Controlling Activity of Ligand-capped Palladium Nanoparticle Catalysts PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Controlling Activity of Ligand-capped Palladium Nanoparticle Catalysts PDF full book. Access full book title Controlling Activity of Ligand-capped Palladium Nanoparticle Catalysts by May Maung. Download full books in PDF and EPUB format.
Author: May Maung
Publisher:
ISBN: 9781339826233
Category : Allyl alcohol
Languages : en
Pages : 48
Get Book Here
Book Description
Abstract: This thesis presents the systematic evaluation of palladium nanoparticles functionalized with well-defined small organic ligands that can provide a spatial control in the surrounding environment of nanoparticle catalyst surfaces. Various thiolate ligand-capped palladium nanoparticles are produced by using different S-alkylthiosufate ligand precursors in a two-phase system composed of toluene and water. These palladium nanoparticles are then characterized using transmission electron microscopy, thermogravimetric analysis, NMR, FT-IR, and UV-vis spectroscopy. The catalysis studies on alkanethiolate-capped palladium nanoparticles with different ligand structures (linear alkyl vs cyclohexyl vs phenyl) show that the chemical and structural composition of a monolayer surrounding the palladium nanoparticles greatly influences the overall activity and selectivity of nanoparticle catalysts for the hydrogenation, isomerization, and hydrogenolysis of allylic alcohols. Especially, the effect of non-covalent interactions between surface ligands and incoming substrates in the near-surface environment is observed. Furthermore, the catalytic properties of & ohgr;-carboxylate-functionalized alkanethiolate-capped palladium nanoparticles are studied for the biphasic reactions of hydrophobic allylic alcohols that are immiscible in aqueous solution. The systematic investigations on the influence of pH and substrate size are performed to check the utility of structurally stable and water-soluble palladium nanoparticles as new micellar catalysts.
Author: May Maung
Publisher:
ISBN: 9781339826233
Category : Allyl alcohol
Languages : en
Pages : 48
Get Book Here
Book Description
Abstract: This thesis presents the systematic evaluation of palladium nanoparticles functionalized with well-defined small organic ligands that can provide a spatial control in the surrounding environment of nanoparticle catalyst surfaces. Various thiolate ligand-capped palladium nanoparticles are produced by using different S-alkylthiosufate ligand precursors in a two-phase system composed of toluene and water. These palladium nanoparticles are then characterized using transmission electron microscopy, thermogravimetric analysis, NMR, FT-IR, and UV-vis spectroscopy. The catalysis studies on alkanethiolate-capped palladium nanoparticles with different ligand structures (linear alkyl vs cyclohexyl vs phenyl) show that the chemical and structural composition of a monolayer surrounding the palladium nanoparticles greatly influences the overall activity and selectivity of nanoparticle catalysts for the hydrogenation, isomerization, and hydrogenolysis of allylic alcohols. Especially, the effect of non-covalent interactions between surface ligands and incoming substrates in the near-surface environment is observed. Furthermore, the catalytic properties of & ohgr;-carboxylate-functionalized alkanethiolate-capped palladium nanoparticles are studied for the biphasic reactions of hydrophobic allylic alcohols that are immiscible in aqueous solution. The systematic investigations on the influence of pH and substrate size are performed to check the utility of structurally stable and water-soluble palladium nanoparticles as new micellar catalysts.
Author: Diego J. Gavia
Publisher:
ISBN: 9781303765926
Category : Allyl alcohol
Languages : en
Pages : 170
Get Book Here
Book Description
Abstract: This thesis presents systematic investigations on the relationship between the catalytic property and the surface ligand density/core size of thiolate ligand-capped Pd nanoparticles (PdNPs). The systematic variations in the two-phase synthesis of PdNPs generated from sodium S-dodecylthiosulfate and sodium co-carboxyl-S'-alkanethiosulfates were performed. The resulting PdNPs were characterized by transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and *H NMR and UV Vis spectroscopy. The catalysis studies on various PdNPs with different surface ligand density and average core size showed a strong correlation between the PdNP composition and the turnover frequency (TOF) of the isomerization of allyl alcohol. Stable watersoluble Pd nanoparticles with the lower surface ligand density were further examined for the catalytic hydrogenation of allyl alcohol in both aqueous and organic solvents. The catalysis results showed that water-soluble Pd nanoparticles dissolved in water favored the hydrogenation product (1-propanol) whereas Pd nanoparticles dispersed in chloroform exhibited a low catalytic activity with some selectivity towards the isomerization product (propanal).
Author: John D. Attelah
Publisher:
ISBN:
Category : Nanostructured materials
Languages : en
Pages : 0
Get Book Here
Book Description
Author's abstract: Rational design of active and stable palladium nanoparticles using peptide is emerging field in nanomaterial technology. Nanoparticles are preferred as catalysts compared to their bulk counter-parts due to their large surface area-to-volume ratio making them more reactive. The use of peptide to facilitate the formation and stabilization of the inorganic nanoparticles such as palladium is desirable due to their less toxic nature, and desired products formed after the completion of the reaction. In addition, peptide is known to impart high level of control over size and shape in nanoparticles. In this work, peptide-driven fabrication of catalytically stable and reactive palladium was conducted in organic solvents and used in Heck reaction catalysis of iodobenzene and butyl acrylate to form butyl cinnamate. The use of a peptide ligands contrasts with the traditional toxic bulky phosphine ligands, which are conventionally used to stabilize and solubilize bulky palladium metal catalyst. The optimum temperature for maximum yield of butyl cinnamate was investigated in series of reactions set up from 25 to 80 °C with other reaction parameters kept constant. Heck coupling reaction is industrially important in synthesis of various pharmaceuticals We successfully conducted, characterized, and quantified the Heck coupling reaction in ethanol and DMSO at 80 °C using palladium-capped peptide nanoparticles and triethyl amine base. Different engineered and control peptides were used to fabricate palladium nanoparticles formation and for enhancing their colloidal and stability during the Heck reaction. The peptides used were engineered from the control Pd4 (TSNAVHPTLRHL) peptide, which is known to specifically bind palladium metal via the histidines at positions six and eleven. The S2 (AFILPTG) peptide, which is specific to silica, was attached at either ends of the Pd4 peptide to form S2Pd4, Pd4S2, and S2Pd4S2. The engineered peptide-capped palladium nanoparticles were investigated for their colloidal stability and catalytic activity.
Author: Kayla Mae Roeser
Publisher:
ISBN:
Category :
Languages : en
Pages : 108
Get Book Here
Book Description
Noble metals are the most sought after elements for catalysis because of their versatility, activity, and recyclability for a variety of applications; however they are limited as a resource and expensive. Noble metal nanoparticles offer a solution for use in catalysis because their high surface area to volume ratio maximizes their available surface sites while minimizing the amount of metal used. Additionally, particularly exposed facets of nanoparticles can increase surface energies for superior catalytic activity and induce novel electronic/physical properties. In the first chapter of my thesis, I synthesized palladium, platinum, and semiconductor titania nanoparticles through a biomimetic approach by using peptides to preferentially bind to and expose particular crystal facets of nanoparticles. Using a combinatorial approach called biopanning to find highly selective surface energy modifiers for particular facets of materials gave insight to unique binding motifs for materials as well as induced morphology controlled nanoparticles at ambient conditions. There are limitless combinations of solvents, capping agents, and inorganic precursors for inorganic nanoparticle synthesis. Understanding these systems in terms of more global trends would circumvent the current colossal approach of empirically screening systems. To do this, considering the inorganic-organic interfacial relationship is key. In the second chapter, I report unique aryl small molecules which preferentially bind to palladium surfaces through electrostatic potentials and epitaxial binding in nanoparticle synthesis. These results offer an understanding to the dynamic binding relationship between capping agents and nanoparticle surfaces. Lastly, I report on the synthesis of gold-palladium nanoparticles and their activity for the benzyl alcohol oxidation reaction. It was found that the (100) facets of gold-palladium were more catalytically active than the (111) surface. Details of the nanoparticle shape, size, and activity add to the understanding how this material behaves at the atomic level and will help to impact future advances in this field of catalysis. The syntheses described here are important because they are environmentally friendly, they offer information about the binding mechanisms at the organic-inorganic interface of the systems, and give insight to catalytic behavior. All of this work is necessary to further exploit nanoparticle synthesis, assembly and provide the precise engineering of nanostructured materials.
Author: Mohammed Mahdaly
Publisher:
ISBN: 9781085570886
Category : Alkenes
Languages : en
Pages : 47
Get Book Here
Book Description
This thesis presents the preparation and catalysis of octanethiolate-capped palladium nanoparticles (C8 PdNP) and phenylethanethiolate-capped palladium nanoparticles (PhC2 PdNP) for chemoselective catalytic hydrogenation reactions of alkene groups in the presence of other reducible functionalities. Kinetic studies are performed and analyzed by 1H NMR spectroscopy to obtain clearer understandings of the catalytic activity. The noncovalent interactions between surface phenyl ligands and aromatic substrates are found to hinder the hydrogenation activity of PhC2 PdNP. In comparison, the C8 PdNP is discovered to be highly active and selective for hydrogenating alkene and alkyne groups without the reduction of other reactive functional groups such as nitro, halo, carbonyls, etc. under the mild reaction condition (room temperature and atmospheric pressure).
Author: Jie S. Zhu
Publisher:
ISBN: 9781085564441
Category : Alkenes
Languages : en
Pages : 45
Get Book Here
Book Description
Abstract: The reactions of palladium are invaluable to modern academic and industrial research, and nanotechnology is the foundation on which the next generation of materials is built upon. Unsupported thiolate-capped palladium nanoparticles were found to be highly substrate selective for alkene hydrogenation and isomerization. A modified Brust-Schiffrin reaction enabled the facile and convenient synthesis of a diverse set of ultra-small thiolate-capped nanoparticles. The physical properties of these nanoparticles were highly tunable due to the widespread availability of ligand precursors. Mechanistic evidence and insights reveal that steric and electronic effects from the ligand environment on the nanoparticle surface controlled reactivity by influencing alkene adsorption via [pi] bond coordination or di-[sigma] bond formation. Only alkenes close enough to the metal surface of the nanoparticles underwent reaction. Dienes with good overlapping p orbitals could overcome these steric effects on the deactivated palladium nanoparticle surfaces. A mechanistic model was built from these completed studies, and this model can be used to predict the selectivity of hydrogenation or isomerization in multiple classes of alkenes with varied substitution patterns. These palladium nanoparticles were also found to be capable of chemoselective alkene hydrogenation in the presence of functional groups that are known to be labile towards reduction by palladium.
Author: Elham Sadeghmoghaddam
Publisher:
ISBN: 9781267703231
Category : Allyl alcohol
Languages : en
Pages : 124
Get Book Here
Book Description
Abstract: This thesis presents a synthetic method for alkanethiolate-functionalized Pd nanoparticles that are efficient catalysts for the isomerization of various allyl alcohols to their corresponding carbonyl compounds. Pd nanoparticles are produced by the borohydride reduction of K 2 PdCl4 in toluene/H2 O using sodium S -dodecylthiosulfate as a source for the stabilizing ligands. The monolayer-capped Pd nanoparticles from sodium S -dodecylthiosulfate are quite comparable in composition (dodecylthiolate) and core size with those previously prepared from dodecanethiol. However, the catalytic activity of Pd nanoparticles generated from S -dodecylthiosulfate is found to be significantly greater than that of Pd nanoparticles prepared from dodecanethiol. Furthermore, the mechanism of the catalytic reactions and the regioselectivity of Pd nanoparticles in different environments are studied by changing the amount of H 2 gas, the type of solvent used for the catalytic reactions and the use of ligands with different chain length. Lastly, the high stability of homogeneous nanocatalysts is demonstrated by recycling dodecanethiolate-capped Pd nanoparticles over ten times for the isomerization reaction of allyl alcohol.
Author: Ashutosh Kumar Shukla
Publisher: Elsevier
ISBN: 0081025807
Category : Technology & Engineering
Languages : en
Pages : 548
Get Book Here
Book Description
Green Synthesis, Characterization and Applications of Nanoparticles shows how eco-friendly nanoparticles are engineered and used. In particular, metal nanoparticles, metal oxide nanoparticles and other categories of nanoparticles are discussed. The book outlines a range of methodologies and explores the appropriate use of each. Characterization methods include spectroscopic, microscopic and diffraction methods, but magnetic resonance methods are also included as they can be used to understand the mechanism of nanoparticle synthesis using organisms. Applications covered include targeted drug delivery, water purification and hydrogen generation. This is an important research resource for those wishing to learn more about how eco-efficient nanoparticles can best be used. Theoretical details and mathematical derivations are kept to a necessary minimum to suit the need of interdisciplinary audiences and those who may be relatively new to the field. Explores recent trends in growth, characterization, properties and applications of nanoparticles Gives readers an understanding on how they are applied through the use of case studies and examples Assesses the advantages and disadvantages of a variety of synthesis and characterization techniques for green nanoparticles in different situations
Author: Emily A.. Groover
Publisher:
ISBN:
Category : Biotechnology
Languages : en
Pages : 0
Get Book Here
Book Description
Author's abstract: The synthesis of palladium nanoparticles (Pd NPs) using materials-directed peptides is a novel, nontoxic approach which exerts a high level of control over the particle size and shape. This biomimetic technique is environmentally benign, featuring nonhazardous ligands and ambient conditions. Nanoparticles are extremely reactive catalysts, boasting a large surface-to-volume ratio when compared to their bulk counterparts. The rational design of these nanoparticles using peptides has been very successful in aqueous environments, but no research has been done to apply it in organic systems. As such, the biomimetic synthesis of Pd NPs in an organic system is here investigated, with ethanol and dimethyl sulfoxide (DMSO) as solvents of interest. These systems adapt palladium-binding peptides to incorporate a hydrophobic region on the -N terminus, -C terminus, and both N and C termini to aid in solvent interaction during nanoparticle synthesis. These peptides proved to successfully synthesize colloidal nanoparticles in both ethanol and DMSO. Their subsequent application as catalysts in the Suzuki-Miyaura carbon cross-coupling reaction facilitated a comparison of the peptide-capped nanoparticles’ catalytic activity. Catalytic studies indicate that the S2Pd4S2 peptide, with two hydrophobic regions, produced nanoparticles with the highest catalytic activity as compared to the other major peptides, suggesting that materials-directed peptides may be adapted and tuned to operate effectively in organic solvents.
Author: Geoffrey C Bond
Publisher: World Scientific
ISBN: 1908979852
Category : Science
Languages : en
Pages : 383
Get Book Here
Book Description
Gold has traditionally been regarded as inactive as a catalytic metal. However, the advent of nanoparticulate gold on high surface area oxide supports has demonstrated its high catalytic activity in many chemical reactions. Gold is active as a heterogeneous catalyst in both gas and liquid phases, and complexes catalyse reactions homogeneously in solution. Many of the reactions being studied will lead to new application areas for catalysis by gold in pollution control, chemical processing, sensors and fuel cell technology. This book describes the properties of gold, the methods for preparing gold catalysts and ways to characterise and use them effectively in reactions. The reaction mechanisms and reasons for the high activities are discussed and the applications for gold catalysis considered./a
