Investigation Of Catalytic Performance Research Articles

Controllable synthesis of CuAlO2 via solid-phase method and its catalytic performance for methanol steam reforming to hydrogen

This study explores the controllable synthesis of CuAlO2 using copper hydroxide and pseudo-boehmite powders as raw materials via a simple solid-phase ball milling method, along with its catalytic performance investigation in methanol steam reforming (MSR). Various catalysts were prepared under different conditions, such as calcination temperature, calcination atmosphere, and heating rate. Characterization techniques including BET, XRD, XPS, SEM and H2-TPR were employed to analyze the samples. The results revealed significant effects of calcination temperature on the phase compositions, specific surface area, reduction performance, and surface properties of the CA-T catalysts. Based on the findings, a synthesis route of CuAlO2 via the solid-phase method was proposed, highlighting the importance of high calcination temperature, nitrogen atmosphere, and low heating rate for CuAlO2 formation. Catalytic evaluation data demonstrated that CuAlO2 could catalyze MSR without pre-reduction, with the catalytic performance of CA-T catalysts being notably influenced by calcination temperature. Among the prepared catalysts, the CA-1100 catalyst exhibited the highest catalytic activity and stability. The findings of this study might be useful for the further study of the catalytic material for sustained release catalysis, including the synthesis of catalytic materials and the regulation of sustained release catalytic performance.

Highly Efficient Nitrogen Reduction to Ammonia through the Cooperation of Plasma and Porous Metal-Organic Framework Reactors with Confined Water.

While the ambient N2 reduction to ammonia (NH3) using H2O as hydrogen source (2N2+6H2O=4NH3+3O2) is known as a promising alternative to the Haber-Bosch process, the high bond energy of N≡N bond leads to the extremely low NH3 yield. Herein, we report a highly efficient catalytic system for ammonia synthesis using the low-temperature dielectric barrier discharge plasma to activate inert N2 molecules into the excited nitrogen species, which can efficiently react with the confined and concentrated H2O molecules in porous metal-organic framework (MOF) reactors with V3+, Cr3+, Mn3+, Fe3+, Co2+, Ni2+ and Cu2+ ions. Specially, the Fe-based catalyst MIL-100(Fe) causes a superhigh NH3 yield of 22.4 mmol g-1 h-1. The investigation of catalytic performance and systematic characterizations of MIL-100(Fe) during the plasma-driven catalytic reaction unveils that the in situ generated defective Fe-O clusters are the highly active sites and NH3 molecules indeed form inside the MIL-100(Fe) reactor. The theoretical calculation reveals that the porous MOF catalysts have different adsorption capacity for nitrogen species on different catalytic metal sites, where the optimal MIL-100(Fe) has the lowest energy barrier for the rate-limiting *NNH formation step, significantly enhancing efficiency of nitrogen fixation.

Highly Efficient Nitrogen Reduction to Ammonia through the Cooperation of Plasma and Porous Metal‐Organic Framework Reactors with Confined Water

While the ambient N2 reduction to ammonia (NH3) using H2O as hydrogen source (2N2+6H2O=4NH3+3O2) is known as a promising alternative to the Haber‐Bosch process, the high bond energy of N≡N bond leads to the extremely low NH3 yield. Herein, we report a highly efficient catalytic system for ammonia synthesis using the low‐temperature dielectric barrier discharge plasma to activate inert N2 molecules into the activated nitrogen species, which can efficiently react with the confined and concentrated H2O molecules in porous metal‐organic framework (MOF) reactors with V3+, Cr3+, Mn3+, Fe3+, Co2+, Ni2+ and Cu2+ ions. Specially, the Fe‐based catalyst MIL‐100(Fe) causes a superhigh NH3 yield of 22.4 mmol g‐1 h‐1. The investigation of catalytic performance and systematic characterizations of MIL‐100(Fe) during the plasma‐driven catalytic reaction unveils that the in situ generated defective Fe‐O clusters are the highly active sites and NH3 molecules indeed form inside the MIL‐100(Fe) reactor. The theoretical calculation reveals that the porous MOF catalysts have different adsorption capacity for nitrogen species on different catalytic metal sites, where the optimal MIL‐100(Fe) has the lowest energy barrier for the rate‐limiting *NNH formation step, significantly enhancing efficiency of nitrogen fixation.

Metal–organic framework-supported ionic liquids for lipase immobilization: design, characterization, and investigation of catalytic performance

Magnetic MOF supported ionic liquids provided a beneficial microenvironment for immobilized lipase. The biocatalyst exhibited enhanced catalytic performance.

Engineered N-doped graphene quantum dots/CoFe2O4 spherical composites as a robust and retrievable catalyst: fabrication, characterization, and catalytic performance investigation in microwave-assisted synthesis of quinoline-3-carbonitrile derivatives.

Nitrogen-doped graphene quantum dots (N-GQDs), which are less than 10 nm in size, are an interesting member of the nanocarbon materials family. N-GQDs nanostructures have been broadly applied in various fields, such as drug-gene delivery systems, photocatalytic reactions, and catalysts, owing to their unique properties. However, N-GQDs have rarely been introduced as a catalyst in organic synthesis. Herein, CoFe2O4 nanocomposites with diverse morphologies are fabricated in various conditions (e.g. green routes, various pH adjusters, temperatures). Due to further active sites on the surface of the nanocomposites, morphology engineering can be effective in catalytic activities. Following the synthesis, the catalytic activity of the engineered CoFe2O4 nanocomposites was screened, and it presented the order of spherical > rod > prism > cubic. The uniform spherical morphology provides more accessible active sites. Then, the novel nano-sized N-GQDs/CoFe2O4 magnetic spherical composite was readily fabricated by a green, low-cost, and easy hydrothermal route. The engineered composite was applied as an efficient magnetic nanocatalyst for the MW-assisted one-pot synthesis of new and known quinoline-3-carbonitrile derivatives (83–96%) in the shortest reaction time (60–90 s). Furthermore, the green route, easy separation of the nanocatalyst, and reusability (7 runs) without noticeable loss of catalytic efficiency are other advantages.

Photocatalytic reduction of CO2 into methanol over Cu–Ni–TiO2 supported on SiO2-Al2O3 catalyst

The photocatalytic reduction of carbon dioxide into hydrocarbon over bimetallic-loaded TiO2 supported on SiO2-Al2O3 (Ni–Cu–TiO2 /SiO2-Al2O3) catalyst was studied. The study also compared the performance of the catalyst with Degussa P25 (TiO2), prepared TiO2, SiO2-Al2O3 loaded with TiO2. The investigation of catalytic performance was carried out in a batch reactor under UV irradiation. All the samples were characterized by X-ray diffractometer (XRD), N2 gas adsorption–desorption, and Ultraviolet–visible diffuse reflectance spectrometer (UV–Vis-DRS). The result showed SiO2-Al2O3loaded with Ni–Cu–TiO2 yielded the highest production rate of methanol (405.08μmol/gcat ) after 2 h of reaction under UV at room temperature and a pressure of 1 atm. The photocatalytic reduction rate over the bimetallic-loaded TiO2 supported on SiO2-Al2O3 catalysts was found to be approximately 2.4 times that over SiO2-Al2O3 loaded with TiO2. This can be explained by the presence of nickel and copper on the catalyst which reduced the energy bandgap of the catalyst and decreased the recombination of electron–hole pairs.

Local environment and catalytic property of External Lewis acid sites in hierarchical lamellar titanium Silicalite-1 zeolites

Abstract Hierarchical two-dimensional (2D) lamellar zeolites represent a young emerging field and a novel expression of the zeolite frameworks. Accompanied with synthesis and catalytic performance investigation, assessment on the local environment and catalytic behavior of acid sites in 2D zeolites are needed. Here, we described the local environment of Lewis acid sites and evaluated catalytic activities of external acid sites (i.e. sites on external surface and in mesopores) in 2D lamellar titanium silicalite-1 (TS-1) zeolites. For comparison purpose, four TS-1 zeolites, including 3D TS-1, multilamellar 2D TS-1 without pillarization and with pillarization by silica and silica/titania, respectively, were prepared. The local environment of Ti-sites, including coordination status of Ti-atom, speciation of hydroxyl (-OH) group that hints degree of confinement, acid site strength and accessibility, was collectively assessed by spectroscopic and organic base titration measurements. Kinetic studies of cyclooctene (C8H14) epoxidation with hydrogen peroxide (H2O2) discerned catalytic activity of external Ti-sites that decreased with increasing mesoporosity due to decrease in site confinement.

Harnessing the Untapped Catalytic Potential of a CoFe2O4/Mn-BDC Hybrid MOF Composite for Obtaining a Multitude of 1,4-Disubstituted 1,2,3-Triazole Scaffolds.

Metal-organic frameworks derived nanostructures with extraordinary variability, and many unprecedented properties have recently emerged as promising catalytic materials to address the challenges in the field of modern organic synthesis. In this contribution, the present work reports the fabrication of an intricately designed magnetic MOF composite based on Mn-BDC (manganese benzene-1,4-dicarboxylate/manganese terephthalate) microflakes via a facile and benign in situ solvothermal approach. Structural information about the as-synthesized hybrid composite has been obtained with characterization techniques such as TEM, SEM, XRD, FT-IR, AAS, EDX, ED-XRF, and VSM analysis. Upon investigation of catalytic performance, the resulting material unveils remarkable efficacy toward facile access of a diverse array of pharmaceutically active 1,2,3-triazoles from a multicomponent coupling reaction of terminal alkynes, sodium azide, and alkyl or aryl halides as coupling partners. In addition to a wide substrate scope, the catalyst with highly accessible active sites also possesses a stable catalytic metal center along with superb magnetic properties that facilitate rapid and efficient separation. The prominent feature that makes this protocol highly desirable is the ambient and greener reaction conditions in comparison to literature precedents reported to date. Further, a plausible mechanistic pathway is also proposed to rationalize the impressive potential of the developed catalytic system in the concerned reaction. We envision that findings from our study would not only provide new insights into the judicious design of advanced MOF based architectures but also pave the way toward greening of industrial manufacturing processes to tackle critical environmental and economic issues.

Design of Silver-Based Controlled Nanostructures for Plasmonic Catalysis under Visible Light Irradiation

Abstract Recent years have marked substantial research interest in the design and development of photocatalyst materials for the conversion of solar to chemical energy. In this brief account, we present some of the recent research on silver-based plasmonic nanocatalysts supported on silica for their preparative techniques, characterization and efficient catalysis under visible light irradiation conditions. Ag nanoparticles (NPs) which can be prepared with different color and morphology, are explored for possible enhancement effects in catalytic performance activities under visible light irradiation. A number of combinations of Ag with other catalytically active metal NPs is studied for exploring the plasmonic enhancement activities. Ag NPs combined with single site Ti-oxide moiety is studied for the enhanced hydrogen production activity attributing to the Ag plasmonic effect under UV-vis light irradiation. The account is further elaborated by citing some recently reported works, plausible mechanism of enhancements, conclusions and outlook. We expect that the present account will provide insights into the design and investigation of catalytic performances in the visible light driven plasmon-mediated chemical reactions.

The role of graphene coating on cordierite-supported Pd monolithic catalysts for low-temperature combustion of toluene

In the present work, a Pd/graphene/cordierite (Pd/Gr/Cor) composite was prepared as a monolithic catalyst for low-temperature combustion of toluene. We mainly focused on understanding the role of graphene coating through investigation of catalytic performance and adsorption behavior of the composite. Compared with the traditional Pd/Cor catalyst without graphene coating, Pd/Gr/Cor catalyst delivered much higher activity and stability for toluene catalytic combustion in both dry and moist conditions. Transmission electron microscopy (TEM) and hydrophobic characterizations indicated that graphene coating can considerably improve the dispersity of Pd nanoparticles and enhance the hydrophobicity of the cordierite support. The adsorption behavior of the above two catalysts, including adsorption isothermal, adsorption kinetics, and adsorption thermodynamics were carefully investigated. The simulation results indicated that a large amount of toluene was adsorbed on graphene surface through relatively weak interaction, whereas only a relatively small amount of toluene was adsorbed on Pd surface with strong affinity. The adsorption thermal calculation indicated that the adsorption of toluene on graphene was a process with reduced entropy, indicating highly-ordered assembly of toluene molecular on graphene. It is the significant concentration and affinity gap between graphene and Pd that ensures a simultaneously and rapid transfer of toluene during the reaction process.

How morphological surface parameters are correlated with electrocatalytic performance of cobalt-based nanostructures

To overcome recent energy and environment challenges, developing efficient and low cost photocatalysts are unavoidable. In this context, design of semiconductor nanostructures modified with earth abundant co-catalysts for water splitting reactions requires well engineered and controlled process to optimize surface interface and maximize nanocomposite system efficiency. Here, TiO2 nanotube were synthesized electrochemically and decorated with cobalt based nanostructure co-catalyst for water oxidation reaction using low cost and scalable electro-deposition approach. By changing deposition parameters and complete studying on samples surface morphology and related statistical analysis data, correlation between all morphological parameters and photoelectrochamical activity of correspondence photoanode was illustrated for the first time. Based on SEM analysis and surface analysis data as well as catalytic performance investigation, nanotubes decorated with Co nanoparticles at 0.1mAcm−2 deposited for 2000s presented the best performance with most isotropic surface. Results suggested that by tuning deposition parameters surface structural parameters like fractal dimension, corner frequency, roughness and feature shape and size can be engineered completely. Moreover, X-ray diffraction data along with Rietveld method revealed coexistence of anatase, rutile and Ti2O3 phases in the photoanode while poor crystallinity of grown cobalt based nanostructures was confirmed.

Cobalt aluminate nanoparticles supported on MIL-101 structure: catalytic performance investigation

Novel heterogeneous catalysts composed by CoAl2O4 nanoparticles supported on MIL-101(Cr) framework exhibiting remarkable catalytic performance for thioanisole oxidation under sustainable conditions.