Author: Ioannis ZuburtikudisPublisher:
ISBN:
Category :
Languages : en
Pages : 252
Book Description
Layered Synthetic Microstructures and Size Effects of Supported-metal Catalysts
Author: Ioannis ZuburtikudisPublisher:
ISBN:
Category :
Languages : en
Pages : 252
Book Description
Dimensional Effects in Controlled Structure Supported Catalysts Derived from Layered Synthetic Microstructures. Final Progress Report for Period March 1, 1997 - February 28, 2000
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 4
Book Description
Several heterogeneous catalytic reactions show size dependence, whereby the specific rate changes with the average diameter of supported metal particles in the nanometer range. Geometric arguments relating the size dependence to the relative concentration of active sites on idealized crystal particles cannot account for all the observed results. In an effort to overcome the geometric limitations of supported particles, the authors had previously created novel supported metal catalysts called Layered Synthetic Microstructures (LSMs) by the physical vapor deposition of alternating thin films of Ni and silica onto 3-in. Si wafer substrates. Subsequent lithography followed by wet etching left an array of micron-sized towers. Relative catalytic rate measured for ethane hydrogenolysis showed that LSMs produced similar size effects as previously found with supported particles. In the current work, experiments were accomplished using LSMs with a wider range of metals (Ni, Pt, Ir, Rh, Ru, etc.) and supports (SiO2 and Al2O3). Dry etching with Ar ions was used. It was found that a distinction can be made between several types of size effects due to the well-defined geometry of LSM catalysts. Rates in some systems are truly size dependent, while in other systems rates are clearly dependent on the metal-support interface. In addition, a lift-off process was developed for fabrication of all kinds of LSMs without resorting to either wet or dry etch techniques.
Size Effects in Heterogeneous Reactions Using Layered Synthetic Microstructures
Author: Zhijian LuMicroelectronics, Microsystems And Nanotechnology: Papers Presented Of At Mmn 2000
Author: Androula G NassiopoulouPublisher: World Scientific
ISBN: 9814489999
Category : Technology & Engineering
Languages : en
Pages : 409
Book Description
This volume contains papers on the following: CMOS devices and devices based on compound semiconductors; processing; silicon integrated technology and integrated circuit design; quantum physics; nanotechnology; nanodevices, sensors and microsystems. The latest news and future challenges in these fields are presented in invited papers.
Microelectronics, Microsystems and Nanotechnology
Author: Androula G. NassiopoulouPublisher: World Scientific
ISBN: 9789812810861
Category : Technology & Engineering
Languages : en
Pages : 198
Book Description
This volume contains papers on the following: CMOS devices and devices based on compound semiconductors; processing; silicon integrated technology and integrated circuit design; quantum physics; nanotechnology; nanodevices, sensors and microsystems. The latest news and future challenges in these fields are presented in invited papers. Contents: Nanotechnology and Quantum Devices: A New Strategy for In Situ Synthesis of Oligonucleotides Arrays for DNA Chip Technology (F Vinet et al.); Magnetotransport Properties of La-Ca-Mn-O Multilayers (C Christides); Charge Effects and Related Transport Phenomena in Nanosize Silicon/Insulator Structures (J A Berashevich et al.); Thermoelectric Properties of Composite Fermions (M Tsaousidou & G P Triberis); Design and Fabrication of Supported-Metal Catalysts Through Nanotechnology (I Zuburtikudis); Ground State Electronic Structure of Small Si Quantum Dots (C S Garoufalis et al.); Processing: Solid Interface Studies with Applications in Microelectronics (S Kennou et al.); Rapid Thermal Annealing of Arsenic Implanted Silicon for the Formation of Ultra Shallow n+p Junctions (N Georgoulas et al.); Simulation of the Formation and Characterization of Roughness in Photoresists (G P Patsis et al.); Development of a New Low Energy Electron Beam Lithography Simulation Tool (D Velessiotis et al.); CMOS Devices and Devices Based on Compound Semiconductors: Microhardness Characterization of Epitaxially Grown GaN Films. Effect of Light Ion Implantation (P Kavouras et al.); Multiple Quantum Well Solar Cells Under AM1 and Concentrated Sunlight (E Aperathitis et al.); The Influence of Silicon Interstitial Clustering on the Reverse Short Channel Effect (C Tsamis & D Tsoukalas); Noise Modeling of Interdigitated Gate CMOS Devices (E F Tsakas & A N Birbas); High Precision CMOS Euclidean Distance Computing Circuit (G Fikos & S Siskos); Microsystems: Alternative Signal Extraction Technique for Miniature Fluxgates (P D Dimitropoulos & J N Avaritsiotis); Silicon Capacitive Pressure Sensors and Pressure Switches Fabricated Using Silicon Fusion Bonding (S Koliopoulou et al.); Microsystems for Acoustical Signal Detection Applications (D K Fragoulis & J N Avaritsiotis); Capillary Format Bioanalytical Microsystems (K Misiakos et al.); Effectiveness of Local Thermal Isolation by Porous Silicon in a Silicon Thermal Sensor (D Pagonis et al.); Silicon Integrated Technology and Integrated Circuit Design: MOSFET Model Benchmarking Using a Novel CAD Tool (N A Nastos & Y Papananos); Power Amplifier Linearisation Techniques: An Overview (N Naskas & Y Papananos); The Design of a Ripple Carry Adiabatic Adder (V Pavlidis et al.); Maximum Power Estimation in CMOS VLSI Circuits (N E Evmorfopoulos et al.); Power Dissipation Considerations in Low-Voltage CMOS Circuits (A A Hatzopoulos); Microelectronics Networks/Technology Transfer and Exploitation: EURACCESS: A European Platform for Access to CMOS Processing (C L Claeys); MMN: Greek Network on Microelectronics, Microsystems and Nanotechnology (A G Nassiopoulou); Simulations of Molecular Electronics (S T Pantelides et al.); and other papers. Readership: Researchers, academics, industrialists and undergraduates in microelectronics, nanoscience, materials science, applied physics and condensed matter physics.
Heterogeneous Gold Catalysts and Catalysis
Author: Zhen MaPublisher: Royal Society of Chemistry
ISBN: 1782621644
Category : Science
Languages : en
Pages : 635
Book Description
Once considered an inert element, gold has recently gained attention as a catalyst. With hundreds of papers being published each year, this book presents a comprehensive review of this rapidly-evolving field, with contributions by leading experts across the globe. Going through the chapters citing the primary literature, the reader will gain a thorough background to the use of gold in catalysis, as well as the latest methods for the preparation of gold catalysts. Other chapters demonstrate the characterisation and modelling of gold-catalysed reactions, with consideration given to both the fundamentals and commercial applications of this emerging group of catalysts. Written to be accessible by postgraduates and newcomers to the field, this book will also benefit experienced researchers and therefore be an essential reference in the laboratory.
Microstructure and Kinetics on Supported Metal Catalysts
Author: Chia-Pyng LeeHeterogeneous Catalysis in Organic Chemistry
Author: Gerard V. SmithPublisher: Academic Press
ISBN: 008052480X
Category : Science
Languages : en
Pages : 363
Book Description
The features of this book which will be of special interest to academic organic chemists are the introduction (Chapter 1), which presents a short course on the concepts and language of heterogeneous catalysis, covers organic reaction mechanisms of hydrogenation (Chapter 2), hydrogenolysis (Chapter 4), and oxidation (Chapter 6), a presents problems and solutions specific for running heterogeneous catalytic organic reactions in solution. These materials can supplement advanced chemistry courses. Most synthetic organic chemists use a variety of "protecting groups" which they attach to functional groups (reactive groups of atoms) while some reaction is being conducted on another part of the molecule. These protecting groups prevent reactions of the functional groups during other reactions and are removed later by a heterogeneous catalytic method called hydrogenolysis. One unique feature of this book, not found in other books on catalysis, is an exhaustive chapter (Chapter 4) on hydrogenolysis, which is dredged from the recent synthetic literature published by modern organic chemists. Academic organic chemists should find this chapter extremely useful and may wish to adopt the book as a supplement for advanced organic chemistry courses designed for seniors and for graduate students. It will also be useful for professors and their research groups engaged in synthetic organic chemistry. Many academic organic chemists are not aware of recent advances in heterogeneous enantioselective catalysis (Chapter 3) or in selective low temperature, liquid phase heterogeneous catalytic oxidations by hydrogen peroxide (Chapter 6). These specialty topics are timely and may be new to academic organic chemists and can be used to supplement their advanced courses. Several features of this book will also be of special interest to industrial chemists who are unfamiliar with heterogeneous catalysis. Many good organic chemists are hire by industry. They synthesize a new compound using standard organic synthetic techniques but are informed by their supervisor that they must convert some of their synthetic steps into heterogeneous catalytic steps. They may not have been exposed to heterogeneous catalysis and have few places to turn. This book offers them a crash course in heterogeneous catalysis as well as many examples of reactions and conditions with which they can start their search. Those industrial organic chemists already familiar with heterogeneous catalysis will find this book useful as a reference to many examples in the recent literature. They will find recent surface science discoveries correlated with heterogeneous catalysis or organic reactions and mechanistic suggestions designed to stimulate innovative nontraditional thinking about organic reactions on surfaces. Written by organic chemists for organic chemists Introduces heterogeneous catalysis concepts and language Presents a comprehensive compilation of protecting group removal procedures Covers liquid-phase hydrogenations, hydrogenolysis, and oxidations Addresses heterogeneous methods for producing pure enantiomers of chiral products Examines the emerging field of heterogenized homogeneous catalysts Mixes practical applications with mechanistic interpretations
Summaries of FY ... Research in the Chemical Sciences
Author: Fundamental Studies of the Reforming of Oxygenated Compounds Over Supported Metal Catalysts
Author: Publisher:
ISBN:
Category :
Languages : en
Pages : 28
Book Description
The main objective of our research has been to elucidate fundamental concepts associated with controlling the activity, selectivity, and stability of bifunctional, metal-based heterogeneous catalysts for tandem reactions, such as liquid-phase conversion of oxygenated hydrocarbons derived from biomass. We have shown that bimetallic catalysts that combine a highly-reducible metal (e.g., platinum) with an oxygen-containing metal promoter (e.g., molybdenum) are promising materials for conversion of oxygenated hydrocarbons because of their high activity for selective cleavage for carbon-oxygen bonds. We have developed methods to stabilize metal nanoparticles against leaching and sintering under liquid-phase reaction conditions by using atomic layer deposition (ALD) to apply oxide overcoat layers. We have used controlled surface reactions to produce bimetallic catalysts with controlled particle size and controlled composition, with an important application being the selective conversion of biomass-derived molecules. The synthesis of catalysts by traditional methods may produce a wide distribution of metal particle sizes and compositions; and thus, results from spectroscopic and reactions kinetics measurements have contributions from a distribution of active sites, making it difficult to assess how the size and composition of the metal particles affect the nature of the surface, the active sites, and the catalytic behavior. Thus, we have developed methods to synthesize bimetallic nanoparticles with controlled particle size and controlled composition to achieve an effective link between characterization and reactivity, and between theory and experiment. We have also used ALD to modify supported metal catalysts by addition of promoters with atomic-level precision, to produce new bifunctional sites for selective catalytic transformations. We have used a variety of techniques to characterize the metal nanoparticles in our catalysts, including scanning transmission electron microcopy (STEM) to measure size and structure, energy dispersive X-ray spectroscopy (EDS) to measure atomic composition, X-ray absorption spectroscopy (XAS) to measure oxidation state and metal coordination, Fourier transform infrared spectroscopy (FTIR) to study adsorbed species, laser Raman spectroscopy to probe metal oxide promoters, and temperature programmed reaction/desorption to study the energetics of adsorption and desorption processes. We have studied our bimetallic catalysts for the selective cleavage of carbon-oxygen bonds, and we have studied the effects of adding metal oxide promoters to supported platinum and gold catalysts for water-gas shift (i.e., the production of hydrogen by reaction of carbon monoxide with water). We anticipate that the knowledge obtained from our studies will allow us to identify promising directions for new catalysts that show high activity, selectivity, and stability for important reactions, such as the conversion of biomass-derived oxygenated hydrocarbons to fuels and chemicals.