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Preparation And Characterization Of Bi Metallic Nanoparticle Catalyst Having Better Anti Coking Properties Using Reverse Micelle Technique
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Book Synopsis Preparation and Characterization of Bi-metallic Nanoparticle Catalyst Having Better Anti-coking Properties Using Reverse Micelle Technique by : Thomas Zacharia
Download or read book Preparation and Characterization of Bi-metallic Nanoparticle Catalyst Having Better Anti-coking Properties Using Reverse Micelle Technique written by Thomas Zacharia and published by . This book was released on 2012 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Reverse Micelle Synthesis and Characterization of Supported Bimetallic Catalysts by : Beth Cheney
Download or read book Reverse Micelle Synthesis and Characterization of Supported Bimetallic Catalysts written by Beth Cheney and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Synthesis of supported nanoparticles with consistent particle size is a bridge between what researchers refer to as the "materials gap," the gap in structure complexity between single crystals and supported catalysts. Controlling particle size during supported catalyst synthesis allows researchers to investigate optimal conditions for desired activity and/or selectivity toward specific chemical reactions. This information can lead to the possibility to tune catalyst synthesis to optimize efficiency and cost while minimizing the waste of precious, nonrenewable resources. This thesis investigates a procedure potentially capable of synthesizing supported catalysts with uniformly-sized nanoparticles. This combines the idealized environment of a model system with the increased complexity associated with nanoparticle size and support effects. To bridge the materials gap, extensive work has been performed to determine how metallic structures affect adsorbate interactions. Chapter 1 discusses density functional theory (DFT) calculations used to predict adsorbate binding energies on metal monolayer bimetallic surfaces and the correlation to single crystal surfaces and polycrystalline foils. Recently, the trends observed on these model systems have provided insight into enhanced reactivity on oxide-supported bimetallic catalysts. Due to limitations of particle size control with traditional catalyst synthesis procedures, there is motivation for a method to synthesize uniform particles to better represent model surfaces. Chapter 2 describes reverse micelle synthesis, a technique which has been shown to control nanoparticle size by chemically reducing metal precursors in surfactant-stabilized water droplets suspended in an oil phase. Techniques used to characterize catalysts synthesized using this method are also discussed in this chapter. Chapter 3 discusses synthesis of supported monometallic platinum (Pt) and bimetallic platinum-cobalt (Pt-Co) catalysts in aqueous/oil/surfactant microemulsions consisting of water/cyclohexane/Brij-30 reduced by sodium borohydride (NaBH4). Although reverse micelle synthesis produced small (~4 nm) reduced, unsupported nanoparticles, supported particles sintered after hightemperature pre-treatments. Extended X-ray absorption fine structure (EXAFS) measurements confirmed bimetallic bond formations between Pt and Co atoms; however, bimetallic catalysts did not exhibit enhanced hydrogenation activity compared to their monometallic Pt catalysts. A half-fractional factorial design of experiments was implemented to determine what synthesis parameters could be altered to decrease solvent quantities, thus decreasing residual carbon which may have inhibited catalytic activity. Statistical analysis could not be performed due to large scatter between repetitions. Due to unsatisfactory reproducibility involved with this synthesis, an alternative reverse micelle synthesis chemistry was investigated. The reverse micelle synthesis chemistry described in Chapter 4 incorporated a co-surfactant, which stabilizes surfactant molecules around water droplets and promotes uniformity. The composition was an aqueous/oil/surfactant/cosurfactant microemulsion consisting of water/cyclohexane/Triton X-100/2-propanol. The reducing agent was hydrazine (N2H4). Two impregnation methods, stepimpregnation and co-impregnation, were tested. Step-impregnation describes the procedure where nickel (Ni) nanoparticles were reduced in microemulsion and supported, followed by depositing Pt using incipient wetness impregnation. Co-impregnation is the procedure where Ni and Pt were reduced simultaneously in microemulsion and then supported. These methods were compared to catalysts synthesized by incipient wetness impregnation, either step-impregnation (supporting Ni then supporting Pt) or co-impregnation (supporting Pt and Ni simultaneously). Final particle sizes of all catalysts were similar; however, micelle catalysts resulted in a narrower distribution of particle size than those synthesized using only incipient wetness impregnation. Step-impregnated catalysts exhibited enhanced activity compared to monometallic Pt and Ni catalysts, suggesting bimetallic bond formation, which was later confirmed by EXAFS measurements. The co-impregnated micelle catalyst had low activity, comparable to data obtained for monometallic Ni. Bimetallic bond formation could not be measured for the co-impregnated micelle catalyst due to insufficient X-ray absorption during EXAFS measurements. Atomic absorption spectroscopy (AAS) revealed that Pt metal uptake for the co-impregnated micelle catalyst was only 25% of Pt uptake for the incipient wetness catalysts and the stepimpregnated micelle catalyst. The low Pt uptake was predicted to be the reason for the low activity and low X-ray absorption. Chapter 5 discusses challenges associated with reverse micelle synthesis including particle size control, effect of solution pH on metal reduction and adsorption on support, and the effect of pre-treatment conditions on nanoparticle size. To take advantage of the ability to create an idealized environment by controlling particle size to study adsorbate interactions, these challenges must be overcome.
Book Synopsis Metal Nanoparticles for Catalysis by : Franklin (Feng) Tao
Download or read book Metal Nanoparticles for Catalysis written by Franklin (Feng) Tao and published by Royal Society of Chemistry. This book was released on 2014-06-30 with total page 285 pages. Available in PDF, EPUB and Kindle. Book excerpt: An introduction to the synthesis and applications of different nanocatalysts.
Book Synopsis Controlled Synthesis of Pt-Ni Bimetallic Catalysts and Study of Their Catalytic Properties by : Yuen Wu
Download or read book Controlled Synthesis of Pt-Ni Bimetallic Catalysts and Study of Their Catalytic Properties written by Yuen Wu and published by Springer. This book was released on 2016-05-14 with total page 119 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis focuses on the controlled synthesis of Pt–Ni bimetallic nanoparticles and the study of their catalytic properties. It discusses in detail the nucleation mechanism and the growth process of bimetallic systems, which is vital for a deeper understanding of the design of bimetallic catalysts. The author presents four pioneering studies: (1) syntheses of water-soluble octahedral, truncated octahedral, and cubic Pt–Ni nanocrystals and the study of their structure-activity relationship in model hydrogenation reactions; (2) a strategy for designing a concave Pt–Ni alloy using controllable chemical etching; (3) defect-dominated shape recovery of nanocrystals, which is a new synthesis strategy for trimetallic catalysts; (4) a sophisticated construction of Au islands on Pt−Ni, which is an ideal trimetallic nanoframe catalyst. This thesis inspires researchers working in materials, catalysis as well as other interdisciplinary areas.
Book Synopsis A Parametric Analysis for the Formation of Nanoparticle Catalyst Sites Using Reverse Micelle Synthesis Techniques by : Ashik Mahmud
Download or read book A Parametric Analysis for the Formation of Nanoparticle Catalyst Sites Using Reverse Micelle Synthesis Techniques written by Ashik Mahmud and published by . This book was released on 2017 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Preparation and Characterization of Highly Dispersed Supported Bimetallic Catalysts from Inorganic and Organometallic Molecular Precursors by : Bert Donald Chandler
Download or read book The Preparation and Characterization of Highly Dispersed Supported Bimetallic Catalysts from Inorganic and Organometallic Molecular Precursors written by Bert Donald Chandler and published by . This book was released on 1999 with total page 576 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Preparation and Characterization of Metallic and Metal Oxide Nanoparticles for Biomedical Applications by : Julia Amici
Download or read book Preparation and Characterization of Metallic and Metal Oxide Nanoparticles for Biomedical Applications written by Julia Amici and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Preparation and Characterization of Bimetallic Platinum Chromium Nanoparticles and Catalysts by : Paul Chang
Download or read book Preparation and Characterization of Bimetallic Platinum Chromium Nanoparticles and Catalysts written by Paul Chang and published by . This book was released on 2009 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis New Methods of Catalyst Preparation and Characterization by : Geoffrey Colin Bond
Download or read book New Methods of Catalyst Preparation and Characterization written by Geoffrey Colin Bond and published by . This book was released on 1988 with total page 163 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Reverse Micelle Synthesis of Nanoscale Metal Containing Catalysts. [Nickel Metal (with a Nickel Oxide Surface Layer) and Iron Oxyhydroxide Nanoscale Powders]. by :
Download or read book Reverse Micelle Synthesis of Nanoscale Metal Containing Catalysts. [Nickel Metal (with a Nickel Oxide Surface Layer) and Iron Oxyhydroxide Nanoscale Powders]. written by and published by . This book was released on 1993 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: The need for morphological control during the synthesis of catalyst precursor powders is generally accepted to be important. In the liquefaction of coal, for example, iron-bearing catalyst precursor particles containing individual crystallites with diameters in the 1-100 nanometer range are believed to achieve good dispersion through out the coal-solvent slurry during liquefaction 2 runs and to undergo chemical transformations to catalytically active iron sulfide phases. The production of the nanoscale powders described here employs the confining spherical microdomains comprising the aqueous phase of a modified reverse micelle (MRM) microemulsion system as nanoscale reaction vessels in which polymerization, electrochemical reduction and precipitation of solvated salts can occur. The goal is to take advantage of the confining nature of micelles to kinetically hinder transformation processes which readily occur in bulk aqueous solution in order to control the morphology and phase of the resulting powder. We have prepared a variety of metal, alloy, and metal- and mixed metal-oxide nanoscale powders from appropriate MRM systems. Examples of nanoscale powders produced include Co, Mo-Co, Ni[sub 3]Fe, Ni, and various oxides and oxyhydroxides of iron. Here, we discuss the preparation and characterization of nickel metal (with a nickel oxide surface layer) and iron oxyhydroxide MRM nanoscale powders. We have used extended x-ray absorption fine structure (EXAFS) spectroscopy to study the chemical polymerization process in situ, x-ray diffraction (XRD), scanning and transmission electron microcroscopies (SEM and TEM), elemental analysis and structural modelling to characterize the nanoscale powders produced. The catalytic activity of these powders is currently being studied.
Book Synopsis Synthesis, Characterization, and Catalysis of Metal Nanoparticles by : Derrick M. Mott
Download or read book Synthesis, Characterization, and Catalysis of Metal Nanoparticles written by Derrick M. Mott and published by ProQuest. This book was released on 2008 with total page 454 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Preparation and Characterization of Molybdena-alumina and Related Catalyst Systems by : Li Wang
Download or read book Preparation and Characterization of Molybdena-alumina and Related Catalyst Systems written by Li Wang and published by . This book was released on 1982 with total page 604 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis New Methods of Catalyst Preparation and Characterization by :
Download or read book New Methods of Catalyst Preparation and Characterization written by and published by . This book was released on 1988 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Catalysis of Uniform Metal Nanoparticles Deposited Onto Oxide Supports by : Nathan Musselwhite
Download or read book The Catalysis of Uniform Metal Nanoparticles Deposited Onto Oxide Supports written by Nathan Musselwhite and published by . This book was released on 2015 with total page 135 pages. Available in PDF, EPUB and Kindle. Book excerpt: Model materials consisting of metal nanoparticles loaded onto oxide supports were synthesized, characterized, and investigated in a number of catalytic chemical reactions. By varying the size, shape, and composition of nanoparticle, as well as the material used to support the nanoparticles, it was found that small changes to the catalyst can have enormous changes to the reaction activity and selectivity. Investigation of these carefully synthesized catalysts via in situ characterization, and reaction studies, leads to a deeper understanding of the molecular level parameters that govern catalysis. Through study of the properties of the nanoparticles it was discovered that nanoparticle size and shape have a dominant role in the chemoselective catalysis of furfural over platinum nanoparticles. When vapor phase furfural and hydrogen gas were passed over Pt nanoparticles ranging in size from 1.5 to 7.1 nm, the catalytic selectivity was found to be dominated by the size of the nanoparticle. Large nanoparticles promoted hydrogenation of furfural to furfuryl alcohol, while smaller nanoparticles favored decarbonylation to furan. The same size specific selectivity was found in the hydrogenative reforming (the transformation of hydrocarbons to branched isomers) of C6 hydrocarbons, in which Pt nanoparticle size controls isomerization selectivity. Methylcyclopentane was found to be extremely size dependent at lower temperatures (553 K). It was found that smaller sized nanoparticles favored isomer formation, while larger sizes catalyzed the aromatization reaction more efficiently. n-hexane was found to be much less dependent on particle size, but still showed an increase in isomerization with small particles over larger sized Pt nanoparticles. The composition of PtxRh1-x bimetallic nanoparticles was also studied. These catalysts were characterized under hexane reforming conditions with Ambient Pressure X-ray Photoelectron Spectroscopy (AP-XPS), in order to find the actual surface atomic composition under real catalytic working conditions. By using AP-XPS and catalytic data in tandem, it was found that an optimum Rh loading occurred when the surface ensemble statistically favored one Rh atom surrounded by Pt atoms. By utilizing different oxide materials for catalytic supports the flow of charge can play a role in the reaction at the surface or interface in a phenomenon known as the strong metal-support interaction (SMSI). When Pt nanoparticles were loaded onto mesoporous supports made of Co3O4, NiO, MnO2, Fe2O3, and CeO2 it was found that their activity for carbon monoxide oxidation was greatly enhanced relative to the support alone or Pt loaded onto inert mesoporous silica. This finding demonstrates that the interface of the metallic Pt nanoparticle and the oxide support is able to produce turnovers that are orders of magnitude higher than the two materials separately. When the same type of experiments were investigated with n-hexane as the reactant and macroporous Al2O3, TiO2, Nb2O5, Ta2O5, and ZrO2 were utilized as supports, it was found that the reaction selectivity was greatly altered depending on the catalytic support material. TiO2, Nb2O5, and Ta2O5 (all of which are strong Lewis acids) were found to be much more selective for isomer production than the standard SiO2 mesoporous silica supported Pt nanoparticle catalyst. Finally, an acidified mesoporous silica material was utilized as the support. This material was synthesized by using AlCl3 to modify the surface of mesoporous silica. This support was found to have no activity for hexane isomerization alone. However, when Pt nanoparticles were supported on the material, the activity and isomer selectivity in hexane reforming was increased several orders of magnitude as compared to the same nanoparticles supported on unmodified mesoporous silica. This dissertation builds on the existing knowledge of known concepts in catalysis science such as structure sensitive reactions, the metal-support interaction, and acid-base chemistry. The results show how small changes in the active sites of a catalyst can create large changes in the catalytic chemistry. This research demonstrates how careful material control, characterization and reaction study can help to elucidate the molecular level components necessary to design efficient catalysts.
Book Synopsis Supported Catalysts and Their Applications by : David C Sherrington
Download or read book Supported Catalysts and Their Applications written by David C Sherrington and published by Royal Society of Chemistry. This book was released on 2007-10-31 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt: The need to improve both the efficiency and environmental acceptability of industrial processes is driving the development of heterogeneous catalysts across the chemical industry, including commodity, specialty and fine chemicals and in pharmaceuticals and agrochemicals. Drawing on international research, Supported Catalysts and their Applications discusses aspects of the design, synthesis and application of solid supported reagents and catalysts, including supported reagents for multi-step organic synthesis; selectivity in oxidation catalysis; mesoporous molecular sieve catalysts; and the use of Zeolite Beta in organic reactions. In addition, the two discrete areas of heterogeneous catalysis (inorganic oxide materials and polymer-based catalysts) that were developing in parallel are now shown to be converging, which will be of great benefit to the whole field. Providing a snapshot of the state-of-the-art in this fast-moving field, this book will be welcomed by industrialists and researchers, particularly in the agrochemicals and pharmaceuticals industries.
Book Synopsis Nonstoichiometric Oxides by : O.T. Soerensen
Download or read book Nonstoichiometric Oxides written by O.T. Soerensen and published by Elsevier. This book was released on 2012-12-02 with total page 454 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nonstoichiometric Oxides discusses the thermodynamic and structural studies of nonstoichiometric oxides. This eight-chapter text also covers the defect-defect interactions in these compounds. The introductory chapters describe the thermodynamic properties of nonstoichiometric oxides in terms of defect complexes using the classical thermodynamic principles and from a statistical thermodynamics point of view. These chapters also include statistical thermodynamic models that indicate the ordered nonstoichiometric phase range in these oxides. The subsequent chapters examine the transport properties, such as diffusion and electrical conductivity. Diffusion theories and experimental diffusion coefficients for several systems, as well as the electrical properties of the highly defective ionic and mixed oxide conductor, are specifically tackled in these chapters. The concluding chapters present the pertinent results obtained in nonstoichiometric oxide structural studies using high-resolution electron microscopy and X-ray and neutron diffraction. Inorganic chemists and inorganic chemistry teachers and students will greatly appreciate this book.
Book Synopsis Photoelectrocatalysis by : Leonardo Palmisano
Download or read book Photoelectrocatalysis written by Leonardo Palmisano and published by Elsevier. This book was released on 2022-10-21 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt: Photoelectrocatalysis: Fundamentals and Applications presents an in-depth review of the topic for students and researchersworking on photoelectrocatalysis-related subjects from pure chemistry to materials and environmental chemistry inorder to propose applications and new perspectives. The main advantage of a photoelectrocatalytic process is the mildexperimental conditions under which the reactions are carried out, which are often possible at atmospheric pressure androom temperature using cheap and nontoxic solvents (e.g., water), oxidants (e.g., O2 from the air), catalytic materials (e.g.,TiO2 on Ti layer), and the potential exploitation of solar light. This book presents the fundamentals and the applications of photoelectrocatalysis, such as hydrogen production fromwater splitting, the remediation of harmful compounds, and CO2 reduction. Photoelectrocatalytic reactors and lightsources, in addition to kinetic aspects, are presented along with an exploration of the relationship between photocatalysisand electrocatalysis. In addition, photocorrosion issues and the application of selective photoelectrocatalytic organictransformations, which is now a growing field of research, are also reported. Finally, the advantages/disadvantages andfuture perspectives of photoelectrocatalysis are highlighted through the possibility of working at a pilot/industrial scale inenvironmentally friendly conditions. Presents the fundamentals of photoelectrocatalysis Outlines photoelectrocatalytic green chemistry Reviews photoelectrocatalytic remediation of harmful compounds, hydrogen production, and CO2 reduction Includes photocorrosion, photoelectrocatalytic reactors, and modeling along with kinetic aspects
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