Catalytic Reaction Intermediates by Sum Frequency Generation Vibrational Spectroscopy on Single Crystal Surfaces of Metals

Catalytic Reaction Intermediates by Sum Frequency Generation Vibrational Spectroscopy on Single Crystal Surfaces of Metals PDF Author: Xingcai Su
Publisher:
ISBN:
Category :
Languages : en
Pages : 334

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In-situ Studies of the Reactions of Bifunctional and Heterocyclic Molecules Over Noble Metal Single Crystal and Nanoparticle Catalysts Studied with Kinetics and Sum-Frequency Generation Vibrational Spectroscopy

In-situ Studies of the Reactions of Bifunctional and Heterocyclic Molecules Over Noble Metal Single Crystal and Nanoparticle Catalysts Studied with Kinetics and Sum-Frequency Generation Vibrational Spectroscopy PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Sum frequency generation surface vibrational spectroscopy (SFG-VS) in combination with gas chromatography (GC) was used in-situ to monitor surface bound reaction intermediates and reaction selectivities for the hydrogenation reactions of pyrrole, furan, pyridine, acrolein, crotonaldehyde, and prenal over Pt(111), Pt(100), Rh(111), and platinum nanoparticles under Torr reactant pressures and temperatures of 300K to 450K. The focus of this work is the correlation between the SFG-VS observed surface bound reaction intermediates and adsorption modes with the reaction selectivity, and how this is affected by catalyst structure and temperature. Pyrrole hydrogenation was investigated over Pt(111) and Rh(111) single crystals at Torr pressures. It was found that pyrrole adsorbs to Pt(111) perpendicularly by cleaving the N-H bond and binding through the nitrogen. However, over Rh(111) pyrrole adsorbs in a tilted geometry binding through the [pi]-aromatic orbitals. A surface-bound pyrroline reaction intermediate was detected over both surfaces with SFG-VS. It was found that the ring-cracking product butylamine is a reaction poison over both surfaces studied. Furan hydrogenation was studied over Pt(111), Pt(100), 10 nm cubic platinum nanoparticles and 1 nm platinum nanoparticles. The product distribution was observed to be highly structure sensitive and the acquired SFG-VS spectra reflected this sensitivity. Pt(100) exhibited more ring-cracking to form butanol than Pt(111), while the nanoparticles yielded higher selectivities for the partially saturated ring dihydrofuran. Pyridine hydrogenation was investigated over Pt(111) and Pt(100). The [alpha]-pyridyl surface adsorption mode was observed with SFG-VS over both surfaces. 1,4-dihydropyridine was seen as a surface intermediate over Pt(100) but not Pt(111). Upon heating the surfaces to 350K, the adsorbed pyridine changes to a flat-lying adsorption mode. No evidence was found for the pyridinium cation. The hydrogenation of the [alpha], [beta]-unsaturated aldehydes acrolein, crotonaldehyde, and prenal were investigated over Pt(111) and Pt(100). The selectivity for the hydrogenation of the C=C bond was found to depend on the number of methyl groups added to the bond. The adsorption modes of the three aldehydes were determined. The hydrogenation of crotonaldehyde was found to be nearly structure insensitive as the TOF and selectivity were very close to the same over Pt(111) and Pt(100). SFG-VS indicated identical surface intermediates over the two crystal faces during crotonaldehyde hydrogenation.

The Effect of Surface Structure on Catalytic Reactions

The Effect of Surface Structure on Catalytic Reactions PDF Author: Keith Ryan McCrea
Publisher:
ISBN:
Category :
Languages : en
Pages : 370

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Advances in Catalysis

Advances in Catalysis PDF Author: Bruce C. Gates
Publisher: Academic Press
ISBN: 9780122772511
Category : Science
Languages : en
Pages : 466

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Book Description
Surface science emerged in the 1960s with the development of reliable ultrahigh vacuum apparatus, providing exact structures of surfaces of metal single crystals, information about their compositions, and relationships between surface structure and composition and catalytic reaction rates. Catalysis, the acceleration of a chemical reaction by a catalyst (substance), provided much of the driving force for the early development of surface science. As surface science continues its rapid development, this book illustrates how it is still driven by the challenges of catalysis and how both theory and scanning tunneling microscopy have forcefully emerged as essential tools. It is also evident how surface science continues to serve as the foundation of catalytic science. This is a compendium written by leading surface scientists presenting an incisive assessment of up-to-date theoretical and experimental results constituting the foundation of fundamental understanding of surface catalysis. This paperback.

Characterization of Solid Materials and Heterogeneous Catalysts

Characterization of Solid Materials and Heterogeneous Catalysts PDF Author: Michel Che
Publisher: John Wiley & Sons
ISBN: 3527645330
Category : Technology & Engineering
Languages : en
Pages : 1313

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Book Description
This two-volume book provides an overview of physical techniques used to characterize the structure of solid materials, on the one hand, and to investigate the reactivity of their surface, on the other. Therefore this book is a must-have for anyone working in fields related to surface reactivity. Among the latter, and because of its most important industrial impact, catalysis has been used as the directing thread of the book. After the preface and a general introduction to physical techniques by M. Che and J.C. Vedrine, two overviews on physical techniques are presented by G. Ertl and Sir J.M. Thomas for investigating model catalysts and porous catalysts, respectively. The book is organized into four parts: Molecular/Local Spectroscopies, Macroscopic Techniques, Characterization of the Fluid Phase (Gas and/ or Liquid), and Advanced Characterization. Each chapter focuses upon the following important themes: overview of the technique, most important parameters to interpret the experimental data, practical details, applications of the technique, particularly during chemical processes, with its advantages and disadvantages, conclusions.

Model Systems in Catalysis

Model Systems in Catalysis PDF Author: Robert Rioux
Publisher: Springer Science & Business Media
ISBN: 0387980490
Category : Science
Languages : en
Pages : 531

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Book Description
This book is an excellent compilation of cutting-edge research in heterogeneous catalysis and related disciplines – surface science, organometallic catalysis, and enzymatic catalysis. In 23 chapters by noted experts, the volume demonstrates varied approaches using model systems and their successes in understanding aspects of heterogeneous catalysis, both metal- and metal oxide-based catalysis in extended single crystal and nanostructured catalytic materials. To truly appreciate the astounding advances of modern heterogeneous catalysis, let us first consider the subject from a historical perspective. Heterogeneous catalysis had its beginnings in England and France with the work of scientists such as Humphrey Davy (1778–1829), Michael Faraday (1791–1867), and Paul Sabatier (1854–1941). Sabatier postulated that surface compounds, si- lar to those familiar in bulk to chemists, were the intermediate species leading to catalytic products. Sabatier proposed, for example, that NiH moieties on a Ni sur- 2 face were able to hydrogenate ethylene, whereas NiH was not. In the USA, Irving Langmuir concluded just the opposite, namely, that chemisorbed surface species are chemically bound to surfaces and are unlike known molecules. These chemisorbed species were the active participants in catalysis. The equilibrium between gas-phase molecules and adsorbed chemisorbed species (yielding an adsorption isotherm) produced a monolayer by simple site-filling kinetics.

In-situ Studies of the Reactions of Bifunctional and Heterocyclic Molecules Over Noble Metal Single Crystal and Nanoparticle Catalysts Studied with Kinetics and Sum-frequency Generation Vibrational Spectroscopy

In-situ Studies of the Reactions of Bifunctional and Heterocyclic Molecules Over Noble Metal Single Crystal and Nanoparticle Catalysts Studied with Kinetics and Sum-frequency Generation Vibrational Spectroscopy PDF Author: Christopher Jesse Kliewer
Publisher:
ISBN:
Category :
Languages : en
Pages : 272

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Advances in Catalysis

Advances in Catalysis PDF Author:
Publisher: Elsevier
ISBN: 0080475779
Category : Technology & Engineering
Languages : en
Pages : 406

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Book Description
Catalysis is the acceleration of a chemical reaction by a catalyst, a substance that notably affects the rate of a chemical reaction without itself being consumed or altered. Since 1948, Advances in Catalysis has filled the gap between the papers that report on and the textbooks that teach in the diverse areas of catalysis research. The editors of and contributors to Advances in Catalysis are dedicated to recording progress in this area. * Provides a comprehensive review of all aspects of catalytic research * Contains in-depth, critical, state-of-the-art reports

Molecular Surface Chemistry by Metal Single Crystals and Nanoparticles from Vacuum to High Pressure

Molecular Surface Chemistry by Metal Single Crystals and Nanoparticles from Vacuum to High Pressure PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Model systems for studying molecular surface chemistry have evolved from single crystal surfaces at low pressure to colloidal nanoparticles at high pressure. Low pressure surface structure studies of platinum single crystals using molecular beam surface scattering and low energy electron diffraction techniques probe the unique activity of defects, steps and kinks at the surface for dissociation reactions (H-H, C-H, C-C, O{double_bond}O bonds). High-pressure investigations of platinum single crystals using sum frequency generation vibrational spectroscopy have revealed the presence and the nature of reaction intermediates. High pressure scanning tunneling microscopy of platinum single crystal surfaces showed adsorbate mobility during a catalytic reaction. Nanoparticle systems are used to determine the role of metal-oxide interfaces, site blocking and the role of surface structures in reactive surface chemistry. The size, shape and composition of nanoparticles play important roles in determining reaction activity and selectivity.

Catalytic Naphtha Reforming, Revised and Expanded

Catalytic Naphtha Reforming, Revised and Expanded PDF Author: George J. Antos
Publisher: CRC Press
ISBN: 0824757122
Category : Science
Languages : en
Pages : 571

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Book Description
Catalytic Naphtha Reforming, Second Edition presents modern, crystal-clear explanations of every aspect of this critical process for generating high-octane reformate products for gasoline blending and production of benzene, toluene, and xylene (BTX) aromatics. The book details the chemistry of naphtha reforming, the preparation and characterization of catalysts, and the very latest commercial technologies and industrial applications. With more than 300 tables and figures, it addresses the development of new catalysts and revamp process improvements propelled by regulations on sulfur, benzene, and oxygenate content in gasoline and refinery pressure to maximize utilization of existing assets.