Hydrogenolysis Reactions Research Articles

Tandem Catalysis for Plastic Depolymerization: In Situ Hydrogen Generation via Methanol APR for Sustainable PE Hydrogenolysis.

Depolymerizing plastic waste through hydrogen-based processes, such as hydrogenolysis and hydrocracking, presents a promising solution for converting plastics into liquid fuels. However, conventional hydrogen production methods rely heavily on fossil fuels, exacerbating global warming. This study introduces a novel approach to plastic waste hydrogenolysis that utilizes in situ hydrogen generated via the aqueous phase reforming (APR) of methanol, a biomass-derived chemical offering a more sustainable alternative. Our results show that a bimetallic Ru-Pt/TiO2 catalyst achieved high conversion (85.1%) and selectivity (81.0%) towards liquid fuels and lubricant oils in a tandem process combining polyethylene (PE) hydrogenolysis and methanol APR. By tuning the metal loading, we identified that Pt enhances hydrogen production through methanol APR, while Ru drives C-C bond cleavage, which is crucial for PE hydrogenolysis. Isotope labeling analysis confirmed that hydrogen generated from methanol APR is effectively utilized in the PE hydrogenolysis reaction. This method was also successfully applied to post-consumer polyolefin waste, with selectivity toward valuable products ranging from 75.0% to 88.9%. This study highlights an innovative strategy to reduce reliance on fossil-fuel-derived hydrogen in plastic waste depolymerization, promoting both sustainability and environmental protection.

Calcination Temperature Impacting the Structure and Activity of CuAl Catalyst in Aqueous Glycerol Hydrogenolysis to 1,2-Propanediol

AbstractThis study investigated the impact of calcination temperature on the structural properties of CuAl catalyst which was found to be a robust nano-structured catalyst calcined directly without ramping at 400 °C and performed exceedingly well for aqueous phase hydrogenolysis of glycerol. Various samples of CuAl catalysts were prepared by co-precipitation at Cu: Al molar ratio 1:1 and were calcined at different temperatures (300–1000 °C). The obtained catalysts were reduced at 200 °C before their activity testing for glycerol hydrogenolysis reaction. To correlate the structure-activity, the catalysts were thoroughly characterized by XRD, XPS, BET, TEM, H2-TPR, NH3-TPD, and pyridine FTIR. It was observed that with an increase in calcination temperature from 300 to 700 °C, the glycerol conversion also increased from 47 to 55% with 93% selectivity to 1,2-PDO. The better performance of these catalysts was mainly related to the predominant presence of Brønsted acid sites, an appropriate ratio of the Cu0 to CuAl2O4 + CuO (0.33) and CuAl2O4 to CuO phases (0.35), the existence of Cu2O phase and the smaller Cu0 particle size. It was shown that altering the ramping rate for the calcination temperature of 400 °C impacted the catalytic activity. The CuAl-400 (DC) (direct calcined) catalyst exhibited a maximum glycerol conversion of 60%.

Enhancing photocatalytic water splitting efficiency of 2D Janus XSSnN2 (X = Cr, Mo, W) monolayers through strain: A first-principles calculation

Two-dimensional Janus materials are renowned for their exceptional photovoltaic properties and have found widespread application in photocatalytic water splitting and solar energy conversion. In this paper, we conducted a comprehensive investigation into the photoelectric properties of Janus XSSnN2 (X = Cr, Mo, W) monolayers and their photocatalytic water decomposition performance, utilizing first-principles calculations and the Heyd-Scuseria-Ernzerhof (HSE06) method. Calculations show that all monolayers are indirect bandgap semiconductors and exhibit remarkable kinetic and thermodynamic stability as well as good oxygen evolution reaction (OER) activity. By applying biaxial strain, each monolayer achieves the photocatalytic band gap requirement of 1.23 eV and satisfies the conditions for OER and HER to proceed spontaneously at −4 %, −4 %, and −1 % strain, respectively. Furthermore, the enlargement of the band gap notably enhances light absorption across the visible and ultraviolet spectra, leading to an improvement in the spectroscopic limited maximum efficiency (SLME). Notably, the hydrogenolysis reaction (HER) on the CrSSnN2 monolayer proceeded spontaneously under light with η′STH up to 36.78 %, exhibiting excellent photocatalytic water splitting performance.

Support induced effects on the activity and stability of Ga2O3 based catalysts for the CO2-assisted oxidative dehydrogenation of propane

The influence of the support nature (Al2O3, TiO2, SiO2) on the activity and stability of supported Ga2O3 (10 wt%) catalysts was investigated for the production of propylene through the CO2-assisted oxidative dehydrogenation of propane (CO2-ODP). Catalytic activity was found to be higher when gallium oxide was dispersed on alumina support which was characterized by the highest acid site density and moderate surface basicity. Below 650 °C propylene yield increased in the order Ga2O3-TiO2<Ga2O3-SiO2<Ga2O3-Al2O3, which was modified as Ga2O3-Al2O3<Ga2O3-TiO2<Ga2O3-SiO2 for higher reaction temperatures. Propylene selectivity decreased with increasing reaction temperature followed by an increase of ethylene and methane selectivity implying that the side reactions of propane hydrogenolysis and propane/propylene decomposition were facilitated at higher temperatures hindering the CO2-ODP reaction. Gallium oxide catalysts supported on TiO2 and SiO2 exhibited sufficient stability for 30-35 hours on stream at 660 and 710 οC, contrary to Ga2O3-Al2O3 which although was stable at 710 οC it was gradually deactivated when the reaction was taking place at 600 °C. Temperature programmed oxidation experiments showed that carbon deposition was favored over Ga2O3-Al2O3 catalyst when the reaction was conducted at low temperature, which may be related to the higher surface acidity of this sample and be responsible for its deactivation with time. SEM images and elemental mapping obtained from both the freshly prepared and used Ga2O3-MxOy samples showed that Ga and M (M: Si, Ti, Al) were uniformly present even after prolonged catalyst interaction with the reaction mixture. EDS analysis indicated that carbon formation was accelerated with increasing reaction temperature.

Water-assisted preparation of Ni/La(OH)3 catalyst for efficient catalytic C-O bond hydrogenolysis of tetrahydrofuran-dimethanol

Due to easy dehydration of La(OH)3 to LaOOH by thermal treatment, it is challenging to prepare highly efficient Ni/La(OH)3 catalyst for hydrogenolysis reactions. Herein, Ni/La(OH)3 (Ni/La-2) catalyst is prepared by thermal reduction of NiO/La(OH)3 in hydrogen flow with vaporized water, while La(OH)3 is partially dehydrated to LaOOH without water vapor affording Ni/(La(OH)3 + LaOOH) (Ni/La-1). Ni/La-2 displays 93 % and 3 % yields of 1,2,6-hexanetriol (HTO) and 1,6-hexanediol (HDO) respectively towards C-O hydrogenolysis of tetrahydrofuran-dimethanol (THFDM) in batch reactor and high stability (200 h) in fixed-bed reactor, which is the best among the reported catalysts to the best of our knowledge. Ni/La-2 possesses pure La(OH)3 as support, enhanced dispersion of Ni species and abundant Niδ+-O-La interfaces in comparison to Ni/La-1, which results in the exceptional catalytic performances in C-O hydrogenolysis of THFDM. A fine control of reaction temperature and time is required to optimize the yields HTO and HDO in hydrogenolysis of THFDM over Ni/La-2. The water-assisted preparation method provides a new perspective for the preparation of La(OH)3 supported metal catalysts.

Synthesis of tamsulosin precursor through palladium nanocatalytic hydrogenolysis: Crystal structure, DFT analysis, and ADME studies

The present work describes a potential method for the synthesis of industrially important Tamsulosine intermediate under milder reaction conditions. The major advantages include i) nano catalytic system and ii) ammonium formate is used as greener alternative during hydrogenolysis with an overall yield of 98 %. Density functional theory (DFT) studies in combination with B3LYP exchange-correlation functional method with split valence basis set 6–311 G is used to understand molecular structure of intermediate is also described. The crystal structure of tamsulosine precursor is elucidated by using single crystal x-ray crystallography is also reported. Therefore, this study is expected to bridge the need to optimize a greener alternative process in this hydrogenolysis reaction to synthesize tamsulosin precursor. ADME studies reveals that better oral bioavailability, aqueous solubility, Gastrointerstinal absorption and option “yes” in Lipinski, Ghose, Veber, Egan and Muegge rules.

Chemical Transformation of Biomass-Derived Furan Compounds into Polyols

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.

Catalytic depolymerization of Camellia oleifera shell lignin to phenolic monomers: Insights into the effects of solvent, catalyst and atmosphere

Camellia oleifera shell (COS) is a renewable biomass resource abundant in lignin with significant potential for producing phenolic monomers. However, the dearth of research has led to considerable resource wastage and environmental pollution. Herein, reductive catalytic fractionation (RCF) of COS was performed using noble metal catalysts in different solvents. An 11.1 wt% yield of phenolic monomers was achieved with 91% selectivity toward propylene-substituted monomers in H2O/EtOH (3:7, v/v) cosolvent under N2 atmosphere. Notably, the highest phenolic monomer yield of 17.0 wt% was obtained with impressive selectivity (86.9%) toward propanol-substituted monomers in the presence of H2. The GPC analysis and 2D HSQC NMR spectra indicated the effective depolymerization of lignin oligomers with catalysts. Phenolic monomers with ethyl, propyl, or propanol side chain could be produced from lignin-derived oligomers through hydrogenolysis, hydrogenation, and decarboxylation reactions. Overall, this study has paved the way for the valorization of COS lignin through the RCF strategy.

Ir-Fe bimetallic catalysts for selective glycerol hydrogenolysis

This work studied the effect of adding Fe to an Ir/γ-Al2O3 catalyst in different Fe/Ir molar ratios (0.5, 1.0, and 2.0) on the conversion and selectivity of the glycerol hydrogenolysis reaction. Additionally, the effect of the calcination of the solids was evaluated. The catalysts were prepared by incipient wetness impregnation of the Ir and Fe salts on the support and were characterized by textural analysis, XRD, TPR, XPS, and TEM-EDS techniques. The interaction between Ir and Fe was evidenced in the characterization of the catalysts. The addition of Fe to the Ir catalyst led to an increase in activity; however, this effect was better observed for the non-calcined catalyst series. The calcined catalyst series did not present a significant increase in glycerol conversion and selectivity to 1,2-PDO, probably due to the sintering of Ir occasioned by the catalyst's calcination, as observed in the characterization. For non-calcined bimetallic catalysts, the conversion increased from 7 % to 21.5 % for IrFe2.0/γ-Al2O3 catalyst, probably due to the synergic effect between both metals and the formation of Ir-Fe bimetallic particles, as evidenced in EDS mapping and XPS analysis. In the presence of this catalyst, selectivity to 1,2-PDO remained high (90.1 %).

Self-hydrogen transfer hydrogenolysis of β-O-4 bonds in lignin model compounds over NiCu/Al2O3 catalyst

Hydrogenolysis of β-O-4 linkages in lignin to produce aromatic compounds is attractive but challenging. Currently, external hydrogen source like hydrogen gas or hydrogen-donor solvent is necessary during hydrogenolysis, leading to high cost and low selectivity of products. Herein, a NiCu/Al2O3 catalyst was prepared for self-hydrogen transfer hydrogenolysis (SHTH) of Cβ-O bond using inherent CαH-OH structure as H-source. A β-O-4 model compound, 2-phenoxy-1-phenethanol, was completely transformed into acetophenone and phenol at 220 ℃ under 1 MPa N2 for 2h. The SHTH reaction proceeded through a dehydrogenation reaction followed by a hydrogenolysis reaction. Hydrogen radicals released from CαH-OH group generated a “hydrogen pool” on the catalyst surface, which inserted into the formed β-O-4 ketone intermediate to cleave the Cβ-O bond. The catalyst presented outstanding reusability and universality during the SHTH reaction. Moreover, the methoxy groups at aryl positions impeded the SHTH process, and the steric effect was related to the amount and position of methoxy groups. This study realizes the utilization of structural hydrogen from lignin model compounds for its Cβ-O bond cleavage, providing an economical and sustainable method toward lignin valorization.

Surface nitrided CuBi2O4 electrocatalysts with excellent selectivity for CO2 reduction to methanol

Developing a high-performance electrocatalyst for converting CO2 into methanol is of utmost importance. However, poor selectivity, and unavoidable competitive hydrogenolysis reaction (HER) are still challenges to be solved. In this study, a surface nitrided strategy was designed to synthesize a series N-copper-bismuth bimetallic oxide electrocatalysts (NCBO-t, t = 1, 2, 4 h) for CO2RR. The electrocatalyst NCBO-2 demonstrated a selectivity for methanol reaching 86.43 %, along with an impressive long-term stability lasting for 11 h, all achieved at a relatively low potential of −0.9 V. Experimental results and density functional theory (DFT) calculations indicated the introduction of nitrogen facilitates methanol production by optimizing binding of the reaction intermediate *OCH while promotes Faradaic efficiency of methanol products by suppressing the competitive HER, resulting in high Faradaic efficiency, current density, and stability of CO2RR at low overpotentials. This study offers a feasible idea for synthesis of high-performance CO2 methanol by electroreduction.

Ring–Opening Mechanism of O‐heterocycles into α,ω‐Diols over Ni−La(OH)3: C−O Bond Hydrogenolysis of THFA to 1,5‐Pentanediol as a Case Study

AbstractThe elucidation of the ring–opening reaction mechanism is a critical step towards improving the catalytic performance for the conversion of biomass into value–added chemicals. Herein, we focused on the stepwise C−O bond hydrogenolysis mechanism of oxygen–containing heterocycles (O‐heterocycles) into α,ω‐diols, in particular THFA to 1,5‐PeD, over selective Ni−La(OH)3 in hydrogen–donor isopropanol. A mechanistic study was carried out on a structurally well–defined Ni−La(OH)3, where the mechanism was elucidated using a combination of kinetic and 13C NMR isotope labeling experiments. It was suggested that both Ni nanoparticles and La(OH)3 support play a critical role in the reaction mechanism, where basic hydroxide species of the support initially deprotonate the CH2OH and −OH modified furan, tetrahydrofuran and tetrahydropyran rings, adsorbing them chemically on the catalyst surface. This step is followed by a direct hydride attack on the second carbon atom of these rings, which is proposed to be the key step for ring cleavage, as indicated by the increased deuteration at this position. In addition to the direct hydrogenolysis using gaseous H2, it is assumed that a catalytic transfer hydrogenolysis reaction (CTH) reaction of THFA is proposed to proceed via the dehydrogenation of isopropanol over isolated Ni species, forming hydrogen species that can be adsorbed on the Ni surface or desorb as H2 molecules.

Hydrolysis-dominated catalytic system: Hydrogen-free hydrogenolysis of lignin from Pd-MoOx/TiO2

Lignin is continuously investigated by various techniques for valorization due to its high content of oxygen-containing functional groups. Catalytic systems employing hydrolysis‑hydrogenolysis, leveraging the synergistic effect of redox metal sites and acid sites, exhibit efficient degradation of lignin. The predominance of either hydrolysis or hydrogenolysis reactions hinges upon the relative activity of acid and metal sites, as well as the intensity of the reductive atmosphere. In this study, the Pd-MoOx/TiO2 catalyst was found to primarily catalyze hydrolysis in the lignin depolymerization process, attributed to the abundance of moderate acidic sites on Pd and the redox-assisted catalysis of MoOx under inert conditions. After subjecting the reaction to 240 °C for 30 h, a yield of 48.22 wt% of total phenolic monomers, with 5.90 wt% consisting of diphenols, was achieved. Investigation into the conversion of 4-propylguaiacol (4-PG), a major depolymerized monomer of corncob lignin, revealed the production of ketone intermediates, a phenomenon closely linked to the unique properties of MoOx. Dehydrogenation of the propyl is a key step in initiating the reaction, and 4-PG could be almost completely transformed, accompanied by an over 97 % of 4-propylcatechol selectivity. This distinctive system lays a new theoretical groundwork for the eco-friendly valorization of lignin.

Predicting hydrogenolysis reaction barriers of large hydrocarbons on metal surfaces using machine learning: Implications for polymer deconstruction

Calculating activation energies of chemical reactions for large reaction networks is computationally demanding. Traditional Brønsted-Evans-Polanyi (BEP) relationships are useful in this regard but are prone to substantial estimation errors. Here, we explore machine learning models to predict activation energies for hydrogenolysis reactions on transition metals, including Ru, Pt, and Rh. The curated dataset includes 380 DFT-calculated activation energies of C-C and C-H scission reactions ranging from C1 to C6 species. The mean absolute error of traditional BEPs is 0.30 eV, and published BEPs on smaller hydrocarbons give even larger errors. In comparison, an XGBoost model achieves a mean absolute error of 0.19 eV for the test set without needing additional DFT-calculated energies. The model selects the homologous series among reactions and the electronegativity and atomic mass of the metal atoms as key features. The model appears transferable across metals. This approach can provide accurate and rapid estimation of activation energies of large reaction networks, such as those in plastics recycling, to accelerate catalyst screening. We showcase the impact of hydrocarbon chain length and branching on the barriers, discuss implications for the depolymerization rate of isotactic polypropylene and low vs. high-density polyethylene, and demonstrate the feasibility of hydrogenolysis catalyst screening.

Coupled conversion of polyethylene and carbon dioxide catalyzed by a zeolite-metal oxide system.

Zeolite-catalyzed polyethylene (PE) aromatization achieves reduction of the aromatic yield via hydrogenation and hydrogenolysis reactions. The hydrogen required for CO2 hydrogenation can be provided by H radicals formed during aromatization. In this study, we efficiently convert PE and CO2 into aromatics and CO using a zeolite-metal oxide catalyst (HZSM-5 + CuZnZrOx) at 380°C and under hydrogen- and solvent-free reaction conditions. Hydrogen, derived from the aromatization of PE over HZSM-5, diffuses through the Brønsted acidic sites of the zeolite to the adjacent CuZnZrOx, where it is captured in situ by CO2 to produce bicarbonate and further hydrogenated to CO. This favors aromatization while inhibiting hydrogenation and secondary hydrogenolysis reactions. An aromatic yield of 62.5 wt % is achieved, of which 60% consisted of benzene, toluene, and xylene (BTX). The conversion of CO2 reaches values as high as 0.55 mmol gPE-1. This aromatization-hydrogen capture pathway provides a feasible scheme for the comprehensive utilization of waste plastics and CO2.

Catalytic hydrogenolysis of polypropylene and polyethylene mixtures: Effect of temperature on liquid alkane components

This study explored the interactions between different polyolefins using a commercial Ru/C catalyst-mediated hydrogenolysis of polypropylene (PP), low-density polyethylene (LDPE), and their mixtures. The effects of the mass ratio of polyolefins to the catalyst, temperature, pressure and time on the yield of products and the internal components of liquid alkane products were studied, and the optimum conditions for solo plastic hydrogenolysis were determined. The highest liquid alkane yields of PP (46.70 %) and LDPE (70.70 %) were obtained at 250 and 210 °C, respectively. Further, the interactions between PP and LDPE during co-hydrogenolysis were observed. The temperature had a significant influence on the gaseous and liquid products, and we proposed a two-step hydrogenolysis reaction process for a mixture of polyethylene with polypropylene conducted at various temperatures. Co-hydrogenolysis provides a high-value utilization path for polyolefins that are difficult to separate during recovery.

Catalytic hydrogenolysis of sorbitol to glycols over chromium oxide silica: Effect of chromium loading

Cr2O3-SiO2 (CrSi) catalysts were prepared using the sol-gel method with varying Cr2O3 loadings (5%, 10%, 15%, 20%, and 25% by weight). The physical properties of the synthesized catalysts were characterized through N2 physisorption analysis, X-ray diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), and Scanning Electron Microscopy (SEM). Additionally, NH3-TPD analysis was employed to assess the acidity of the catalysts. The results indicated the presence of ordered mesopores with uniform pore sizes in the synthesized catalysts. The 20CrSi catalyst exhibited high total acidity, which correlated with its catalytic performance. The catalytic activities of the synthesized samples were tested in the sorbitol hydrogenolysis reaction to produce propylene glycols (PG) and ethylene glycols (EG) in a stirred high-pressure reactor under various process conditions. It was found that 20CrSi catalyst recorded maximum sorbitol conversion (70.08%) at optimum reaction condition. The catalyst was reusable up to 5 times with only a minor activity loss. This work contributes to sustainable and green chemical synthesis from renewable sources, offering insights into catalyst design for efficient glycol production.

Enhanced hydroconversion of polyethylene via dual-functional catalysis: Exploiting ZSM-22 pore-mouth catalysis and Ru electronic effect

The subject of extensive research, the low-temperature hydrocracking of polyethylene reveals the one-step synthesis of iso-alkanes via metal–acid bifunctional catalysis as an emerging strategy. Zeolites, with their superior compatibility with existing petrochemical infrastructure, serve as the acidic supports of choice. In this research, Ru nanoparticles were loaded onto ZSM-22, a zeolite known for its effective pore-mouth catalysis. Mechanical ball milling enhanced the pore-mouth area and the proximity of metal–acid sites, significantly boosting the hydrocracking reaction. The electronic properties of Ru were modified by selecting various Ru precursors and adjusting loading amounts. In-situ infrared studies showed the detachment of olefin intermediates from Ru sites as a critical factor in controlling hydrocracking and the terminal hydrogenolysis reactions. By combining catalyst characterization with reaction barrier calculations from density functional theory (DFT), it was found that oxidized Ru species aid in the release of olefin intermediates, facilitating Brønsted acid-driven β-scission and isomerization reactions. The study achieved a liquid-phase yield exceeding 82 wt% and an iso/n ratio surpassing 60% under low-energy consumption conditions using commercially available catalysts.

Atomically dispersed cobalt catalysts for tandem synthesis of primary benzylamines from oxidized β-O-4 segments.

This work presents an innovative approach focusing on fine-tuning the coordination environment of atomically dispersed cobalt catalysts for tandem synthesis of primary benzylamines from oxidized lignin model compounds. By meticulously regulating the Co-N coordination environment, the activity of these catalysts in the hydrogenolysis and reductive amination reactions was effectively controlled. Notably, our study demonstrates that, in contrast to cobalt nanoparticle catalysts, atomically dispersed cobalt catalysts exhibit precise control of the sequence of hydrogenolysis and reductive amination reactions. Particularly, the CoN3 catalyst with a triple Co-N coordination number achieved a remarkable 94% yield in the synthesis of primary benzylamine. To our knowledge, there is no previous documentation of the synthesis of primary benzylamines from lignin dimer model compounds. Our study highlights a promising one-pot route for sustainable production of nitrogen-containing aromatic chemicals from lignin.

Recent advances in single-atom alloys: preparation methods and applications in heterogeneous catalysis.

Single-atom alloys (SAAs) are a different type of alloy where a guest metal, usually a noble metal (e.g., Pt, Pd, and Ru), is atomically dispersed on a relatively more inert (e.g., Ag and Cu) host metal. As a type of atomic-scale catalyst, single-atom alloy catalysts have broad application prospects in the field of heterogeneous catalysis for hydrogenation, dehydrogenation, oxidation, and other reactions. Numerous experimental and characterization results and theoretical calculations have confirmed that the resultant electronic structure caused by charge transfer between the host metal and guest metal and the special geometric structure of the guest metal are responsible for the high selectivity and catalytic activity of SAA catalysts. In this review, the common methods for the preparation of single-atom alloys in recent years are introduced, including initial wet impregnation, physical vapor deposition, and laser ablation in liquid technique. Afterwards, the applications of single-atom alloy catalysts in selective hydrogenation, dehydrogenation, oxidation reactions, and hydrogenolysis reactions are emphatically reviewed. Finally, several challenges for the future development of SAA catalysts are proposed.