Catalysts For Hydrogenation Research Articles

Effect of Calcination Atmosphere on the Performance of Cu/Al2O3 Catalyst for the Selective Hydrogenation of Furfural to Furfuryl Alcohol.

The selective hydrogenation of the biomass platform molecule furfural (FAL) to produce furfuryl alcohol (FA) is of great significance to alleviate the energy crisis. Cu-based catalysts are the most commonly used catalysts, and their catalytic performance can be optimized by changing the preparation method. This paper emphasized the effect of calcination atmosphere on the performance of a Cu/Al2O3 catalyst for the selective hydrogenation of FAL. The precursor of the Cu/Al2O3 catalyst prepared by the ammonia evaporation method was treated with different calcination atmospheres (N2 and air). On the basis of the combined results from the characterizations using in situ XRD, TEM, N2O titration, H2-TPR and XPS, the Cu/Al2O3 catalyst calcined in the N2 atmosphere was more favorable for the dispersion and reduction of Cu species and the reduction process could produce more Cu+ and Cu0 species, which facilitated the selective hydrogenation of FAL to FA. The experimental results showed that the N2 calcination atmosphere improved the FAL conversion and FA selectivity, and the FAL conversion was further increased after reduction. Cu/Al2O3-N2-R exhibited the outstanding performance, with a high yield of 99.9% of FA after 2 h at 120 °C and an H2 pressure of 1 MPa. This work provides a simple, efficient and economic method to improve the C=O hydrogenation performance of Cu-based catalysts.

Sn-doped PdAg/Al2O3 catalysts: Efficient catalysts for the selective hydrogenation of acetylene to ethylene under industrial conditions

PdAg/Al2O3 catalysts were prepared using a simple and scalable preparation method. A systematic approach established a preparation-performance relationship which revealed that the Pd:Ag ratio and Pd reduction method affects the overall performance for the selective hydrogenation of acetylene to ethylene under industrially relevant tail-end reaction conditions. The addition of Sn improved selectivity with the optimum system achieving 97% selectivity towards ethylene, outperforming two industrial references. Density functional theory (DFT) simulations and electron microscopy analysis revealed that Sn integrates into the Pd lattice and increases the energy barrier for ethylene adsorption. This work demonstrates that Sn can be used to tailor catalyst performance for industrially relevant PdAg/Al2O3 catalysts.

Hydrogen-rich surface of MoC catalysts for efficient CO2 hydrogenation induced by a coupled hydrogen donator

Hydrogen-rich surface of MoC catalysts for efficient CO2 hydrogenation induced by a coupled hydrogen donator

Structural, electronic and superconducting properties of room temperature deposited VN[formula omitted] thin films

In recent years, vanadium mononitride (VN) thin films have emerged for their multifaceted functionalities e.g. as electrodes in battery and supercapacitors, as catalysts for hydrogen and oxygen evolution reactions, as superconductors for hot-electron bolometer detectors. In this study, we investigate the structural, electronic and superconducting properties of polycrystalline VNx thin films synthesized at room temperature using a reactive dc magnetron sputtering. The structural evolution of VNx samples with increase in partial N2 gas flow (RN2) during the reactive sputtering and corresponding change in the oxidation states were systematically studied. At a first glance, no visible changes appear in the lattice parameters within RN2= 5–50% samples. Despite this, only RN2 = 5 and 10% samples exhibit superconductivity. Probing the electronic structure around the V L-edges and O, N K-edge again did not reflect any minimal changes in RN2 = 5–100% samples. Across the V K-edge, the oxidation state was also found to be similar. However, the ambiguity was resolved from the Fourier transformed EXAFS spectra immediately revealing presence of a higher number of cationic vacancies. These vacancies drive the VNx system towards poor metals exhibiting dρ/dT = negative in the temperature dependent resistivity. This is in sharp contrast to the previous reports so far exhibiting positive slopes evident for metals. The present work insights on several ambiguities observed for the first time in the V-N system. The work further emphasizes the need to perform a similar study on epitaxially grown VNx thin film samples with reduced defects.

Fe2O3@ZrO2 catalyst derived from MOF-on-MOF for direct CO2 hydrogenation to light olefins

The utilization of CO2 for the production of light olefins through catalysis with iron-based catalysts presents a viable strategy to address the challenges of carbon neutrality. In this study, we synthesized a novel hybrid catalyst Fe2O3@ZrO2, derived from the pyrolysis of dual metal–organic frameworks (NH2-MIL-88B@UiO-66). Under specific conditions (340 °C, 3.0 MPa, CO2/H2 = 1:3, 10000 mL gcat−1h−1), the Fe2O3@ZrO2 catalyst exhibited a notable space–time yield of light olefins at 12.7 mmol g−1h−1. The characterizations results show an electron transfer from ZrO2 to the Fe2O3 surface was observed at the heterointerface of Fe2O3 and ZrO2. This electron transfer mechanism was identified as advantageous for the formation of the active phase Fe5C2. This research introduces an innovative use of the hybrid Fe2O3@ZrO2 catalyst derived from MOF-on-MOF, holding significant promise in advancing the field of CO2 hydrogenation catalysts.

Kinetics insights into size effects of carbon nanotubes’ growth and their supported platinum catalysts for 4,6-dinitroresorcinol hydrogenation

Size effects are a well-documented phenomenon in heterogeneous catalysis, typically attributed to alterations in geometric and electronic properties. In this study, we investigate the influence of catalyst size in the preparation of carbon nanotube (CNT) and the hydrogenation of 4,6-dinitroresorcinol (DNR) using Fe2O3 and Pt catalysts, respectively. Various Fe2O3/Al2O3 catalysts were synthesized for CNT growth through catalytic chemical vapor deposition. Our findings reveal a significant influence of Fe2O3 nanoparticle size on the structure and yield of CNT. Specifically, CNT produced with Fe2O3/Al2O3 containing 28% (mass) Fe loading exhibits abundant surface defects, an increased area for metal-particle immobilization, and a high carbon yield. This makes it a promising candidate for DNR hydrogenation. Utilizing this catalyst support, we further investigate the size effects of Pt nanoparticles on DNR hydrogenation. Larger Pt catalysts demonstrate a preference for 4,6-diaminoresorcinol generation at (1 0 0) sites, whereas smaller Pt catalysts are more susceptible to electronic properties. The kinetics insights obtained from this study have the potential to pave the way for the development of more efficient catalysts for both CNT synthesis and DNR hydrogenation.

Promotion of Mg(OH)2 in Cu-Based Catalysts for Selective Hydrogenation of Acetylene

Promotion of Mg(OH)2 in Cu-Based Catalysts for Selective Hydrogenation of Acetylene

Nonsilyl Bicyclic Secondary Amine Catalysts for the Asymmetric Transfer Hydrogenation of α,β-Unsaturated Aldehydes.

The first chiral synthesis of nonsilyl bicyclic secondary amine organocatalysts and their application to the asymmetric transfer hydrogenation of α,β-unsaturated aldehydes are disclosed. A lower catalytic loading (5 mol %) is demonstrated for the reduction of a wide range of α,β-unsaturated aldehydes (up to 97% yield and up to 99% ee). The application of this scalable methodology is showcased for the asymmetric synthesis of bioactive molecules such as phenoxanol, citronellol, ramelteon, and terikalant.

Development of Multifunctional Catalysts for the Direct Hydrogenation of Carbon Dioxide to Higher Alcohols.

The direct hydrogenation of greenhouse gas CO2 to higher alcohols (C2+OH) provides a new route for the production of high-value chemicals. Due to the difficulty of C-C coupling, the formation of higher alcohols is more difficult compared to that of other compounds. In this review, we summarize recent advances in the development of multifunctional catalysts, including noble metal catalysts, Co-based catalysts, Cu-based catalysts, Fe-based catalysts, and tandem catalysts for the direct hydrogenation of CO2 to higher alcohols. Possible reaction mechanisms are discussed based on the structure-activity relationship of the catalysts. The reaction-coupling strategy holds great potential to regulate the reaction network. The effects of the reaction conditions on CO2 hydrogenation are also analyzed. Finally, we discuss the challenges and potential opportunities for the further development of direct CO2 hydrogenation to higher alcohols.

Tailoring the Active Sites of Nanosheet NiSe/NiSe2 Catalyst by Pulse Electrodeposition on the 3D Microporous Ni-Cu/NF Substrate for both Hydrogen and Oxygen Evolution Reactions

Establishing proper intrinsic catalysts with nanostructured high active surfaces endows the paramount electrocatalytic activity. A Ni-Se@Cu-Ni/NF catalyst for hydrogen and oxygen evolution reactions (HER and OER) is prepared via an efficient two-step pulse current (PC) electrodeposition method. The initial 3D film of Cu-Ni is synthesized via the dynamic hydrogen bubble template (DHBT) method to attain further active surface area. Then, Ni-Se film is prepared by direct current (DC) and PC electrodeposition. Morphological, chemical, and electrocatalytic characteristics of the Ni-Se electrodeposited films are evaluated. X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy results show a NiSe/NiSe2 nanofilm on the 3D microporous nanostructured Cu-Ni substrate which reveals an efficient bifunctional electrocatalytic behavior with overpotentials of 74 and 272 mV in the current density of 10 mA cm−2, and Tafel slopes of 78 and 50 mV dec−1 for HER and OER, respectively. The two-electrode examination with NiSe/NiSe2@Cu-Ni/NF catalyst in overall water splitting indicates a required potential of 1.57 V in the current density of 10 mA cm−2.

The Impact of Different Catalysts on Heterogeneous Hydrogenation of Hydroxyl‐Terminated Polybutadiene

AbstractHydroxyl‐terminated polybutadiene (HTPB) is hydrogenated using catalytic hydrogenation with HTPB as a precursor using various catalysts. The hydrogenation is carried out using iso‐propyl alcohol (IPA) and toluene as an active solvent media. The present paper used (a) charcoal, (b) palladium supported by charcoal (Pd−C), (c) palladium supported by zirconium oxide (Pd‐ZrO2), and (d) copper chromite (CC) as catalysts for hydrogenation of HTPB to study the influence on the degree of hydrogenation with respect to each catalyst. The experimental data shows that hydrogenated HTPB (HHTPB) formation is predominantly controlled by physisorption and chemical reaction with a catalyst. Various techniques like NMR, FTIR and chemical analysis are used to characterize HTPB and HHTPB. Degree of hydrogenation of HTPB is found to be higher with copper chromite when compared to other catalysts in this work. Post‐hydrogenation, no significant change in hydroxyl value and a marginal increase in molecular weight is noticed with all catalysts. HTPB and HHTPB samples are analyzed using FTIR, 1H‐NMR, and 13C‐NMR and TG‐DSC studies, and inferences are derived with respect to the change in the olefinic region, microstructural changes, molecular weight, and thermal decomposition characteristics.

Green synthesis of silver nanoparticles-capped aminated lignin as a robust active catalyst for dye discoloration

Considering the severity of global environmental issues, biomass-derived products have received significant attention as alternatives to foster sustainability and eco-friendliness. The use of metal nanoparticle catalysts for dye decomposition is emerging as a promising approach for environmentally friendly dye removal. In this study, an aminosilane-modified lignin (AML)/silver nanoparticle (AgNP) composite was fabricated and used as a hydrogenation catalyst. The AgNPs were well dispersed on the AML surface and formed strong bonds within the AML/AgNP complex. AML also served as an effective reducing and capping agent for Ag(I) ions. The AML/AgNPs were found to be an efficient catalyst with excellent dye degradation ability and easy reusability. Biomass-derived lignin can be used as a reducing and capping agent for metals and this complex can be used as a high-value bio-catalyst for wastewater remediation.

Polyether-functionalized ionic liquid-assisted Rh-AMPP-catalyzed asymmetric hydrogenation of ketopantoyl lactone to D-(−)-pantolactone

Abstract In this paper, the reaction of chiral Rh-AMPP catalysts for the asymmetric hydrogenation of ketopantoyl lactone to D-(-)pantolactone under a polyether guanidinium salt ionic liquid ([Me(EO)16TMG][OMs])/toluene homogeneous catalytic system was investigated. The impact of polyether ionic liquid doping on the catalytic activity and enantioselectivity was investigated. To separate and recycle chiral Rh-AMPP catalysts, a “homogeneous catalytic-liquid/solid separation” system on the basis of [Me(EO)16TMG][OMs] was constructed. The catalytic system exhibited high catalytic activity, enantioselectivity, and long-term stability, and no obvious reduction in enantioselectivity was found after four cycles.

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

Chemoselective hydrogenation of quinolines and imines using unsupported nanoporous ruthenium catalyst

Unsupported nanoporous ruthenium (RuNPore) is a highly efficient, practically applicable, and recyclable heterogeneous catalyst for hydrogenation of CN bonds exist in quinolines and imines using H2 molecular as reductants. A variety of quinolines and imines with a broad functional groups were transformed to the corresponding desired compounds under mild conditions. The selective hydrogenation reaction occurred exclusively in the existence of Cl and Br atoms.

Sulfurization of bimetallic (Co and Fe) oxide and alloy decorated on multi-walled carbon nanotubes as efficient bifunctional electrocatalyst for water splitting

The advancement in electrocatalysis, particularly in the development of efficient catalysts for hydrogen and oxygen evolution reactions (HER and OER), is crucial for sustainable energy generation through processes like overall water splitting. A notable bifunctional electrocatalyst, CoFe2O4/Co7Fe3, has been engineered to facilitate both OER and HER concurrently, aiming to reduce overpotentials. In the pursuit of further enhancing catalytic efficiency, a morphological transformation has been achieved by introducing a sulphur source and multi-walled carbon nanotubes (MWCNTs) into the catalyst system, resulting in S–CoFe2O4/Co7Fe3/MWCNTs. This modification has significantly improved the activity for both OER and HER. An onset overpotential of 250 mV@10 mAcm−2 for the OER and 270 mV@50 mAcm−2 for the HER, indicating efficient catalytic activity at relatively low overpotentials. S–CoFe2O4/Co7Fe3/MWCNTs display an outstanding long-term stability in alkaline electrolytes, with minimal Tafel slopes of 77 mV/dec for the OER and 70 mV/dec for the HER, suggesting sustained catalytic performance over extended periods. Furthermore, when employed as both the cathode and anode in the context of complete water splitting, S–CoFe2O4/Co7Fe3/MWCNTs demonstrate an impressive cell voltage of 1.52 V at a current density of 10 mA cm−2 in a 1 M KOH solution, showcasing its viability for practical applications. Given its cost-effectiveness and superior activity, S–CoFe2O4/Co7Fe3/MWCNTs hold significant promise for widespread applications in overall water splitting electrocatalysis, contributing to the advancement of cleaner and sustainable fuel generation technologies.

Discovery of Alloy Catalysts Beyond Pd for Selective Hydrogenation of Reformate via First‐Principle Screening with Consideration of H‐Coverage

AbstractThe highly selective hydrogenation to remove olefins is a significant refining approach for the reformate. Herein, a library of transition metal for reformate hydrogenation is tested experimentally to validate the predictive level of catalytic activity from our theoretical framework, which combines ab initio calculations and microkinetic modeling, with consideration of surface H‐coverage effect on hydrogenation kinetics. The favorable H coverage of specific alloy surface under relevant hydrogenation condition, is found to be determined by its corresponding alloy composition. Besides, olefin hydrogenation rate is determined as a function of two descriptors, i.e. H coverage and binding energies of atomic hydrogen, paving the way to computationally screen on metal component in the periodic table. Evaluation of 172 bimetallic alloys based on the activity volcano map, as well as benzene hydrogenation rate, identifies prospective superior candidates and experimentally confirms that Zn3Ir1 outperforms pure Pd catalysts for the selective hydrogenation refining of reformate. The insights into H‐coverage‐related microkinetic modelling have enabled us to both theoretically understand experimental findings and identify novel catalysts, thus, bridging the gap between first‐principle simulations and industrial applications. This work provides useful guidance for experimental catalyst design, which can be easily extended to other hydrogenation reaction.

Discovery of Alloy Catalysts Beyond Pd for Selective Hydrogenation of Reformate via First-Principle Screening with Consideration of H-Coverage.

The highly selective hydrogenation to remove olefins is a significant refining approach for the reformate. Herein, a library of transition metal for reformate hydrogenation is tested experimentally to validate the predictive level of catalytic activity from our theoretical framework, which combines ab initio calculations and microkinetic modeling, with consideration of surface H-coverage effect on hydrogenation kinetics. The favorable H coverage of specific alloy surface under relevant hydrogenation condition, is found to be determined by its corresponding alloy composition. Besides, olefin hydrogenation rate is determined as a function of two descriptors, i.e. H coverage and binding energies of atomic hydrogen, paving the way to computationally screen on metal component in the periodic table. Evaluation of 172 bimetallic alloys based on the activity volcano map, as well as benzene hydrogenation rate, identifies prospective superior candidates and experimentally confirms that Zn3Ir1 outperforms pure Pd catalysts for the selective hydrogenation refining of reformate. The insights into H-coverage-related microkinetic modelling have enabled us to both theoretically understand experimental findings and identify novel catalysts, thus, bridging the gap between first-principle simulations and industrial applications. This work provides useful guidance for experimental catalyst design, which can be easily extended to other hydrogenation reaction.

Boundary Conditions for Promotion versus Poisoning in Copper–Gallium-Based CO2-to-Methanol Hydrogenation Catalysts

Boundary Conditions for Promotion versus Poisoning in Copper–Gallium-Based CO₂-to-Methanol Hydrogenation Catalysts

Metal-free catalysts for hydrogenation.

Metal-free catalysts for hydrogenation.