Bimetallic metal-organic frameworks(MOFs) possess tunable skeletal structures and synergistic effects between multiple metals, demonstrating significant application potential in the field of catalysis. In this study, Cu2+ and Co2+, which have similar electronic structures and ionic radii, were selected as metal centers to successfully construct a bimetallic CuCo-MOF catalyst, achieving efficient and mild air-mediated epoxidation of cycloalkenes without the addition of external initiators or co-reductants. The Cu0.1Co-MOF-BTC-S-150-24 catalyst prepared via static hydrothermal method was characterized by X-ray diffraction(XRD), field emission scanning electron microscope(FESEM), X-ray photoelectron spectroscopy(XPS) and NH3-temperature programmed desorption(NH3-TPD). Under optimized conditions(using 1,4-dioxane as the solvent, 80 degrees C, 5 h, and air as the oxidant), the catalyst demonstrates excellent catalytic performance in the air-catalyzed epoxidation of 3-methyl-1-cyclohexene, achieving a substrate conversion rate of up to 97.2% and epoxide product selectivity >= 99%. Additionally, the catalyst demonstrates good substrate universality, achieving conversion rates of 79.4% and 80.3% for cyclooctene and 4-vinyl-1-cyclohexene, respectively, with corresponding epoxide product selectivities of 98.0% and 74.3%. After five cycles of use, the catalyst maintains stable catalytic activity, indicating excellent cyclic stability.

The activation of molecular oxygen under mild, additive-free conditions remains a fundamental challenge in the development of sustainable catalytic oxidation processes. Here, we report the rational design and synthesis of a trimetallic Cu2Co3Zr1-MOF-SHM catalyst via a static hydrothermal strategy, which enables the efficient and selective aerobic oxidation of vanillyl alcohol to vanillin using flowing air as the sole oxidant under ambient temperature and pressure. Comprehensive characterization (XRD, FT-IR, XPS, NH3-TPD, SEM) confirms the successful construction of the MOF framework and reveals the structural and electronic roles of each metal component. Mechanistic studies demonstrate that Zr modulates the acidity of the catalyst through enhanced electronic delocalization, while the Cu-Co dual centers work synergistically to promote oxygen activation and selective C-H bond cleavage, collectively driving high catalytic efficiency. The optimized catalyst achieves a vanillyl alcohol conversion of 96.6% with 74.8% selectivity toward vanillin, substantially outperforming monometallic counterparts. Notably, the catalyst maintains >90% of its initial activity after six consecutive cycles, demonstrating excellent stability and recyclability. This work not only provides a robust, non-noble metal catalyst for biomass-derived alcohol oxidation under mild conditions but also offers a blueprint for the design of multimetallic MOF systems for selective aerobic oxidation reactions.

The selective partial hydrogenation of pyridine rings, particularly in functionalized nitrogen heterocycles, remains a significant challenge due to the tendency of conventional catalysts to over-hydrogenate or exhibit poor regioselectivity. Herein, we report a bimetallic PdCo/C catalyst supported on coconut shell carbon (CSC), synthesized via a simple impregnation method, for the selective hydrogenation of methyl nicotinate to methyl 3-tetrahydropyridinecarboxylate (MTPC). Comprehensive characterization by XRD, SEM, and N2 adsorption-desorption confirms the formation of a micro-mesoporous carbon architecture with uniformly dispersed Pd-Co bimetallic particles. Catalytic evaluation reveals a pronounced synergistic effect between Pd and Co, wherein Pd doping modifies the electronic properties of Co and optimizes the catalyst surface for partial hydrogenation. Systematic investigation of metal loading, reaction temperature, and time establishes that the optimized 1%Pd-10%Co/C-350 catalyst achieves complete conversion of methyl nicotinate with 86.0% selectivity toward MTPC under mild conditions (70 °C, 2 h), while successfully preserving the ester functionality. This work demonstrates that bimetallic synergy in PdCo/C provides an effective strategy for controlling chemoselective hydrogenation of pyridine derivatives, offering a promising and sustainable approach for the selective reduction of nitrogen-containing heteroaromatic compounds.

The development of efficient heterogeneous catalysts for olefin epoxidation under sustainable conditions remains a significant challenge. Herein, we report a morphology-controlled synthesis of two monometallic cobalt-based metal-organic frameworks (Co-MOFs) and their application as highly active catalysts for the aerobic epoxidation of mixed olefins. A bulk-type Co-MOF-I was prepared via a static hydrothermal method, while a spindle-shaped Co-MOF-II was obtained through a static mixed-solvothermal method. Both catalysts enable the direct epoxidation of mixed olefins using molecular oxygen (air) as the sole oxidant under mild, additive-free conditions, eliminating the need for reductants, initiators, or energy-intensive activation methods. The catalysts exhibited outstanding activity and selectivity across different olefin combinations. Co-MOF-I achieved 97.1% conversion of alpha-pinene and 98.4% conversion of alpha-methylstyrene with epoxide selectivities >91.0%. Co-MOF-II demonstrated remarkable versatility, delivering >90.0% selectivity in both its native alpha-pinene/styrene system (conversions of 91.3% and 95.3%) and the alpha-pinene/alpha-methylstyrene system (both conversions >98.6%). Furthermore, both Co-MOFs showed excellent structural stability and could be readily recovered and reused for at least five consecutive cycles without appreciable loss in catalytic performance. This work underscores the critical influence of MOF morphology-tunable via synthetic route-on catalytic behavior and presents green, atom-economical, and easily scalable strategy for the epoxidation of olefin mixtures.

The selective hydrogenation of cinnamaldehyde (CAL) to cinnamyl alcohol (COL) is challenging because the hydrogenation of C = C bonds is thermodynamically favored over that of the C = O group. In this work, Ni-3/Fe@CN-x materials prepared by loading metal Ni onto carbon materials derived from Fe-ZIF were successfully used to selectively hydrogenate the C = O bond of cinnamaldehyde, while single metal Ni@CN-x materials derived from Ni-ZIF materials were successfully used to selectively hydrogenate the C = C bond in the side chain of CAL. Both catalysts shows admirable catalytic activity in the selective hydrogenation reaction of CAL. The reaction results show that the introduction of Ni species into Fe@CN-350 material significantly improved the conversion of CAL and the selectivity of COL, which is attributed to the synergistic effect of bimetallic Ni and Fe, and the excellent hydrogenation activity of metallic Ni. The Ni-3/Fe@CN-350 catalytic system can achieved 94.3 % CAL conversion and 86.3 % COL selectivity, and the catalyst could be stably recycled 5 times. Under mild conditions (90 degrees C, 4 h), the single metal Ni@CN-600 catalytic system achieved 100 % CAL conversion and >99 % hydrocinnamaldehyde (HCAL) selectivity, and the catalyst could be stably recycled 10 times.

The activation of oxygen molecules in air has always been a huge challenge, especially under mild conditions. The development of efficient and sustainable catalysts for air activation has attracted widespread attention in recent years. In this study, a novel multi-metal MOF material, Ce1Zr1Co4-MOF-BTC, was designed to activate molecular oxygen in air for the selective oxidative dehydrogenation of high-boiling-point alcohols under mild conditions without additional oxidants, co-catalysts, or additives. The XRD and IR characterizations proved the successful synthesis of this multi-metal MOF material. XPS characterization confirmed the existence of electronic interactions between different metal centers, which is crucial for catalytic performance. The synergistic effects of Co2+ and Ce4+ active sites enabled the efficient activation of oxygen molecules, achieving a remarkable conversion of 1-phenyl ethanol (>99%) and selectivity for acetophenone (>99%). The NH3-TPD and pyridine-IR analyses revealed the regulating effect of Zr on the acidity of the catalyst, and the results of the reaction confirmed that Lewis acids promoted the adsorption and activation of reactant molecules on the catalysts. The Gaussian 09 software with the M06 density functional was used to calculate the HOMO and LUMO energies and electron-charge distribution of molecules. The mechanism of molecular oxygen activation was studied through relevant experiments and characterizations, suggesting a possible pathway involving singlet oxygen species (O-1(2)) and the mutual transformation of valence states (Co2+/Co3+). Recycling experiments and characterizations demonstrated that Ce1Zr1Co4-MOF-BTC has potential for sustainable applications in catalytic air oxidation.

Catalytic oxidation of biomass-derived 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA, an alternative bioplastic monomer to petroleum-derived terephthalic acid), has been identified as an important biomass conversion reaction in bio-based polyester industry. However, it is still challenging to acquire a high FDCA yield from the selective oxidation of HMF at low temperatures. Herein, a ternary metal-based catalyst was prepared by loading AuPdPt noble metal nanoparticles on the oxygen-rich vacancy titanium dioxide layer deposited on natural clay mineral halloysite nanotubes (HNTs), and the catalytic activity was examined for air-oxidation of HMF to FDCA in water at ambient temperature (30 °C). By adjusting the Au/Pd/Pt ratio, a 93.6% FDCA yield was achieved with the optimal Au0.5Pd0.2Pt0.3/TiO2@HNTs catalyst, which revealed an impressive FDCA formation rate of 67.58 mmol g−1 h−1 and an excellent TOF value of 17.54 h−1 under normal air pressure at 30 °C, surpassing the performance of mono- and bimetallic-based catalysts. Theoretical calculation and catalytic performance study clarified the structure–activity relationship. It was found that the ternary metal and oxygen vacancies revealing synergistic enhancement of ambient temperature catalyzed HMF air-oxidation via electronic structure tuning and adsorption intensification. DFT and kinetics study demonstrated that the presence of ternary metal significantly improved the adsorption capacity of substrate and enhanced the rate-determining step of the key intermediate 5-hydroxymethyl-2-furanocarboxylic acid (HMFCA) oxidation when compared to mono- and bimetal. Additionally, the TiO2@HNTs support with high oxygen vacancy concentration facilitated the adsorption of oxygen, synergistically working with the ternary metal to activate and low the energy barriers for the generation of superoxide radical, thus enhancing the FDCA formation. This work offers a novel strategy for designing ternary metal-based catalysts for low-energy catalytic oxidation reactions.

Hydration/hydrolysis of organic compounds are the fundamental reactions to synthesis functional chemicals. In the recent decade, the requirement for catalytic hydration/hydrolysis of organic compounds in aqueous phase without using any organic solvent has begun to increase due to the advantages of green reaction process, mild reaction condition, and so on, in which water acts as not only reactant but also solvent. However, it is noteworthy that bulky and hydrophobic chemicals have accounted for a considerable proportion of organic chemicals. Therefore, efficiently catalytic hydration/hydrolysis of these compounds in aqueous phase have aroused people's great interest. Among various types of heterogeneous catalysts, zeolite-based catalysts have become the focus of research due to their excellent physical and chemical properties. However, for traditional three-dimentional zeolites, the balance between hydrophobicity and acid density are hard to be controlled because that both of them are related with the Si/Al ratio of zeolite framework but in opposite direction, and the steric limitation of micropore is not beneficial for the diffusion and mass transfer of bulky compounds. Herein, sulfonic acid functionalized hollownest-structure zeolite have been prepared and applied in the ring-opening hydration of epoxides and hydrolysis of aryl (or naphthalene) esters, which exhibits efficiently catalytic performance and recycling stability. It is mainly ascribed to its unique structure constructed from the highly intergrowth of MWW zeolite lamellae, over which the compatibility of highly exposed and available acid sites, amphiphilic surface, and hierarchical pores is possible. This work not only provides a applicable route for the catalytic conversion of bulky and hydrophobic organic compounds in aqueous phase, but also is instructive for the construction of zeolite-based solid acids with adjustable acid property.

Amorphous MOFs (a-MOFs) could be highly promising cocatalysts of 3-D alpha-Fe2O3 to greatly improve its photoelectrochemical oxygen evolution performance, but their effective synthesis and assembly on 3-D alpha-Fe2O3 presents formidable challenges. A conformal and ultrathin layer of amorphous Co-TDPAT (a-Co-TDPAT) MOF cocatalyst has been in situ self-assembled on an alpha-Fe2O3 nanosheet array (NSA) by employing 5,5 ',5 ''-(1,3,5-triazine-2,4,6-triyl)tris(azanediyl)triisophthalic acid (H6TDPAT) as the organic ligand. The obtained alpha-Fe2O3 NSA@a-Co-TDPAT core-shell NSA exhibits a photocurrent density of 1.54 mA cm-2 (1.23 V), onset potential of similar to 0.48 V, and photoconversion efficiency of 0.25%, 6.2 times higher, 290 mV lower, and 12.5 times higher, respectively, than those of the alpha-Fe2O3 NSA. The photocurrent density and the photoconversion efficiency are among the highest reported for photoanodes based on the FTO-supported alpha-Fe2O3 NSA without addition of noble metals, and the onset potential is the lowest among those of FTO-supported alpha-Fe2O3-based photoanodes reported. It is discovered that a-Co-TDPAT significantly enhances charge separation and accelerates charge transport and transfer for a fast oxygen evolution reaction, thus greatly boosting PEC oxygen evolution. This work not only provides a novel strategy to produce highly efficient, highly stable, low-cost, and earth-abundant core-shell water splitting photoanodes via in situ self-assembly of conformal, ultrathin a-MOFs on an alpha-Fe2O3 NSA, but sheds light on the mechanisms for controlled self-assembly of MOFs and PEC performance enhancement of alpha-Fe2O3-based photoelectrodes.

Metal-organic frameworks(MOFs), renowned for their adjustable acidity and surface architecture, have garnered significant attention in the realm of heterogeneous catalysis. The present study introduces the design and synthesis of the cobalt-incorporated, shuttle-shaped bimetallic MOF that facilitates the air epoxidation of mixed bi-olefins under water bath heating conditions, effectively overcoming the challenges of bi-olefins reactions under water bath heating. The synthesized material was comprehensively characterized through X-ray diffraction(XRD), scanning electron microscopy(SEM), and X-ray photoelectron spectroscopy(XPS). The cobalt-containing MOFs exhibited the unique capability to catalyze the air epoxidation of bi-olefins in the absence of reducing agents or initiators, achieving a marked enhancement in efficiency when compared to the epoxidation of mono-olefin. N,N-dimethyl formamide(DMF) as the solvent and in a simple water bath with magnetic stirring at 90 degrees C for 5 h, the material demonstrated excellent conversion of 97.0% and 98.8%, respectively, for the mixture of cyclooctene and styrene; concurrently, their epoxide selectivities were found to be 98.4% and 92.7%, respectively. Furthermore, the catalyst has not been deactivated after being recycled for many times, which indicated the good cycle stability of the catalyst.

Niacin is well known not only as vitamin B3 but also as an important chemical, and has wide applications in the fields of food, farming, medicine, pharmaceuticals, and industry. With the rapid development of human society, the requirement for niacin has been increasing constantly worldwide. Meanwhile, development of green routes to produce niacin under mild conditions has become particularly urgent to substitute the conventional reaction process with the consideration of energy conservation and emission reduction. Among various synthesis routes of niacin, selective oxidation of 3-methyl-pyridine and hydrogen peroxide (H2O2) in the liquid phase has become the focus of research due to its distinct advantages, such as mild reaction conditions, environmentally friendly reaction processes, and so on. Herein, zeolite-based catalysts have been first applied in the liquid phase synthesis of niacin from 3-methyl-pyridine and 30%H2O2 under mild reaction conditions. In addition, Cu-based 13X zeolite is found to show the highest catalytic performance, and optimal catalytic reaction systems have been established. This work provides a green and optional route for the synthesis of niacin.

Bimetallic or polymetallic materials often exhibit different catalytic activities due to the interaction between different metal centers compared with monometallic materials. Here, we designed and synthesized a new bimetallic catalyst SnMo-MOF with tin and molybdenum as metal centers by solvothermal synthesis, which could realize the oxidation of diphenyl sulfide (Ph2S) and difurfuryl sulfide (FFS) under mild conditions, and selectively generate sulfoxide and sulfone, respectively. The introduction of Sn enhanced the Lewis acidity of the catalyst surface and the electron transfer between Sn and Mo led to bimetallic synergistic catalysis, which made a great contribution to the high conversion and selectivity of sulfide oxidation. This is reflected in the complete conversion of Ph2S and FFS with 91.8% and 98.1% selectivity of diphenyl sulfoxide (Ph2SO) and difurfuryl sulfone (FFSO2), respectively. The composite material had good substrate adaptability for the catalytic oxidation of other phenyl sulfides and furfuryl sulfides, which opens interesting prospects for the development of new MOF materials as efficient heterogeneous catalysts for the oxidation of thioethers.

The hydrogenation of nitrogen-containing heterocyclic compounds and their derivatives to obtain the corresponding valuable products is of great practical significance. In this work, a highly active and selective Ni/NC hydrogenation catalyst was developed by utilizing melamine-modified high-specific surface carbon (NC) as a carrier for nickel nanoparticles (NPs), which showed excellent catalytic activity in the selective hydrogenation of methyl nicotinate, where the Ni/NC catalyst was first used for this reaction (selective hydrogenation of methyl nicotinate). It was found that nitrogen species on the surface of NC significantly promoted the decomposition of the nickel precursor and the high dispersion of nano-Ni, which effectively affected the agglomeration of the nickel metal, resulting in the distribution of nickel metal with a smaller particle size. In the selective hydrogenation of methyl nicotinate under mild conditions (130 degrees C, 3 h), the conversion of methyl nicotinate reached the optimal catalytic activity over the catalyst of 10% Ni/NC-1-M-I-300, in which the conversion of methyl nicotinate was 98.5% and the selectivity of methylpiperidine-3-carboxylate was 97.2%. After 5 recycles, the catalyst maintained a conversion of 95.4% for methyl nicotinate. The Ni/NC catalyst has good substrate adaptability in the selective hydrogenation of N-heterocyclic carboxylate, O-heterocyclic carboxylate, and aromatic carboxylate.

Ti-containing hollownest-structured zeolite (Ti-HSZ), constructed by the highly intergrowth of MWW lamellar crystals, has been proven to show excellent catalytic performance in the epoxidation of alkenes due to its highly exposed Ti catalytic active sites and unique hollownest morphology. However, up to date, only piperidine is reported to act as the structure directing agent of MWW crystalline phase for the formation of Ti-HSZ, which has limited its application in a wider range. In this work, Ti-HSZ has been successfully synthesized by using dual templates, including hexamethyleneimine as main template and dicyclohexylamine (or piperidine) as secondary template. Systematical experiments, including composition of synthetic gel, rotation rate of autoclave, and time of crystallization, have been conducted to explore the optional synthesis conditions of Ti-HSZ catalyst with high catalytic performance. It is found that, compared with HMI as solely template, the usage of dual templates HMI/PI or HMI/DCHA is important for the synthesis of Ti-HSZ material, which has important influence on its catalytic performance. In addition, the ratio of main template and secondary template also plays an important role on the catalytic activity of Ti-HSZ catalyst. Moreover, Ti-HSZ material prepared by dual templates owes good recycling stability. This work provides a new route to synthesize Ti-HSZ materials with high catalysis activity.

In this paper, the bimetallic ZrCo-MOF materials were synthesized via static hydrothermal synthesis with the introduction of the more acidic metal Zr. The morphological and physicochemical studies demonstrated a successful fabrication of the targeted material, and the catalyst has a three-dimensional hexagonal block lamellar structure. The catalytic performance of the synthesized catalyst was investigated in the limonene epoxidation with air as oxidant without any initiator or co-reducer. Because of the synergistic effect of electron transfer between Zr and Co, the bimetallic ZrCo-MOF catalyst showed limonene conversion significantly higher compared to those of Zr-MOF and Co-MOF. The best catalytic activity of Zr0.7Co3 static -MOF-BTC-S-H-170–24 h was demonstrated, with limonene conversion up to 96.4% and >99% selectivity of the epoxidation products. In addition, the Zr0.7Co3−MOF-BTC-S-H-170–24 h catalyst could be recycled six times without significant reduction of the catalytic activity, indicating the stability of the bimetallic catalyst material under mild reaction conditions. This study provided a foreseeable possibility for obtaining universal synergistic catalysts in industrial heterogeneous catalysis.

As a new type of porous material, porous organic polymers(POPs) is widely used in heterogeneous catalysis because of its unique advantages. In this paper, a series of ZnCo-POPs bimetallic catalytic materials with different compositions were prepared by impregnation method and characterized by means of X-ray diffraction (XRD), field emission scanning electron microscope(FESEM), X-ray photoelectron spectroscopy(XPS), specific surface area and pore size analysis(BET). The Zn0.3Co0.6-POP-250-2 catalyst prepared by impregnation method showed the best catalytic activity. When N,N-dimethyl formamide(DMF) was used as the reaction solvent and the reaction temperature was 90 degrees C for 5 h, 94.3% alpha-pinene conversion and 95.2% epoxide selectivity were obtained, and the catalytic activity of the catalyst did not decrease obviously after being recycled for 5 times, which indicated that Zn0.3Co0.6-POP-250-2 catalyst has excellent catalytic performance and good stability.

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Metal-organic framework materials are composite materials composed of inorganic metal ions and organic ligands,which have high metal dispersion and catalytic activity.In this paper,an organic framework material Mo-MOF was synthesized using molybdic acid as molybdenum source and terephthalic acid as ligand by static mixed solvothermal crystallization method.The morphology,structure and composition of the materials were characterized by X-ray diffraction(XRD),Fourier exchange infrared spectroscopy(FTIR),scanning electron microscopy(SEM)and X-ray photoelectron spectroscopy(XPS).Mo-MOF catalysts synthesized by static mixed solvothermal method(water and ethanol)showed the best catalytic activity,with 100 % conversion of conversion of diphenylthioether and 86.4%selectivity of diphenylsulfoxide in the selective oxidation using oxygen without other additives.