Hydrogenation Of Furfural Research Articles

Optimizing Electrochemical Furfural Hydrogenation on Pt via Bimetallic Colocalization of Cu

Optimizing Electrochemical Furfural Hydrogenation on Pt via Bimetallic Colocalization of Cu

Intensifying Cyclopentanone Synthesis from Furfural Using Supported Copper Catalysts.

This work addresses catalytic strategies to intensify the synthesis of cyclopentanone, a bio-based platform chemical and a potential SAF precursor, via Cu-catalyzed furfural hydrogenation in aqueous media. When performed in a single step, using either uniform or staged catalytic bed configuration, high temperature and hydrogen pressures (180 °C and 38 bar) are necessary for maximum CPO yields (37 and 49 %, respectively). Parallel furanic ring hydrogenation of furfural and polymerisation of intermediates, namely furfuryl alcohol (FFA), limit CPO yields. Employing a two step configuration with optimal catalyst bed can curb this limitation. First, the furanic ring hydrogenation can be suppressed by using milder conditions (i. e., 150 °C and 7 bar, and 14 seconds of residence time). Second, FFA hydrogenation using tandem catalysis, i. e., a mix of β-zeolite and Cu/ZrO2, at 180 °C, 38 bar and 0.6, allows sufficient time for CPO formation and minimises polymerisation of FFA, thereby resulting in 60 % CPO yield. Therefore, this work recommends a split strategy to produce CPO from furfural. Such modularity may aid in addressing flexible market needs.

Pd Nanoparticles Decorated CeZrOx for Enhanced Photocatalytic Hydrogenation of Biomass‐Derived Compounds

The photocatalytic conversion of biomass‐derived compounds into value‐added chemicals presents a promising protocol for the sustainable production of renewable chemicals. Our study explores the hydrogenation of biomass model compounds under visible light illumination. Zr was incorporated into the CeO2 framework, forming a CeZrOx(1:0.5) solid solution, confirmed by powder X‐ray diffraction (PXRD) and X‐ray photoelectron spectroscopy (XPS) analyses. The light uptake capacity of the CeZrOx solid solution was characterized using UV‐visible spectroscopy. Additionally, the band structure of the CeZrOx solid solution was assessed using valance band X‐ray photoelectron spectroscopy (VB‐XPS) and Ultraviolet photoelectron spectroscopy (UPS) analysis, revealing a Z‐Scheme, which was further confirmed by various control experiments. Upon decorating the CeZrOx(1:0.5) solid solution with 1 wt% palladium (Pd), the resulting 1Pd/CeZrOx(1:0.5) composite exhibited improved charge separation and enhanced visible light absorption capacity. This composite achieved ~99% conversion of furfural to tetrahydrofurfuryl alcohol under a 15 W blue LED illumination and 0.2 MPa hydrogen. Similarly, it demonstrated ~99% conversion of benzyl phenyl ether (BPE) to toluene and phenol under a 10 W blue LED illumination. Our findings elucidate the active sites and demonstrate the recyclability of mixed metal oxides for selective furfural hydrogenation and BPE hydrogenolysis under visible light.

Insights Into Electrocatalytic Hydrogenation of Furfural on Nanoparticulate Pd/C Under Acidic Conditions

AbstractIn this work, we present an insight into the mechanism of electrochemical hydrogenation of furfural on carbon supported palladium nanoparticles. By directly coupling electrochemistry with mass spectrometry, we were able to, for the first time, deconvolute the hydrogen evolution reaction and electrochemical hydrogenation by measuring the mass signal for hydrogen and 2‐methylfuran. This approach also allowed us to extract the Tafel slopes for each reaction and get insights into mechanisms. The results indicate that the hydrogenation occurs by a Langmuir–Hinshelwood type process rather than by proton‐coupled electron transfer. Further findings recognize the blocking character of furfuryl alcohol (FA) where the latter or one of its intermediates blocks the electrochemical hydrogenation. Additionally, FA is shown to be a precursor for 2‐methyl furan formation. Accordingly, specific guidelines towards improvement of reaction performance are suggested.

Achieving Product Control in Furfural Hydrogenation Using Intermetallic Catalysts

Achieving Product Control in Furfural Hydrogenation Using Intermetallic Catalysts

Single nickel atoms anchored on porous N-doped nanocarbon with dual reaction sites for highly-efficient transfer hydrogenation of furfural to furfuryl alcohol

The non-precious metal single-atom catalysts (SACs) supported on carbon materials for the catalytic transfer hydrogenation (CTH) of α,β-unsaturated aldehydes (UAL) still suffer from the problems of harsh reaction conditions and low activity. In this work, nickel SACs anchored on porous N-doped nanocarbon (Ni1/NC900) with dual reaction sites were synthesized using the high internal-phase emulsion (HIPE) template method combined with impregnation. The Ni1/NC900 catalyst exhibited remarkable catalytic activity for the CTH of furfural (FF) to furfuryl alcohol (FFA), achieving >99.0 % conversion and selectivity at 100 °C for 60 min, with a turnover frequency (TOF) of 2908.1 h−1, surpassing other reported nickel-based catalysts by 1–3 orders of magnitude. The excellent catalytic performance of Ni1/NC900 was attributed to the high mass transfer efficiency (HMTE) of the support and the dual reaction sites of Ni–N4 and pyridinic N, where Ni–N4 as Lewis acidic site for adsorption of FF and isopropanol (i-PrOH), while the adjacent pyridinic N as Lewis basic site for the deprotonation of i-PrOH. The isotope labeling experiments revealed that the hydrogenation of FF was accomplished by proton transfer with i-PrOH, in agreement with the intermolecular hydride transfer mechanism. Furthermore, Ni1/NC900 demonstrated excellent stability and well general applicability, demonstrating its potential for industrial applications. This work provides a reference for the application of carbon-based non-precious metal SACs in the CTH reaction of UAL.

The hydrogenation of furfural, 5-hydroxymethylfurfural and 5-methylfurfural over platinum and palladium catalysts based on porous aromatic frameworks.

Platinum and palladium catalysts supported on two types of porous aromatic frameworks, PAF-30 and PAF-30-NH2 (modified with amino groups), were examined in furfural hydrogenation. The influence of temperature, reaction time and solvent on selectivity and activity of the catalysts was investigated. Using isopropanol as solvent and conducting experiments at 40 ℃ led to sufficient decrease of side products yields. According to TEM Pt-PAF-30 and Pd-PAF-30-NH2 catalysts are characterized with uniform particles distribution on support. Elemental analysis shows a difference in palladium content between Pd-PAF-30 and Pd-PAF-30-NH2: 4.6% and 6.8% respectively. Whereas platinum catalysts have both 5.4% of metal. Catalyst Pt-PAF-30 was highly selective to tetrahydrofurfuryl alcohol (83% yield), whereas the catalyst Pd-PAF-30-NH2 exhibited unusually high selectivity towards tetrahydrofurfural (77% yield). All studied catalysts were also tested in the hydrogenation of 5-hydroxymethylfurfural and 5-methylfurfural, in these experiments up to 20% yield of 1-hydroxy-4-hexen-2-one was observed.

A Bamboo-structured N-Doped Carbon Nanotubes Encapsulated PdCo Nanoparticles: Synthesis and Catalytic Performance for Furfural Hydrogenation to Furfural Alcohol

A Bamboo-structured N-Doped Carbon Nanotubes Encapsulated PdCo Nanoparticles: Synthesis and Catalytic Performance for Furfural Hydrogenation to Furfural Alcohol

Engineering Active Sites of Metal/Metal Oxide Catalysts by Oxide Ligand Overlayers.

Engineering sites of supported metal catalysts is essential to enhancing activity and selectivity. Such enhancement is typically achieved by particle size modification, surface alloying, or attaching molecular ligands. Yet, control strategies for complex, multifunctional molecules and catalysts, where selectivity is crucial, are lacking. Here, we demonstrate that submonolayer WOx with tunable coverage preferentially decorates well-coordinated Pt terrace sites as a stable ligand. By combining experimental kinetics with probe molecules, in situ spectroscopies, and first-principles modeling, we show that the WOx coverage on Pt modifies the metal-to-acid site balance while retaining the acid strength intact and results in optimal reactivity for metal-acid catalyzed reactions at a specific metal, size, and support-dependent WOx coverage. The oxide can also alter the reactant adsorption mode, reversing selectivity and pathways from terrace- to step-dominated, as evidenced in furfural decarbonylation and hydrogenation. The insights open avenues for improving metal/metal oxide catalysts beyond the specific system.

Engineering Active Sites of Metal/Metal Oxide Catalysts by Oxide Ligand Overlayers

Engineering sites of supported metal catalysts is essential to enhancing activity and selectivity. Such enhancement is typically achieved by particle size modification, surface alloying, or attaching molecular ligands. Yet, control strategies for complex, multifunctional molecules and catalysts, where selectivity is crucial, are lacking. Here, we demonstrate that submonolayer WOx with tunable coverage preferentially decorates well‐coordinated Pt terrace sites as a stable ligand. By combining experimental kinetics with probe molecules, in situ spectroscopies, and first‐principles modeling, we show that the WOx coverage on Pt modifies the metal‐to‐acid site balance while retaining the acid strength intact and results in optimal reactivity for metal‐acid catalyzed reactions at a specific metal, size, and support‐dependent WOx coverage. The oxide can also alter the reactant adsorption mode, reversing selectivity and pathways from terrace‐ to step‐dominated, as evidenced in furfural decarbonylation and hydrogenation. The insights open avenues for improving metal/metal oxide catalysts beyond the specific system.

Selective Hydrogenation of Furfural Under Mild Conditions Over Single-Atom Pd1/α-MoC Catalyst.

The selective activation of C=O bonds was the key challenge in the field of biomass utilization. Researchers worked on this purpose by developing high-active and high-selective catalysts. In this study, a Pd1/α-MoC single-atom catalyst was synthesized and applied in selective hydrogenation of biomass-derived furfural with 96.7 % conversion and 92.4 % selectivity under a near-room temperature. With various characterizations, the formation of Pd single-atom sites over the surface of α-MoC was confirmed. Then, the dominant structure of Pd single-atom site and the reaction pathway were proposed with experimental and Density Functional Theory (DFT) studies. Compared with undecorated α-MoC, the introduction of Pd single-atom species significantly altered the reaction mechanism from Meerwein-Ponndorf-Verley (MPV) process. Moreover, the Pd single-atoms loading on α-MoC(111) surface notably reduced the energy barriers of H2 activation and C=O bond hydrogenation, which may lead to the improving catalytic performance of α-MoC based catalyst. Hence, this investigation could provide a new strategy and understanding for the development of high-active and low-cost catalysts.

Development of Robust CuNi Bimetallic Catalysts for Selective Hydrogenation of Furfural to Furfuryl Alcohol under Mild Conditions

Furfuryl alcohol represents a pivotal intermediate in the high-value utilization of renewable furfural, derived from agricultural residues. The industrial-scale hydrogenation of furfural to furfuryl alcohol typically employs Cu-based catalysts, but their limited catalytic activity necessitates high-temperature and high-pressure conditions. Here, we develop robust CuNi bimetallic catalysts through direct calcination of dried sol–gel precursors under H2 atmosphere, enabling the complete conversion of furfural to furfuryl alcohol under mild conditions. By adjusting the calcination atmosphere and introducing small amounts of Ni, we achieve the formation of highly dispersed, ultrasmall Cu nanoparticles, resulting in a significant enhancement of the catalytic activity. The optimized 0.5%Ni-10%Cu/SiO2-CA(H2) catalyst demonstrates superior catalytic performance, achieving 99.4% of furfural conversion and 99.9% of furfuryl alcohol selectivity, respectively, at 55 °C under 2 MPa H2, outperforming previously reported Cu-based catalysts. The excellent performance of CuNi bimetallic catalysts can be attributed to the highly dispersed Cu nanoparticles and the synergistic effect between Cu and Ni for H2 activation. This research contributes to the rational design of Cu-based catalysts for the selective hydrogenation of furfural.

Highly efficient selective hydrogenation of furfural to tetrahydrofurfuryl alcohol over MOF-derived Co-Ni bimetallic catalysts: The effects of Co-Ni alloy and adsorption configuration

The targeted conversion of furfural (FA) over inexpensive catalyst is a critical and challenging project. Herein, CoNi alloy catalysts (xCoyNi/C) were prepared through one-step pyrolysis of metal–organic frameworks and used in furfural (FA) hydrogenation to tetrahydrofurfuryl alcohol (TFOL). The formation of CoNi alloy leads to a reconfiguration of the electronic structure on the metal surface, which affects the adsorption of functional groups on FA and furfuryl alcohol (FOL). In situ FT-IR analysis and DFT calculations verify that bimetallic CoNi alloy catalyst exhibits more suitable reactants adsorption and hydrogenation rate in comparison with the monometallic Co and monometallic Ni catalysts. Meanwhile, CoNi alloy significantly reduces the activation barrier from FOL to TFOL. Hence, the 1Co1Ni/C catalyst gives the highest TFOL yield of > 99 %. This study provides a simple strategy for the preparation of alloy catalysts for tuning product selectivity and presents practical potential for upgrading biomass-derived platform molecules.

The Role of Frustrated Lewis Pair in Catalytic Transfer Hydrogenation of Furfural using Nickel Single-Atom Catalysts: A Theoretical Study.

The burgeoning field of frustrated Lewis pair (FLP) heterogeneous catalysts has garnered significant interest in recent years, primarily due to their inherent ability to activate H-source molecules, such as H2, thereby facilitating hydrogenation reactions. However, the application of single metal atom catalysts incorporating FLP sites has been relatively under-explored. In this study, non-precious transition metal atoms were anchored onto a C2N framework with an intrinsic cavity and a defective N-C sheet. Theoretical calculations substantiated energy barriers as low as 0.10 eV for isopropanol activation, thereby positioning these catalysts as highly promising candidates for catalytic transfer hydrogenation of furfural. Electronic structure analyses revealed that the H-O bond breakage in isopropanol molecules was significantly facilitated by the presence of FLP sites within the catalysts. Notably, both Ni-C2N and Ni-N6-C demonstrated exceptional potential as selective catalysts for the hydrogenation of furfural into furfuryl alcohol, exhibiting remarkably low barriers of only 0.65-0.72 eV for the rate-determining steps, which are notably lower than those observed in many traditional catalysts. Theoretical investigations strongly imply that the construction of single atom catalysts with FLP sites could significantly enhance the activity and selectivity for hydrogenation reactions, thus stimulating the experimental synthesis of such catalysts.

Unveiling the effects of support crystal phase on Cu/Al2O3 catalysts for furfural selective hydrogenation to furfuryl alcohol

Support crystal phase plays a crucial role in the controlled CO hydrogenation over the supported catalysts. Herein, the effects of Al2O3 crystal phase (α, θ, η, and γ) on the supported Cu-based catalyst is highlighted for furfural (FAL) hydrogenation to furfuryl alcohol (FA). The evaluation results show that Cu/η-Al2O3 exhibits the best performance (FAL conversion: 99.7 %, FA selectivity: 94.0 %), highest TOF value (29.3 h−1) and lowest apparent activation energy (66.3 kJ/mol). The comprehensive characterizations unravel that Cu/η-Al2O3 has the smallest Cu nanoparticles and the highest content of Cu+ and Cu0, which facilitates H2 dissociation and FAL adsorption. The reaction mechanisms suggest that Cu/η-Al2O3 has the strongest FAL adsorption and FA desorption capacity. Moreover, it is demonstrated that FAL is linear chemical adsorption on the catalyst surface in the η1(O) configuration, which avoids the furan ring hydrogenation, and thereby, results in the high FA selectivity. This work would provide some references for developing the high-efficiency CO hydrogenation catalysts.

Alloying and Segregation in PdRe/Al2O3 Bimetallic Catalysts for Selective Hydrogenation of Furfural

X-ray absorption fine structure (XAFS) spectroscopy, temperature-programmed reduction (TPR), and temperature-programmed hydride decomposition (TPHD) were employed to elucidate the structures of a series of PdRe/Al2O3 bimetallic catalysts for the selective hydrogenation of furfural. TPR evidenced low-temperature Re reduction in the bimetallic catalysts consistent of the migration of [ReO4]− (perrhenate) species to hydrogen-covered Pd nanoparticles on highly hydroxylated γ-Al2O3. TPHD revealed a strong suppression of β-PdHx formation in the reduced catalysts prepared by (i) co-impregnation and (ii) [HReO4] impregnation of the reduced Pd/Al2O3, indicating the formation of Pd-rich alloy nanoparticles; however, reduced catalysts prepared by (iii) [Pd(NH3)4]2+ impregnation of calcined Re/Al2O3 and subsequent re-calcination did not. Re LIII X-ray absorption edge shifts were used to determine the average Re oxidation states after reduction at 400 °C. XAFS spectroscopy and high-angle annular dark field (HAADF)-scanning transmission electron microscopy (STEM) revealed that a reduced 5 wt.% Re/Al2O3 catalyst contained small Re clusters and nanoparticles comprising Re atoms in low positive oxidation states (~1.5+) and incompletely reduced Re species (primarily Re4+). XAFS spectroscopy of the bimetallic catalysts evidenced Pd-Re bonding consistent with Pd-rich alloy formation. The Pd and Re total first-shell coordination numbers suggest that either Re is segregated to the surface (and Pd to the core) of alloy nanoparticles and/or segregated Pd nanoparticles are larger than Re nanoparticles (or clusters). The Cowley short-range order parameters are strongly positive indicating a high degree of heterogeneity (clustering or segregation of metal atoms) in these bimetallic catalysts. Catalysts prepared using the Pd(NH3)4[ReO4]2 double complex salt (DCS) exhibit greater Pd-Re intermixing but remain heterogeneous on the atomic scale.

Enhancing the Electrocatalytic Hydrogenation of Furfural via Anion-Induced Molecular Activation and Adsorption.

The electrocatalytic hydrogenation (ECH) of furfural (FF) to furfuryl alcohol, which does not require additional hydrogen or high pressure, is a green and promising production route. In this study, we explore the effects of anions on FF ECH in two buffer electrolytes (KHCO3 and phosphate-buffered saline [PBS]). Anions influence the yield of furfuryl alcohol through molecular activation and adsorption. Molecular dynamics simulations show that bicarbonate is present in the first shell layer of the FF molecule and induces strong hydrogen bonding interactions. In contrast, hydrogen phosphate is present only in the second shell layer, resulting in weak hydrogen bonding interactions. Owing to the interfacial anions and hydrogen bonding, FF molecules exhibit strong flat adsorption on the electrode surface in the KHCO3 solution, while weak adsorption is observed in the PBS solution, as confirmed by operando synchrotron-radiation Fourier-transform infrared spectroscopy and in situ Raman spectroscopy. Density-functional theory calculations reveal that the overall anionic hydrogen bonding network promotes the activation of the carbonyl group in the FF molecule in KHCO3, whereas electrophilic activity is inhibited in PBS. Consequently, FF ECH demonstrates much faster kinetics in KHCO3, while it exhibits sluggish ECH kinetics and a severe hydrogen evolution reaction in PBS. This work introduces a new strategy to optimize the catalytic process through the modulation of the microenvironment.

Construction of Ni−Re Supported on Hydrotalcite‐Derived MgAl Catalysts for Promoting the Ring Hydrogenation of Furfural into Tetrahydrofurfuryl Alcohol in Water

AbstractBiomass‐derived feedstocks play a vital role in sustainable economies for renewable energy, waste management, energy security, and commercial prospects. This study focused on promoting the ring hydrogenation of furfural (FAL) into tetrahydrofurfuryl alcohol (THFA) in an aqueous solution using a potential Ni−Re‐supported hydrotalcite‐derived MgAl catalyst at different Ni : Re molar ratios. Structural analyses, such as an in situ time‐resolved X‐ray absorption near edge structure, under H2 reduction elucidated the simultaneous transformation of Re6+ and Re7+ to Re0 with the remaining highly stable Ni2+. The construction of Ni−Re on hydrotalcite‐derived MgAl catalyst resulted in the alleviated H2 reduction behavior, facilitated H2 adsorption and desorption processes, and suitable catalyst acidity detected by H2 temperature‐programmed reduction, and H2 and NH3 temperature‐programmed desorption experiments, respectively. Under optimized conditions, a maximum THFA yield of 78 % with a complete FAL conversion was attained using Ni1Re0.16/MgO−Al2O3 catalyst at a reaction temperature of 140 °C, H2 pressure of 20 bar, catalyst loading of 20 %, and reaction time of 2 h in a H2O system. Isotopic deuterium (D2O) labeling revealed that D substitution was notably pronounced through isotopic exchange between the D atom from D2O and H atom in FAL during its hydrogenation to THFA.

The Support and Bimetallic Synergy Effects in Cu‐Ni/SiO2 Catalysts for Hydrogenation of Furfural

AbstractHerein, a series of Cu, Ni catalysts were synthesized using mesoporous SiO2 (MCM‐41) and fumed SiO2 as supports for the catalytic hydrogenation of furfural (FF). The MCM‐41 support facilitated the high dispersion of Cu, Ni nanoparticles (NPs), and the hydrogenation products are primarily in the form of alcohols. For fumed SiO2, the proper amounts of acid sites contributed to the better selectivity of 2‐methyltetrahydrofuran(2‐MTHF). Hydrogenation results showed that the 10Cu10Ni/MCM‐41 catalyst afforded a 93.6 % yield of tetrahydrofurfuryl alcohol (THFA), while the 10Cu10Ni/SiO2 catalyst afforded a 61.73 % yield of 2‐MTHF and a 31.63 % yield of THFA. Meanwhile, it is also found that impregnating nickel salt before copper salt is more likely to promote the formation of deep hydrogenation products. Cyclic experiments indicate that developing a one‐step hydrogenation process with selective production of fully hydrogenated products is still a daunting and challenging task.

Synergistic effects of La loading on furfural hydrogenation using wrinkled silica-supported Pd catalysts: Role of partially oxidized Pd and base sites

The catalytic hydrogenation of furfural (FF) to tetrahydrofurfuryl alcohol (THFAL) is complicated by competing hydrogenation reactions involving the carbonyl group and furan ring. To address this challenge, we developed Pd/xLa@wrinkled silica (Pd/xLa@KCC) catalysts exhibiting excellent efficiency via the optimization of La/Si molar ratios, improved Pd dispersion, and stabilization of partially oxidized Pd particles (Pdδ+). These catalysts were designed for the selective hydrogenation of FF to THFAL. Pd/0.2La@KCC, characterized by a high level of oxygen defects, good basicity, and abundant Pdδ+ species, achieved complete conversion and 91.2 % THFAL selectivity at 45 °C within 6 h. Pd/0.2La@KCC exhibited a THFAL formation rate of 100.9 mmol/g/h, 10.8 times higher than that of Pd/0.02La@KCC. Improved Pd dispersion increased the available metallic surface area for H2 dissociations, whereas abundant Lewis-base sites and Pdδ+ species served as adsorption sites for the carbonyl group and furan ring, respectively. The catalyst facilitated the activation and conversion of the furan ring and carbonyl group to THFAL owing to the parallel adsorption geometry of FF. This approach highlights the importance of the surface characteristics of the catalyst for achieving exceptional selectivity and efficiency. Our findings provide valuable insights into the development of advanced catalysts exhibiting excellent selectivity for biomass-derived chemicals.