Size Of Palladium Nanoparticles Research Articles

Boosting catalytic activity of π-π interactions-stabilized PdNPs for water-mediated Suzuki couplings of aryl chlorides

Utilizing unique interactions to enhance the catalytic performance of supported metal catalysts is a crucial strategy in catalyst design, albeit one that presents a significant challenge. This study introduces an original approach involving the use of π-π interactions to stabilize palladium nanoparticles (PdNPs) with a 2Br-substituted imidazolium-based covalent organic framework (COF, IHP-Br-PdNPs) for efficient water-mediated Suzuki reactions involving deactivated aryl chlorides and arylboronic acids at ambient conditions. Through extensive structural characterization employing techniques including Fourier transform infrared spectroscopy (FT-IR), cross-polarization magic angle spinning carbon-13 nuclear magnetic resonance (CP/MAS 13C NMR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), N2 adsorption, and X-ray photoelectron spectroscopy (XPS), we demonstrate the immobilization of highly stable and well-dispersed PdNPs was obtained. The designed IHP-Br-PdNPs demonstrate stability for up to 36 months in ambient air and can be efficiently recycled. After 9 catalytic cycles, there was no significant decline in catalytic performance, and the particle size of PdNPs remained constant at approximately 4–8 nm throughout the reactions. The coordination mode between the stabilizer and metal, specifically the π-π interaction between the 2Br-substituted imidazolium moiety and the Pd metal surface, plays a key role in stabilizing various active species and facilitating distinct catalytic pathways. This study provides valuable insights into the development of π-π interactions supported metal catalysts, which enhance stability and catalytic activity in advanced water-mediated synthesis applications.

Morphology effect of Pd/In2O3/CeO2 catalysts on methanol steam reforming for hydrogen production

Catalyst support morphology strongly influences its surface and structural properties, therefore, may have a significant impact on their reactivity in heterogeneous catalysis. Herein, the Pd/In2O3/CeO2-x (loaded with 1 wt% Pd and In2O3) catalysts with different morphologies of rods(r), cubes(c) and irregularity(w) shapes were prepared by hydrothermal method and impregnation method. At temperature of 275–425 °C, as-prepared catalysts were evaluated for hydrogen production from methanol steam reforming (MSR). The activity data showed the outstanding performance of the rod-shaped Pd/In2O3/CeO2 catalysts, exhibiting the complete conversion of methanol and particularly low CO (1.3%) at 375 °C. The structural properties and physicochemical of Pd/In2O3/CeO2-x with different morphologies were characterized by means of X-ray diffraction (XRD), high resolution transmission microscopy (HR-TEM), CO pulse chemisorption, X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption of methanol (CH3OH-TPD). Activity data and catalyst characterization results correlated, and indicated that the excellent reactivity for the rod-shaped Pd/In2O3/CeO2 catalysts in MSR is ascribed to the large particle size of palladium nanoparticles and the abundant oxygen vacancies induced by the strong interaction between Pd, In and Ce. HR-TEM results revealed that rod-like CeO2 mainly expose (110) crystalline surface with high mobility of surface oxygen and possess the most abundant surface oxygen vacancies with the low formation energy, facilitating the formation of active species of Pd0 on catalyst surface, and promoting the activation and adsorption of methanol and water molecules. Furthermore, the rod-shaped Pd/In2O3/CeO2 catalysts showed excellent reactivity and stability in MSR for 30 h, demonstrating its potential of being used as catalysts in methanol steam reforming in PEMFC systems.

Zwitterionic daptomycin stabilized palladium nanoparticles with enhanced peroxidase-like properties for glucose detection

Mimic enzymes, especially noble metal nanomaterials, replace natural horseradish peroxidase due to the artificial regulation of catalytic activity by adjusting particle size and morphology. However, the existing mimic enzymes still have disadvantages such as large particle size, easy clustering and poor biocompatibility. Herein, well-dispersed daptomycin stabilized palladium nanoparticles (Dap-Pdn NPs) were synthesized by using daptomycin as a biological template. The average particle size of palladium nanoparticles of Dap-Pd0.25 NPs was 1.73 nm, the hydrodynamic size of Dap-Pd0.25 NPs detected by DLS method was 49.97 nm, Dap-Pd0.25 NPs were stable in fibrinogen solution. In addition, Dap-Pd0.25 NPs had excellent peroxidase-like activity, which effectively catalyzed the colorimetric oxidation reaction of 3,3′,5,5′-tetramethylbenzidine (TMB) by H2O2. Dap-Pd0.25 NPs were used to detect glucose concentration based on the colorimetric reaction of TMB, which had a wide detection range (0.02–1 mM) and low detection limit (5.6 μM) for glucose. Besides, fluorescence experiments proved that Dap-Pdn NPs catalyzed H2O2 to generate·OH. Taken together, a simple, green and inexpensive synthesis method of palladium nanoparticles with enhanced peroxidase-like activity was proved in this research. Dap-Pdn NPs will have great application prospects in biological detection in the future.

Characterization, Antimicrobial and Anticancer Properties of Palladium Nanoparticles Biosynthesized Optimally Using Saudi Propolis.

Due to their unique physicochemical characteristics, palladium nanoparticles (Pd-NPs) have shown tremendous promise in biological applications. The biosynthesis of Pd-NPs employing Saudi propolis has been designed to be environmental, fast, controlled, and cost-effective. The formation and stability of biosynthesized Pd-NPs by Saudi propolis extract were proved by ultraviolet–visible spectrophotometry (UV-Vis), Fourier-transform infrared spectroscopy (FT-IR), and Zeta potential analysis. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray diffraction (XRD) findings show that the average particle size of Pd-NPs is between 3.14 and 4.62 nm, which is in quantum scale. The Saudi propolis enhanced the antimicrobial activity against B. subtilis, S. aureus, E. coli, K. pneumoniae, and C. albicans. Pd-NPs show effective anticancer activity against ductal carcinoma (MCF-7) with IC50 of 104.79 µg/mL.

The Effect of Alcohol on Palladium Nanoparticles in i-Pd(OAc)2(TPPTS)2 for Aerobic Oxidation of Benzyl Alcohol

In the heterogeneous catalyst i-Pd(OAc)2(TPPTS)2, Pd(II) was reduced to Pd(0) by using different alcohol solvents, and the catalyst’s activity was studied in the aerobic oxidation of benzyl alcohol. We studied the effects of the impregnation time in ethanol as a solvent and the use of various alcoholic solvents on the size of palladium nanoparticles. We found that the reduction of palladium by the various alcohols yielded palladium nanoparticles that were active in the aerobic oxidation of benzyl alcohol. As determined by DLS, TEM, and zeta potential analyses, both the impregnation time in ethanol and the type of alcohol used were observed to affect nanoparticle formation, particle size distribution, and agglomeration, as well as the conversion rate. The palladium nanoparticles’ hydrodynamic diameter sizes obtained during the 24 h of impregnation time were in the range of 10–200 nm. However, following 24 h of impregnation in ethanol the nanoparticles tended to form aggregates. The conversion rates of all the primary alcohols were similar, while for secondary alcohol, in which the hydrogen of the hydroxyl is less acidic and there is steric hindrance, the conversion was the lowest. Performing the oxidation using the solvent 1-propanol yielded smaller nanoparticles with narrower distributions in comparison to the reaction that was observed when using the ethanol solvent. On the other hand, the relatively high particle size distribution in 1-hexanol yielded agglomerates.

Controlled Synthesis of Palladium Nanoparticles with Size-Dependent Catalytic Activities Enabled by Organic Molecular Cages.

Particle size plays a key role in the performance of metal nanoparticles (MNPs). However, the size-controlled synthesis of MNPs still represents a challenging task. In this work, we revealed a strong solvent effect on the growth of palladium nanoparticles (PdNPs), which was directed by a porous [2 + 3] organic molecular cage (OMC, Phos-cage) containing triphenylphosphine moieties. PdNPs with different average diameters of 0.8, 1.2, and 3.3 nm supported by Phos-cage were obtained by simply varying the reaction media. The catalytic performance of such ultrafine PdNPs in the reduction of p-nitrophenol and a Suzuki-Miyaura coupling reaction has been studied, which clearly shows size-dependent catalytic activity and stability. The knowledge gained in this study, controlling the size of PdNPs supported by the OMC template in different solvents, will open new possibilities for size-controlled synthesis of ultrafine MNPs with high catalytic activity and stability.

Padina boryana mediated green synthesis of crystalline palladium nanoparticles as potential nanodrug against multidrug resistant bacteria and cancer cells

Green synthesized nanoparticles (NPs) have emerged as a new and promising alternative to overcome the drug resistance problem. Peculiar nano-specific features of palladium NPs (Pd-NPs) offer invaluable possibilities for clinical treatment. Due to the development of multi-drug resistance (MDR) in pathogenic bacteria and the prevalence of cancers, use of algae-mediated Pd-NPs could be a prospective substitute. Therefore, Pd-NPs were synthesized by a one-step, cost-effective, and environmentally friendly green method using the extract from a brown alga, Padina boryana (PB-extract), and evaluated for their antibacterial, antibiofilm, and anticancer activities. Pd-NPs were physicochemically characterized for size, shape, morphology, surface area, charge, atomic composition, crystal structure, and capping of Pd-NPs by PB-extract biomolecules by various techniques. The data revealed crystalline Pd-NPs with an average diameter of 8.7 nm, crystal size/structure of 11.16 nm/face-centered cubic, lattice d-spacing of 0.226 nm, 28.31% as atomic percentage, surface area of 16.1 m2/g, hydrodynamic size of 48 nm, and zeta-potential of − 28.7 ± 1.6 mV. Fourier-transform infrared spectroscopy (FT-IR) analysis revealed the role of PB-extract in capping of Pd-NPs by various functional groups such as –OH, C=C, C–O, and C–N from phenols, aliphatic hydrocarbons, aromatic rings, and aliphatic amine. Out of 31, 23 compounds were found involved in biosynthesis by Gas chromatography–mass spectrometry (GC–MS) analysis. Isolated strains were identified as MDR Staphylococcus aureus, Escherichia fergusonii, Acinetobacter pittii, Pseudomonas aeruginosa, Aeromonas enteropelogenes, and Proteus mirabilis and Pd-NPs exhibited strong antibacterial/antibiofilm activities against them with minimum inhibitory concentration (MIC) in the range of 62.5–125 μg/mL. Moreover, cell viability assays showed concentration-dependent anti-proliferation of breast cancer MCF-7 cells. Pd-NPs also enhanced mRNA expression of apoptotic marker genes in the order: p53 (5.5-folds) > bax (3.5-folds) > caspase-3 (3-folds) > caspase-9 (2-folds) at 125 μg/mL. This study suggested the possible role of PB-extract capped Pd-NPs for successful clinical management of MDR pathogens and breast cancer cells.

Green palladium nanoparticles prepared with glycerol and supported on maghemite for dye removal application

This study aims to synthesize palladium nanoparticles (PdNPs) in presence of glycerol as green reducing/stabilizing agent, supported on γ-Fe2O3 (maghemite), as catalysts for dye removal. Three materials were prepared with different Pd loadings, from 0.43 to 0.63 wt%. PdNPs at the surface were composed of Pd0, Pd2+ and Pd4+ species, at average oxidation state of +1.6 and Pd2+:Pd0 atomic ratio up to 1:0.9, which showed that glycerol was able to partially reduce Pd2+. PdNPs of spherical shaped clumps morphology, predominantly well dispersed on the γ-Fe2O3 surface were formed. High resolution scanning transmission electron microscopy images of the materials with higher Pd content revealed PdNPs smaller than 5 nm with crystal interplanar distance compatible with Pd(0). The catalysts were applied in the adsorption as well as in the heterogeneous Fenton degradation of the azo dye methyl orange with 90% of decolourization after 240 min. It was possible to observe an improvement in the catalytic activity with the Pd content increase as well as with the PdNPs size distribution. The dye removal followed pseudo-first-order kinetics. The effect of catalyst dosage and temperature were evaluated. The acidic character of the iron compounds as well as of the glycerol acidic hydrogens constituents of the catalyst can be released in the reaction medium, being responsible to adjust the reaction pH to 3, which is the optimum pH for Fenton process.

Electrodeposition of Palladium Nanoparticles on Carbon Nanotubes Dispersed in an Ionic Liquid

Electrodeposition of palladium nanoparticles (PdNPs) was investigated on single walled carbon nanotubes (SWCNTs) or few walled carbon nanotubes (FWCNTs) dispersed in 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (BMPTFSA) containing [PdBr4]2 -. Ionic liquids have been expected to be alternative electrolytes for electrodeposition of various metals and alloys because of such unique characteristics as wider electrochemical potential window, negligible vapor pressure, less flammability, and wider usable temperature range, compared with conventional organic electrolytes. In addition, the ionic liquids have been known to have ability to disperse nanoparticles without any additives[1]. Although several studies have reported the preparation of metal nanoparticles by electrochemical cathodic reduction in ionic liquids, there are some problems in the utilization of the nanoparticles dispersed in ionic liquids. Platinum nanoparticles (PtNPs) prepared in ionic liquids have been reported to be collected on such carbon materials as carbon nanotubes (CNTs) and carbon black with elevating temperature[2,3]. It has been reported that CNTs are dispersed in ionic liquids and act as an electrode[4]. We have already reported the electrodeposition of PtNPs is possible on CNTs dispersed in BMPTFSA containing [PtBr4]2–[5]. The average particle size of the PtNPs was 1.7 nm, which was independent on the concentration of [PtBr4]2– and the kind of CNTs. In the present study, the electrodeposition of PdNPs was investigated on SWCNTs and FWCNTs dispersed in BMPTFSA containing [PdBr4]2– in order to examine the effect of the deposition potential on the average particle size of PdNPs because the deposition potential of Pd is more positive than that of Pt[3,6]. In addition, the effect of the catalyst remaining in CNTs on electrodeposition of PdNPs was examined using high purity (> 99.6% purity) FWCNT synthesized by the fluidized bed method[7].Galvanostatic cathodic reduction was conducted in BMPTFSA containing CNTs and [PdBr4]2– at room temperature, resulted in deposition of NPs, which were identified as metallic Pd by energy dispersive X-ray analysis (EDX) and transmission electron mocroscopy (TEM). The average potential of [PdBr4]2– during the galvanostatic cathodic reduction was –1.2 V, which was close to that reported on a planar glassy carbon electrode[6]. Potentiostatic cathodic reduction at different potentials indicated that the average particle size of PdNPs decreased with lowering the potential. Pd nuclei are considered to occur and grow on the CNTs dispersed in the ionic liquid. As the potential becomes more negative, the cations of the ionic liquid are expected to be accumulated on the surface of the nuclei and CNTs in order to compensate the excess negative charge. The cations strongly attracted on the surface are considered to inhibit the growth of the PdNPs and affect their average particle size. On the other hand, the remaining catalyst in the CNTs was found to have little effect on the average particle size of PdNPs.

Minimizing the Size of Palladium Nanoparticles Immobilized within the Channels of Ionic Liquid-Derived Magnetically Separable Heteroatom-Doped Mesoporous Carbon for Aerobic Oxidation of Alcohols

An efficient and well-designed nanocasting procedure has been developed for the synthesis of a series of nitrogen and sulfur codoped magnetically separable ordered mesoporous carbons using an imida...

Green synthesis, characterization and catalytic activity evaluation of palladium nanoparticles facilitated by Punica granatum peel extract

In the present report, we describe the biosynthesis of palladium nanoparticles (PdNPs) using nontoxic and renewable Punica granatum peel extract. Synthesis of PdNPs was monitored via color change and confirmed by Ultraviolet-visible (UV-vis) spectroscopy. Fourier-transform infrared spectroscopy (FT-IR) revealed the active role of phytochemicals derived from Punica granatum in reduction and stabilization of nanoparticles. X-ray diffraction (XRD) pattern showed that the synthesized PdNPs have face-centered cubic crystalline structure. The morphological characterizations carried out using scanning electron microscopy (SEM) equipped with energy dispersive X-ray and high-resolution transmission electron microscopy (HRTEM) revealed that PdNPs are spherical and well distributed and the average size of PdNPs is 22 ± 5 nm. Then, the catalytic activity of PdNPs was tested successfully in the reduction of 4-nitrophenol. Biosynthesis of PdNPs using pomegranate peel extracts was remarked as an alternative low-cost and eco-friendly green method alternative to the conventional chemical and physical methods.

Acacia gum versus pectin in fabrication of catalytically active palladium nanoparticles for dye discoloration

Obedience to the aspects of green chemistry and due to its high catalytic potency, ecofriendly synthesis of palladium nanoparticles (PdNPs) was performed using pectin versus acacia gum as polysaccharides. The viscous solution of alkali solubilized polysaccharides acted superiorly in stabilization of MNPs by decreasing their Brownian motions and sequentially decreased their collision and coagulation. Production of PdNPs preliminary was confirmed via UV–visible spectra. Zetasizer and transmission electron microscopy data, the particle size of PdNPs were prepared by pectin (27.9 nm) is larger than that by acacia gum (5.3 nm). XRD and FT-IR data affirmed the redox reaction between biopolymers and metal ions to produce PdNPs. PdNPs synthesized by acacia gum were characterized by higher surface area (19.54 m2/g) compared to that prepared by pectin (3.67 m2/g). Additionally, PdNPs synthesized by acacia gum were exhibited by fastest rate of dye discoloration, resulting in complete reductive discoloration of dye after only 5 min and t1/2 was estimated to be 1.70 min, while, k1 was 408.8 × 10−3 min−1. The presented green technique could be successively applicable for synthesis of size regulated catalytically active PdNPs to be employable in various industrial purposes.

Синтез наночастиц палладия на поверхности оксида церия(IV) под воздействием ультрафиолетового излучения и их диагностика

Проведен синтез наночастиц палладия с использованием комплексного оксалата палладия в качестве прекурсора в водной среде методом УФ-облучения. Образцы исследованы различными лабораторными методиками, такими как просвечивающая электронная микроскопия, рентгенофлуоресцентный анализ, рентгеновская порошковая дифракция, XAFS-спектроскопия и ИКспектроскопия диффузного отражения с использованием зондирующих молекул CO. Микроизображения, полученные с помощью просвечивающей электронной микроскопии, не позволили отличить наночастицы Pd от материала подложки, но показали отсутствие влияния УФ-излучения на размеры наночастиц CeO2. Данные рентгенофлуоресцентного анализа показали наличие в материале атомов церия и палладия. Дифрактограммы свидетельствуют о присутствии фаз диоксида церия и металлического палладия, также анализ спектров XAFS за K-краем палладия показал наличие в системе фазы PdO. Приблизительный размер наночастиц палладия оценен по ИК-спектрам после адсорбции CO, он составил не более 2 нм, что существенно меньше среднего размера наночастиц Pd, полученных аналогичным способом без подложки CeO2(1.5–9.5 нм).

Green synthesis of a palladium nanocatalyst anchored on magnetic lignin-chitosan beads for synthesis of biaryls and aryl halide cyanation

Aryl nitriles, Ar–C ≡ N, and biaryls are important precursors of many compounds commonly used in the industry. Production of aryl nitriles and biaryls through a facile method is therefore of significance. In the study the synthesis of aryl nitriles and biaryls with various substituted groups was successfully achieved using a simple but efficient palladium nanocatalyst system. The nano-catalyst system, (Pd NPs@Fe3O4/lignin/chitosan), was easily prepared by decorating palladium nanoparticles on the magnetic lignin/chitosan microbeads without using any toxic reducing agents. Characterization of the catalyst revealed that the size of palladium nanoparticles was lower than 20 nm and the palladium nanoparticles were homogeneously dispersed on the catalyst support; Fe3O4/lignin/chitosan. The catalytic activity of Pd NPs@Fe3O4/lignin/chitosan was tested in the synthesis of a number of various aryl nitriles and biaryls. Pd NPs@Fe3O4/lignin/chitosan catalyzed the conversion of different aryl halides into aryl nitriles in the presence of K4[Fe(CN)6] by producing conversion yields as high as 97%. The system also exhibited good reactions yields up to 98% for synthesis of biaryls. More importantly, due to its magnetic nature, the used catalyst was easily recovered from the reaction media with a magnet, and regenerated and reused for seven runs.

A new approach of pH-IEGFET sensor based on the surface modification of macro porous silicon with palladium nanoparticles

This work investigates the effect of the Palladium nanoparticles (PdNPs) on the characteristics and pH sensitivity of an interdigitated electrode extended-gate field-effect transistor (pH-IEGFET) sensors based on the bare n-type macro porous Si (n-macro PSi) layer. The synthesized bare porous layer was fabricated by photo electrochemical etching process of n-type (100) using short-wavelength 410 nm and intensive laser power density 80 mW/cm2. The surface morphology of n-macro PSi was modified by inserting PdNPs to form PdNPs/n-macro PSi hetero structure layers via simple and fast immersing process in PdCl2 solution for about 14 min and 20 min by the ion reduction process. The fabricated sensors have been verified in the range of pH from 3 to 11 at the ambient temperature. Specific features of n-macro PSi and hybrid structure were investigated using a scanning electron microscope, energy dispersive x-ray spectroscopy (EDX) analysis and x-ray diffraction. It was found that the morphology and the size of the deposited PdNPs intensely influence on the PdNPs/ n-macro PSi hetero structure pH-IEGFET sensor. The efficient pH sensing process was obtained for n-macro PSi pH sensor with the lowest size of PdNPs deposited on the external walls of the n-macro PSi pores. Significant enhancement of sensitivity of about 42.89 mV/pH and linearity of 0.9948 was achieved, compared with the bare n-macro PSi pH sensor having a sensitivity of 25.12 mV/pH and linearity of 0.9392. This sensitivity enhancement is due to the additional specific surface area of PdNPs which causes improved it.

HIGHLY ACTIVE AND ROBUST PALLADIUM NANOPARTICLES IMMOBILIZED ON BIODEGRADABLE MICROCAPSULES CONTAINING CHITOSAN-GUAR GUM COMPOSITE FOR SYNTHESIS OF BIARYL COMPOUNDS

In this study, highly stable biodegradable microcapsules, which are composed of chitosan-guar gum composite (CS-GG), were prepared as catalyst support. Then, palladium nanoparticles were successfully decorated on the designed support without using any toxic reducing agent (Pd NPs@CS-GG). Structural characterizations of CS-GG and Pd NPs@CS-GG were carried out by different analytical techniques and it was detected that the size of palladium nanoparticles changed in the range of 23-48 nm. Then, the catalytic activity of Pd NPs@CS-GG was evaluated in the fabrication of various biaryl compounds under solventless media using microwave heating. Pd NPs@CS-GG showed high catalytic performance in the conversion of various aryl halides to desired biaryl compounds with good reaction yields. Moreover, it was found that Pd NPs@CS-GG was a catalyst having long life time because of its reuse at least seven times.

Simple, green, and low-temperature method for preparation of palladium nanoparticles with controllable sizes and their characterizations

Palladium nanoparticles (PdNPs) are gaining great interest owing to their excellent physicochemical properties and their wide range of applications. Nanoparticles’ size directly affects the properties and potential applications of PdNPs. Here, we reported a scalable, efficient, green, and one-step method to synthesize PdNPs with controllable sizes. In that, biocompatible polymer chitosan was used as a stabilizer and nontoxic chemical vitamin C was used as a reducing agent. Interestingly, the size of PdNPs could be controlled by adjusting the reaction temperature. The resulting PdNPs were characterized by TEM, XRD analysis, EDS analysis, UV-Vis, and DLS. When the temperature was increased from 25 to 95 °C, the shape of resulting PdNPs changed from flower shape to spherical shape and their hydrodynamic sizes decreased from 64 to 29 nm. The obtained PdNPs were relatively uniform in size and shape, and stable in aqueous solution. The photothermal behavior of PdNPs which resulted from the experiment at 95 °C was further tested. The photothermal results revealed that these PdNPs had excellent photostability and high photothermal conversion efficiency. In conclusion, the proposed method can be used for the preparation of PdNPs with desired sizes for various applications.

Facile Preparation of Pd/UiO-66-v for the Conversion of Furfuryl Alcohol to Tetrahydrofurfuryl Alcohol under Mild Conditions in Water.

The hydrogenation of furan ring in the biomass-derived furans is of great importance for the conversion of biomass to valuable chemicals. Fabrication of high activity and selectivity catalyst for this hydrogenation under mild conditions was one of the focuses of this research. In this manuscript, UiO-66-v, in which vinyl bonded to the benzene ring, was first prepared. Then, the uniformly distributed vinyl was used as the reductant for the preparation of Pd/UiO-66-v. The catalyst was characterized by X-ray diffraction, thermogravimetric, N2 physical adsorption/desorption, X-ray photoelectron spectroscopy, scanning electron microscope, transmission electron microscopy, energy dispersive spectrometer elemental mappings, and inductively coupled plasma atomic emission spectroscopy to find the Pd/UiO-66-v had a narrow palladium nanoparticles size of 3–5 nm and maintained the structure and thermal stability of UiO-66-v. The Pd/UiO-66-v was used for the hydrogenation of furfuryl alcohol to tetrahydrofurfuryl alcohol in water. 99% conversion of furfuryl alcohol was obtained with 90% selectivity to tetrahydrofurfuryl alcohol after reacted at 0.5 MPa H2, 303 K for 12 h. The Pd/UiO-66-v was proved to be effective for the hydrogenation of furan ring in furans and could be used for at least five times.

Effect of the Size of Polyacrylamide-Stabilized Palladium Nanoparticles Supported on γ-Fe2O3 on Their Catalytic Properties in the Hydrogenation of Phenylacetylene

Hydrogenation catalysts derived from palladium nanoparticles varying in size supported on maghemite (γ-Fe2O3) were obtained by varying the concentration of K2PdCl4 and polyacrylamide as well as the solution pH during catalyst preparation. These catalysts were characterized by electron microscopy, dynamic light scattering, energy dispersive analysis, and IR spectroscopy. Decreasing the size of the palladium nanoparticles leads to enhanced activity of the catalyst in the hydrogenation of phenylacetylene by molecular hydrogen

Synthesis of Highly Active Pd Nanoparticles Supported Iron Oxide Catalyst for Selective Hydrogenation and Cross‐Coupling Reactions in Aqueous Medium

AbstractPost synthetic approach was successfully employed for the synthesis of Pd supported iron oxide (Pd‐Fe2O3TA) catalyst using polyvinylpyrrolidone as capping agent and triethanolamine as reducing agent. Performance of Pd‐Fe2O3TA catalyst was investigated for selective hydrogenation of nitro compounds and Suzuki coupling reactions. Prepared catalyst exhibited excellent yield of corresponding substituted amines and biphenyls, under optimized reaction conditions. Different analytical techniques such as BET‐surface area measurements, XRD, ICP‐AES, SEM, TEM, XPS, TPR, FT‐IR, RAMAN, UV‐Vis and EXAFS analysis were employed to characterize the catalyst. Average particle size of palladium nanoparticles (NPs) was found to be ∼5.2 nm supported on 60–120 nm size of iron oxide nanocrystals. Various reaction parameters such as time, temperature, solvents, active metal loading, base and different substituent were investigated in detail. Different catalysts were also prepared and compared their activity with that of Pd‐Fe2O3TA catalyst. Experimental observations revealed that size of palladium NPs and metal‐support interaction favoured the superior activity of Pd‐Fe2O3TA catalyst compared to other catalysts. Stability of Pd‐Fe2O3TA catalyst was confirmed by its recyclability tests indicated true heterogeneous nature of catalyst.