaction results showed that EGCG and EC significantly inhibited 5‐HMF formation with a decline rate of 33.33% and 72.22%, respectively, mainly by trapping glucose. Gallic acid (GA) also had an inhibitory effect on the formation of AA (decreased by 92.86%) and 5‐HMF (44.44%), mainly through impeding the preliminary reaction of asparagine and glucose. CONCLUSION: The roasting temperature determined the levels of AA and 5‐HMF in teas. Catechins inhibited the formation of 5‐HMF and AA mostly through trapping monosaccharides, while the inhibitory effect of GA was achieved by impeding the reaction. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Photoinduced chemical reactions and the development of new materials represent a current and significant topic. We present a sustainable and eco-friendly approach to the Knoevenagel condensation reaction involving carbonyl and active methylene compounds. Our method utilizes photo-activated carbon dots (CDs) derived from 5-hydroxymethylfurfural (5HMF) within an aqueous medium and does not require acidic, basic, or thermal conditions. This protocol operates effectively with aromatic, aliphatic, and heteroaromatic aldehydes and ketones. The 5HMF-derived-CDs can be reused four times without significant loss of activity. Moreover, this methodology is suitable for scaling up reactions, thereby highlighting its potential for industrial applications.

This study elucidated the effects of sucrose degradation products, 2-furaldehyde (2-F) and 5-hydroxymethylfurfural (5-HMF), on the stability and antioxidant activity of anthocyanins under different processing and storage conditions. The results showed that during processing, controlling the temperature not more than 85 ℃ and the pH at 3.0 provided the best protection and highest retention rate for anthocyanins, as well as the strongest antioxidant activity. In addition, when the concentration of malic acid was below 0.1 mol/L and the mass fraction of VC was in the range of 0.05%–0.5%, the stability of anthocyanins was obviously disrupted. Dark storage reduced the generation of 2-F and 5-HMF, which in turn improved the stability of anthocyanins. These results provide a reference and technical guidance for the preparation and storage of anthocyanin products containing sucrose in the future, and are of great significance for maintaining the stability of anthocyanins during processing.

Abstract Catalytic hydrogenolysis systems of C-O bonds in furan ring, tetrahydrofuran ring and tetrahydropyran ring in biomass-derived cyclic compounds are reviewed. Furfural or its hydrogenation products (furfuryl alcohol and tetrahydrofurfuryl alcohol) have been frequently used as substrates for this type of reactions. Ring-opening of furfuryl alcohol over metal catalysts combined with basic components gives a mixture of 1,2-pentanediol, 1,5-pentanediol and other by-products. The selectivity much depends on catalysts and reaction conditions, and good 1,2-pentanediol selectivity can be obtained. For 1,5-pentanediol synthesis, more selective approaches have been reported such as Cu-zeolite catalysts for furfuryl alcohol hydrogenolysis in flow reactor and M-M’Ox-type (M: noble metal; M’: transition metal) supported catalysts or Ni-LnOx (Ln: rare earth element) catalysts for tetrahydrofurfuryl alcohol hydrogenolysis. The metal catalysts and M-M’Ox-type catalysts can be applied to ring-opening hydrogenolysis of other furan- and tetrahydrofuran-based compounds, respectively. Among the products of ring-opening hydrogenolysis of biomass-derived compounds, 1,5-pentanediol seems to be the most important because of the potential use as a monomer. The recent progress and reported properties of polymers using 1,5-pentanediol as a monomer are also summarized.

The formation of humins hampers the large-scale production of 5-hydroxymethylfurfural (HMF) in biorefinery. Here, a detailed reaction network of humin formation at the initial stage of fructose-to-HMF dehydration in water is delineated by combined experimental, spectroscopic, and theoretical studies. Three bimolecular reaction pathways to build up soluble humins are demonstrated. That is, the intermolecular etherification of β-furanose at room temperature initiates the C12 path, whereas the C–C cleavage of α-furanose at 130–150 °C leads to C11 path, and that of open-chain fructose at 180 °C to C11′ path. The successive intramolecular dehydrations and condensations of the as-formed bimolecular intermediates lead to three types of soluble humins. We show that the C12 path could be restrained by using HCl or AlCl3 catalyst, and both the C12 and C11′ paths could be effectively inhibited by adding THF as a co-solvent or accelerating heating rate via microwave heating.

In this work, a simple hydrothermal synthesis method is used to prepare photocatalytic NiO/WO 3 -biochar composite material, which is applied to catalyze the one-step conversion of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid with synergistic hydrogen production. The optoelectronic properties of NiO/WO 3 -biochar composite material are characterized. The results indicate that the p-n heterojunction-coupled biochar structure between NiO and WO 3 in the NiO/WO 3 -biochar composite is an important prerequisite for ensuring the one-step oxidation reaction of 5-hydroxymethylfurfural. The experimental results reveal the possible reaction pathways. Under the optimal ratio of NiO/WO 3 -biochar composite material, the 5-hydroxymethylfurfural conversion rate reaches 100%, the 2,5-furandicarboxylic acid yield reaches 99.6%, and the Faraday efficiency of hydrogen evolution is 98%. This study provides a new approach for the one-step photocatalytic synthesis of 2,5-furandicarboxylic acid from 5-hydroxymethylfurfural, as well as a novel and efficient catalyst for photocatalytic oxidation technology. [Display omitted] • NiO/WO 3 -biochar composite is successfully prepared. • Mechanism of hydrogen production by photocatalytic reaction of straw is analyzed. • HMF undergoes photocatalytic one-step oxidation to FDCA with 99.6% efficiency. [ABSTRACT FROM AUTHOR]

In this work, partial reductive amination of 5‐hydroxymethylfurfural (HMF) with gaseous ammonia over iridium supported on γ‐Al2O3, TiO2, SiO2 and carbon has been studied. The influence of the support and pressure was investigated in the valorization under mild conditions of HMF to 5‐(aminomethyl)‐2‐furanmethanol (AMFM). The catalysts were characterized by TEM, SEM‐EDS, N2 sorption Isotherms, TGA, CO‐Chemisorption, TPR, XRD, NH3‐TPD, ICP‐AES and XPS. The maximum activity and high rates were obtained for all catalytic systems. At 50 minutes of the reaction the Ir/C catalyst achieved 93 % of conversion and exhibited the highest yield and selectivity of 92 % and 99 % respectively, to the desired product 5‐(aminomethyl)‐2‐furanmethanol. The main properties that influence activity and selectivity are related to the amount of iridium on the surface and catalyst acidity. After the third cycle, 63 % and 59 % of selectivity and yield to AMFM respectively at 93 % of conversion were obtained. [ABSTRACT FROM AUTHOR]

The research progress on the conversion of cellulose into typical platform compound molecules 5-hydroxymethylfurfural under different catalytic systems is systematically summarized, and the advantages and disadvantages of the different catalytic systems used are described. The main factors limiting the efficient conversion of cellulose into platform compounds at present are analyzed, and it is pointed out that future efficient catalysts should have both efficient catalytic activity and easy separation. Among them, the coupled reaction of temperature-responsive ionic liquid catalyst and two liquid phase system can achieve the efficient homogeneous catalytic reaction, and the purpose of product separation, which will be widely used in this field in the future. It will provide a reference for future research on the efficient conversion of cellulose into platform compounds. [ABSTRACT FROM AUTHOR]

The catalytic oxidation of 5‐hydroxymethylfurfural (HMF) is an important process for producing a renewable furan‐2,5‐dicarboxylic acid (FDCA). Although several Pt‐based catalysts have been reported to efficiently catalyze the oxidation of HMF, the functional roles of catalyst supports, as corroborated by spectroscopic techniques, have not been fully described. Here, we report on Pt nanoparticles supported on metal‐organic frameworks (MOFs) that catalyze the oxidation of HMF to FDCA in the absence of base. Several catalysts are prepared by immobilizing pre‐synthesized Pt nanoparticles on supports, allowing for the investigation of the role of the supports without the influence of the size of Pt nanoparticles (Pt NPs). By analyzing the catalytic performances along with the electronic properties using X‐ray photoelectron spectroscopy and surface properties of the catalysts using in situ infrared spectroscopy of adsorbed CO2, we find that the presence of Pt NPs in the metallic phase and basic hydroxyl groups on the support promote the HMF oxidation. [ABSTRACT FROM AUTHOR]

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