Immobilization Of Palladium Nanoparticles Research Articles

In situ immobilized palladium nanoparticles (Pd NPs) on fritillaria imperialis flower extract-modified graphene and their catalytic activity for reduction of 4-nitrophenol

Abstract In this study, a complete green synthesis method to reduced graphene oxide-Pd nanoparticles hybrid by applying extract of Fritillaria imperialis flower as both stabilizing and reducing agent was reported. Fritillaria imperialis flower extract reduce graphene oxide and adsorb on the reduced graphene oxide surface. Moreover, the surface adsorbed Fritillaria imperialis flower extract can more in situ reduce Pd ions to Pd nanoparticles and stabilize them. The physicochemical and structure properties of the produced nanohybrid were examined in detail by X-ray diffraction (XRD), UV–vis spectroscopy, field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), wavelength-dispersive X-ray spectroscopy (WDX), inductively coupled plasma (ICP) and X-ray photoelectron spectroscopy (XPS). The obtained results showed that Pd nanoparticles uniformly distributed on the functionalized graphene surface. The catalytic efficiency of the resulting heterogeneous nanocatalyst (Pd NPs/FGO) was evaluated at room temperature for the 4-nitrophenol (4-NP) reduction in an environmental friendly medium. The enhanced catalytic activity observed with our nanocatalyst is attributed to the graphene surface's coated by biopolymers of Fritillaria imperialis flower extract which stabilizes and attracting the aryl nitro substrates adjacent to the catalytic sites which in turn facilitates the reduction of nitro groups. The catalyst was recycled by centrifugation and reapplied several times without any significant catalytic activity loss.

In-Situ Growth of NiFe2O4/2D MoS2 p-n Heterojunction Immobilizing Palladium Nanoparticles for Enhanced Visible-Light Photocatalytic Activities

Solar energy is considered as a green and abundant energy for catalytic reactions. In this work, a magnetically recoverable NiFe2O4/2D MoS2–Pd nanocomposite is successfully synthesized via a simple one-pot hydrothermal method. The intimate interfacial contact between NiFe2O4 nanocubes and corrugated MoS2 nanosheets forms the NiFe2O4/2D MoS2 p-n heterojunction, while plasmonic Pd nanoparticles are uniformly immobilized on the surface of it. Dye degradation and Suzuki-Miyaura coupling reaction are employed to evaluate the photocatalytic activity of the NiFe2O4/2D MoS2–Pd nanocomposite. Significantly, both dye degradation and Suzuki-Miyaura coupling reaction can be efficiently performed in a short time under mild conditions. In comparison, the physically mixed NiFe2O4+2D MoS2 heterojunction immobilizing palladium nanoparticles shows poor photocatalytic activity. Photocatalytic results demonstrate that the in situ formation of NiFe2O4/2D MoS2 p-n heterojunction greatly improves the visible-light absorption an...

Immobilization of palladium nanoparticles as a recyclable heterogeneous catalyst for the Suzuki–Miyaura coupling reaction

This work describes the synthesis of Pd nanoparticles that are stabilized on CaAl-layered double hydroxide functionalized with Tris (tris(hydroxymethyl)aminomethane). The synthesized catalyst is characterized by several different analyses and has been successfully applied to the Suzuki–Miyaura reaction.

In Situ Green Synthesis of Pd Nanoparticles on Tannic Acid‐Modified Magnetite Nanoparticles as a Green Reductant and Stabilizer Agent: Its Application as a Recyclable Nanocatalyst (Fe3O4@TA/Pd) for Reduction of 4‐Nitrophenol and Suzuki Reactions

AbstractTannic acid, as a humic‐like substance with phenolic hydroxyl and carbonyl functional groups, can modify surface of Fe3O4 NPs. Moreover, it can improve surface properties and capacity of Fe3O4 for adsorption and reduction of palladium ions through complexing with them, in aqueous solutions. Therefore, Fe3O4@TA NPs have potentials of reducing, stabilizing and immobilizing palladium nano particles to generate novel magnetic palladium nanocatalysts. Inductively coupled plasma (ICP), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X‐ray photoelectron spectroscopy (XPS), energy‐dispersive X‐ray spectrum (EDS), vibrating sample magnetometer (VSM) and Fourier transform infrared (FTIR) methods unraveled the catalyst properties. Investigation of Fe3O4@TA/Pd NPs performance illustrated its recycle nature and high catalytic activity towards Suzuki‐Miyaura cross‐coupling reactions and reduction of 4‐nitrophenol (4‐NP), at room temperature.

Immobilization of palladium nanoparticles on ionic liquid-triethylammonium chloride functionalized magnetic nanoparticles: As a magnetically separable, stable and recyclable catalyst for Suzuki-Miyaura cross-coupling reactions

A facile procedure was applied to successfully synthesize novel Pd nanoparticles immobilized on triethanolamine-functionalized magnetic nanoparticles [Fe3O4/IL/Pd]. Diverse characterizations (HR-TEM, XRD, FT-IR, TGA, EDX, FE-SEM, ICP, XPS and VSM) were carried out to identify intrinsic traits of the nanoparticles. At room temperature, Fe3O4/IL/Pd demonstrated high catalytic activity toward Suzuki-Miyaura cross-coupling reactions in aqueous solution. Based on the results, Fe3O4/IL/Pd acted as zwitterionic IL-type heterogeneous catalyst, which could be separated from the reaction mixture, conveniently. Moreover, it exhibited excellent recyclability for at least eight cycles without considerable loss of its activity.

Immobilizing Palladium Nanoparticles on Nitrogen‐Doped Carbon for Promotion of Formic Acid Dehydrogenation and Alkene Hydrogenation

AbstractA novel palladium (Pd)‐supported Nitrogen‐doped carbon catalyst (Pd@CN) is prepared via polymerization of 1,3,5‐triacryloylhexahydro‐1,3,5‐triazine (TAT), adsorption of Pd nanoparticles (Pd NPs), and followed by pyrolysis treatment. The TAT polymer (PTAT) was revealed to be an ideal precursor with strong adsorb ability for Pd NPs, and the pyrolysis treatment of Pd/PTAT not only led to the generation of nitrogen‐doped carbon support but also significantly enhanced the Pd‐support interaction for the target catalyst Pd@CN. Catalytic tests demonstrate that Pd@CN shows superior catalytic activity and selectivity toward the hydrogen production and alkene hydrogenation with formic acid as the carrier. Besides, the catalyst presents improved reusability, structure stability and could be reused five runs without finding significant decrease of activity and obvious leaching of Pd species. Such excellent catalytic performance of Pd@CN is mostly attributed to the prominent surface electronic modulation with pyridinic‐N in CN. This work displays a facile and effective way for the rational design of excellent Pd‐supported catalysts for better hydrogen energy exploitation and applications.

Immobilized Palladium Nanoparticles on Zirconium Carboxy-Aminophosphonates Nanosheets as an Efficient Recoverable Heterogeneous Catalyst for Suzuki–Miyaura and Heck Coupling

Zirconium phosphate glycine diphosphonate nanosheets (ZPGly) have been used as support for the preparation of solid palladium nanoparticles, namely Pd@ZPGly. Thanks to the presence of carboxy-aminophosponate groups on the layer surface, ZPGly-based materials were able to stabilize a high amount of palladium (up to 22 wt %) also minimizing the amount of metal leached in the final products of representative important cross-coupling processes selected for proving the catalysts’ efficiency. The catalytic systems have been fully characterized and used in low amounts (0.1 mol %) in the Suzuki–Miyaura and Heck cross-couplings. Moreover, the protocols were optimized for the use of recoverable azeotropic mixtures (aq. EtOH 96% or aq. CH3CN 84%, respectively) and in the flow procedure allowing one to isolate the final pure products, without any purification step, with very low residual palladium content and with a very low waste production.

WITHDRAWN: Metformine-functionalized graphene oxide to immobilization of palladium nanoparticles as a heterogeneous and recyclable nanocatalyst for Suzuki coupling reactions and reduction of 4-nitrophenol

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Fabrication of hollow carbon nanospheres introduced with Fe and N species immobilized palladium nanoparticles as catalysts for the semihydrogenation of phenylacetylene under mild reaction conditions

Palladium nanoparticles immobilized on hollow carbon nanospheres introduced with both Fe and N species, denoted as Pd/Fe-N/C, have been designed as an efficient, heterogeneous, environmentally friendly catalyst for the semihydrogenation of phenylacetylene in liquid-phase under mild conditions (298K, H2 1atm) without any additive. A high selectivity towards styrene (higher than 96.2%) was achieved with the total conversion of phenylacetylene within 80min. The synergistic effect of doped N and Fe with Pd might be an important influence on improving the catalytic performance. Moreover, the Pd/Fe-N/C could be easily recycled by centrifugation and is reusable without obvious decrease of catalytic activity and selectivity. Therefore, the Pd/Fe-N/C nanocatalyst is highly attractive as selective hydrogenation heterogeneous catalyst for important industrial reactions.

Palladium nanoparticles immobilized on magnetic methionine‐functionalized chitosan: A versatile catalyst for Suzuki and copper‐free Sonogashira reactions of aryl halides at room temperature in water as only solvent

The preparation of an efficient heterogeneous catalyst system based on the immobilization of palladium nanoparticles on a magnetic nanoparticle core (ImmPd(0)‐MNPs) is described. The new catalytic system was characterized using transmission and scanning electron microscopies, X‐ray diffraction, energy‐dispersive X‐ray and Fourier transform infrared spectroscopies, thermogravimetric analysis, vibrating sample magnetometry and inductively coupled plasma analysis. We have demonstrated that ImmPd(0)‐MNPs is an efficient and reusable catalyst for the Suzuki–Miyaura and Sonogashira coupling reactions of various types of aryl halides in water as a green and environmentally acceptable solvent. Moreover, the reactions were carried out efficiently at room temperature. The catalyst was easily separated using an external magnet from the reaction mixture and recycled ten times without significant loss of activity.

Palladium nanoparticles immobilized on amphiphilic and hyperbranched polymer‐functionalized magnetic nanoparticles: An efficient semi‐heterogeneous catalyst for Heck reaction

To address the obstacles facing the use of palladium‐based homogeneous and heterogeneous catalysts in C─C cross‐coupling reactions, a novel semi‐heterogeneous support was developed based on hyperbranched poly(ethylene glycol)‐block‐poly(citric acid)‐functionalized Fe3O4 magnetic nanoparticles (Fe3O4@PCA‐b‐PEG). Because of the surface modification of the Fe3O4 nanoparticles with amphiphilic and hyperbranched polymers (PCA‐b‐PEG), these hybrid materials are not only soluble in a wide range of solvents (e.g. water, ethanol and dimethylformamide) but also are able to trap Pd2+ ions via complex formation of free carboxyl groups of the PCA dendrimer with metal ions. The reduction of trapped palladium ions in the dendritic shell of Fe3O4@PCA‐b‐PEG leads to immobilized palladium nanoparticles. The morphology and structural features of the catalyst were characterized using various microscopic and spectroscopic techniques. The catalyst was effectively used in the palladium‐catalysed Mizoroki–Heck coupling reaction in water as a green solvent. In addition, the catalyst can be easily recovered from the reaction mixture by applying an external magnetic field and reused for more than ten consecutive cycles without much loss in activity, exhibiting an example of a sustainable and green methodology.

Palladium nanoparticles onto ethylenediamine functionalized silica–cellulose substrates [Pd(0)-EDA/SCs]: An efficient and sustainable approach for hydrogenation of nitroarenes and carbonyl compounds under mild conditions

This paper aimed to report a green and efficient approach for the Pd(0)-EDA/SCs catalyzed hydrogenation of nitroarenes and carbonyl compounds using environment friendly molecular hydrogen at room temperature under benign reaction media. Three different catalysts, Pd(0)-EDA/SC-1, Pd(0)-EDA/SC-2 and Pd(0)-EDA/SC-3 based on immobilization of palladium nanoparticles onto ethylene diamine functionalized silica–cellulose substrates were prepared. Among various catalysts tested, Pd(0)-EDA/SC-2 showed superior catalytic activity. Further, excellent yield of the products, recyclability and the facile work-up make the catalyst more versatile, eco-friendly and economical to perform the desired organic transformations.

Biguanidine‐functionalized chitosan to immobilize palladium nanoparticles as a novel, efficient and recyclable heterogeneous nanocatalyst for Suzuki–Miyaura coupling reactions

Biguanidine‐functionalized chitosan was synthesized and combined with palladium nanoparticles to yield a recyclable, environmentally benign, heterogeneous catalytic system for the Suzuki–Miyaura C–C coupling reaction. The catalyst was characterized using various techniques. The catalyst was used in Suzuki cross‐coupling reactions of various aryl halides, including less reactive chlorobenzenes, with phenylboronic acid to give biaryls without any additive or ligand. A reusability test demonstrated that the catalyst was highly efficient even after six runs. Solid‐phase poisoning and leaching tests indicated that the catalyst has a heterogeneous nature. Copyright © 2016 John Wiley & Sons, Ltd.

Highly Efficient Ethanol Electrooxidation on a Synergistically Active Catalyst Based on a Pd‐Loaded Composite of Hydroxyapatite

AbstractBy using a well‐structured composite of hydroxyapatite and carbon nanotubes and the immobilization of palladium nanoparticles (Pd NPs), a synergistically active catalyst toward the ethanol electrooxidation reaction (EOR) is proposed herein. The application of hydroxy‐rich substrates, such as hydroxyapatite, for the immobilization of Pd NPs could be promising to enhance electrocatalyst activity toward the ethanol oxidation reaction. The hydroxyapatite–carbon nanotubes composites were synthesized through two distinct precipitation approaches. The structural features of each composite were characterized by using X‐ray diffraction spectroscopy and transmission electron microscopy. According to electrochemical tests, remarkable enhancements were achieved in the electrocatalytic activity, kinetic parameters, and catalyst durability. The proposed catalyst showed a mass‐independent current of 1874.6 mA mgPd−1 and an onset potential of −650 mV versus Ag/AgCl reference electrode toward EOR. The catalytic improvements can be attributed to synergetic effects between the immobilized Pd NPs and the functionalities on the carbon nanotube–hydroxyapatite substrate.

Immobilized palladium nanoparticles within polymers as active catalysts for Suzuki–Miyaura reaction

A highly active and reusable catalyst Pd@PNP was developed for Suzuki–Miyaura reaction of aryl chlorides and bromides with aryl boronic acids, and the corresponding biphenyl compounds were obtained in good to excellent yields.

ChemInform Abstract: Suzuki Coupling Reaction in the Presence of Polymer Immobilized Palladium Nanoparticles: A Heterogeneous Catalytic Pathway.

AbstractA Pd—poly(1,2‐diaminobenzene) composite material with palladium nanoparticles with an average size of 3 nm are synthesized from 1,2‐diaminobenzene (DAB) and K2PdCl4 and successfully used as a catalyst for Suzuki coupling reactions in the absence of any phosphine ligand.

Highly porous amidoximed carbon nanofibers supported palladium(0) nanoparticle catalyzed Heck reaction

Highly porous amidoximed carbon nanofibers(AOCNFs), which were fabricated via a conventional electrospinning technique followed by chemically modification, impregnation-reduction and carbonization process, had been used for the immobilization of palladium nanoparticles(Pd NPs) catalyst. During the carbonization process, polystyrene( PS) was selectively decomposed from bicomponent fibers, generating porous fibers. Fourier transform infrared spectroscopy(FTIR) result revealed the functional groups on PAN-PS fibers(PAN=polyacrylonitrile), AOPAN-PS fibers and AOCNFs; scanning electron microscopy(SEM) was used to observe the morphology of all stages of nanofibers; transmission electron microscopy(TEM) result gave the structure of through-hole morphology clearly visible and the dispersion of Pd NPs on the surface of nanofibers; and X-ray photoelectron spectra(XPS) confirmed that Pd nanoparticles on the surface of AOCNFs was of the metallic state. Moreover, the as-prepared catalyst exhibited high catalytic activity and efficient recycle for Heck coupling reactions between iodobenzene and acrylates.

Palladium nanoparticles supported on a two-dimensional layered zeolitic imidazolate framework-L as an efficient size-selective catalyst

A new Pd@ZIF-L hybrid catalyst having a unique crosshair-star shape with a size of about 20 μm was synthesized, in which a two-dimensional layered zeolitic imidazolate framework-L (ZIF-L) was used as a support to immobilize palladium nanoparticles via an assembly method. The hybrid catalyst with unique cushion-shaped cavities between layers with a size of 6.64 Å can be used for the diffusion of specific reactants not achievable by other ZIF systems such as ZIF-8. The crystal structure and morphology of Pd@ZIF-L are strongly dependent on the synthesis conditions. Palladium nanoparticles with an average size of 3 nm are homogeneously encapsulated in the ZIF-L crystals. The as-synthesized Pd@ZIF-L catalyst favors the conversion of alkenes with larger molecular sizes, and exhibits excellent molecule-size-selectivity and anti-leaching performance.

In Situ Trapped and Immobilized Palladium Nanoparticles as Active and Clean Catalysts for Suzuki–Miyaura Reaction

AbstractActive palladium nanoparticles were trapped and immobilized in situ by Pd‐catalyzed Suzuki–Miyaura reaction to form heterogeneous Pd catalysts. This Pd@PhPad2 catalyst was found to be highly active, recyclable and clean for the Suzuki–Miyaura reaction. Both the anchored diadamantylphosphine ligand and the formation of polyphenylene polymer improved the activity and stability of the Pd@PhPad2 catalyst for Suzuki–Miyaura reaction. The Pd@PhPad2 catalyst was reusable, and no contamination (P ligand or Pd) was detected from the catalyst system for the coupling reaction.magnified image

Synthesis of catalytic systems based on nanocomposites containing palladium and hydroxycarbonates of rare-earth elements

The preparation, characterization, and catalytic activity of nanocomposites containing palladium nanoparticles supported on yttrium and cerium hydroxycarbonates in the Suzuki cross-coupling reaction between phenylboronic acid and iodobenzene are described. All catalytic systems were characterized by means of SEM, EDS, and their surface areas were determined with N2 physisorption. The conversion degree of the Suzuki reaction was characterized with gas chromatography, and the reaction products were identified with 1H and 13C{1H}–NMR spectra. Nanocomposites Pd/Y(OH)CO3 and Pd/Ce(OH)CO3 were synthesized according to two methods: the first one—simultaneous production of nanoscale substrate and immobilization of palladium nanoparticles on its surface (nanocomposites 1), the second one—the prior synthesis of polyvinylpyrrolidone stabilized palladium nanoparticles followed by their immobilization on the nano-sized substrate surface (nanocomposites 2). Both groups of catalysts showed high catalytic activity with the highest TOF values 8.5 × 103 h–1 for nanocomposites 1 and 78.9 × 103 h–1 for nanocomposites 2 allowing to decrease the palladium content in the nanocomposites and, consequently, reduce the cost of the catalyst while maintaining its high catalytic activity.