Aggregation Features of Monodisperse Palladium Nanoparticles  Supported on g-Al2O3

The production of supported on γ-A12O3 palladium catalysts by colloidal solution deposition method have been improved. Influence of temperature on the structure and dispersion characteristics of supported nanosized palladium particles during catalyst preparation and activation was investigated. It has been shown that at temperatures below 300oC monodisperse particles palladium catalysts are stable. Further temperature increase leads to aggregation of monodisperse metal nanoparticles by the mechanism of reaction-limited aggregation (RLA) to form polydisperse system.

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Synthesis and Thermal Stability of Palladium Nanoparticles Supported on γ-Αl2O3

Current Nanomaterials ◽

10.2174/2405461505666191220114659 ◽

2020 ◽

Vol 5 (1) ◽

pp. 79-90

Author(s):

Yevhen Y. Kalishyn ◽

Vladislav V. Ordynskyi ◽

Mykola V. Ishchenko ◽

Igor B. Bychko ◽

Zinaida V. Kaidanovych ◽

...

Keyword(s):

Thermal Stability ◽

Size Distribution ◽

Palladium Nanoparticles ◽

Palladium Catalysts ◽

Colloidal Solution ◽

X Ray Diffraction ◽

Supported Nanoparticles ◽

Transmission Electron ◽

Al2o3 Composite ◽

High Temperature Processes

Background: Deposition of palladium nanoparticles from colloidal solution on various supports produces palladium catalysts with a predetermined size and concentration of the palladium nanoparticles, which allows to study the nanoparticle size effects and support influence on palladium catalytic properties. Objective: The goal of the present work was the development of a preparation method of systems supported on γ-Al2O3 palladium nanoparticles with a controlled size and determination of their thermal stability in oxidizing and reducing atmospheres. Methods: We demonstrated the preparation of Pd/γ-Al2O3 composite by precipitation of the size-controlled palladium nanoparticles with a narrow size distribution from colloidal solution. The composites were characterized by X-ray diffraction (XRD), and transmission electron microscope (TEM) methods. Result: The size and size distribution of the nanoparticles supported on γ-Al2O3 were found to be increasing upon precipitation due to strong Pd/γ-Al2O3 interaction. A significant enlargement of the supported nanoparticles occured at 300°C. The aggregation of the nanoparticles was observed at temperatures above 500°C resulting in an increase in their size. Conclusion: Our findings are not only applicable for the preparation of a model Pd supported on the γ-Al2O3 catalyst but could be applicable to the designing of the Pd-containing catalyst for important industrial high-temperature processes.

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Development of Highly Efficient, Glassy Carbon Foam Supported, Palladium Catalysts for Hydrogenation of Nitrobenzene

Nanomaterials ◽

10.3390/nano11051172 ◽

2021 ◽

Vol 11 (5) ◽

pp. 1172

Author(s):

Ádám Prekob ◽

Mahitha Udayakumar ◽

Gábor Karacs ◽

Ferenc Kristály ◽

Gábor Muránszky ◽

...

Keyword(s):

Zeta Potential ◽

Glassy Carbon ◽

Palladium Nanoparticles ◽

Palladium Catalysts ◽

Sucrose Solution ◽

Supported Catalyst ◽

Carbon Foam ◽

Hydroxyl Groups ◽

Polyurethane Elastomers ◽

Oh Groups

Glassy carbon foam (GCF) catalyst supports were synthesized from waste polyurethane elastomers by impregnating them in sucrose solution followed by pyrolysis and activation (AC) using N2 and CO2 gas. The palladium nanoparticles were formed from Pd(NO3)2. The formed palladium nanoparticles are highly dispersive because the mean diameters are 8.0 ± 4.3 (Pd/GCF), 7.6 ± 4.2 (Pd/GCF-AC1) and 4.4 ± 1.6 nm (Pd/GCF-AC2). Oxidative post-treatment by CO2 of the supports resulted in the formation of hydroxyl groups on the GCF surfaces, leading to a decrease in zeta potential. The decreased zeta potential increased the wettability of the GCF supports. This, and the interactions between –OH groups and Pd ions, decreased the particle size of palladium. The catalysts were tested in the hydrogenation of nitrobenzene. The non-treated, glassy-carbon-supported catalyst (Pd/GCF) resulted in a 99.2% aniline yield at 293 K and 50 bar hydrogen pressure, but the reaction was slightly slower than other catalysts. The catalysts on the post-treated (activated) supports showed higher catalytic activity and the rate of hydrogenation was higher. The maximum attained aniline selectivities were 99.0% (Pd/GCF-AC1) at 293 K and 98.0% (Pd/GCF-AC2) at 323 K.

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Particle size effects in the selective hydrogenation of cinnamaldehyde over supported palladium catalysts

RSC Advances ◽

10.1039/c6ra17000e ◽

2016 ◽

Vol 6 (79) ◽

pp. 75541-75551 ◽

Cited By ~ 37

Author(s):

Feng Jiang ◽

Jian Cai ◽

Bing Liu ◽

Yuebing Xu ◽

Xiaohao Liu

Keyword(s):

Particle Size ◽

Size Effect ◽

Selective Hydrogenation ◽

Size Effects ◽

Palladium Catalysts ◽

Particle Size Effect ◽

Particle Size Effects ◽

Supported Palladium Catalysts ◽

Supported Palladium ◽

Palladium Particles

Palladium particles of different sizes obtained directly and indirectly by various methods were studied to clarify the particle size effect in the selective hydrogenation of cinnamaldehyde (CAL).

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Role of polyaniline morphology in Pd particles dispersion. Hydrogenation of alkynes in the presence of Pd-polyaniline catalysts

Chemical Papers ◽

10.2478/s11696-013-0383-z ◽

2013 ◽

Vol 67 (8) ◽

Cited By ~ 6

Author(s):

Robert Kosydar ◽

Monika Goral ◽

Alicja Drelinkiewicz ◽

Jaroslav Stejskal

Keyword(s):

Palladium Catalysts ◽

Active Sites ◽

Pd Nanoparticles ◽

Liquid Phase Hydrogenation ◽

Close Proximity ◽

Physicochemical Features ◽

Molecular Masses ◽

Palladium Particles ◽

Pani Sample

AbstractTwo polyaniline (PANI) samples of various molecular masses were used for the preparation of palladium catalysts (with 2 mass % of Pd). The physicochemical features of starting polyanilines were found to substantially affect the size and extent of palladium nanoparticles aggregation. Strongly aggregated large palladium particles appeared in the PANI sample of more compact morphology (PANI-H), higher crystallinity and lower specific surface area. Pd nanoparticles of a definitively smaller size were formed in the more amorphous PANI sample of looser morphology (PANI-L) and the extent of particles aggregation was markedly lower. The catalytic properties of Pd/PANI samples were studied in a liquid phase hydrogenation of unsaturated triple bond (C≡C) in alkynes reactants, phenylacetylene, and cyclohexylacetylene. The 2 mass % Pd/PANI-L catalyst prepared using polymer of less compact texture exhibited much higher activity in both reactions. In the presence of the 2 mass % Pd/PANI-L catalyst, alkene products were formed with a high selectivity (approximately 90 %) attained at the almost complete conversion of alkynes. This highly selective hydrogenation of the C≡C to the C=C bond was related to the presence of an electroactive polymer, PANI, in close proximity with Pd active sites. Polyaniline could have a role in a steric effect as well as in a modification of adsorptive properties of Pd centres.

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Palladium nanoparticles supported by alumina nanofibers synthesized by electrospinning

Journal of Materials Research ◽

10.1557/jmr.2008.0173 ◽

2008 ◽

Vol 23 (5) ◽

pp. 1193-1196 ◽

Cited By ~ 23

Author(s):

S.J. Park ◽

S. Bhargava ◽

E.T. Bender ◽

G.G. Chase ◽

R.D. Ramsier

Keyword(s):

Photoelectron Spectroscopy ◽

Palladium Nanoparticles ◽

Electrospun Nanofibers ◽

Palladium Chloride ◽

Raman Scattering Spectroscopy ◽

X Ray ◽

Alumina Nanofibers ◽

Transmission Electron ◽

Metallic Palladium ◽

Palladium Particles

Palladium nanoparticles supported by alumina nanofibers have been successfully synthesized by electrospinning using palladium chloride incorporated into a solution of polyvinyl pyrrolidone and aluminum acetate. Palladium agglomerate sizes and the surface morphology of the electrospun nanofibers were determined by transmission electron microscopy. Palladium nanoparticles appeared to be well dispersed within the electrospun nanofiber structure. X-ray diffraction, x-ray photoelectron spectroscopy, and Raman scattering spectroscopy techniques were used to identify the crystalline form and distinguish between oxidized and metallic palladium particles after heating and hydrogenation.

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Controllable synthesis of palladium nanoparticles via a simple sonoelectrochemical method

Journal of Materials Research ◽

10.1557/jmr.2003.0192 ◽

2003 ◽

Vol 18 (6) ◽

pp. 1399-1404 ◽

Cited By ~ 36

Author(s):

Xiao-Feng Qiu ◽

Jin-Zhong Xu ◽

Jian-Ming Zhu ◽

Jun-Jie Zhu ◽

Shu Xu ◽

...

Keyword(s):

Growth Mechanism ◽

Current Density ◽

Palladium Nanoparticles ◽

Room Temperature ◽

Controllable Synthesis ◽

Highly Dispersed ◽

Ultrasonic Intensity ◽

Palladium Particles ◽

Shape And Size

A simple pulse sonoelectrochemical technique was used to synthesize highly dispersed spherical palladium particles and a dendritic Pd superstructure in the presence of cethyltrimethylammonium bromide (CTAB) at room temperature. The shape and size of spherical nanocrystalline Pd can be controlled by varying current density, the interval between two continuous ultrasonic pulses, ultrasonic intensity, and the concentration of CTAB. The possible growth mechanism of dendritic-structured Pd is discussed.

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Kinetics of the Hydrogenation of Sunflower Oil over Alumina Supported Palladium Catalyst

International Journal of Chemical Reactor Engineering ◽

10.2202/1542-6580.1380 ◽

2007 ◽

Vol 5 (1) ◽

Cited By ~ 7

Author(s):

María B. Fernández ◽

Gabriela M Tonetto ◽

Guillermo Crapiste ◽

Daniel E Damiani

Keyword(s):

Activation Energy ◽

Sunflower Oil ◽

Palladium Catalysts ◽

Reaction Rate ◽

Surface Kinetics ◽

Trans Isomers ◽

Geometric Isomerization ◽

Influence Of Temperature On ◽

Supported Palladium ◽

Kinetics Of

The present work studies the sunflower oil hydrogenation on supported palladium catalysts, by analyzing the surface kinetics and the mass transfer limitations of products and reactants. Initially, a simplified model was studied. This model took into account only the consecutive hydrogenation of linoleic acid (diene), to reach the production of oleic (monoene) and stearic (saturated) acids. Using the adjusted values of the kinetic constants and the activation energies of the hydrogenation obtained with this model, a new scheme was investigated considering the geometric isomerization reactions (cis-trans). The diene hydrogenation constant was larger than that of the monoene. This fact confirms the higher reaction rate of the diene hydrogenation in comparison with that of the monoene. With respect to the isomerization rates, these have an activation energy superior to that of the monoene hydrogenation, and slightly superior to the diene hydrogenation activation energy. This fact verifies the influence of temperature on the formation of trans-isomers.

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Formation and Stabilization of Anisotropic Palladium and Platinum Nanoparticles in Aqueous Polymer Solution Using Microwave Irradiation

Australian Journal of Chemistry ◽

10.1071/ch07353 ◽

2008 ◽

Vol 61 (11) ◽

pp. 833 ◽

Cited By ~ 4

Author(s):

Angshuman Pal ◽

Sunil Shah ◽

Debjani Chakraborty ◽

Surekha Devi

Keyword(s):

Microwave Irradiation ◽

Platinum Nanoparticles ◽

Palladium Nanoparticles ◽

Pt Nanoparticles ◽

Visible Spectroscopy ◽

Aqueous Polymer ◽

Transmission Electron ◽

Aqueous Polymer Solution ◽

Uv Visible ◽

Palladium Particles

Anisotropic palladium and platinum nanoparticles were synthesized by reduction of the corresponding metal ions with hydrazine using polyacrylamide as a stabilizing agent in aqueous medium under microwave irradiation. The formation of particles was confirmed by UV-visible spectroscopy. The size and shape of the particles were determined using transmission electron microscopy. Rapid microwave heating resulted in ‘star-shaped’ palladium nanoparticles, but platinum nanoparticles were observed to be spherical with a distinctly visible 3–4 nm coating of polyacrylamide on their surface, which was not observed for the palladium particles. The Pt nanoparticles were used as a catalyst in the redox reaction.

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Palladium Nanoparticles Supported on Graphene Oxide as Catalysts for the Synthesis of Diarylketones

Catalysts ◽

10.3390/catal9040319 ◽

2019 ◽

Vol 9 (4) ◽

pp. 319 ◽

Cited By ~ 1

Author(s):

Anna Trzeciak ◽

Przemyslaw Wojcik ◽

Radoslaw Lisiecki ◽

Yuriy Gerasymchuk ◽

Wieslaw Strek ◽

...

Keyword(s):

Graphene Oxide ◽

Catalytic Reaction ◽

Palladium Nanoparticles ◽

Palladium Catalysts ◽

Structural Changes ◽

Boronic Acids ◽

Size Distributions ◽

Supported Palladium ◽

Different Diameters

Three palladium catalysts supported on graphene oxide (GO) and on its composite with TiO2 (GO-TiO2) were prepared and characterized. The presence of Pd NPs of different diameters (4–89 nm) and size distributions was evidenced by TEM measurements. GO-supported palladium efficiently catalysed the carbonylative coupling of iodobenzenes with aryl boronic acids forming relevant diarylketones at 1 atm CO. The highest activity and recyclability were obtained for Pd/GO-TiO2. The emission behaviour of Pd/GO and Pd/GO-TiO2 catalysts indicated structural changes occurring during the catalytic reaction.

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