Hydrogen Transfer Pathway Research Articles

Improving CO2 desorption performance in monoethanolamine solutions by adding titanium pyrophosphate catalyst

Catalytic CO2 desorption has emerged as a crucial strategy for enhancing the efficiency of CO2 capture and reducing energy requirements, thereby advancing chemical absorption methods. This study examines the catalytic effectiveness of titanium pyrophosphate (TiP2O7) in improving monoethanolamine (MEA)-based CO2 absorption and desorption processes, comparing its performance with other titanium-based catalysts, including titanium dioxide (TiO2), titanium tetrahydroxide (TiO(OH)2), and titanium carbide (TiC). In TiP2O7, Ti ions function as Lewis acid sites by accepting electron pairs (LASs), P2O74− anions act as proton carriers, facilitating rapid proton transfer as Lewis base sites (LBSs), and active hydroxyl groups on the surface, resulting from water molecule dissociation or the deprotonation reaction, function as Brönsted acid sites (BASs). These sites work synergistically to accelerate CO2 desorption. TiP2O7 outperforms the other catalysts tested, primarily due to its optimal Brönsted/Lewis (B/L) ratio. This characteristic is particularly advantageous for regenerating RNHCOO−, as the reaction predominantly follows a hydrogen transfer pathway facilitated by the BASs. Consequently, TiP2O7 enhances the CO2 desorption rate by 41.5% at a desorption temperature of 91 °C, while simultaneously reducing the relative heat duty by 13% compared to processes without catalysts.

Heterogeneously Catalyzed Reductive Depolymerization of Lignin to Value-Added Chemicals.

Lignin is an abundant renewable source of aromatics, but its complex heterogeneous structure poses challenges for its depolymerization and valorization. Heterogeneously catalyzed reductive depolymerization (HCRD) has emerged as a promising approach, utilizing heterogeneous catalysts to facilitate selective bond cleavage in lignin and hydrogen transfer to stabilize the products under mild conditions. This review provides a comprehensive understanding of the hydrogen transfer mechanisms in HCRD, involving different hydrogen sources, including molecular hydrogen, alcohols, formic acid, etc., and the native hydrogen donor groups in lignin. The interaction between hydrogen sources and catalyst design is explored, emphasizing how catalyst characteristics must align with specific hydrogen transfer pathways to optimize efficiency and selectivity. Precious metal-based and non-precious metal-based catalysts are examined, highlighting advances that enhance hydrogen activation and transfer. Comparative analyses of hydrogen sources reveal distinct advantages and limitations. The significance of HCRD in lignin valorization and the development of integrated biorefineries is underscored, emphasizing its potential to contribute to a sustainable bioeconomy through improved process integration and economic viability.

Coupling Conversion of CO2 and High‐Carbon Alkane to CO and Gasoline

AbstractCatalytic conversion of CO2 to valuable products is a promising way to reduce anthropogenic CO2 emission. Herein, a strategy for coupling conversion of CO2 and high‐carbon alkane to CO and gasoline is developed, which is a feasible choice for the combination of CO2 recycling and petroleum refining. The CO2 conversion reaches 2.6% under mild condition (270 °C), and the selectivity of gasoline in the cracking products exceeds 70 wt%. Additionally, the introduction of CO2 improves the selectivity of aromatic hydrocarbons and increases the octane number of gasoline. Mechanism studies indicate that synergistic effect between Brønsted acid centers and Ni sites on the Beta zeolite supported Ni (20 wt%) catalyst (20Ni/β) plays the key role in alkane cracking and CO2 reduction. Notably, 13CO2 isotopic experiments show that the hydrogen produced during the aromatization can be captured by CO2, inhibiting undesired hydrogen transfer pathways and enhanced the yield of aromatics, while CO2 is converted into valuable CO.

Hydrogen-donating behavior and hydrogen-shuttling mechanism of liquefaction solvents under Fe- and Ni-based catalysts

The H-donating solvent plays a crucial role in both oil yield and products distribution during direct coal liquefaction. Meanwhile, liquefaction catalyst significantly influences the H-donating behavior of the solvent and the pathways of hydrogen transfer. In view of insufficient understanding on the impact of catalysts on H-donating behavior of solvent and hydrogen transfer pathways in direct liquefaction, in this study, non-H-donating solvents including naphthalene, 1-methylnaphthalene and pyrene (Py) and H-donating solvents including tetralin (THN) and 9,10-dihydroanthracene (DHA) were chosen as the solvents. The Shenhua nano-sized Fe-based and the prepared Ni/Al2O3 catalysts were used to investigate their effect on H-donating behavior of the solvent and H-shuttling mechanism. Results show that liquefaction solvent obviously affects coal conversion and products distribution no matter Fe-based or Ni-based catalyst was used. When non-H-donating solvent is used as liquefaction solvent, coal conversion is lower than that with THN or DHA as solvent. The addition of Py to THN as solvent improves the utilization of effective hydrogen in non-catalytic liquefaction, which is ascribed to hydrogen transfer effect of Py; however, hydrogen transfer mainly occurs through direct combination of gaseous H2 with radicals generated from coal pyrolysis in presence of Fe-based catalyst, with minimal shuttle action of solvent hydrogen. On the contrary, the Ni-based catalyst aids in enhancing the hydrogen shuttle effect of the solvent, and the hydrogen transfer path primarily involves H2 to solvent and then to coal, which is ascribed to good hydrogenation ability of Ni-based catalyst. Under the action of Fe-based catalyst, DHA as liquefaction solvent exhibits lower H-donating capability compared to THN, and approximately 65% of total hydrogen consumption is effectively utilized for coal liquefaction, along with about 35% of total hydrogen consumption for the hydrogenation, ring opening, and side-chain scission reactions of DHA. However, about 96% of total hydrogen consumption is effectively utilized for coal liquefaction when THN used as solvent, indicating that THN as liquefication solvent is more conducive to the transfer of gaseous hydrogen to free radical fragments from coal pyrolysis compared to DHA.

Ionic Route to Atmospheric Relevant HO2 and Protonated Formaldehyde from Methanol Cation and O2.

Gas-phase ion chemistry influences atmospheric processes, particularly in the formation of cloud condensation nuclei by producing ionic and neutral species in the upper troposphere-stratosphere region impacted by cosmic rays. This work investigates an exothermic ionic route to the formation of hydroperoxyl radical (HO2) and protonated formaldehyde from methanol radical cation and molecular oxygen. Methanol, a key atmospheric component, contributes to global emissions and participates in various chemical reactions affecting atmospheric composition. The two reactant species are of fundamental interest due to their role in atmospheric photochemical reactions, and HO2 is also notable for its production during lightning events. Our experimental investigations using synchrotron radiation reveal a fast hydrogen transfer from the methyl group of methanol to oxygen, leading to the formation of CH2OH+ and HO2. Computational analysis corroborates the experimental findings, elucidating the reaction dynamics and hydrogen transfer pathway. The rate coefficients are obtained from experimental data and shows that this reaction is fast and governed by capture theory. Our study contributes to a deeper understanding of atmospheric processes and highlights the role of ion-driven reactions in atmospheric chemistry.

Approach to Low Contact Resistance Formation on Buried Interface in Oxide Thin-Film Transistors: Utilization of Palladium-Mediated Hydrogen Pathway.

Amorphous oxide semiconductors (AOSs) with low off-currents and processing temperatures offer promising alternative materials for next-generation high-density memory devices. The complex vertical stacking process of memory devices significantly increases the probability of encountering internal contact issues. Conventional surface treatment methods developed for planar devices necessitate efficient approaches to eliminate contact issues at deep internal interfaces in the nanoscale complex structures of AOS devices. In this work, we report the pioneering use of palladium thin film as a high-efficiency active hydrogen transfer pathway from the outside to the internal contact interface via low-temperature postannealing in the H2 atmosphere, and the formation of highly conductive metallic interlayer effectively solves the contact issues at the deeply buried interfaces in devices. The application of this method reduced the contact resistance of Pd electrodes/amorphous indium-gallium-zinc oxide (a-IGZO) thin-film by 2 orders of magnitude, and thereby the mobility of thin-film transistor was increased from 3.2 cm2 V-1 s-1 to nearly 20 cm2 V-1 s-1, preserving an excellent bias stress stability. This technology has wide applicability for the solution of contact resistance issues in oxide semiconductor devices with complex architectures.

Synthesis of Dihydroquinoxalinones from Biomass-Derived Keto Acids and o-Phenylenediamines.

A novel catalyst-free cascade amination/cyclization/reduction reaction was developed for the synthesis of various Dihydroquinoxalinones under mild conditions from accessible biomass-derived keto acids and 1,2-phenylenediamines with ammonia borane as a hydrogen donor. This single-step approach enables a simple and eco-friendly route toward the direct synthesis of 12 kinds of Dihydroquinoxalinones in moderate to excellent yields in the green solvent dimethyl carbonate. The results of deuterium-labeling experiments and density function calculations demonstrate that the reductive process proceeds along a double hydrogen transfer pathway. An acceptable yield of Dihydroquinoxalinone can be afforded in a gram-scale experiment, illustrating the practicality of the as-reported reaction system.

Mechanistic insight into the borrowing hydrogen reaction catalysed by a Pd MLC catalyst: unveiling the ligand-to-ligand hydrogen transfer pathway

This theoretical study unveils a novel ligand-to-ligand hydrogen transfer mechanism in the borrowing hydrogen reaction.

Excited state hydrogen or proton transfer pathways in microsolvated n-cyanoindole fluorescent probes.

The sensitivity of the fluorescence properties of n-cyanoindole (n-CNI) fluorescent probes to the microenvironment makes them potential reporters of protein conformation and hydration. The fluorescence intensity of 5-CNI, 6-CNI, and 7-CNI is quenched when exposed to water solvent whereas substitution on position 4 of indoles dramatically increases it. A potential mechanism for this sensitivity to water may be similar to that found in indole. The fluorescence of indole is found to be quenched when interacting with water and ammonia solvent molecules via radiationless decay through an S1 (πσ*)/S0 conical intersection caused by excited state proton or hydrogen transfer to the solvent molecules. In this study we examine this fluorescence quenching mechanism along the N-H bond stretch of n-CNI probes using water cluster models and quantum mechanical calculations of the excited states. We find that n-CNI-(H2O)1-2 clusters form cyclic or non-cyclic structures via hydrogen bonds which lead to different photochemical reaction paths that can potentially quench the fluorescence by undergoing internal conversion from S1 to S0. However, the existence of a high energy barrier along the potential energy surface of the S1 state in most cases prevents this from occurring. We show that substitution on position 4 leads to the highest energy barrier that prevents the fluorophore from accessing these non-radiative channels, in agreement with its high intensity. We also find that the energy barrier in the S1 state of non-cyclic 5-CNI-(H2O)1-2 excited complexes decreases as the number of water molecules increases, which suggests great sensitivity of the fluorescence quenching on the aqueous environment.

Beyond the triple bond: unlocking dinitrogen activation with tailored superbase phosphines.

Activating atmospheric dinitrogen (N2), a molecule with a remarkably strong triple bond, remains a major challenge in chemistry. This theoretical study explores the potential of superbase phosphines, specifically those decorated with imidazolin-2-imine ((ImN)3P) and imidazolin-2-methylidene ((ImCH)3P) to facilitate N2 activation and subsequent hydrazine (H2NNH2) formation. Using density functional theory (DFT) at the M06L/6-311++G(d,p) level, we investigated the interactions between these phosphines and N2. Mono-phosphine-N2 complexes exhibit weak, noncovalent interactions (-0.6 to -7.1 kcal mol-1). Notably, two superbasic phosphines also form high-energy hypervalent complexes with N2, albeit at significantly higher energies. The superbasic nature and potential for the hypervalency of these phosphines lead to substantial N2 activation in bis-phosphine-N2 complexes, where N2 is "sandwiched" between two phosphine moieties through hypervalent P-N bonds. Among the phosphines studied, only (ImN)3P forms an exothermic sandwich complex with N2, stabilized by hydrogen bonding between the ImN substituents and the central N2 molecule. A two-step, exothermic hydrogen transfer pathway from (ImN)3P to N2 results in the formation of a bis-phosphine-diimine (HNNH) sandwich complex. Subsequent hydrogen transfer leads to the formation of a bis-phosphine-hydrazine (H2NNH2) complex, a process that, although endothermic, exhibits surmountable activation barriers. The relatively low energy requirements for this overall transformation suggest its potential feasibility under the optimized conditions. This theoretical exploration highlights the promise of superbase phosphines as a strategy for metal-free N2 activation, opening doors for the development of more efficient and sustainable nitrogen fixation and utilization methods.

Structural Characterization of the Metalized Radical Cations of Adenosine ([Ade+Li-H]•+ and [Ade+Na-H]•+) by Infrared Multiphoton Dissociation Spectroscopy and Theoretical Studies.

Nucleoside radicals are key intermediates in the process of DNA damage, and alkali metal ions are a common group of ions in living organisms. However, so far, there has been a significant lack of research on the structural effects of alkali metal ions on nucleoside free radicals. In this study, we report a new method for generating metalized nucleoside radical cations in the gas phase. The radical cations [Ade+M-H]•+ (M = Li, Na) are generated by the 280 nm ultraviolet photodissociation (UVPD) of the precursor ions of lithiated and sodiated ions of 2-iodoadenine in a Fourier transform ion cyclotron resonance (FT ICR) cell. Further infrared multiphoton dissociation (IRMPD) spectra of both radical cations were recorded in the region of 2750-3750 cm-1. By combining these results with theoretical calculations, the most stable isomers of both radicals can be identified, which share the common characteristics of triple coordination patterns of the metal ions. For both radical species, the lowest-energy isomers undergo hydrogen transfer. Although the sugar ring in the most stable isomer of [Ade+Li-H]•+ is in a (South, syn) conformation similar to that of [Ado+Na]+, [Ade+Na-H]•+ is distinguished by the unexpected opening of the sugar ring. Their theoretical spectra are in good agreement with experimental spectra. However, due to the flexibility of the structures and the complexity of their potential energy surfaces, the hydrogen transfer pathways still need to be further studied. Considering that the free radicals formed directly after C-I cleavage have some similar spectral characteristics, the existence of these corresponding isomers cannot be ruled out. The findings imply that the structures of nucleoside radicals may be significantly influenced by the attached alkali metal ions. More detailed experiments and theoretical calculations are still crucial.

Mechanistic insight into the hydrogen transfer pathway for selective upcycling of PET to arenes

Selective upcycling of waste plastics into value-added chemicals is of great significance for achieving the resource utilization. In the present study, the selective transformation of polyethylene terephthalate (PET) into arenes (benzene, toluene and p-xylene, labeled as BTX) via one-pot reaction in methanol without external hydrogen supply was put forward, which included methanol reforming, PET methanolysis and following in-situ hydrodeoxygenation. Mechanistic insight into the hydrogen transfer pathway in methanol-mediated PET upcycling into BTX over Pt/TiO2 was systematically elucidated. Remarkably, isotope labeling experiments revealed that hydrogen atoms from methanol could be transferred to the aromatic rings, owing to the formation of electron-deficient sites during conjugation. Density functional theory (DFT) calculations further confirmed that the cleavage of C–O bond in PET methanolysis derivatives took precedence over direct saturation of CO bond, followed by in-situ hydrodeoxygenation transformation for the production of BTX. Using Pt/TiO2 as catalyst for H-transfer upcycling of PET in methanol, desirable BTX yield of 77.96% could be achieved after 3 h reaction. The present research will supply a novel perspective for the high-value utilization of waste oxygen-rich plastics via hydrogen transfer manner.

N-Alkylation of Amines by C1-C10 Aliphatic Alcohols Using A Well-Defined Ru(II)-Catalyst. A Metal-Ligand Cooperative Approach.

A Ru(II)-catalyzed efficient and selective N-alkylation of amines by C1-C10 aliphatic alcohols is reported. The catalyst [Ru(L1a)(PPh3)Cl2] (1a) bearing a tridentate redox-active azo-aromatic pincer, 2-((4-chlorophenyl)diazenyl)-1,10-phenanthroline (L1a) is air-stable, easy to prepare, and showed wide functional group tolerance requiring only 1.0 mol % (for N-methylation and N-ethylation) and 0.1 mol % of catalyst loading for N-alkylation with C3-C10 alcohols. A wide array of N-methylated, N-ethylated, and N-alkylated amines were prepared in moderate to good yields via direct coupling of amines and alcohols. 1a efficiently catalyzes the N-alkylation of diamines selectively. It is even suitable for synthesizing N-alkylated diamines using (aliphatic) diols producing the tumor-active drug molecule MSX-122 in moderate yield. 1a showed excellent chemo-selectivity during the N-alkylation using oleyl alcohol and monoterpenoid β-citronellol. Control experiments and mechanistic investigations revealed that the 1a-catalyzed N-alkylation reactions proceed via a borrowing hydrogen transfer pathway where the hydrogen removed from the alcohol during the dehydrogenation step is stored in the ligand backbone of 1a, which in the subsequent steps transferred to the in situ formed imine intermediate to produce the N-alkylated amines.

Stereoselective Pd-Catalyzed Remote Hydroamination of Skipped Dienes with Azoles

AbstractA novel palladium-catalyzed stereoselective remote ­hydroamination reaction is disclosed. A series of azoles and skipped dienes undergo the migratory allylic C–H amination in good yields and selectivities. A desymmetric migratory azolation process is also developed to highlight the reliability of the transformation. Preliminary mechanistic experiments corroborate the designed metal walking and allylic substitution cascade strategy via Pd–H catalysis, different from prior ligand-to-ligand hydrogen transfer pathway for conjugated dienes.

Engineering the hydrogen transfer pathway of an alcohol dehydrogenase to increase activity by rational enzyme design

The reduction catalyzed by an alcohol dehydrogenase (ADH) consists of two steps, hydride transfer (HT) from the NAD(P)H cofactor to the substrate followed by proton transfer (PT) originating from the aqueous solvent. We report a rational enzyme design strategy in the quest to improve the catalytic efficiency of an ADH by targeting appropriately chosen remote residues that function in PT. An ADH from Thermoanaerobacter brockii (TbSADH) was selected as the catalyst involving the enantioselective reduction of a bulky prochiral ketone (4-chlorophenyl)(pyridin-2-yl)-methanone (CPMK). Previous studies demonstrated that the protonated histidine residue H42 in TbSADH plays a key role in PT. In order to explore any change of the HT mechanism possibly affecting enzyme activity, the residue H42 was rationally mutated to other amino acids. After experimental validation, the substitution H42T was found to confer enhanced reduction ability in the transformation of CPMK to the corresponding (S)-configured product with a high activity (kcat/Km = 787.38 s−1 mM−1), a 9-fold increase relative to that of the starting enzyme. We performed molecular dynamics (MD) simulations together with quantum mechanical (QM) calculations which shed light on the origin of the improved activity. It revealed that the enlarged volume of the substrate-binding pocket brought by mutation H42T appears to be the main reason for the increase of activity. QM calculations displayed that the water-linked hydrogen bond network through H42T lead to lower activate energy. Our study indicates that the key residues participating in the catalytic proton transfer process may also serve as hotspots for engineering the activity of ADHs. The detailed information that we have learned about the mechanism can be exploited in the study of other NAD(P)H-dependent dehydrogenases.

Novel insight into the mechanism of coal hydropyrolysis using deuterium tracer method

In this work, the mechanism of coal hydropyrolysis was investigated by using deuterium tracer method. To figure out how hydrogen reacts with coal at the temperature below 400 °C, chars from coal pyrolysis in D2 and N2 atmospheres when the pyrolysis temperature is at 150 to 400 °C were measured by isotope ratio mass spectrometry (IRMS) and electron paramagnetic resonance spectroscopy. The results show that H2 can react with stable radicals in coal during coal pyrolysis without catalyst at temperature as low as 200 °C. To obtain deep insight on which hydrogen transfer pathways affect pyrolysis product distributions of coal, IRMS combined with elemental analyzer and 2H NMR were used to obtain quantitative and qualitative date of deuterium in products. The results suggest that hydrogen atoms are introduced into tar mainly through radicals induce effect during coal pyrolysis without catalyst. And some of non-volatile radicals can abstract hydrogen atoms from H2. Hydrogen atom of H2 can incorporate all structural groups in the tar during coal pyrolysis, and it incorporates preferentially into 1-and 2-ring aromatic carbon and aliphatic carbon in the β or further positions of aromatic ring.

Mechanistic and Kinetic Studies of the Radical Scavenging Activity of 5-O-Methylnorbergenin: Theoretical and Experimental Insights.

5-O-Methylnorbergenin (5-OMB), a natural compound isolated from Rourea harmandiana, is a compound with potential antioxidant activity based on its chemical structure; however, this activity has not been investigated thus far. In this study, the antioxidant activity of 5-OMB was evaluated by experimental and computational methods. 5-OMB exhibited high activity in DPPH (IC50 = 7.25 ± 0.94 μM) and ABTS•+ (IC50 = 4.23 ± 0.12 μM) assays, higher than the reference compound Trolox. The computational results consistently show that 5-OMB is an excellent HOO• radical scavenger (koverall = 8.14 × 108 M-1 s-1) in water at physiological pH, however it only exerts weak activity in lipid medium (koverall = 3.02 × 102 M-1 s-1). The reaction follows the formal hydrogen transfer mechanism in nonpolar solvents, whereas both the sequential proton loss electron transfer and the formal hydrogen transfer pathways contribute to the activity in aqueous solution. There is a good agreement between experimental and computational data, suggesting that 5-OMB is a promising natural radical scavenger in aqueous physiological environment.

Facile Synthesis of a Novel Heterogeneous Rh/COF Catalyst and Its Application in Tandem Selective Transfer Hydrogenation and Monomethylation of Nitro Compounds with Methanol

The development of transition-metal heterogeneous catalysts for economical and effective synthesis of N-methylamine, especially for the monomethylation of amines, is still challenging. Herein, two Rh-supported covalent organic framework (COF) heterogeneous catalysts Rh/MelCOF were facile-synthesized by a Schiff base reaction using melamine as a precursor, and, for the first time, it was successfully applied to the effective and high selective tandem reaction of transfer hydrogenation and monomethylation of nitroaromatic hydrocarbons, with methanol as a C1 and hydrogenation source. A series of nitroaromatic hydrocarbons, including heterocyclic or sterically hindered derivatives, can be well tolerated, and the catalyst could also be reused four times without losing significant reactivity. At the same time, the study of the Rh/MelCOF mechanism supports the hydrogen-borrowing mechanism and puts forward the reaction pathway of azobenzene as an intermediate, which is better than the hydrogen-transfer pathway from N-phenylhydroxylamine to aniline directly. This work expands the application of COF catalysts and provides an effective way to obtain mono-N-methylated amines from nitroaromatic hydrocarbons, as well as the detailed mechanism of Rh/COF-catalyzed tandem transfer hydrogenation and monomethylation of amines.

Oxoberberine: a promising natural antioxidant in physiological environments.

Oxoberberine (OB, 2,10-dihydroxy-3,9-dimethoxy-8-oxo-protoberberine, artathomsonine), which was isolated from Artabotrys thomsonii, was shown to exhibit potent antioxidant activity in vitro, however that is the only reported evidence of the radical scavenging activity of this compound thus far. In the present study, thermodynamic and kinetic calculations were used to determine the free radical scavenging activity of OB against a range of biologically important species, under physiological conditions. In the first part the activity is calculated against the HOO˙ radical that is both biologically important and a reference radical for comparison. It was found that OB has high antiradical capacity against HOO˙ in both lipid medium and water at physiological pH with koverall = 1.33 × 105 and 1.73 × 106 M−1 s−1, respectively. The formal hydrogen transfer mechanism defined the activity in nonpolar environments, whereas in the aqueous solution the single electron transfer competes with the hydrogen transfer pathway. The results showed that, in lipid medium, the HOO˙ trapping capability of OB is better than typical antioxidants such as Trolox, BHT, resveratrol and ascorbic acid. Similarly, the activity of OB in water at pH 7.4 is roughly 19 and 7 times faster than those of Trolox and BHT, respectively, but slightly lower than the activities of resveratrol or ascorbic acid. In the second part, it was found that OB also exhibits high activity against other typical free radicals such as CH3O˙, CH3OO˙, CCl3OO˙, NO2, SO4˙−, DPPH and ABTS˙+ with kf ranging from 2.03 × 105 to 5.74 × 107 M−1 s−1. Hence, it is concluded that OB is a promising radical scavenger in the physiological environment.

Theoretical study on the feasibility of intramolecular hydrogen transfer reaction of 5-hydroxymethylfurfural

• Intramolecular hydrogen transfer reaction (IHTR) mechanism within 5-HMF is proposed. • The feasibility of IHTR reaction on Cu, Pd and Cu 3 Pd 2 was studied by DFT. • The favorable pathways for IHTR reaction on different catalysts were determined. • Cu 3 Pd 2 is predicted to be the most active catalyst for IHTR reaction of 5-HMF. The intramolecular hydrogen transfer reaction (IHTR) of 5-hydroxymethylfurfural can potentially reach a 100% atomic economic efficiency, which is of great significance to the utilization of biomass raw materials. In this work, the feasibility of IHTR on Cu, Pd and Cu 3 Pd 2 bimetallic catalysts was investigated by density functional theory (DFT) calculations. Eight intramolecular hydrogen-transfer pathways, consisting of four elementary reactions each, are proposed. The elementary reactions were categorized and discussed as follows: C-H bond cleavage, C 2 (H)=C 3 hydrogenation, O-H bond cleavage and C 2 =C 3 (H) hydrogenation. The relevant adsorption, activation and reaction energies were calculated and compared. Results reveal that the C-H bond is not easy to break on Cu(111) . On the surface of Pd(111), both the O-H bond cleavage and C=C bond hydrogenation reactions require higher energy barriers to overcome. Cu 3 Pd 2 (111) demonstrates high activity for both hydrogenation and dehydrogenation reactions. The reaction steps of the lowest energy path on Cu 3 Pd 2 (111) involve C-H bond cleavage, C 2 =C 3 (H) hydrogenation, O-H bond cleavage and C 2 (H)=C 3 hydrogenation. The rate-limiting step is the cleavage of the C-H bond, and its activation barrier is 0.89 eV. As a result, the Cu 3 Pd 2 (111) catalyst is predicted to be the most active catalyst for intramolecular hydrogen migration, while the Cu(111) surface is also conducive to the IHTR reaction with slightly higher energy barrier. The calculation results provide valuable theoretical basis for the optimization of experimental research.