Efficient Selective Hydrogenation Research Articles

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

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

Efficient selective hydrogenation of phenylacetylene over Pd-based rare earth dual-atomic catalysts

Selective hydrogenation of phenylacetylene to styrene plays a vital role in fine chemical synthesis with palladium (Pd)-based catalysts as the active components and usually suffered from low selectivity due to over-hydrogenation and low stability through polymerization (c.a. green oil generation). In this work, we found that by confining the Pd atom within a Pd-Ln (Ln: rare earth elements, such as Y, Lu, etc. ) diatomic structure [diatomic catalyst (DAC)], the reaction performance of selective hydrogenation of phenylacetylene has been greatly promoted, in which 92% styrene selectivity has been determined at 100% phenylacetylene conversion. This would be attributed to the diatomic structure established, which was achieved by introducing Pd-Ln precursors and confirmed by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and X-ray adsorption fine structure (XAFS) characterizations and it was demonstrated that slight electron transfer from Ln to the adjacent isolated Pd makes it slightly negatively charged and facilitated the styrene formation. Besides, a Langmuir-Hinshelwood model was established to describe the whole reaction mechanism. After a systematic kinetic investigation, it suggests that the C8H6* + H* elementary step is probably the kinetically relevant for the whole reaction and the surface of the catalyst is mainly covered by C8H6*. The energy relationship of each step along phenylacetylene hydrogenation was quantitatively described by means of parity fitting and gas isothermal adsorption, providing insights into the selective hydrogenation of phenylacetylene over 0.02%Pd-Ln/C (Ln = Y/Lu) catalysts and pave the way of catalytic design at the atomic level.

Multidimensional Engineering to Construct Ru/TiO2 Catalysts Enriched with Pores and Ti3+ Defects for Highly Efficient Selective Hydrogenation of Benzene

AbstractStructural engineering, coupled with crystalline phase engineering and surface engineering, serves as a practical and effective strategy for enhancing catalytic performance through the fine design of catalysts in terms of their structure, physical phases and surface defects. In this work, a set of strategies were employed for structural transformation and crystalline phase transition of Ru/TiO2 catalysts, utilizing multidimensional regulation. Ru nanoparticles loaded on a unique TiO2 nanosheet flowers (Ru/TSFs) enriched with pores and Ti3+ defects were prepared by solvothermal and impregnation‐chemical reduction methods. The Ru/TSFs exhibited an outstanding catalytic performance in the reaction of selective hydrogenation of benzene for the preparation of cyclohexene, with a selectivity of 79 % and a maximum yield of 52.8 % along with a benzene conversion of 45.9 % and a good stability. The excellent catalytic performance attributes to the distinctive structure of three‐dimensional nanosheet flowers, which offers a high specific surface area and improvs the effective contact between the catalyst and the reaction substrate. Meanwhile, the porous Ru/TSFs exhibit exceptional hydrophilicity and abundant Ti3+ defects on their surface, which is quite favorable for the desorption of cyclohexene from the reaction system, thus improving the selectivity of cyclohexene. The multidimensional engineering may provide an efficient approach for constructing high‐performance loaded catalysts for potential industrial applications.

Subnanometric bimetallic Pt–Pd clusters in zeolites for efficient hydrogen production and selective tandem hydrogenation of nitroarenes

Subnanometric bimetallic Pt–Pd clusters in zeolites for efficient hydrogen production and selective tandem hydrogenation of nitroarenes

Nickel Nanoparticles on Hydroxyl and Defect-rich Hollow Carbon Spheres as Catalysts for Efficient Selective Hydrogenation of Phenol

Nickel Nanoparticles on Hydroxyl and Defect-rich Hollow Carbon Spheres as Catalysts for Efficient Selective Hydrogenation of Phenol

Carburization in the Crystalline Structure of the Metal Ag for Efficient Selective Hydrogenation of Acetylene

Carburization in the Crystalline Structure of the Metal Ag for Efficient Selective Hydrogenation of Acetylene

Microwave-Assisted Efficient Intercalation for Fast Fabrication of High-Quality and Large-Size Single-Layer Ti3C2Tx Nanosheets.

A novel microwave-assisted intercalation (MAI) strategy is proposed for fast and efficient intercalation of layered MXene to prepare large-size single-layer MXene. After LiF-HCl etching of Ti3AlC2, the as-prepared multi-layer Ti3C2Tx (M-T) are intercalated with Li3AlF6 as an intercalator and ethylene glycol (EG) as a solvent under microwave irradiation for 5min. Furthermore, the dispersed high-quality large-sized single-layer Ti3C2Tx (S-T) nanosheets with a thickness of 1.66nm and a large lateral size over 20µm are achieved with a yield of over 60% after a further ultrasonic delamination followed by electrostatic precipitation, acid washing, and calcination. In addition, Pd/S-T composite catalyst, which is constructed with Pd nanoparticles supported on the as-prepared S-T nanosheets, exhibits an excellent performance for rapid and efficient selective hydrogenation of nitroarenes with H2 under a mild condition. At room temperature, full conversion of nitrobenzene and 100% aniline selectivity are achieved over Pd/S-T catalyst in 20min with 0.5MPa of H2 pressure. This work provides a novel method for facile, fast, and large-scale preparation of single-layer MXene and develops a new approach for constructing efficient nanocatalytic systems.

In-situ constructing ultrafine NiCo alloy confined in LDH nanoflower for efficient selective hydrogenation of furfural

Directional activation of oxygen-containing groups is a crucial challenge in the catalytic conversion of renewable biomass to high-value products. Herein, we fabricated uniform dispersed NiCo alloy nanoparticles by direct reduction flower-like layer double hydroxides (LDHs) precursors. The as-obtained Ni2Co1AlO exhibited outstanding yield (97.6 %) of tetrahydrofurfuryl alcohol (THFOL) in furfural hydrogenation, which is significantly superior to those of monometallic Ni-based (75 %) and Co-based (0 %) LDH catalysts and even higher than the most noble metal catalysts. The Ni2Co1AlO showed robust stability, e.g., the catalyst can be recycled up to 10 times without loss of its conversion and selectivity, which is attributed to the ultra-dispersed metal cations in layers and the confined effect of metal oxides. Characterizations and theoretical calculations demonstrate that alloying Ni with Co can downshift the d-band center of Ni in NiCo alloys, which facilitates the H* desorption to improve hydrogenation activity. The unique electronic interactions between Ni and Co facilitated the parallel adsorption of furfural while reduced the energy barriers of the furan ring hydrogenation, promoting the production of THFOL. This work provides a promising strategy of tailoring d-band center, which can shed light on the design of heterogeneous catalysts.

NaOH-assisted synthesis of N-doped carbon-encapsulated trimetallic CoNiZnO@NC catalyst for efficient selective hydrogenation of furfural to furfuryl alcohol

NaOH-assisted synthesis of N-doped carbon-encapsulated trimetallic CoNiZnO@NC catalyst for efficient selective hydrogenation of furfural to furfuryl alcohol

Highly efficient selective hydrogenation of adiponitrile to hexamethylene diamine over barium and melamine formaldehyde resin-modified nickel–cobalt-based zeolitic imidazolate framework-derived catalyst

In the present study, the catalyst modified with alkaline oxide can enhance the selectivity to primary amines. However, the addition of alkaline oxide inevitably reduces catalytic activity. In this study, NiCo-NC@BaO-MFC catalyst derived from zeolitic imidazolate framework-67, Ba(CH3COO)2, and melamine formaldehyde (MF) resin was prepared and used for the hydrogenation of adiponitrile (ADN) to hexamethylene diamine (HDMA). The carbon layer obtained from the MF resin effectively prevents the interaction between barium (Ba) and the active center, thus improving target product selectivity without decreasing catalytic activity. The results of the density functional theory (DFT) calculation and characterization indicated that the effect of synergy between nickel (Ni) and cobalt (Co) bimetals induces an electron density growth on the Ni surface, bringing the d-band center toward the Fermi surface. Meanwhile, the high electron density of the active center compensates for the electron-deficient state of the carbon atom in –CN, thus improving the catalytic activity. Furthermore, it was found that the introduction of Ba promotes the formation of nucleophilic hydrogen anions, which facilitates the hydrogenation of 6-aminohexylimine (AHIM) to HDMA and inhibits the intramolecular condensation of AHIM, hence improving the selectivity to HDMA. The NiCo-NC@BaO-MFC catalyst gives 98.6 % ADN conversion and 97.2 % selectivity to HDMA in an alkali-free system.

Highly efficient selective hydrogenation of isophthalonitrile to M-xylenedimethylamine over Co–CaO/g-C3N4 without alkaline additives

Highly efficient selective hydrogenation of isophthalonitrile to M-xylenedimethylamine over Co–CaO/g-C3N4 without alkaline additives

Partial carbon encapsulation synthesis of separated Ni-Ag catalyst for efficient selective hydrogenation of acetylene: Synergizing hydrogen spillover and steric hindrance

The selective hydrogenation of acetylene is a vital process to for the purification of crude ethylene in petroleum industry. Achieving high activity and selectivity simultaneously over Ni-based catalysts is still challenging. Herein, a partial encapsulation strategy is proposed by fabricating carbon-encapsulated Ag nanoparticles and un-encapsulated Ni nanoparticles on Al2O3 surface (Ni-Ag@C/Al2O3) toward the enhanced selectivity without loss of activity. In particular, the Ni-Ag@C/Al2O3 exhibits higher ethylene selectivity of 81% at the complete acetylene conversion along with excellent stability for 30-h, in sharp with the Ni/Al2O3 (6%) and Ni-Ag/Al2O3 (54%) catalyst. The enhanced selectivity is attributed to the promotion of hydrogen spillover by the carbon species on Al2O3 surface and the inhibition of oligomer formation by a steric hindrance formed by the carbon layer on the Ag surface. This study provides a new structural design avenue of bifunctional bimetallic catalyst for selective hydrogenation reaction.

Catalytic synthesis of renewable 2-methylfuran from furfural

The efficient catalytic selective hydrogenation of furfural to produce 2-methylfuran was accomplished through the introduction of a small quantity of hydroquinone over a monometallic catalyst comprising solely of Co and its oxides.

Rapid plasma electrolytic oxidation preparation of sub-3 nm half-embedded intermetallic nanocatalysts for efficient selective hydrogenation

Monodisperse sub-3 nm ordered intermetallic nanoparticles half-embedded in a porous MgO support layer on a Mg plate were prepared for the first time.

Isomorphous Substitution of Organic Cage Crystal by Pd Nanoclusters for Selective Hydrogenation.

For supporting active metal, the cavity confinement and mass transfer facilitation lie not in one sack, a trade-off between high activity and good stability of the catalyst is present. Porous organic cages (POCs) are expected to break the trade-off when metal particles are properly loaded. Herein, three organic cages (CC3, RCC3, and FT-RCC3) are employed to support Pd nanoclusters for catalytic hydrogenation. Subnanometer Pd clusters locate differently in different cage frameworks by using the same reverse double-solvents approach. Compared with those encapsulated in the intrinsic cavity of RCC3 and anchored on the outer surface of CC3, the Pd nanoclusters orderly assembled in FT-RCC3 crystal via isomorphous substitution exhibit superior activity, high selectivity, and good stability for semi-hydrogenation of phenylacetylene. Isomorphous substitution of FT-RCC3 crystal by Pd nanoclusters is originated from high crystallization capacity of FT-RCC3 and specific interaction of each Pd nanocluster with four cage windows. Both confinement function and H2 accumulation capacity of FT-RCC3 are fully utilized to support active Pd nanoclusters for efficient selective hydrogenation. The present results provide a new perspective to the heterogeneous catalysis field in terms of crystalizing metal nanoclusters in POC framework and outside the cage for making the best use of both parts.

Efficient selective hydrogenation of terminal alkynes over Pd–Ni nanoclusters encapsulated inside S-1 zeolite

Selective hydrogenation of alkynes is a challenging reaction that requires selective and efficient catalysts to achieve the desired alkenes. The development of general and robust catalysts that can operate under mild conditions and tolerate a wide range of functional groups is still an active area of research. Here, Pd-M bimetallic clusters (M = Ni, Cu, Mn, Fe) encapsulated inside S-1 zeolite were prepared and applied in the selective hydrogenation of substituted terminal alkynes. Among them, the Pd0.6Ni@S-1 catalyst displayed 91 % selectivity to styrene at the full conversion of phenylacetylene. Derivatives of phenylacetylene containing either electron withdrawing/donating or sensitive functional groups were effectively converted into the corresponding alkenes. The confinement effect of zeolite effectively inhibited the over-hydrogenation reaction and enhanced the stability of the catalysts. Furthermore, the product distribution was solvent-dependent by correlating the reaction selectivity with solvent properties. Apolar solvent showed the highest selectivity to styrene in the selective hydrogenation of phenylacetylene due to the competitive adsorption of apolar solvent and styrene on catalysts.

Defect-Driven Efficient Selective CO2 Hydrogenation with Mo-Based Clusters.

Synthetic fuels produced from CO2 show promise in combating climate change. The reverse water gas shift (RWGS) reaction is the key to opening the CO2 molecule, and CO serves as a versatile intermediate for creating various hydrocarbons. Mo-based catalysts are of great interest for RWGS reactions featured for their stability and strong metal-oxygen interactions. Our study identified Mo defects as the intrinsic origin of the high activity of cluster Mo2C for CO2-selective hydrogenation. Specifically, we found that defected Mo2C clusters supported on nitrogen-doped graphene exhibited exceptional catalytic performance, attaining a reaction rate of 6.3 gCO/gcat/h at 400 °C with over 99% CO selectivity and good stability. Such a catalyst outperformed other Mo-based catalysts and noble metal-based catalysts in terms of facile dissociation of CO2, highly selective hydrogenation, and nonbarrier liberation of CO. Our study revealed that as a potential descriptor, the atomic magnetism linearly correlates to the liberation capacity of CO, and Mo defects facilitated product desorption by reducing the magnetization of the adsorption site. On the other hand, the defects were effective in neutralizing the negative charges of surface hydrogen, which is crucial for selective hydrogenation. Finally, we have successfully demonstrated that the combination of a carbon support and the carbonization process synergistically serves as a feasible strategy for creating rich Mo defects, and biochar can be a low-cost alternative option for large-scale applications.

Engineering the Structure of ZIF-Derived Hierarchically Porous CoZn Catalysts for Efficient Selective Hydrogenation of Nitroarenes

Engineering the Structure of ZIF-Derived Hierarchically Porous CoZn Catalysts for Efficient Selective Hydrogenation of Nitroarenes

Acid-durable intermetallic CaNi2Si2 catalyst with electron-rich Ni sites for aqueous phase hydrogenation of unsaturated organic anhydrides/acids

The study of the aqueous-phase selective hydrogenation of maleic anhydride to succinic acid is important for expanding the coal chemical industry chain and promoting biomass conversion. The key lies in the development of highly efficient and stable non-noble metal catalysts. Herein, we report a novel intermetallic CaNi2Si2 catalyst with high activity and stability for the aqueous-phase selective hydrogenation of maleic anhydride. The results from the experiments and theoretical calculations demonstrated that the high catalytic performance was due to the synergy of the electron-rich Ni active sites, enhanced adsorption of C=C bonds, and favorable activation of H2. The yield of succinic acid can be 100% over the CaNi2Si2 catalyst at the contact time of 5.4 gcat/(mmolreactant·min−1) under 3 MPa and 120 °C in the continuous flow reactor. Furthermore, the special coordination environment and electronic structure of Ni in CaNi2Si2 inhibit the formation of carboxylates, thus enhancing the acid resistance in the reaction environment. The fine design and regulation of the structure of intermetallic silicides will be important references for the controllable optimization of maleic anhydride hydrogenation catalysts and provide new insights into the development of efficient and stable selective hydrogenation catalysts in harsh reaction environments.

Regulating metal-support interactions of Pd/MgAl2O4 for efficient selective hydrogenation of acetylene

Selective hydrogenation of a trace amount of acetylene to ethylene is a green and economical process to purify the ethylene stream in the olefin industry. Pd-based catalysts are widely explored for this process due to their excellent H2 and C2H2 activation abilities. However, the strong adsorption of C2H4 on metallic Pd sites often leads to the undesired over-hydrogenation product (i.e., ethane). Herein, we fabricated Pd/MgAl2O4 catalysts with tunable metal-support interactions by changing calcination temperatures to efficiently modify the electronic structure of Pd species. The Pd/MgAl2O4 with the optimized calcination temperature exhibits 96 % acetylene conversion and enhanced ethylene selectivity of 87 % due to weak adsorption of intermediates at 120 ℃, and shows excellent stability with negligible activity decay during a 50 h test. This work provides a strategy for designing catalysts with regulated metal-support interactions for selective hydrogenation processes.