HMF Conversion Research Articles

Strengthening the Stability of the Reconstructed NiOOH Phase for 5-Hydroxymethylfurfural Oxidation.

Electrochemical oxidation of biomass-derived 5-hydroxymethylfurfural (HMF) is a promising approach to produce high-value chemicals such as 2,5-furandicarboxylic acid (FDCA). However, the undesirable stability of catalysts commonly limits its potential application value. In this work, NiOOH derived from Ni(OH)2 was determined as the main catalytic site for HMF oxidation, but the collapse of Ni(OH)2 caused severe instability during the electrocatalytic process because of the crystal structure mismatch between NiOOH and Ni(OH)2. The implantation of Ce in Ni(OH)2 (Ce-Ni(OH)2) was successfully realized to address the stability issue of bare Ni(OH)2, since the larger ion radius of Ce could increase the Ni-O bond length and d-spacing. As a result, the activity of 14%Ce-Ni(OH)2 has not obviously decayed after the 50 cyclic voltammetry (CV)-cycle test. HMF conversion is close to 100%, and the Faraday efficiency (FE) reaches 86.6% at the potential of 0.45 V vs Ag/AgCl. This study provides a new strategy to design stable catalysts for the conversion of biomass derivatives.

Selective oxidation of 5-HMF to DFF over alkali promoted Mn nanocomposite

Various compositions of Cs promoted Mn catalysts were synthesized and investigated for selective oxidation of 5-HMF to DFF, among which Mn-Cs(80:20) was found to be most efficient giving 91 % conversion of 5-HMF and 99 % selectivity to DFF. Detail characterization like N2-sorption, BET surface area, TG-DTA, XRD, XPS, FE-SEM-EDX, TEM, HR-TEM, CO2-TPD, H2-TPR, O2-TPO, FTIR, Raman spectra and CH3OH-IR were done to establish structure-activity correlation. Enhanced surface area, porosity, thermal stability, dual morphologies were observed due to inclusion of Cs in Mn lattice domain which further enhanced the crystallinity, and oxygen diffusion on the surface. Mixed morphologies comprising nanoparticles (4–5 nm) and nanocubes (50–60 nm) were observed with enhanced redox potential and reduced work function due to weakening of Mn-O bonds. Significant increase in the basicity of catalyst, interfacial redox properties and lattice oxygen led to highly efficient oxidation of 5-HMF to DFF via Mars-van Krevelen mechanism at relatively milder conditions i.e. T = 90 °C and PO2= 200 psig. The catalyst was easily recyclable up to 7 times with minor loss in activity which was regenerated heat treatment protocol.

Efficient reduction of 5-hydroxymethylfurfural to 2,5-bis(hydroxymethyl)furan by Bacillus subtilis HA70 whole cells

2,5-bis(hydroxymethyl)furan (BHMF) is an important reduction product from biomass-based 5-hydroxymethylfurfural (HMF), and microbial whole-cells are usually employed as the biocatalysts for HMF reduction. Due to the cell toxicity of HMF, the substrate loading was limited to a low concentration (100–200 mM). Herein, we isolated a highly HMF-tolerant strain, Bacillus subtilis HA70, as a whole-cell biocatalyst for the reduction of HMF. The strain exhibited high catalytic activity and excellent selectivity to HMF conversion, and the catalytic activity was significantly improved with the addition of glycine. Under the optimized conditions, 350 mM of HMF was transformed into BHMF with a yield of 91.2% and a selectivity of 99%. In the fed-batch conversion, 443.8 mM of BHMF was obtained within 15 h, giving a productivity of 29.6 mmol/(L h) and a total yield of 88.7%. Additionally, this strain also could selectively transform 100 mM of furfural into furfuryl alcohol with a yield of 97.6% within 4 h. The strong catalytic activity confers B. subtilis HA70 a promising potential for efficient synthesis of BHMF from HMF.

Catalytic oxidation of biomass-derived 5-hydroxymethylfurfural to 5-hydroxymethyl-2-furancarboxylic acid by Co-based MOFs

The selective oxidation of 5-hydroxymethylfurfural (HMF) to 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) has been investigated on Co-based MOF catalysts. ZIF-67 (ZIF, Zeolitic Imidazolate Framework), Co-BTC and Co-BTC-2mim were solvothermally synthesized by the association of cobalt with 2-methylimidazole (2-mim), 1,3,5-benzenetricarboxylic acid (H3BTC), or a mixture of the two linkers. Besides these, a novel core-shell Co3O4 @Co-BTC structure with a core of Co3O4 and Co-BTC on its outer layer has also been synthesized by a simple replacement of the cobalt nitrate precursor with Co3O4. Among the prepared materials the core-shell Co3O4 @Co-BTC catalyst afforded the proper catalytic features (i.e., specific density of the acid and base site combined with the high accessibility of the HMF molecules to the active Co sites) for a high selectivity to HMFCA (89%) at a HMF conversion (XHMF) of 79%, at 60 ℃ and after only 1 h, in the presence of t-BuOOH as oxidant and acetonitrile as solvent.

Importance of oxyphilic FeNi alloy in NiFeAl catalysts for selective conversion of biomass-derived 5-hydroxymethylfurfural to 2,5-dimethylfuran

2,5-Dimethylfuran (DMF) is a promising fuel additive. Its selective production from 5-hydroxymethylfurfural (HMF) requires effective hydrodeoxygenation and simultaneous retainment of CC in furan ring, which is challenging over nickel-based catalysts. In this work, an alloying method was explored for selective conversion of HMF to DMF by introducing Fe species into Ni–Al catalysts to form oxyphilic FeNi alloy. The results showed that the formation of alloy in Ni–Fe–Al lowered the capability for adsorption and activation of hydrogen, reducing the activity for hydrogenation of the furan ring in HMF, forming mainly 2,5-dihydroxymethyl furan (DHMF) and 5-methylfurfuryl alcohol (5-MFA). In addition, the oxyphilic FeNi alloy had the high affinity for the adsorption/activation of C–OH in DHMF and 5-MFA, enhancing their hydrogenolysis to DMF. The kinetic study indicated that the hydrogenolysis of 2,5-dihydroxymethyl furan was the rate-determining step, showing a higher Ea (89.2 kJ mol−1) than that in hydrogenation of CO in HMF (59.7 kJ mol−1). Under optimized condition, DMF with yield of 93.4% from HMF was achieved over 1.5Ni-1.5Fe-1.0Al catalyst. In comparison with Ni–Al, 1.5Ni-1.5Fe-1.0Al also showed much higher resistivity towards sintering of metallic species, rendering the catalyst with superior catalytic stability.

Interfacial Engineering of Ni/Ni0.2Mo0.8N Heterostructured Nanorods Realizes Efficient 5-Hydroxymethylfurfural Electrooxidation and Hydrogen Evolution.

Simultaneously achieving electrochemical conversion of biomass-derived molecules into value-added products and energy-efficient hydrogen production is a highly attractive strategy but challenging. Herein, we reported a heterostructured Ni/Ni0.2Mo0.8N nanorod array electrocatalyst deposited on nickel foam (Ni/Ni0.2Mo0.8N/NF), which exhibited excellent electrocatalytic activity toward 5-hydroxymethylfurfural (HMF) oxidation, and nearly 100% conversion of HMF and 98.5% yield of 2,5-furandicarboxylic acid (FDCA) products can be achieved. The post-reaction characterizations unveil that Ni species in Ni/Ni0.2Mo0.8N/NF would be readily converted to NiOOH as the real active sites. Furthermore, a two-electrode electrolyzer was assembled with Ni/Ni0.2Mo0.8N/NF utilized as a bifunctional electrocatalyst for both the cathode and anode, giving rise to a low voltage of 1.51 V to concurrently produce FDCA and H2 at 50 mA cm-2. This work enlightens the significance of regulating redox activities of transition metals via interfacial engineering and constructing heterostructured electrocatalysts toward more efficient energy utilization.

Highly efficient aerobic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid over halloysite nanotubes-templated nitrogen-doped carbon supported bimetallic AuPd catalyst

Aerobic oxidation of biomass-derived 5-hydroxymethylfurfural (HMF) to 2, 5-furandicarboxylic acid (FDCA) is an important way to produce bioplastic monomer. Herein, halloysite nanotubes (HNT)-templated layered porous hollow rod-shaped nitrogen-doped carbon supported bimetallic AuPd catalysts (AumPdn/HRNxC) with different nitrogen contents and bimetallic nanoparticles size were employed for the highly efficient aerobic oxidation of HMF to FDCA in sodium carbonate aqueous solution. Catalytic experimental results uncovered the possible reaction pathway, and the kinetics study further confirmed the oxidation of intermediate FFCA to FDCA was the rate-controlled step. Benefiting from the synergy between nitrogen-doped carbon support and bimetallic nanoparticles, the Au3Pd1/HRN5C catalyst obtained the highest HMF conversion of 100% and FDCA yield of 99.9% under the optimal reaction conditions. In-situ FT-IR study revealed the adsorption configuration of HMF, and the ESR test proved that the active substance was superoxide radical. Furthermore, the catalyst showed good stability and reusability. This work provides an efficient, economical and environmentally friendly raw clay mineral derived heterogeneous catalyst for the large-scale production of FDCA from HMF.

Engineering aldehyde dehydrogenase PaALDH70140 from Pseudomonas aeruginosa PC-1 with improved catalytic properties for 5-hydroxymethyl-2-furancarboxylic acid synthesis

The catalytic transformation of biomass-derived 5-hydroxymethylfurfural (HMF) into value-added chemicals and biofuels has received considerable interest. Previously, we demonstrated that Pseudomonas aeruginosa PC-1 could be used for selective 900 mM HMF oxidation into 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) with over 90% yield. Here, we aimed to mine the potential aldehyde dehydrogenases (ALDHs) for HMF biocatalysis and improved the catalytic activity and tolerance through protein engineering. ALDHs were heterologously expressed in E. coli BL21 (DE3) and subsequently the most efficient HMF oxidation conditions of E. coli/pET-PaALDH70140 were identified. Based on the structural analysis of PaALDH70140 with the HMF and NAD+ complexes, the engineering hotspots in the active site architecture were identified and subjected to saturation mutagenesis. The mutant L172R displayed 175% higher HMF catalytic efficiency than PaALDH70140, and the mutant also showed improved HMF-tolerance. Kinetic parameters suggested that L172R had higher HMF affinity and catalytic efficiency, indicating a higher HMF conversion efficiency than the wild-type. Molecular docking revealed that the mutation introduced new hydrogen bonds between the enzyme and HMF, which fixed the spatial position of HMF and shortened the reaction time of the catalysis, thus enhancing the catalytic efficiency of HMF. In the fed-batch process, E. coli/pET-PaALDH70140-L172R exhibited a 166% increase in the yield of HMFCA within 22 h, proving its potential for HMF bioconversion applications.

Efficient synthesis of 5-hydroxymethyl-2-furancarboxylic acid from bio-based high-concentration 5-hydroxymethylfurfural via highly tolerant aldehyde dehydrogenase

The important bio-based platform chemical 5-Hydroxymethylfurfural (HMF) can be oxidized for use in several products that serve as versatile building blocks of polymers. Previously, we had demonstrated that Pseudomonas aeruginosa PC-1 can selectively produce 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) from 800 mM HMF, with a yield greater than 90%. In this study, an aldehyde dehydrogenase (PaALDH64) was identified from P. aeruginosa PC-1 for selective HMF oxidation to HMFCA. The HMF tolerance level of E. coli/pET-PaALDH64 was over 300 mM, which was greater than the tolerance levels of all other reported enzymes. The proposed biocatalyst could be used to catalyze the biotransformation of other aldehydic furans, with carboxylic acid yields over 92%. Molecular docking revealed that the catalytic active site cleft in PaALDH64 formed more hydrogen bonds with HMF compared to other enzymes, which stabilized the enzyme–substrate interaction and enhanced the catalytic efficiency. In a fed-batch process, 547.8 mM HMFCA was produced from 600 mM HMF by E. coli/pET-PaALDH64 within 19 h only, which showed an excellent HMF conversion rate. Overall, PaALDH64 constitutes a promising enzyme for the industrial production of HMFCA.

NiFe Layered Double Hydroxide-Derived Catalysts with Remarkable Selectivity for the Oxidation of 5-Hydroxymethylfurfural to 2,5-Furanedicarboxylic Acid under Base-Free Conditions

In this work, we report the exciting discovery of inexpensive and durable catalysts for the selective oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furanedicarboxylic acid (FDCA) under base-free conditions. A nickel-iron layered double hydroxide (NiFe-LDH) precursor was first prepared then subjected to hydrothermal sulfidation with thioacetamide at 120 °C or thermal phosphidation with sodium hypophosphite at 400 °C to produce NiFeS and NiFeP-400 catalysts, respectively. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) showed these catalysts to contain FeNi2S4 and FeNi2P, respectively, as the dominant phases. The catalytic activity of each catalyst was optimized by studying the effect of the solvent, reaction temperature, oxidant, and reaction time on HMF conversions and product distributions. Under optimized conditions (acetonitrile solvent, 120 °C, tert-butanol peroxide as an oxidant, 12 h, respectively), the NiFeS catalyst afforded 100% HMF conversion with an 83.2% FDCA selectivity with the performance of the NiFeP-400 catalyst being almost identical (HMF conversion of 100%; FDCA selectivity of 82.7%). Both catalysts showed excellent stability over five cycles of catalyst tests with the catalysts able to be easily collected after use with a magnet. Based on the experimental findings, the similar reaction mechanisms used are to be proposed for HMF oxidation to FDCA over the two catalysts. Results show that metal sulfide-based and metal phosphide-based catalysts are promising alternatives to traditional noble metal-based catalyst for the valorization of bio-derived HMF.

Enhanced catalysis of a vanadium-substituted Keggin-type polyoxomolybdate supported on the M3O4/C (M = Fe or Co) surface enables efficient and recyclable oxidation of HMF to DFF.

In the reaction of oxidizing 5-hydroxymethylfurfural (HMF), attaining high efficiency and selectivity in the conversion of HMF into DFF presents a challenge due to the possibility of forming multiple products. Polyoxometalates are considered highly active catalysts for HMF oxidation. However, the over-oxidation of products poses a challenge, leading to decreased purity and yield. In this work, metal-organic framework-derived Fe3O4/C and Co3O4/C were designed as carriers for the vanadium-substituted Keggin-type polyoxomolybdate H5PMo10V2O40·35H2O (PMo10V2). In this complex system, spinel oxides can effectively adsorb HMF molecules and cooperate with PMo10V2 to catalyze the aerobic oxidation of HMF. As a result, the as-prepared PMo10V2@Fe3O4/C and PMo10V2@Co3O4/C catalysts can achieve efficient conversion of HMF into DFF with almost 100% selectivity. Among them, PMo10V2@Fe3O4/C exhibits a higher conversion rate (99.1%) under milder reaction conditions (oxygen pressure of 0.8 MPa). Both catalysts exhibited exceptional stability and retained their activity and selectivity even after undergoing multiple cycles. Studies on mechanisms by in situ diffuse reflectance infrared Fourier transform spectroscopy and X-ray photoelectron spectroscopy revealed that the V5+ and Mo6+ in PMo10V2, together with the metal ions in the spinel oxides, act as active centers for the catalytic conversion of HMF. Therefore, it is proposed that PMo10V2 and M3O4/C (M = Fe, Co) cooperatively catalyze the transformation of HMF into DFF via a proton-coupled electron transfer mechanism. This study offers an innovative approach for designing highly selective and recyclable biomass oxidation catalysts.

Mn-doped Ni2P: nanocrystal-decorated amorphous nanosheets for efficient electrooxidation of 5-hydroxymethylfurfural.

A Mn-doped Ni2P electrocatalyst with a unique microstructure of nanocrystal-decorated amorphous nanosheets was, for the first time, reported for the electrooxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). This electrocatalyst demonstrated superior HMF electrooxidation performance with 100% HMF conversion, 98.0% FDCA yield, and 97.8% Faraday efficiency.

Highly dispersed Co anchored on Ce-doped hydroxyapatite as a dual-functional catalyst for selective hydrogenolysis of 5-hydroxymethylfurfural.

Hydrodeoxygenation (HDO) is an indispensable approach to produce renewable biofuels and value-added chemicals using natural biomass and its derivatives. 2,5-Dimethylfuran (DMF) is considered to be a very promising liquid biofuel, and it can be fabricated by HDO of the biomass derivative 5-hydroxymethylfurfural (HMF). Herein, a highly efficient bifunctional catalyst, Co/HAP(Ce), was fabricated by anchoring highly dispersed Co on Ce-doped hydroxyapatite (HAP(Ce)). Co/HAP(Ce) displayed excellent HDO catalytic activity to convert HMF to DMF, and 99% HMF conversion and 96% DMF selectivity can be obtained under 150 °C, 2 MPa H2 conditions for 5 h. Density functional theory calculations revealed that H2 can be more easily activated by Co/HAP(Ce). Systematic studies confirmed that the high activity of Co/HAP(Ce) can be ascribed to the desired acid-alkali properties, highly dispersed cobalt species and strong metal-support interactions. This research provides a cost effective approach for designing efficient catalysts for HDO of biomass and its derivatives.

Identification of catalytic activity descriptors for selective 5-hydroxymethyl furfural electrooxidation to 2,5-furandicarboxylic acid

Relationship between d-metal active species (Co, Ni, & Cu) in Prussian blue analogue derived metal oxide/hydroxide films and the activation energy needed for full conversion of 5-HMF to 2,5-FDCA in alkaline solution.

Spatial charge separation on the (110)/(102) facets of cocatalyst-free ZnIn2S4for the selective conversion of 5-hydroxymethylfurfural to 2,5-diformylfuran

ZnIn2S4has been screened as the best photocatalyst for selective HMF conversion (91.1%) into DFF (99.4% selectivity). The active site retrieval has been found to be an efficent approach to extend the photocatalyst durability.

Photocatalysis of Cr- and Fe-Doped CeO2 Nanoparticles to Selective Oxidation of 5-Hydroxymethylfurfural

Oxygen vacancies (Vo) present in CeO2 nanoparticles (NPs) can effectively boost their photocatalytic activity under ultraviolet (UV) light. To improve photocatalytic performance, Cr- and Fe-doped CeO2 NPs with increased Vo were prepared using a simple method of doping Cr and Fe ions into CeO2 NPs, which was confirmed by an in-depth analysis of the structural and electronic changes. Through photocatalytic degradation (PCD) experiments with 5-hydroxymethylfurfural (HMF), we found that the PCD rates of the two doped CeO2 NPs were faster than that of the CeO2 NPs. In addition, the conversion of HMF to 2,5-furandicarboxylic acid (FDCA) using the doped CeO2 NPs occurred only through the mechanism of the selective oxidation to 5-hydroxymethyl-2-furancarboxylic acid (HMFCA), exhibiting better efficiency than using CeO2 NPs.

Efficient acceptorless dehydrogenation of 5-Hydroxymethylfurfural (HMF) to 2,5-Diformylfuran (DFF) over Pt/CdS under visible light

The selective transformation of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) with coproduction of hydrogen under visible light is appealing yet still challenging. In this manuscript, Pt/CdS nanocomposites obtained via photoreduction of [PtCl6]2- over CdS were found to be an efficient and chemoselective photocatalyst for dehydrogenation of HMF to produce DFF under visible light, with simultaneously generation of stoichiometric hydrogen. An optimum performance was observed over 1.0 wt% Pt/CdS nanocomposite, with a complete conversion of HMF to DFF and stoichiometric hydrogen generated in 14 h. By comparison with the performance over MoS2/CdS, it is revealed that the superior performance for photocatalytic dehydrogenation of HMF over Pt/CdS should be ascribed to the strong interaction between the furan ring in HMF with Pt nanoparticles (NPs), which enables the protons released from HMF to fast transfer to Pt NPs in close vicinity for further reduction to generate hydrogen. This study provides an efficient and green strategy for the simultaneous transformation of biomass-derived HMF to DFF and the production of clean energy hydrogen. This work also highlights the great potential of photocatalysis in biomass valorization.

Unveiling the Adsorption Behavior and Redox Properties of PtNi Nanowire for Biomass-Derived Molecules Electrooxidation.

Ni-based materials are auspicious electrocatalysts for 5-hydroxymethylfurfural oxidation reaction (HMFOR), including the adsorption and conversion of HMF and OHad on the electrocatalyst surface. However, the intrinsic HMFOR activity of Ni-based catalysts is far from satisfactory due to the weak adsorption of HMF and OHad species. Herein, a set of PtxNi100-x bundle nanowires (NWs) were prepared for HMFOR, which enables a low onset-potential and large current density. Operando methods reveal that Pt modulates the redox property of Ni in PtNi NWs and accelerates the oxidation of Ni2+-OH to Ni3+-O species during HMFOR. Moreover, the adsorption studies demonstrate the synergetic roles of Pt and Ni in enhancing the HMFOR activity by forming Pt-O-Ni bonds. In detail, Ni atoms modulate the d band of Pt to alter the adsorption behavior of HMF. Pt atoms promote the adsorption of OHad on Ni sites. This work provides design principles for HMFOR electrocatalysts by modulating the adsorption behaviors of organic molecules and OHad.

Photocatalytic Aerobic Oxidation of Biomass-Derived 5-HMF to DFF over MIL-53(Fe)/g-C3N4 Composite

A MIL-53(Fe)/g-C3N4 heterogeneous composite was synthesized and applied in photocatalytic oxidation of 5-hydroxymethylfurfural (5-HMF) to 2,5-diformylfuran (DFF). The systematic investigation indicated that the introduction of MIL-53(Fe) into g-C3N4 increased the specific surface area, broadened the visible-light response region, and promoted the separation efficiency of the photo-generated electron-hole pairs. The 10% MIL-53(Fe)/g-C3N4 heterogeneous composite achieved the best photocatalytic oxidation activity with 74.5% of 5-HMF conversion under simulated sunlight, which was much higher than that of pristine g-C3N4 and MIL-53(Fe). The MIL-53(Fe)/g-C3N4 composite displayed good photocatalytic reusability and stability. Based on the characterization results and photocatalytic performance, a Z-scheme photocatalytic mechanism of the MIL-53(Fe)/g-C3N4 composite was suggested, and a possible reaction route was deduced.

Complete oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid by a novel enzyme–nanozyme hybrid catalyst

• A robust and efficient nanocatalyst for the cascade oxidation of HMF to FDCA. • Latent activity of AAO on FFCA was activated by the designed nanozyme. • Novel oxidizability of HP-7@Fe 3 (PO 4 ) 2 nanozyme on FFCA was discovered. • A complete conversion of HMF with excellent (100%) selectivity toward FDCA. 2,5-Furandicarboxylic acid (FDCA) is a well-known biobased platform chemical to produce sustainable polyethylene furanoate (PEF) and other valuable furanic chemicals. The eco-friendly enzyme cascade reactions have been adopted to synthesize FDCA using the multistep oxidation of biomass-derived 5-hydroxymethylfurfural (HMF) based on different oxidoreductases. However, the coordination of natural oxidoreductases in cascade reactions presents challenges because of their different adaptabilities and catalytic environments. A robust and efficient catalyst herein was developed by the hybridization of a designed hemin–peptide (HP-7) complex and natural aryl-alcohol oxidase (AAO) in iron phosphate solution to achieve the cascade oxidation of HMF to FDCA. HMF is first transformed in 5-formylfurancarboxylic acid (FFCA) based on the oxidizability of AAO toward benzylic alcohol, and then the latent activity of AAO on FFCA was activated by the catalase activity of the HP-7@Fe 3 (PO 4 ) 2 nanozyme with the in situ consumption of H 2 O 2 initially produced by AAO. Moreover, closer inspection demonstrated the oxidizability of the HP-7@Fe 3 (PO 4 ) 2 nanozyme on FFCA in both the presence and absence of H 2 O 2 for the first time. Consequently, the hybrid catalyst AAO/HP-7@Fe 3 (PO 4 ) 2 enabled the self-activated and efficient oxidation of HMF by integrating multiple reaction processes. A complete conversion of HMF with excellent selectivity (100%) toward FDCA was finally observed.