Activity For Selective Hydrogenation Research Articles

Facile Construction of Alloy‐Metal Oxide Interfaces Boosting the One‐Pot Conversion Of Methyl Levulinate to 1,4‐Pentanediol

AbstractIn this work, a series of N‐doped carbon supported FeCo bimetallic catalysts with plentiful FeCo alloy‐FeO interfaces, which are derived from metal‐organic frameworks (MOFs) ZIF‐67, are designed for the one‐pot direct conversion of methyl levulinate to 1,4‐pentanediol. The FeCo alloy‐FeO interfaces are precisely controlled via tuning the reduction temperatures and Fe/Co ratios. The optimal catalyst gives a high 1,4‐pentanediol yield of 90.5 % along with complete conversion of methyl levulinate. These catalysts are carefully characterized by multiple techniques, such as HRTEM, XRD, XPS, NH3−TPD, and Py−IR. It is found that Co presents in electron deficiency caused by the electron transference from Co to Fe in FeCo alloy, which in turn enhances the heterolysis of H2. In addition, plentiful Lewis acid sites derived from interfacial FeO species favour the re‐adsorption and the ring‐opening reaction of γ‐valerolactone. With the synergy between FeCo alloy and Lewis acid, the FeCo alloy‐FeO interfaces exhibit excellent catalytic activity for selective hydrogenation of methyl levulinate to 1,4‐pentanediol.

Metal-metal oxide synergistic catalysis: Pt nanoparticles anchored on mono-layer dispersed ZrO2 in SBA-15 for high efficiency selective hydrogenation

It is generally believed that noble metal catalysts exhibited higher activity for selective hydrogenation, while metal oxides were almost inactive. Here, we report metal-metal oxide synergistic catalysis for high efficiency selective hydrogenation by a hybrid nano-structure Pt/@-ZrO2/SBA-15 catalyst, which was fabricated by anchored Pt nanoparticles on the mono-layer dispersed ZrO2 film layer coated in SBA-15 support via a photochemical route. This Pt/@-ZrO2/SBA-15 catalyst exhibited remarkable catalytic activity in the selective hydrogenation of CO bond, NO2, and CC bond. For the selective hydrogenation of benzaldehyde, conversion >99.9% was achieved with >99% selectivity, and the turnover frequency (TOF) can be achieved up to 4822 h−1, which was much higher than that of the atomically dispersed Pd1/TiO2-EG catalyst (1002 h−1) reported in the literature, no decay in the activity was observed by several cycles. Combined the experimental and characterization results, proved that the ZrO2 was dispersed in a mono-layer in the channel of SBA-15, and the results showed that an appropriate loading of ZrO2 in this catalyst could maximize the advantage of this hybrid nano-structure to achieve the best catalytic activity. The superior activity of Pt/@-ZrO2/SBA-15 was attributed to the synergistic catalysis, strong interface electronic effect, and the unique properties of the special hybrid nano-structure. This work demonstrated synergistic catalysis of metal Pt nanoparticles and monolayer dispersion ZrO2 for high efficiency selective hydrogenation.

Selective hydrogenation of detrimental 4-nitrophenol to desired 4-aminophenol over potent PtCo intermetallic nanoparticles entrapped within the pores of Cr-BDC MOFs

Engineering of economical and stabilized precious metal based catalysts are crucial in recent ages to achieve the desirable catalytic performance as they tend to destabilize easily. Herein, Cr-BDC MOF was prepared that provides high surface area and pore volumes to evenly distribute, host, and stabilize the Pt and Co intermetallic nanoparticles (IMNs). Among these, the PtCo/Cr-BDC catalyst showed superior selective hydrogenation activity for 4-Nitrophenol (4-NP) to 4-Aminophenol (4-AP) as an exemplary reaction. A number of characterization techniques were carried out to study the influence of the Cr-BDC support and Co metal on the surface and bulk structural properties of active Pt metal species. The Cr-BDC support imparts uniform distributions while the Co metal species influenced the catalytic activity. The maximum conversion (99.3 %) of 4-NP to 4-AP was observed with PtCo/Cr-BDC in 2 min at a reaction rate constant (k) of 1.27 min−1 at room temperature, which is superior than Pt/Cr-BDC (0.64 min−1) and Co/Cr-BDC (0.14 min−1). The superior hydrogenation activity was credited to the addition of electropositive Co species to Pt/Cr-BDC catalyst that synergistically interacts with active Pt species within the pores of Cr-BDC MOFs and making PtCo IMNs system. As a result of this synergistic interaction, new additional interfacial electrophilic and nucleophilic metallic sites are generated within the pores of MOFs, which enormously encourage the selective hydrogenation of lethal 4-NP to valued 4-AP. Besides, the PtCo/Cr-BDC catalysts revealed remarkable durability up to several repeated rounds, validating its real-world applicability.

Microstructure and catalytic properties of rapidly solidified Al-28.5 at% Fe and Al-28.5 at% Co alloys applied for selective hydrogenation of phenylacetylene

The Al 71.5 Fe 28.5 and Al 71.5 Co 28.5 (at.%) melt-spun alloys were examined in terms of microstructure evolution and catalytic response in the semihydrogenation reaction of phenylacetylene to styrene. In the as-spun state ribbons showed a single-phase composition. The Al 71.5 Co 28.5 alloy contained columnar grains of a metastable decagonal quasicrystal, which transformed into hexagonal Al 5 Co 2 and monoclinic Al 3 Co phases after heat treatment at 900 °C. The Al 71.5 Fe 28.5 ribbon had an ordered orthorhombic Al 5 Fe 2 phase structure in both the as-spun and annealed states. The pulverized ribbons revealed considerable catalytic activity for selective hydrogenation of phenylacetylene to styrene. The best results were achieved for the as-spun quasicrystalline Al 71.5 Co 28.5 alloy, showing a conversion rate of above 80% after 2 h reaction time. The selectivity to styrene was 60% for all catalysts. The tested powders retained their phase composition following liquid reaction therefore the proposed materials can be considered for catalytic use. • The Al5Co2 and Al5Fe2 ribbons were prepare by melt spinning methods • Decagonal quasicrystal in the Al5Co2 transforms into Al 5 Co 2 and Al 3 Co after annealing • Ordered orthorhombic Al 5 Fe 2 phase in both the as-spun and the annealed Al5Fe2 ribbons • Catalytic activity of the powdered ribbons in hydrogenation of phenylacetylene • The conversion rate exceeds 80% after 2 h reaction time for quasicrystalline Al5Co2

Enhanced selective hydrogenation of glycolaldehyde to ethylene glycol over Cu0-Cu+ sites

Selective hydrogenation of hydroxyaldehydes to polyalcohols is challenging due to the competitive hydrogenation of CO and CO. This study develops heterogeneous Cu catalysts for the selective synthesis of ethylene glycol via batch liquid-phase hydrogenation of glycolaldehyde. SiO2 supported Cu, fabricated by ammonia evaporation, enables to catalyze the CO bond hydrogenation with retaining the CO bond intact, yielding higher selective hydrogenation activity with ethylene glycol selectivity up to 99.8 % relative to MgO, Al2O3, CeO2, and TiO2 supports and Cu/SiO2 synthesized by deposition–precipitation and impregnation. Characterizations confirm that highly efficient 20Cu/SiO2-AE-623 K catalyst fabricated by ammonia evaporation is featured with larger Cu0 and Cu+ surface areas, of which the Cu+ species created from reducing copper phyllosilicate exhibit higher reactivity. A synergistic effect between Cu+ and Cu0 facilitates the selective adsorption/activation of glycolaldehyde on Cu+ sites and the dissociation of H2 on Cu0 sites, bringing a remarkable improvement in the selective hydrogenation performance.

Nickel and oxygen-containing functional groups co-decorated graphene-like shells as catalytic sites with excellent selective hydrogenation activity and robust stability

Encapsulation of metal nanoparticles is one of the promising strategies to overcome the instability of supported metal catalysts. However, improving the hydrogenation activity of multilayer graphene-like encapsulationremains a critical challenge. To address this issue, multilayer graphene-like shells (MGSs) doped with oxygen-containing functional groups (OFGs) encapsulated Ni nanoparticles catalysts (Ni@OC) were synthesized via calcining the calcination of Ni-based metal-organic framework. The Ni@OC catalysts exhibited 100 % nitroaromatics conversion, excellent product selectivity, and superior stability in harsh conditions. Experimental results indicate that the dissociation of H2 and the activation of nitrobenzene compounds can be achieved with the OFGs doped MGSs as the catalytic site in Ni@OC catalysts. In addition, OFGs promote the electron transfer from Ni core to graphene-like shells and result in structural defects of the MGSs to adsorb hydrogenation substrates. Thus, a reasonable design concept was provided to improve the hydrogenation activity of MGSs encapsulated catalysts with the stable existence of metal.

Amino acid (histidine) modified Pd/SiO2 catalyst with high activity for selective hydrogenation of acetylene

Suppressing the excessive hydrogenation capacity of palladium has great significance for selective hydrogenation of acetylene. Herein, an amino acid (histidine or His in abbreviation) modified Pd/SiO2 catalyst (Pd-His/SiO2) for selective hydrogenation of acetylene was prepared by incipient wetness impregnation, followed by hydrogen reduction at 240 °C. The intense interaction between Pd and histidine greatly affects the structure and properties of Pd-His/SiO2. The Pd nanoparticles are highly dispersed on the support with an average diameter of 1.0 nm and positively charged. The use of histidine weakens the adsorption of acetylene and ethylene on the metal. Especially, the adsorption of di-σ-bonded ethylene is significantly impaired on the catalyst, which is beneficial to improve the ethylene selectivity. The conversion of acetylene is up to 100.0 % at 160 °C on Pd-His/SiO2 while the ethylene selectivity reaches 81.5 %. A 50-hour test at 160 °C confirms the good stability of Pd-His/SiO2.

Budget MOF-derived catalyst to realize full conversion from furfural to furfuryl alcohol

Furfuryl alcohol, a significant raw material for production of valuable chemicals, is currently manufactured from selective hydrogenation of furfural relying on polluting copper chromate and expensive noble metal catalysts. On account of inherent advantages, exploiting the low-cost and high-efficient catalysts based on metal-organic framework materials for the selective conversion of furfural is extraordinarily promising. Herein, a series of carbon-supported Cu-nanoparticles (denoted as HK-1-T, T refers to the calcination temperature) can be easily obtained via a one-step pyrolysis conversion of HKUST-1 at large scale. Fascinatingly, the constructed copper catalyst calcined at 350 °C (HK-1-350) exhibits striking activity for selective hydrogenation of furfural, affording complete conversion of furfural and 100% furfuryl alcohol selectivity at 120 °C under 1.5 MPa H2 within 3 h, with the superior cyclic stability at the same time proved by leaching test and reusability experiment. This report provides an attractive route for the highly efficient conversion of furfural to furfuryl alcohol of the industrial production employing non-noble metal catalysts.

New monoclinic ruthenium dioxide with highly selective hydrogenation activity

HxRuO2 acts as a standalone catalyst exhibiting selective hydrogenation under mild conditions. Mobile protons embedded in the oxide lattice play an important role in stabilizing the distorted structure, and facile proton dynamics is key to improving catalytic properties.

Nickel and Oxygen-Containing Functional Groups Co-Decorated Graphene Shells as Catalytic Sites with Excellent Selective Hydrogenation Activity and Robust Stability

Nickel and Oxygen-Containing Functional Groups Co-Decorated Graphene Shells as Catalytic Sites with Excellent Selective Hydrogenation Activity and Robust Stability

Facile fabrication of TiO2 with 3D hierarchical structure and its supported Pd catalysts for high catalytic hydrogenation performance of 4-Nitrophenol to 4-Aminophenol

TiO2 with different morphology as supports can lead to different surface properties and catalytic activities of catalysts. Herein, we reported a novel facile evaporation-induced assisted hydrothermal approach to synthesize three-dimensional hierarchical structure TiO2 assembled from needle flakes by using Brij-35 as the morphology-directing agent. The morphology of the prepared TiO2 from flower-like (TiO2-FT), sea urchin-like (TiO2-SUT), to ball-like (TiO2-BT), as well as the size of needle flakes, were controlled by adjusting the amount of Brij-35. These TiO2 supported palladium catalysts were facilely prepared using a green bio-reductive method with Catalpa Fruit extract as reducing agent, where they showed remarkable catalytic activity in selective hydrogenation of 4-nitrophenol by sodium borohydride. Especially, 1 wt%Pd/TiO2-SUT with sea urchin-like exhibited higher reaction rate constant (1.44 min−1) than 1 wt%Pd/TiO2-FT (1.08 min−1) and 1 wt%Pd/TiO2-BT (0.72 min−1). Furthermore, XRD, N2 adsorption–desorption, SEM, TEM, CO-FTIR, XPS and CO chemisorption measurements were performed to study the effects of different surface morphologies on the surface properties of catalysts. It reveals that the high catalytic performance of 1 wt%Pd/TiO2-SUT can be attributed to its specific hierarchical structure and much higher surface area, improving the uniform dispersion of Pd nanoparticles on the support to expose extra active surface Pd atoms (Pd0 species) over 1 wt%Pd/TiO2-SUT.

Heterogeneous additive‐free highly selective synthesis of 2,5‐bis(hydroxymethyl)furan over catalysts with ultra‐low Pt content

AbstractUltra‐low‐loaded supported Pt catalysts showed an extremely high activity in selective hydrogenation of bioavailable 5‐hydroxymethylfurfural (5‐HMF) to the corresponding diol, i.e. 2,5‐bis(hydroxymethyl)furan (BHMF); among the synthesized catalysts with a Pt content varying in the range 0.025–0.25 wt%, the most active one appeared to be the sample 0.1% Pt/CeO2–ZrO2, which allows us to obtain BHMF with a 97% yield and 100% selectivity from 5‐HMF without the use of alkali or any other additives at a temperature of 170 °C and H2 pressure of 1 MPa, with the 5‐HMF:Pt ratio higher than 1000 mol mol–1. © 2021 Society of Chemical Industry (SCI).

The feasibility study of the indium oxide supported silver catalyst for selective hydrogenation of CO2 to methanol

Silver catalyst has been extensively investigated for photocatalytic and electrochemical CO2 reduction. However, its high activity for selective hydrogenation of CO2 to methanol has not been confirmed. Here, the feasibility of the indium oxide supported silver catalyst was investigated for CO2 hydrogenation to methanol by the density functional theoretical (DFT) study and then by the experimental investigation. The DFT study shows there exists an intense Ag–In2O3 interaction, which causes silver to be positively charged. The positively charged Ag species changes the electronic structure of the metal, facilitates the formation of the Ag–In2O3 interfacial site for activation and dissociation of carbon dioxide. The promoted CO2 dissociation leads to the enhanced methanol synthesis via the CO hydrogenation route as CO2∗→CO∗→HCO∗→H2CO∗→H3CO∗→H3COH∗. The Ag/In2O3 catalyst was then prepared using the deposition-precipitation method. The experimental study confirms the theoretical prediction. The methanol selectivity of CO2 hydrogenation on Ag/In2O3 reaches 100.0% at reaction temperature of 200 °C. It remains more than 70.0% between 200 and 275 °C. At 300 °C and 5 MPa, the methanol selectivity still keeps 58.2% with a CO2 conversion of 13.6% and a space-time yield (STY) of methanol of 0.453 gmethanol gcat−1 h−1, which is the highest methanol STY ever reported for silver catalyst. The catalyst characterization confirms the intense Ag–In2O3 interaction as well, which causes high Ag dispersion, increases and stabilizes the oxygen vacancies and creates the active Ag–In2O3 interfacial site for the enhanced CO2 hydrogenation to methanol.

Facile Redox Synthesis of Novel Bimetallic Crn+/Pd0 Nanoparticles Supported on SiO2 and TiO2 for Catalytic Selective Hydrogenation with Molecular Hydrogen

The bimetallic Crn+/Pd0 nanoparticles have been synthesized for the first time by a two-step redox method. The method includes the deposition of Pd0 nanoparticles on the surface of SiO2 and TiO2 carriers followed by the deposition of Crn+ on the surface of Pd0 nanoparticles using the redox procedures, which are based on the catalytic reduction of Crn+ with H2 in aqueous suspensions at ambient conditions. Transmission (TEM) and scanning (SEM) electron microscopy, X-ray photoelectron spectroscopy (XPS), Fourie-transformed infrared spectroscopy of adsorbed CO (FTIR-CO), and CO chemisorption studies were performed to characterize the morphology, nanoparticle size, element, and particle distribution, as well as the electronic state of deposited metals in the obtained catalysts. A decrease in nanoparticle size from 22 nm (Pd/SiO2) to 2–6 nm (Pd/TiO2) makes possible deposition of up to 1.1 wt.% Cr most likely as Cr3+. The deposition of CrOx species on the surface of Pd nanoparticles was confirmed using FTIR of adsorbed CO and the method of temperature-programmed reduction with hydrogen (TPR-H2). The intensive hydrogen consumption in the temperature ranges from −50 °C to 40 °C (Cr/Pd/SiO2) and from −90 °C to −40 °C (Cr/Pd/TiO2) was first observed for the supported Pd catalysts. The decrease in the temperature of β-PdHx decomposition indicates the strong interaction between the deposited Crn+ species and Pd0 nanoparticle after reduction with H2 at 500 °C. The novel Crn+/Pd/TiO2 catalysts demonstrated a considerably higher activity in selective hydrogenation of phenylacetylene than the Pd/TiO2 catalyst at ambient conditions.

Two-Dimensional Pd Nanosheets with Enhanced Catalytic Activity for Selective Hydrogenation of Nitrobenzene to Aniline

Two-dimensional (2D) metallic Pd nanosheets were synthesized by an ion-exchange method using PdCl42– and magnesium- and aluminum-based metallic (LDH) as intercalation ion and host material, respect...

Selective Hydrogenation of C=C bond in Cinnamaldehyde on Pd Step Sites of Pd/Al2O3

Abstract We found a positive correlation between C=C selective hydrogenation activity of cinnamaldehyde (CAL) and the fraction of the Pd step site on Pd nanoparticles. Owing to a high fraction of step sites, Pd/θ-Al2O3 catalysts with Pd particle size of 5–10 nm were highly active for the C=C selective hydrogenation of CAL.

Pd/Mo2N-TiO2 as efficient catalysts for promoted selective hydrogenation of 4-nitrophenol: A green bio-reducing preparation method

The addition of a suitable co-catalyst is an encouraging way to enhance the catalytic performance of Pd based catalyst with low content. Herein, we describe an easy synthesis of Mo2N-TiO2 with well-dispersed Mo2N nanoparticles through one pot evaporation-induced self-assembly and nitridation treatment method. Moreover, a green bio-reductive approach with Catalpa Fruit (CF) extract was adopted to fabricate Pd/Mo2N-TiO2 catalysts for promoting selective hydrogenation of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) as model reaction. Among these Pd/Mo2N-TiO2 catalysts, 0.8 wt%Pd/Mo2N-TiO2 exhibits significantly high catalytic activity for selective hydrogenation of various nitrophenols and cinnmaldehyde. Importantly, the catalytic activity of the catalyst prepared by the reduction method of the CF extract is higher than that prepared by the reduction method of NaBH4. A serials of characterization, including XRD, N2 adsorption–desorption, TEM, XPS, CO chemisorption and CO-FTIR etc., was carried out to investigate the influence of the prepared method on the surface Pd species and activity. The high performance can be attributed to the specific nanostructure characteristics of the catalyst and the good synergistic effect between Pd and Mo2N, improving the dispersion of Pd nanoparticles atoms and the exposure of more active Pd atoms (surface Pd0 species) on 0.8 wt%Pd/Mo2N-TiO2 due to the CF extract as reductant.

MOF-derived AgCo alloy nanoparticle protected by mesoporous carbon as chemoselective catalyst for hydrogenation of citral

A new robust AgCo alloy catalyst which presents as clean uniform bimetallic nanoparticles (NPs) protected by a mesoporous carbon layer was feasibly produced from a controllable pyrolysis strategy of metal-organic frameworks (MOFs) precursor. The pyrolysis destroyed the microporous structure of Ag(I)-doped Co-MOF but generated a new mesoporous carbon layer, which led to effective substrates diffusion and in situ reduction and generation of the highly active alloy nanoparticles. Benefited from the well dispersed bimetallic alloy NPs and the interaction with Ag and Co, which can adjust the electron distribution on the catalyst surface, the as-prepared AgCo alloy catalyst delivered remarkably selective hydrogenation activity of citral with nearly full conversion and 70% selectivity for hydrogenation of citral to nerol and geraniol under the optimum reaction conditions, which is comparable to the reported Pt, Ru and Re catalysts. In addition, since the AgCo alloy NPs were well protected from aggregation and leaching by the mesoporous carbon, the magnetic catalyst exhibited extremely high catalytic recyclability without any decrease of conversion and selectivity after ten cycles of reuse.

Measurable surface d charge of Pd as a descriptor for the selective hydrogenation activity of quinoline

AbstractAuPd nanoalloys with tunable Pd concentrations have been synthesized and used as model catalysts. They have been directly imaged by high-angle annular dark-field scanning transmission electron microscopy and investigated by thorough analyses of their extended X-ray absorption fine structure, X-ray absorption near-edge structure, X-ray diffraction and X-ray photoelectron spectroscopy measurements. The bimetallic nanoparticles are embedded in a carbonaceous matrix and have almost an identical structure at the atomic level and the same electronic properties as AuPd bulk alloys with the same compositions. The d-electron increase at surface Pd sites is determined by the Pd concentration of the alloy. Similarly, their activation entropy and catalytic activity for the hydrogenation of quinoline is related to the Pd concentration, with Au50Pd50 the most active of the alloys investigated. An almost 11 times higher activity was achieved compared to a pure Pd catalyst. The experimentally measurable surface d charge at the Pd sites in the AuPd was found to linearly correlate with the activation entropy and catalytic activity for the hydrogenation of quinoline. The alloy structure is stable, showing negligible metal segregation, dissolution-redeposition and aggregation during the hydrogenation process which involves strong adsorption.

Microstructure and catalytic activity for selective hydrogenation of phenylacetylene of intermetallic Ni70Ga30, Ni70In30, and Ni70Sn30 melt-spun alloys

The Ni70Ga30, Ni70In30, Ni70Sn30 alloys were manufactured by melt spinning technique. The as melt-spun ribbons showed a multiphase microstructure prone to alteration by heat treatment at 800 °C. The average grain size in the as melt-spun ribbons was circa 3–4 μm and it increased after heat treatment; the increase is tenfold in the case of the Ni70In30 ribbon due to its low homologues temperature. The ribbons show strongly developed <100> fiber texture with high concentration of high angle grain boundaries. Martensite microstructure was found in the Ni70Ga30 ribbon. At room temperature all the studied ribbons were found active for selective hydrogenation of phenylacetylene with conversion rates after 4 h reaction time of around 20%. Further improvement of catalytic activity is expected with surface pretreatment, pulverization and increasing of the reaction temperature. Altogether the as melt spun ribbons present an attractive alternative to cold rolled and annealed ribbons and to nanocrystalline intermetallics for application in a range of chemical reactions.