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A scalable, and cost-effective method was employed to prepare self-supported CuSn bimetallic catalyst on carbon paper. The obtained CuSn catalyst demonstrates high faradaic efficiency of CO around or above 90% at a broad potential range from −0.7 to −1.8 V vs. reversible hydrogen electrode, greatly surpassing Cu or Sn counterparts. [ABSTRACT FROM AUTHOR]

Developing high-efficiency electrocatalysts for the hydrogen evolution reaction (HER) is of great importance. In this paper, dendrite-free Ni–Cu catalysts were synthesised via one-step pulse electrodeposition under a weak magnetic field (0.5 T). Regardless of the direction of the magnetic field, the ions were affected by the magnetohydrodynamic (MHD) effect, which greatly promoted the mass transfer and dispersion uniformity, and suppressed the uncontrollable agglomeration by electrodeposition. It was found that the nucleation mechanism changed from progressive nucleation under a 0 T magnetic field to instantaneous nucleation under a 0.5 T magnetic field. Large-scale (325 nm, 0 T) dendrite growth on the single-sided plane was successfully suppressed, and replaced by smaller (90 nm, 0.5 T) and uniformly distributed cluster growth around the carbon paper. In addition, the (111) plane was strengthened by the magnetic field. Electrochemical analysis showed that the Ni–Cu catalysts exposed more surface area and exhibited greatly enhanced catalytic activity, which only needed −57.3 mV to deliver the current density of 10 mA cm−2 with a small Tafel slope of 99.4 mV dec−1 in 1 M KOH. Overall, magneto-electrodeposition, especially under weak magnetic field conditions, provides great promise for the preparation of HER catalysts. [ABSTRACT FROM AUTHOR]

Fe, N co-doped carbon electrocatalyst is one of the most attractive alternatives to Pt/C catalysts due to its high catalytic activity, excellent stability and low cost. However, obtaining stable and efficient Fe, N co-doped carbon oxygen reduction reaction (ORR) catalysts based on simple processes is still a challenge. Herein, Fe, N co-doped porous carbon (Fe–N–C) with an open macroporous frame structure is prepared by using inorganic molten salts (FeCl3·6H2O and ZnCl2) and ethylenediaminetetraacetic acid as the template and nitrogen-containing carbon precursor, respectively. The open pore structure of the Fe–N–C material precisely tailored with the inorganic molten salt template exhibits high specific surface area (676.5 m2 g−1) and appropriate pore size, which can promote oxygen adsorption and expand the oxygen reduction interface, resulting in the acceleration of the electron/charge transfer processes and an improved electrocatalytic performance. The optimized Fe3–N–C-800 electrocatalyst exhibits good catalytic activity for ORR, such as high onset potential of 0.998 V and half wave potential of 0.84 V in alkaline media, as well as high stability and methanol tolerance. Furthermore, a novel Zn–air battery assembled with carbon paper containing Fe3–N–C-800 electrocatalyst as air cathode shows high open-circuit voltage (1.485 V), high specific capacity (870 mA h g−1 at 10 mA cm−2), excellent reversibility and stability. The proposed synthetic strategy provides new opportunities to design and construct carbon frame materials with the desired open macroporous structure to improve their electrocatalytic performance. [ABSTRACT FROM AUTHOR]

CuO/CeO2 catalysts were widely studied as an alternative to precious metal catalysts, and the Cu–Ce synergy was essential to improve the catalytic performance. In this paper, the effects of CuO loading on Cu–Ce synergy in CuO/CeO2 nanorod catalysts and their performance in toluene combustion were systematically investigated. It was found that non-equilibrium plasma facilitated the dispersion of CuO active species on the CeO2 surface. With the increase of the CuO loading from 1 wt% to 4 wt%, the Cu–Ce synergistic effect was gradually improved, which generated Cu+/Cu2+ and Ce3+/Ce4+ redox electron pairs. The highest oxygen vacancy concentration and Cu+ content of CuCe-4 (4 wt%) resulting from strong Cu–Ce synergy accelerated the activation of chemisorbed oxygen and consequently improved the efficiency of toluene catalytic combustion. [ABSTRACT FROM AUTHOR]

Methyltrioxorhenium(VII) (MTO) is a widely employed catalyst for metathesis, olefination, and most importantly, oxidation reactions. It is often preferred to other oxometal complexes due to its stability in air and higher efficiency. The seminal papers of K. B. Sharpless showed that when pyridine derivatives are used as co-catalysts, MTO-catalyzed olefin epoxidation with H2O2 as oxidant, a particularly useful reaction, is accelerated, with pyridine speeding up catalytic turnover and increasing the lifetime of MTO under the reaction conditions. In this paper, combined experimental and theoretical results show that the occurrence of σ-hole interactions in catalytic systems extends to MTO. Four crystalline adducts between MTO and aliphatic and heteroaromatic bases are obtained, and their X-ray analyses display short Re⋯N/O contacts opposite to both O–Re and C–Re covalent bonds with geometries consistent with σ-hole interactions. Computational analyses support the attractive nature of these close contacts and confirm that their features are typical of σ-hole interactions. The understanding of the nature of Re⋯N/O interactions may help to optimize the ligand-acceleration effect of pyridine in the epoxidation of olefins under MTO catalysis. [ABSTRACT FROM AUTHOR]

Chemical catalytic conversion of biomass-derived sugars to lactic acid has attracted considerable attention due to the cheap, abundant and renewable nature of biomass and its huge potential application in the synthesis of biocompatible and biodegradable polylactic acid resins. However, this route is still a huge challenge in view of the transformation efficiency. This paper reports a series of Zn-based catalysts, which are facile and cheap to prepare and highly efficient for the conversion of biomass-derived carbohydrates to ethyl lactate (EL). The microstructure, active site composition and surface properties were characterized by TEM, HRTEM, XRD, NH3-TPD, CO2-TPD, Py-IR, and XPS. The catalytic performance of catalysts in the conversion of biomass-derived carbohydrates to ethyl lactate (EL) and the effect of water content were investigated. It was found that the Zn species played a decisive role in regulating the strengths of the acidic and basic sites to match the rate of each reaction in the tandem reactions. The basic sites are beneficial for isomerization and retro-aldol condensation, while the temperature-responsive released H+ protons are responsible for the dehydration of triose to methylglyoxal, a rate-determining step in the conversion of triose to EL. Addition of a small amount of water could enhance the release of the protons and thus accelerate the dehydration reaction, but excessive water would favor the formation of humins. Using ZnSi-2 as a catalyst under optimal conditions, yields as high as 74.5% of EL from glucose, 81.0% from fructose, 70.9% from mannose, and 80.3% from sucrose could be achieved with tens of times higher productivity than the previously reported values in the literature. DFT calculations revealed that Zn(OEt)Cl, Zn(OH)Cl, and Zn(OH)(OEt) were probably the active components. In addition, the stability of the catalyst as well as the deactivation and regeneration was also studied. The findings in this research provide new insights into the exploration of efficient catalysts for biomass conversion to value-added chemicals. [ABSTRACT FROM AUTHOR]

The development of efficient and stable non-precious-metal-based electrocatalysts is essential for practical water splitting applications. The electrolysis of water for hydrogen production is a green and efficient method, while urea electrolysis can improve energy conversion efficiency. In this paper, W–Ni3S2/NiS catalysts with heterogeneous structures were synthesized via a one-step hydrothermal method using a W-doping-induced phase transition strategy. The doping of W modulates the morphology of the catalyst, which can form uniform nanorod arrays and improve the activity of the electrocatalyst. In an alkaline solution of 1 M KOH and 0.5 M urea, W–Ni3S2/NiS requires a potential of only 1.309 V to achieve a current density of 10 mA cm−2. An electrolyzer containing urea with W–Ni3S2/NiS as both the cathode and anode can drive a current density of 10 mA cm−2 with a potential of only 1.569 V and has relatively good stability after testing for 20 h. Experimental results show that the improvement in the catalytic activity is due to the rapid charge transfer, exposure of more active sites and better conductivity. Density functional theory calculations show that the W–Ni3S2 material exhibits higher urea adsorption energy, indicating that urea is preferentially adsorbed on its surface. The NiS material shows more state density near the Fermi level, indicating that the introduction of this material enhances the conductivity of the W–Ni3S2/NiS material. The synergistic catalysis of the two materials promoted the improvement of the catalytic activity. This work provides new ideas for the development of highly efficient and stable catalysts by means of doping and interface construction. [ABSTRACT FROM AUTHOR]

The production of ammonia under ambient conditions has been a long-standing challenge for the chemical industry. The electroreduction of nitrate presents a promising solution for nitrate wastewater treatment and decentralized ammonia production. However, traditional Ag-based catalysts suffer from nitrate-to-nitrite conversion, leading to toxicity concerns and hampering ammonia preparation. In this study, we synthesized an innovative Ag–Cu–P catalyst that effectively tunes the d-band centre and electronic structure. The catalyst exhibited a remarkable NH4+ yield rate of 566.30 μmol cm−2 h−1 at −0.3 V (vs. RHE), reducing nitrite content to below the drinking water standard. Characterization results revealed a distinctive fern leaf-like morphology, providing an expanded active surface area. The challenge of facile nitrate conversion to nitrite on Ag-based catalysts has been addressed through the implementation of electronic structure modulation in this work. Theoretical calculations confirmed the substantial reduction in the energy barrier by modulating the d-band centre and electronic structure, facilitating the conversion of nitrite to ammonia. The regulation and analysis of d-band centres yielded valuable insights for catalyst material design. Meanwhile, direct evidence for potential intermediates has also been presented through in situ spectroscopy. These findings hold significant potential for practical applications, such as enhanced wastewater treatment and decentralized ammonia production, and provide support in the pressing need for sustainable ammonia synthesis under ambient conditions. [ABSTRACT FROM AUTHOR]

It is of great significance for chemical energy storage devices, especially for the practical application of rechargeable zinc–air batteries (ZABs), to find efficient and economical bifunctional catalysts. Metal–organic frameworks (MOFs) have recently become hot research materials, and are often used as precursors of catalysts. This paper reports a carbon skeleton-coated bimetallic sulfide derived from MOF nanostructures that were used as cathode catalysts for ZABs. The N,S co-doped carbon-loaded FeS2,CoS2 ((Co,Fe)S2/CNS) catalysts exhibit excellent electrochemical properties in alkaline solutions due to the protection of metal sulfides by the carbon structure, the synergy of bimetallic Fe and Co, and the high surface area of the carbon skeleton. (Co,Fe)S2/CNS catalysts show a very low potential difference (ΔE = 0.68 V), a high specific capacity (759.1 mA h g−1) and good charge–discharge cycling performance (360 cycles/120 h) when applied to ZABs. This indicates that the prepared (Co,Fe)S2/CNS catalysts have a broad application prospect in the field of ZABs. [ABSTRACT FROM AUTHOR]

Liquid phase oxidation of 2-methylnaphthalene (2-MN) is a common synthetic route for the preparation of 2-methyl-1,4-naphthoquinone (2-MNQ). Metal-free carbon materials doped with heteroatoms have been proven to have excellent catalytic potential in various reaction fields. In this paper, the catalytic performance of N, F co-doped benzoxazine carbon materials for the selective oxidation of 2-MN was studied. The results show that the catalyst obtained at a carbonization temperature of 700 °C has the best catalytic performance. Under optimized conditions, the 2-MN conversion is 97.9%, and the 2-methyl-1,4-naphthoquinone selectivity is 84.3%. In addition, this catalyst still exhibits good catalytic activity after five cycles. Based on the experimental and characterization results, graphitic nitrogen species play a key role in the catalytic reaction and there is an almost linear relationship between the F content and the selectivity of 2-MNQ. This work provides a greener and more efficient method for the preparation of 2-MNQ with N/F co-doped mesoporous carbon. [ABSTRACT FROM AUTHOR]

In this paper, we compare the reactivity of a series of triaryl borates B(OArx)3 as catalysts for the hydroboration of alkenes and alkynes. It was observed that commercially available B(OPh)3 performed the poorest, whereas catalysts with o-F atoms appeared to perform much better. [ABSTRACT FROM AUTHOR]

In this paper, the effects of Zr, Al or Sr doped Mn/MCM-41 on NH3-SCR activity, SO2/H2O resistance and mechanism were studied. The results showed that Mn/Zr-MCM-41 has 100% NOx conversion at 175–300 °C while Mn/Al-MCM-41 achieves about 94% N2 selectivity at 120–400 °C. Zr doping significantly enhances the resistance to SO2 at 200 °C while Sr plays a negative role. Doped metal does not change the ordered hexagonal arrangement of MCM-41, but can cause the specific surface area enrichment of Mn while Al doping leads to the entry of Mn into the channel of MCM-41. Mn/MCM-41 has only Lewis acid sites, but Zr, Al or Sr doped catalysts have Lewis and Brønsted acid sites. Moreover, the reaction path on Mn/MCM-41 and Mn/Zr-MCM-41 mainly conforms to the L–H mechanism while Mn–Al or Mn–Sr doped catalysts follow L–H and E–R mechanisms. However, the deposited sulfates change the progress of the NH3-SCR process and cause a decline of SCR activity. [ABSTRACT FROM AUTHOR]

In this paper, the effects of sulfuric acid treatment of a ZrO2 support (ZrO2-S) on the Ca resistance of CeO2 catalysts were investigated. The results showed that the CeO2/ZrO2-S catalyst exhibited much better SCR activity and Ca resistance compared with the CeO2/ZrO2 catalyst. To further reveal the Ca resistance mechanism, BET, XRD, Raman, XPS, H2-TPR, NH3-TPD and in situ DRIFTS were used to characterize the changes in structure and properties of the CeO2/ZrO2 and CeO2/ZrO2-S catalysts before and after the Ca deactivation tests. The Ca poisoning of the CeO2/ZrO2 catalysts was mainly due to the decrease in specific surface area and surface acidity, the loss of reducibility and the enhanced stabilization of adsorbed nitrate/nitrite species. The treatment of ZrO2 with sulfate acid led to an increased specific surface area and highly-dispersed Ce species at the catalyst surface. It was also beneficial to inhibiting the transformation of ZrO2 from the tetragonal to the monoclinic phase. Moreover, it also enhanced the redox properties, Ce3+ species ratio, total surface acidity (especially Brønsted acid sites), and adsorption of NH3 species. The SCR reactions via both Langmuir–Hinshelwood (L–H) and Eley–Rideal (E–R) mechanisms could proceed well even after the CeO2/ZrO2-S catalysts were subjected to Ca poisoning. [ABSTRACT FROM AUTHOR]

In this work, the effect of catalyst viscosity on diamond growth was studied by simulating and analyzing the catalyst convection field in a diamond synthesis chamber in different viscous catalyst systems. The results showed that the low-viscosity catalyst had a high convection velocity, fast carbon flow, and large crystal growth volume, but it easily produced defects during long growth times. The convection velocity in the high-viscosity catalyst was slow, the precipitation rate of carbon was moderate, and the crystal quality was good. It is suitable for growing high-quality large-sized diamond single crystals. The structural properties of the synthesized samples were characterized by optical microscopy and Raman spectroscopy. The synthesis experiment and simulation results were consistent. In this experiment, a new viscosity concept is proposed to control the quality of diamond crystals, in which the crystal morphology is controlled by adjusting the flow field in the catalyst. This is not limited to controlling the synthesis of crystals with different morphologies by changing the temperature gradient in the diamond synthesis chamber. Therefore, this paper establishes the characteristics of a convection field suitable for the growth of diamond crystals using different viscous catalysts and provides an important theoretical reference for cavity optimization and the design of flow fields for new catalysts. [ABSTRACT FROM AUTHOR]

Fossil fuels have been increasingly consumed since the industrial revolution, causing rapid increases in carbon dioxide emissions and disrupting the global carbon cycle. With increasing attention being paid to the harmful effects of carbon dioxide as a "greenhouse gas", its use as a feedstock for basic chemical production is an attractive topic. Nature benefits humans through "crops brought by thunderstorms". Combining these two methods to produce urea containing nitrogen is the focus of this paper. In this paper, a series of catalysts supported on the substituted corrole substrates in the form of a double transition metal are investigated by DFT calculations. The best catalyst was selected and combined with carbon and nitrogen reduction to further explore the catalytic performance of urea synthesis. Based on this study, it was found that the synergistic catalytic strategy of double active sites had broad prospects in urea synthesis, and could also provide new development strategies for the design of other efficient molecular catalysts. [ABSTRACT FROM AUTHOR]

In this paper, a Ce-W/TiO2-mSiO2 catalyst was prepared by a co-precipitation method with the addition of silicon acid to enhance and broaden the denitrification (deNOx) efficiency and temperature range of the Ce-W/TiO2 catalyst. The test results of deNOx performance showed that temperature ranges of the 80% and 90% deNOx efficiencies of the Ce-W/TiO2 catalyst with 30% silicic acid were increased by 35 °C and 30 °C, respectively, and the highest deNOx efficiency was increased to 99.53% compared with that without silicic acid. Moreover, the XRD, BET, SEM, XPS, NH3-TPD and H2-TPR analysis revealed that strong water absorption of silicic acid provided more SiO2 for the catalyst to increase its specific surface area. Meanwhile, the volume of a TiO2 cell increased and the crystallinity of CeO2 decreased, which enhanced the number of Lewis and Brønsted acid sites on the catalyst surface and promoted the deNOx reaction. Besides, the ratios of Ce3+ and Oα on the catalyst surface were about doubled with the addition of 30% silicic acid, thus improving the deNOx performance of the catalyst. [ABSTRACT FROM AUTHOR]

Exploring active catalyst components is very important to develop high-performance and highly stable ORR electrocatalysts to replace costly Pt-based catalysts, though it remains an ongoing challenge. In this paper, three ORR catalysts with different active components were obtained by calcination of different proportions of mixed precursors simply and delicately. Among them, precursor 1 (bimetallic polymer Fe/Zn-ZIFs@ZnCO3) played the role of a self-sacrificing template, while precursor 2 (an N, P-co-doped polymer) played the role of a volatile atmosphere. Precursor 2 also embedded N and P heteroatoms into the carbon framework during high-temperature volatilization, which resulted in subtle changes in the active catalyst components. Finally, a hybrid of metal Fe and α-Fe2O3 nanoparticles embedded in N, P-codoped carbon nanotubes with many separated gullies (named α-Fe2O3/Fe@NPC) exhibited excellent ORR catalytic activity in an alkaline solution as compared to commercial Pt/C. This work provides a new strategy for designing controllable active components using volatile precursors. [ABSTRACT FROM AUTHOR]

Although cobalt(I) bis-phosphine complexes have been implicated in many selective C–C bond-forming reactions, until recently relatively few of these compounds have been fully characterized or have been shown to be intermediates in catalytic reactions. In this paper we present a new practical method for the synthesis and isolation of several cobalt(I)-bis-phosphine complexes and their use in Co(I)-catalyzed reactions. We find that easily prepared (in situ generated or isolated) bis-phosphine and (2,6-N-aryliminoethyl)pyridine (PDI) cobalt(II) halide complexes are readily reduced by 1,4-bis-trimethylsilyl-1,4-dihydropyrazine or commercially available lithium nitride (Li3N), leaving behind only innocuous volatile byproducts. Depending on the structures of the bis-phosphines, the cobalt(I) complex crystallizes as a phosphine-bridged species [(P∼P)(X)CoI[μ-(P∼P)]CoI(X)(P∼P)] or a halide-bridged species [(P∼P)CoI[μ-(X)]2CoI(P∼P)]. Because the side-products are innocuous, these methods can be used for the in situ generation of catalytically competent Co(I) complexes for a variety of low-valent cobalt-catalyzed reactions of even sensitive substrates. These complexes are also useful for the synthesis of rare cationic [(P∼P)CoI-η4-diene]+ X− or [(P∼P)CoI-η6-arene]+ X− complexes, which are shown to be excellent single-component catalysts for the following regioselective reactions of dienes: heterodimerizations with ethylene or methyl acrylate, hydroacylation and hydroboration. The reactivity of the single-component catalysts with the in situ generated species are also documented. [ABSTRACT FROM AUTHOR]

In this paper, a Co--Fe LDO catalyst was prepared by combining K2Cr2O7 and Cr(NO3)3 to modify the LDH precursor. The catalytic activity of NOx and o-DCB was systematically studied, and the effect of gas composition on the catalytic activity was investigated. The prepared Cr (0.25)/Co--Fe LDO catalyst showed the best catalytic performance, with conversion efficiencies of NOx and o-DCB of 89.0% and 81.6% at 250 °C, respectively. The catalysts were characterized by XRD, BET, SEM, XPS, H2-TPD and NH3-TPD to explore the reaction activity. In addition, the interaction between NH3-SCR and o-DCB oxidation was investigated by changing the gas atmosphere. The results showed that the inhibition at low temperature (< 200 °C) could be attributed to the residues of the by-products of incomplete oxidation. The further oxidation of NO to NO2, and the dissociation of NH3 are the reasons for the mutual promotion of the two reactions in the middle and high temperature sections. Water vapor has little effect on the reaction and the introduction of SO2 will cause irreversible inactivation of the catalyst. [ABSTRACT FROM AUTHOR]

Due to the synergistic effects of different metal sites, the double atom or multiple atomic catalysts are very promising for use in electrocatalysis. This paper focuses on the synthesis of urea [CO(NH2)2] under the synergistic effects of bimetallics. The heteronuclear diatomic molecular catalysts were designed and screened, and the details and energy information of the elementary reactions were provided from the atomic level using theoretical simulation, which provided a new understanding for the study of the reaction mechanism. It was found that the NbVN6C catalyst was the best catalyst for the electrosynthesis of CO(NH2)2 (0.37 eV < 0.44 eV < 0.67 eV < 0.74 eV < 0.84 eV for NbVN6C, TaVN6C, WVN6C, MoVN6C, ReVN6C, respectively), and the optimal path was * → *N2 → *NN → *NNH → *NNH2 → *HNNH2 → *H2NNH2 → *H2NNH2–CO2 → *H2NNH2–COOH → *H2NCONH2. At the same time, compared with the homonuclear diatomic catalyst V2N6C, the heteronuclear diatomic molecular catalyst NbVN6C had a smaller limiting potential (−0.37 V and −0.59 V), which demonstrated the usefulness of this study. [ABSTRACT FROM AUTHOR]

The synthesis of three N-heterocyclic carbene complexes by stepwise grinding is described in this paper. The benzimidazolium salts ([H2L]Br2 and [H2L](PF6)2 ([H2L] = 1,1′-di(2-picolyl)-3,3′-methylenedibenzoimidazolium)) were initially prepared. Their reactions with Ni(OAc)2·4H2O by grinding afforded three nickel complexes, [NiL]Br2·CH3OH (1), [NiL]Br2·2H2O (1′) and [NiL](PF6)2·0.5CH3CN (2), respectively. A five-coordinated complex [NiLBr]PF6 (3) was further obtained by grinding NH4PF6 with complex 1 or 1′, or grinding KBr with complex 2. Complex 3 can also be obtained by direct grinding of complexes 1/1′ and 2. Complex 3 was subsequently used as a catalyst in the C–S bond cross-coupling of 2-bromoacetophenone and 2-mercaptobenzothiazole. The entire procedure from the synthesis to the catalytic reaction was performed by mechanochemistry. The green metrics E-factor and EcoScale close to ideal values showed the eco-friendly nature of the entire procedure. [ABSTRACT FROM AUTHOR]

The treatment of mercury pollutants in water has been wide concern. Adsorption is a promising method for mercury removal that has been extensively studied. Nevertheless, the secondary application of the immobilized Hg is seldom investigated. In this paper, the Hg adsorption behavior of UiO-66 bearing sulfhydryl groups is studied. The research shows that the porous structure and sulfhydryl groups of UiO-66-SH can effectively promote the removal of mercury from water. In addition, this work also pushes forward the sequential application of the recovered adsorbent, which contains the adsorbed mercury that may cause secondary pollution. The recovered waste adsorbent, UiO-66-S-Hg, was successfully used as an efficient catalyst for transfer vinylation, which produces value-added products, vinyl benzoates. Eight vinyl esters have been successfully synthesized with a yield of up to 89%. This methodology provides a promising way for not only the treatment of mercury contamination, but also secondary pollution protection and the resource utilization of immobilized Hg. [ABSTRACT FROM AUTHOR]

The synthesis of a hierarchical SSZ-13 zeolite with mesopores and micropores is one of the most effective strategies to overcome the diffusion limitation imposed by the micropores of SSZ-13 in reactions involving bulky reactants or intermediates. A zeolite with nanosheet morphology possesses the advantages of large inter-sheet mesopore volume, more accessible acid sites and short diffusion path lengths. Nevertheless, only a few works focused on the synthesis of the nanosheet-assembled SSZ-13 zeolite. In this work, a nanosheet-assembled hierarchical SSZ-13-TP0.03 (thickness of 20 nm) zeolite was synthesized in a seed-assisted synthesis system by coupling a small amount of N, N, N-trimethyl-1-adamantylammonium hydroxide (TMAdaOH) with octadecyl-(3-trimethoxysilylpropyl)-ammonium chloride (TPOAC). In this strategy, the Si/Al ratio of the initial gel, seed, TPOAC and TMAdaOH amount in the synthesis system and the synergistic effects among them lead to the synthesis of SSZ-13 samples with various textural properties and morphologies. The distinct textural properties and morphologies of SSZ-13 result in the preparation of Pt/SSZ-13 catalysts with varied Pt dispersions. The catalyst, Pt supported on the nanosheet-assembled hierarchical SSZ-13 (Pt/SSZ-13-TP0.03), exhibits higher hydrogenation ability than its corresponding catalyst, Pt supported on microporous or hierarchical SSZ-13 in the hydrogenation of naphthalene. [ABSTRACT FROM AUTHOR]

Bi-based materials are promising catalysts for electrochemical reduction of carbon dioxide (CO2) to formate, but remain challenging in terms of activity and stability. Herein, we report the facile synthesis of Zn-doped Bi nanosheets (Zn–Bi NSs) as a highly active and robust catalyst for electrochemical reduction of CO2 to formate. Specifically, the Zn–Bi NS catalyst can be obtained using a hydrothermal method to prepare a Zn-decorated Bi2O2CO3 nanosheet followed by electrochemical reduction treatment. The as-prepared catalyst exhibits a remarkable formate faradaic efficiency of 94.6% and a high formate current density of 40.5 mA cm−2 at −1.2 V vs. reversible hydrogen electrode (RHE). In particular, the faradaic efficiency of formate remained at above 90% over a wide potential window from −0.8 to −1.2 V vs. RHE. In the H-type electrolytic cell, the Zn–Bi NS catalyst can be operated stably for 10 h at a cathode potential of −1.0 V vs. RHE with good retention of the physical phase. [ABSTRACT FROM AUTHOR]

Carbon-supported non-precious metal catalysts with highly exposed active sites have great potential for applications in the hydrogenation reduction of nitro compounds. Herein, a strategy for the preparation of carbon-supported Mo-based catalysts (Mo@C/MC) is proposed. Protein–Mo ion networks are first coated on the surface of microsphere carbons (MC). The coated MC employed as a precursor is then pyrolyzed to produce carbon-supported Mo-based catalysts. Notably, neither pore-forming agents nor post-treatment is required in the preparation of the catalyst. The active sites tend to disperse uniformly on the surface of the carbon matrix, facilitating the exposure of the active sites of the catalyst. The as-prepared catalyst Mo@C/MC shows high conversion (>99%) and selectivity (>98%) for the hydrogenation of nitro compounds under mild reaction conditions (100 °C, 5 bar H2). [ABSTRACT FROM AUTHOR]

Developing low-cost and efficient catalysts for the oxidation of formaldehyde (HCHO) is crucial for preservation of the environment. The main challenge of this study is how to develop an efficient, stable, and inexpensive catalyst that can oxidize HCHO at low temperatures. Herein, the reduced Mn-doped cobalt tetroxide R-MnxCo3−xO4 catalyst was prepared by simple co-precipitation and annealing treatment followed by reduction of NaBH4. The prepared R-MnxCo3−xO4 showed remarkable enhanced activity for HCHO oxidation at low temperature. The R-MnCo2O4 catalyst can oxidize and decompose 79% of HCHO at a low temperature of 50 °C and exhibits excellent catalytic stability. The improved catalytic activity can be attributed to the increase in oxygen vacancy concentration and the improvement in redox performance. The TGA test shows that the content of oxygen vacancies in the R-MnCo2O4 catalyst can reach 5.77% (atomic ratio). The H2-TPR, O2-TPD and O2-TPO tests indicated that the surface oxygen vacancies can promote oxygen mobility and facilitate the formation of reactive oxygen species during the formaldehyde catalytic oxidation process. This study reveals the importance of surface oxygen vacancies in improving the catalytic oxidation activity of catalysts, providing possibilities for the development of high-performance catalysts through atomic doping and reduction modification. [ABSTRACT FROM AUTHOR]

The present study is focused on the synthesis of DHPMs by using NiCoSe2 and NiCo2S4 as heterogeneous catalysts, and they are characterized by using XRD, SEM, TEM, BET and XPS. The NiCoSe2 and NiCo2S4 catalysts proved to be the most suitable catalytic system when compared to conventionally reported catalysts in terms of yield and reaction time. NiCoSe2 and NiCo2S4 are environment-friendly catalysts and can be recycled over 5 cycles with a negligible loss in the catalytic performance. Thus, the synthesized catalysts were successfully utilized in the synthesis of biologically active DHPMs, and all compounds were characterized using mass and NMR spectroscopic techniques. [ABSTRACT FROM AUTHOR]

A potassium (K)-promoted Ru-based siliceous molecular sieve catalyst, K-nRu-MCM-41, was successfully synthesized via a hydrothermal method. The combined analysis of XRD, FT-IR and XPS data revealed that Ru exists in the framework of the molecular sieves as RuO2 species, leading to structural alterations. SEM and TEM images demonstrated that Ru doping disrupts the morphology of the molecular sieves, while K addition effectively preserves the original morphology and further enhances particle dispersion. The ammonia decomposition performance test indicated that K promotes the activity of the molecular sieve catalysts. At 450 °C and 12 000 mL gcat−1 h−1, K-4Ru-MCM-41 achieved 82.7% ammonia conversion and 253.6 mmol gRu−1 min−1 hydrogen production, respectively, which was a 7.6% increase in ammonia conversion compared with 4Ru-MCM-41. Furthermore, the K-4Ru-MCM-41 catalyst exhibited excellent reusability, maintaining its stable catalytic activity performance after 30 h. [ABSTRACT FROM AUTHOR]

A series of SO42−/TiO2 solid superacid catalysts were prepared under different conditions. The effect of different preparation conditions on the SO42−/TiO2 catalyst was investigated by evaluating the change of its crystallinity, chemical structure and acid content. The catalytic performance of the SO42−/TiO2 catalyst was evaluated by α-pinene isomerization in a continuous fixed bed reactor. When ammonia was used as the precipitation agent, the concentration of sulfuric acid impregnation solution was 2 M, and the calcination temperature was 500 °C, the activity of the SO42−/TiO2 catalyst reached the maximum, the conversion rate of α-pinene was stable at about 95%, and the selectivity of camphene reached 40%. It was found that the structure and textural properties of the SO42−/TiO2 catalyst did not change significantly after regeneration by studying the regeneration performance of the SO42−/TiO2 catalyst. [ABSTRACT FROM AUTHOR]

This study presents a pioneering nanohybrid catalyst featuring hierarchically porous dual-functional (acid–base) active sites, which is a versatile catalyst for the crucial bio-glycerol acetalization reaction. The nanohybrid catalyst demonstrated remarkable efficiency in converting bio-diesel derived waste glycerol into excellent green fuel additive 'solketal,' achieving an unprecedented yield of approximately 99%. Insights into the structural properties and the relationship between the structure and properties of the catalyst were obtained through various characterization techniques, including FTIR spectroscopy, XRD, NH3-TPD, CO2-TPD, 27Al-NMR spectroscopy, SEM, TEM, UV-Vis spectroscopy, and X-ray photoelectron spectroscopy. The hybrid catalyst shows several highly desirable properties, including enhanced acidity, a strong affinity for reactants, mesoporosity, stability, and the proximity of potent acidic and basic sites. Simplicity, cost-effectiveness, exceptional recyclability, and resistance to moisture make the synthesized MgAl-oxide/HZSM-5 (MAZ) nanohybrid catalyst an appealing candidate for potential commercial applications in bio-refinery processes. [ABSTRACT FROM AUTHOR]

Non-precious metal catalysts play a significant role in the field of hydrogenation. This study synthesized Co-BTC from cobalt nitrate hexahydrate and 1,3,5-tricarboxylic acid benzene. By changing the calcination temperature of Co-BTC in an inert atmosphere, a series of novel non-precious metal Co/C microsphere catalysts were successfully prepared. The composition and structure of the Co/C-n catalysts were characterised by FESEM, TEM, XRD, IR, XPS and BET. These results confirm that 1,3,5-benzenetricarboxylic acid provides a rich carbon matrix and metallic Co nanoparticles are generated by self-reduction on the carbon matrix. The graphite matrix formed during the calcination process has a rich pore structure and good dispersion of active components on the catalyst surface, which is very favourable for the catalytic reaction. In the hydrogenation of o-chloronitrobenzene (o-CNB) to o-chloroaniline (o-CAN), the Co/C-500 catalyst showed the best catalytic performance. At 80 °C and 2 MPa H2 for 60 minutes, the conversion rate of o-CNB reached 99% and the selectivity reached 99%. When the reaction takes 5 minutes, the conversion rate reaches 10.5%, and the TOF value reaches 36.3 h−1. The Co/C-500 catalyst can be easily recycled and reused after reaction with the help of a magnetic field. Moreover, this catalyst is also effective in the selective hydrogenation of other nitroaromatic hydrocarbons containing halogen or unsaturated groups to corresponding aniline. This simple and direct synthesis method may lead to the economic production of large-scale Co/C catalysts, which is an attractive prospect for the industrial trial production of corresponding aniline. [ABSTRACT FROM AUTHOR]

Designing an efficient zeolite-introduced novel Fe-based catalyst is essential for the direct production of gasoline fuels via coupling Fischer–Tropsch synthesis (FTS) and catalytic cracking reactions. Herein, we constructed a novel Fe2O3 cage catalyst with a hierarchical porous structure, which served as FTS sites for physically mixing with porous ZSM5 to provide catalytic cracking sites. The hybrid Fe + ZSM5(27) catalyst achieved an excellent gasoline fuel (C5–C11) selectivity of 62.7 wt%, outperforming traditionally supported and physically mixed catalysts. Moreover, the aromatic content was 22.1% in terms of C5+ hydrocarbons, which was within the range of the restricted aromatic content. The enhanced catalytic performance can be attributed to the Si/Al ratio governing the oligomerization reaction. ZSM5 with a suitable Si/Al ratio can promote the oligomerization of C2–C4 olefins to produce desired C5–C11 hydrocarbons. Fe + ZSM5(27) with a Si/Al ratio of 27 demonstrated a prominent CO conversion of 93.6% with a higher C5–C11 selectivity of 62.7 wt%. This work provides a promising strategy for designing multifunctional catalysts to modulate product distribution. [ABSTRACT FROM AUTHOR]

Ni-based catalysts have been considered as an efficient anode material for urea fuel cells due to their low cost and high activity in alkaline media. Ni2P/NiCo2S4 catalyst grown on nickel foam was synthesized by hydrothermal synthesis and solid phosphating. The cathode material Pt/C was prepared using the drop-coating method, which has good oxygen reduction reaction (ORR) activity. H-type urea/O2 fuel cell was assembled and showed high energy density in alkaline solution at room temperature. X-Ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy-dispersive spectroscopy (EDS) were employed to characterize the Ni2P/NiCo2S4/NF catalyst. Results confirmed the formation of 3D flower-like microspheres from Ni2P/NiCo2S4/NF catalyst nanosheets. Electrochemical testing results indicated that the Ni2P/NiCo2S4/NF catalyst-decorated electrode can effectively promote urea oxidation and plays a leading role in improving the performance of fuel cells in 1 M KOH + 0.33 M urea. The H-type urea/O2 fuel cell possesses a high power density of 0.42 mW cm−2 at a cell potential of 0.45 V. To summarize, this study introduces a cheap but efficient electrode material as an anode catalyst for constructing urea fuel cells. [ABSTRACT FROM AUTHOR]

Mg–Ba mixed oxide catalysts are synthesized using the co-precipitation method by varying the molar compositions of MgO and BaO. The catalysts' surface/structural properties are characterized by N2 physisorption, PXRD, CO2-TPD, FT-IR spectroscopy, X-ray photoelectron spectroscopy, and laser Raman spectroscopy. The characterization results showed that the insertion of Mg2+ into the BaO lattice results in the generation of stable mixed oxide solid solutions. These catalysts are evaluated for continuous glycerol transesterification with dimethyl carbonate to yield glycerol carbonate under solvent free and atmospheric pressure conditions. The activity of catalysts mainly relied on strong basic centres (c-MgO) originating from Mg and Ba of different molar ratios and the catalyst with a 3 : 1 molar ratio exhibited an excellent glycerol carbonate yield of up to 70% with nearly 100% selectivity. The activities of the catalysts are well explained based on their surface-structural integrity. The catalysts exhibited exceptional stability during the time on stream study over a period of 100 h. [ABSTRACT FROM AUTHOR]

Direct methanol fuel cells (DMFC) are a promising new energy source. However, the lack of high-performance and low-cost methanol oxidation electrocatalysts hinders their commercial application. Firstly, we successfully prepared NENU-5-derived molybdenum carbide material (Cu-MoC) via a co-precipitation and high-temperature carbonization method using a material composed of a copper-based metal–organic skeleton and a molybdenum-based carbide as the main body. Secondly, PtCu nano-alloy catalysts (Pt/Cu-MoC) were prepared using a unique, spontaneous single replacement reaction after metal–organic skeleton (MOF) carbonization. Through the synergistic effect between Pt and Cu and the strong interaction between Mo2C and PtCu, the electronic structure of the Pt is modified, the energy of the d-band center is reduced, electron exchange is accelerated, and catalytic activity is enhanced. Compared with a commercial Pt/C catalyst in alkaline environments, the Pt0.10/Cu-MoC catalyst has a better MOR catalytic activity (563.25 mA mgPt−1), which is 1.5 times higher than that of commercial Pt/C (376.67 mA mgPt−1). The Pt0.10/Cu-MoC catalyst has an onset potential for CO oxidation that is 16 mV lower than that of commercial Pt/C, indicating better resistance to CO poisoning. Exploring carbon materials derived from MOFs with excellent junction support and using them as carriers to prepare Pt-based catalysts is a practical and feasible approach. It provides a way to develop new Pt-based catalysts that perform efficient MOR. [ABSTRACT FROM AUTHOR]

Oxidative esterification of furfural to methylfuroate was conducted in base-free medium over Au catalysts supported on ZrO2, CeO2, TiO2, ZnO and Al2O3, and the Au/Al2O3 catalyst exhibited a higher activity than the other prepared catalysts. The characterization results of these Au catalysts showed that the Au/Al2O3 catalyst possessed good dispersion of Au nanoparticles and suitable surface acidity, leading to better performance of the catalyst. The effects of reaction time, reaction temperature, initial O2 pressure and catalyst dosage on the oxidative esterification of furfural over Au/Al2O3 were investigated, and furfural conversion and methylfuroate selectivity reached 99.8% and ∼100%, respectively, under the conditions of 140 °C, 1 MPa O2, 1 h and 0.2 g catalyst. Meanwhile, the furfural/methanol mole ratio in this work was as high as 1/27, which is higher than that reported in the literature and is more promising for commercial application. The catalytic performance of Au/Al2O3 was found to decrease slightly with the use time, and the aggregation of Au particles in the reaction was suggested to account for the decrease in activity. The functional mechanism of the catalyst was investigated via contrast experiments, and it was speculated that the acid sites of Al2O3 might promote the adsorption of furfural on the surface of catalyst, and Au catalyzed both steps of the oxidative esterification of furfural to methylfuroate. [ABSTRACT FROM AUTHOR]

The development of carbon-based catalysts to substitute Pt-based catalysts for the oxygen reduction reaction is highly important for promoting their practical application in energy conversion. Herein, we prepare Zn, Fe and N-codoped porous carbon (Zn/Fe-NC-x) as a cathode catalyst via a facile one-step pyrolysis predesigned bimetallic zeolitic imidazole framework. Systematic electrochemical studies demonstrated that the synthesized Zn/Fe-NC-0.5 exhibits higher electrocatalytic activity towards the oxygen reduction reaction. In particular, Zn/Fe-NC-0.5 has a smaller charge transfer resistance, larger exchange current density, and much higher open circuit potential and mainly proceeds via an efficient four-electron pathway. A microbial fuel cell equipped with the synthesized catalyst exhibited the highest maximum power density of 1954 ± 20 mW m−2. In addition, the effects of the iron doping content on the oxygen reduction reaction performance and maximum power density were evaluated: a moderate Fe doping content plays a crucial role in improving the catalytic activity, and the synergistic effect of Zn, Fe and N codoping promotes cathodic performance. In brief, Zn/Fe-NC, which has the advantages of facile synthesis, environmental friendliness and excellent electrochemical activity, is a promising Pt-alternative catalyst for the oxygen reduction reaction in air-cathode microbial fuel cells. [ABSTRACT FROM AUTHOR]

The highly efficient synthesis of benzoxazole, benzothiazole and benzimidazole has attracted much attention due to their superior biological activities. However, developing environmentally friendly and poisoning-resistant catalysts in heterogeneous catalytic systems remains a critical challenge. Herein, an atomically dispersed Co1/NC catalyst was fabricated by facile pyrolysis of a zeolitic imidazolate framework (ZnCo-ZIF). The Co1/NC catalyst exhibited excellent oxidation catalysis, sulfur-resistance and reusability performance. The mass specific activity (MSA) of Co1/NC was up to 42.0 mol2-PBO molCo−1 h−1, much higher than that of the Co/NC nano-catalyst (15.6 mol2-PBO molCo−1 h−1). Mechanism studies showed that O2 was activated by atomically dispersed Co active species to form 1O2 and ˙O2−, which were responsible for the dehydrogenation of the key imine intermediates to produce 2-phenylbenzoxazole (2-PBO). The current work represents a novel feasible strategy for the synthesis of bioactive heterocyclic compounds using efficient, stable and green heterogeneous catalysts. [ABSTRACT FROM AUTHOR]

Furfural is an industrial renewable platform chemical, which can be converted to useful furanics such as α-angelica lactone, carboxylic acids such as levulinic acid and valeric acid, or to higher carbon content products via condensation routes for producing drop-in fuel replacements and chemicals with diverse applications. These important conversion processes may be carried out in selective fashions, although they require adequate catalysts. They were successfully carried out using versatile, stable silica-wrapped niobium oxide nanostructured catalysts. For example, α-angelica lactone was converted in an integrated fashion to ethyl levulinate in 90% yield, and the esterification of levulinic and valeric acids gave ethyl levulinate in quantitative yield and ethyl valerate in 90% yield, respectively, at 140 °C. Catalytic, mechanistic and kinetic modelling studies shed light on the influence of the materials properties on the catalytic performances. These catalysts outperformed pure Nb2O5, as well as hydrothermally synthesized composites consisting of Nb2O5 nanoparticles embedded in a mesoporous siliceous matrix. [ABSTRACT FROM AUTHOR]

Lignin is composed of phenylpropyl alcohol through the C–O and C–C bonds, where β-O-4 accounts for the majority. Self-transfer hydrogenolysis (STH) is a promising method to produce valuable chemicals and fuels from lignin by cleaving the β-O-4 bond without exogenous hydrogen, but all the reported work used noble metal-based catalysts. In this work, a highly efficient Ni/C catalyst was derived from a Ni-containing metal–organic framework (Ni-MOF), and its self-transfer hydrogenolysis performance towards ether bonds in lignin model compounds was evaluated using 2-phenoxy-1-phenylethanol as a model compound in detail. It was found that the catalyst pyrolyzed under a nitrogen atmosphere at 500 °C (Ni-NDC-500) was very efficient for the reaction. Moreover, it could also catalyze the reaction of native lignin into monomers effectively without exogenous hydrogen. In addition, Ni-NDC-500 was recycled three times without an obvious reduction of the activity. [ABSTRACT FROM AUTHOR]

This study introduces a novel catalyst designated as 2.6% Co/MXene, comprising cobalt (Co) nanoparticles supported by MXene. The synthesis of the 2.6% Co/MXene catalyst involved direct pyrolysis of a composite material, composed of a Co/Zn bimetal metal–organic framework and MXene. Catalytic transfer hydrogenation of functionalized nitro compounds into the corresponding formamides employed formic acid as both the hydrogen donor and formylation agent, demonstrating remarkable activity and selectivity. Control experiments validated that Co nanoparticles served as the active sites for reductive transformation. Systematic characterization and comprehensive experiments have confirmed that the superior catalytic performance of the 2.6% Co/MXene catalyst can be attributed to the uniform distribution of Co nanoparticles, a high density of basic sites, and the 3D porous architecture of the MXene support. Furthermore, the 2.6% Co/MXene catalyst exhibited excellent recyclability, preserving its catalytic activity and selectivity across four consecutive cycles. [ABSTRACT FROM AUTHOR]

Herein, Ni–Co alloy particles embedded in mesoporous carbon hollow sphere (MCHS) catalysts were prepared by the one-pot Stöber method using SiO2 as a hard template and resorcinol–formaldehyde (RF) resin as a carbon source, and they were tested for in situ aqueous phase hydrodeoxygenation of methyl palmitate to hydrocarbons using methanol as a hydrogen donor. The formation of the catalyst precursors involves nucleation, growth and co-assembly of RF and SiO2. The introduction of SiO2 can facilitate the construction of the mesoporous and hollow structure and improve the specific surface area. It also reduces the micropore volume due to the reduced graphitization degree of the catalysts induced by SiO2. Thus, the internal diffusion resistance is decreased. Particularly, the Ni–Co alloy particles formed during carbonization are embedded in the mesoporous carbon layer, effectively hindering their sintering and leaching under the harsh hydrothermal conditions. Moreover, the metal sites can be exposed on both mesoporous channels and inner/outer surfaces of the carbon hollow spheres, making the reactants easily accessible. In the in situ hydrodeoxygenation of methyl palmitate, the as-prepared catalyst gives the pentadecane yield of 89.0% at 310 °C for 1 hour. It is noted that the facile diffusion in MCHSs suppresses the undesired C–C bond hydrogenolysis. The catalyst is not obviously deactivated during five reaction cycles. [ABSTRACT FROM AUTHOR]

Single-atom catalysts (SACs) have attracted significant attention due to their unique electronic structure and extraordinary catalytic reaction activity. In this work, single-atom Au1/TiO2 catalysts were successfully prepared using cold plasma. Notably, plasma-treated TiO2 introduces a substantial number of oxygen vacancies, which played a confinement effect on gold atoms. Au1/TiO2 achieved a remarkable 67% degradation of RhB in just 120 minutes, surpassing the performance of AuNPs/TiO2 by 2.8 times. The high catalytic activity can be attributed to several factors. Firstly, plasma-treated TiO2 contained a higher density of oxygen vacancies and exhibited a narrower band gap, which improved light absorption and facilitated the anchoring of monoatomic Au on the catalyst surface. Additionally, the single-atom Au species exhibited stronger interactions with TiO2, enhancing light absorption and charge transfer capability. Simultaneously, the presence of SACs on the catalyst surface increased the number of active sites, promoting efficient separation of electron–hole pairs and consequently enhancing the photocatalytic degradation activity. Cold plasma technology offers a simple and environmentally friendly platform for the fabrication of SACs, opening up exciting possibilities for catalytic applications. [ABSTRACT FROM AUTHOR]

The quantitative structure-property relationship (QSPR) of constrained geometry catalysts (CGCs) has been analyzed by combining density functional theory (DFT) and multivariate linear regression (MLR). QSPR models for determining the reaction energy barriers of ethylene and 1-octene and molecular descriptors were established and validated with a testing set. At the initiation stage, the quaternary QSPR models for ethylene and 1-octene feature R² values of 0.90 and 0.82, respectively, while the corresponding leave-one-out Q² values for ethylene and 1-octene are determined to be 0.82 and 0.69. Using the generated QSPR models, the electronic effect was proven to be more critical for determining the energy barriers of ethylene and 1-octene insertion processes. At the propagation stage, the quaternary QSPR models for ethylene and 1-octene feature R² values of 0.97 and 0.96, respectively, while the corresponding leave-one-out Q² values for ethylene and 1-octene are determined to be 0.93. Particularly, the impact of the steric effect on the energy barriers of ethylene and 1-octene insertion is more pronounced. Furthermore, the correlation between the corresponding energy barriers and experimental activities with three series of CGCs was discussed, which revealed that theoretical calculations are consistent with the experimental results. [ABSTRACT FROM AUTHOR]

The hydrogenation of acetic acid-derived cyclohexyl acetate (CHA) is becoming a safe, efficient and promising route for the production of cyclohexanol (CHOL), an important chemical to produce e-caprolactam. In this work, Cu-Zr catalysts were prepared via different methods for the hydrogenation of CHA. The results showed that a Cu3Zr7-SG catalyst prepared by the sol-gel (SG) method was superior to Cu3Zr7-CP and Cu3Zr7-IM catalysts prepared by the coprecipitation (CP) and impregnation (IM) method, respectively. The Cu3Zr7-SG catalyst showed 97.4% CHA conversion and 95.5% selectivity to CHOL along with 96.3% selectivity to ethanol at 250 1C under 3 MPa of H2. Moreover, the Cu3Zr7-SG catalyst showed a mass specific activity of up to 29.8 gCHA gCu-1 h-1, higher than other Cu-based catalysts under similar conditions. Based on detailed characterization studies, it was found that the larger weak acid sites, more weak and moderate basic sites, higher Cu+/(Cu0 + Cu+) and oxygen vacancies on the surface of the Cu3Zr7-SG catalyst were beneficial for the hydrogenation of CHA. [ABSTRACT FROM AUTHOR]

A new copper(II) bromide/N-methylmorpholine N-oxide (NMO)-promoted method for α-amination of esters under continuous-flow conditions, with reduced catalyst loading is reported. The α-amino esters are precursors for the synthesis of α-amino acids. This method provides α-amino esters in 58-83% yields. The desired Cu(II)Br catalyst is regenerated by in situ oxidation of Cu(I)Br in the presence of NMO. [ABSTRACT FROM AUTHOR]

The availability of catalytic sites for contact with reactants is a key issue to improve the performance of a catalyst, where constructing hollow structured nanomaterials has been considered as an effective strategy. Here, an N-doped carbon supported Ru catalyst with an interior cavity was synthesized by etching a MOF-derived core–shell precursor, in which metal Ru can be highly dispersed in the porous shell. This catalyst shows 98.7% conversion and >99% selectivity towards p-chloroaniline in the hydrogenation of p-chloronitrobenzene, which is better than the corresponding supported catalyst. Moreover, it also displays excellent stability with 5 cycle runs and good substrate universality for the hydrogenation of extensive substituted nitroarenes. Various characterization techniques and control experiments reveal the advantage of the unique structure to promote the mass transport and adsorption of reactant molecules on Ru sites. This work provides a novel strategy to design an efficient Ru-based catalyst for chemoselective hydrogenation. [ABSTRACT FROM AUTHOR]

Three mononuclear Ge(IV) compounds, [(C6H5)2Ge(C13H8N2O4)] (1), [(C6H5)2Ge(C14H10N2O5)] (2), and [(C6H5)2Ge(C14H11NO3)] (3), have been synthesized by the reaction of pro-ligands H2L1 (C13H10N2O4), H2L2 (C14H12N2O5), and H2L3 (C14H13NO3) with (C6H5)2GeCl2 in the presence of triethylamine. All compounds were characterized by FT-IR spectroscopy and NMR spectroscopy. Single crystal X-ray diffraction analysis shows that the germanium(IV) atom exhibits a five-coordinated geometry in compounds 1 and 2. All compounds were screened as Lewis acid catalysts in the [3 + 2] cycloaddition reaction between sodium azide and various nitriles. The reactions resulted in the formation of 5-substituted 1H-tetrazoles with yields of up to 96%. Based on the experimental findings and DFT calculations, a plausible mechanism is proposed for the [3 + 2] cycloaddition reaction. [ABSTRACT FROM AUTHOR]

A set of mononuclear cobalt(III) octahedral complexes {[Co(LH)(acac)] (Co-1H), [Co(LBr)(acac)] (Co-1Br), and [Co(LNO2)(acac)] (Co-1NO2)} were synthesized using new-generation N/O donors, maleonitrile-tethered, tetradentate heteroscorpionate half-reduced Schiff base ligands, 2-((E)-2-hydroxybenzylideneamino)-3-(pyridin-2-ylmethylamino)maleonitrile (H2LH), 2-((E)-(5-bromo-2-hydroxybenzylidene)amino)-3-((pyridin-2-ylmethyl)amino)maleonitrile (H2LBr), and 2-((E)-2-hydroxy-5-nitrobenzylideneamino)-3-(pyridin-2-ylmethylamino)maleonitrile (H2LNO2). All the compounds were well characterized spectroscopically and structurally. The non-covalent interactions present in the lattice of Co-complexes were studied in detail to explain the molecular architecture using the Hirshfeld surface (HS) analysis. The catalytic activity of CO2 fixation towards epoxides under mild and solvent-free conditions was demonstrated. The synthesized complexes are catalysts that are well-active towards the CO2 activation under ambient conditions, whereas most of the reported catalysts require harsh conditions. [ABSTRACT FROM AUTHOR]

Improving the dispersion of metal nanoparticles and suppressing metal aggregation have long been the keys to constructing efficient metal-loaded catalysts. Herein, catalysts of cobalt (Co) supported on nitrogen (N)-doped carbon were prepared by a simple hydrothermal method using folic acid (FA) as the carbon source. Surprisingly, hydrazine hydrate not only facilitated the loading of metal Co, but also regulated the morphology of the catalyst, promoted the uniform distribution of metal Co, and effectively improved the catalytic hydrogenation activity of the catalyst. It was found that the catalyst mediated with 10 mL hydrazine hydrate and pyrolyzed at 900 °C exhibited the best catalytic performance (99.6% conversion of quinoline and 98.0% selectivity for 1,2,3,4-tetrahydroquinoline). In addition, it exhibited satisfying adaptability for diverse substrates. This study can provide great theoretical significance and practical guidance for the preparation of Co–N–C catalysts. [ABSTRACT FROM AUTHOR]