Download or read book Heterogeneous Nanoalloyed Precious Metal Catalysts written by Alexander Howe and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Catalysis by Precious Metals Past and Future written by Marcela Martinez Tejada and published by MDPI. This book was released on 2020-04-15 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: The future of the precious metals is shiny and resistant. Although expensive and potentially replaceable by transition metal catalysts, precious metal implementation in research and industry shows potential. These metals catalyze oxidation and hydrogenation due to their dissociative behavior toward hydrogen and oxygen, dehydrogenation, isomerization, and aromatization, etc. The precious metal catalysts, especially platinum-based catalysts, are involved in a variety of industrial processes. Examples include Pt–Rh gauze for nitric acid production, the Pt/Al2O3 catalyst for cyclohexane and propylene production, and Pd/Al2O3 catalysts for petrochemical hydropurification reactions, etc. A quick search of the number of published articles in the last five years containing a combination of corresponding “metals” (Pt, Pd, Ru, Rh and Au) and “catalysts” as keywords indicates the importance of the Pt catalysts, but also the continuous increase in the contribution of Pd and Au. This Special Issue reveals the importance of precious metals in catalysis and focuses on mono- and bi-metallic formulations of any supported precious metals and their promotional catalytic effect of other transition metals. The application of precious metals in diverse reactions, either homogeneous or heterogeneous, and studies of the preparation, characterization, and applications of the supported precious metal catalysts, are presented.

Download or read book Catalysis by Precious Metals Past and Future written by Marcela Martinez Tejada and published by . This book was released on 2020 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: The future of the precious metals is shiny and resistant. Although expensive and potentially replaceable by transition metal catalysts, precious metal implementation in research and industry shows potential. These metals catalyze oxidation and hydrogenation due to their dissociative behavior toward hydrogen and oxygen, dehydrogenation, isomerization, and aromatization, etc. The precious metal catalysts, especially platinum-based catalysts, are involved in a variety of industrial processes. Examples include Pt-Rh gauze for nitric acid production, the Pt/Al2O3 catalyst for cyclohexane and propylene production, and Pd/Al2O3 catalysts for petrochemical hydropurification reactions, etc. A quick search of the number of published articles in the last five years containing a combination of corresponding “metals” (Pt, Pd, Ru, Rh and Au) and “catalysts” as keywords indicates the importance of the Pt catalysts, but also the continuous increase in the contribution of Pd and Au. This Special Issue reveals the importance of precious metals in catalysis and focuses on mono- and bi-metallic formulations of any supported precious metals and their promotional catalytic effect of other transition metals. The application of precious metals in diverse reactions, either homogeneous or heterogeneous, and studies of the preparation, characterization, and applications of the supported precious metal catalysts, are presented.

Download or read book Carbon Supported Precious Metal based Single Metal Site Heterogeneous Catalysts written by Tanja Parmentier and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Selective Nanocatalysts and Nanoscience written by Adriano Zecchina and published by John Wiley & Sons. This book was released on 2011-08-15 with total page 349 pages. Available in PDF, EPUB and Kindle. Book excerpt: Filling a gap in the catalysis and nano literature, this monograph is unique in focusing on both nanostructured heterogeneous and homogeneous catalysis. As such, it describes a selection of heterogeneous catalysts in use, showing that the dimension of the relevant portions of the catalysts are always in the 1-100 nm range, and so may be properly understood as nanomachines for the chemical manipulation of molecules to perform high precision selective synthesis. The prominent international authors then go on to show that the concept of nanoscience can be equally applied to artificial homogeneous catalysts whose active sites are generally considered as "single-sites" having a "molecular" dimension. The result is an excellent overview of such hot topics as nanoparticles, MOFs and more, making this indispensable reading for catalytic and organic chemists, as well as those working on organometallics.

Download or read book Heterogenization of Precious Metal Catalysts and Enzymes by Radiation induced Graft Copolymerization written by Ronald Gifford Levot and published by . This book was released on 1982 with total page 428 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Metal Catalysts in Olefin Polymerization written by Zhibin Guan and published by Springer Science & Business Media. This book was released on 2009-03-31 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polyolefin is a major industry that is important for our economy and impacts every aspect of our lives. The discovery of new transition metal-based catalysts is one of the driving forces for the further advancement of this field. Whereas the classical heterogeneous Ziegler-Natta catalysts and homogeneous early transition metal metallocene catalysts remain the workhorses of the polyolefin industry, in roughly the last decade, tremendous progress has been made in developing non-metallocene-based olefin polymerization catalysts. Particularly, the discovery of late transition metal-based olefin polymerization catalysts heralds a new era for this field. These late transition metal complexes not only exhibit high activities rivaling their early metal counterparts, but more importantly they offer unique properties for polymer architectural control and copolymerization with polar olefins. In this book, the most recent major breakthroughs in the development of new olefin polymerization catalysts, including early metal metallocene and non-metallocene complexes and late transition metal complexes, are discussed by leading experts. The authors highlight the most important discoveries in catalysts and their applications in designing new polyolefin-based functional materials.

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.

Download or read book Synthesis and Characterization of Nanoalloys and Non precious Metal Catalysts for Energy and Environmental Applications written by Heather Marie Barkholtz and published by . This book was released on 2016 with total page 251 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two major project areas are reported in this work. First, a new lithium-assisted dissolution-alloying nanoalloy synthesis technique will be introduced. The development of a new nanoalloy synthesis method is desirable to circumvent issues with traditional co-reduction of metal salt methodology. Co-reduction of metal salts can result in unintended core-shell formation due to different metal ion reduction potentials, as well as oxidation of one component resulting in dealloying of the material when it is exposed to air. In order to best address these issues with a new technique, Pd3Ag, PdPt, and PdZn systems were studied because Pd3Ag and PdPt tend to form core-shell structures while PdZn is incredibly difficult to synthesize due to the propensity of Zn to oxidize. The metal nanoalloy systems described in this work (Pd 3Ag, PdPt, and PdZn) were prepared by directly dispersing individual bulk metal alloys (Pd3Ag) or individual bulk metals (Pd, Pt, and Zn) into molten lithium to form an atomic metal dispersion. The lithium melt is then cooled, removed from the glove box, and converted to LiOH, which allows for the metal atoms to self-assemble into nanoalloys. Alloy structure and nanoscale size were confirmed via XRD, TEM, EXAFS, and XANES methods. The catalytic activity of the Pd3Ag system was investigated towards the hydrogenation of acrolein, and the PdPt system was used for methanol electro-oxidation. Both Pd3Ag and PdPt nanoalloy systems gave substantial improvements in their respective catalytic applications over a Pd or Pt standard, respectively. The next project focuses on the rational design and preparation of metal-organic framework (MOF)-derived electrocatalyst materials for the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). MOF-derived electrocatalysts are non-platinum group metal (non-PGM) materials and are leading candidates for transportation applications due to their low cost, relatively low operating temperature, capacity to achieve high power density, and direct conversion of chemical to electrical energy acting to improve fuel utilization efficiency. Cathodic ORR is typically sluggish compared to the anodic hydrogen oxidation reaction, requiring more catalyst material to achieve comparable performance. Therefore, research into non-PGM catalysts focuses on the cathodic material design and activation. In this part of the dissertation the focus is to tackle the aggressive milestones set by the U.S. Department of Energy for non-PGM catalysts. First, a series of investigations into the effect of different iron additives and carbon additives on the ORR performance and electrode characteristics was carried out using a one-pot all solid-state synthesis technique to prepare ZIF-8 materials. ZIF-8 is a specific type of MOF which has a Zn2+ metal center bonded to two 2-methylimidazole ligands, forming a three-dimensional matrix with high surface area. After the ZIF-8 was prepared, it was ball milled, pyrolyzed, acid washed, and thermally activated once again in a NH3 environment to yield ORR electrocatalysts consisting of an iron and nitrogen-doped carbon (Fe-N-C) morphology. This one-pot all solid-state synthesis method also allows for investigation into the effect of changing 2-methylimidazole to imidazole on the ORR activity. The effect of this change was determined through catalyst morphology and component characterization and well and electrochemical methods. Finally, ZIF-8 synthesized by wet chemistry was used to prepare the same type of Fe-N-C material as described above. A simple method of tailoring the surface structure and porosity is introduced through careful control of the time spent in NH3 environment. NH3 serves to etch the surface of the material as a function of time spent, which results in widening of pores and removal of surface atoms. Careful control and optimization of NH3 activation conditions allowed for significant improvements in ORR activity in a single fuel cell. Finally, the impact of triple phase boundary penetration on air fed fuel cell data was investigated. Furthermore, it was discovered than when air is used as the oxidant fuel, a break-in period of catalyst improvement exists during the first few polarization curves. It is proposed that scanning to high currents produces water in microporous areas, wetting Nafion ionomer and including those areas in the TPB network.

Download or read book Tailored Metal Catalysts written by Y. Iwasawa and published by Springer. This book was released on 2012-04-17 with total page 333 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Advances in Heterocatalysis by Nanomaterials written by Ioannis V. Yentekakis and published by MDPI. This book was released on 2020-05-13 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heterogeneous catalysis played, plays, and will continue to play, a major key role in industrial processes for large-scale synthesis of commodity chemicals of global importance, and in catalytic systems that possess a critical role in energy generation and environmental protection approaches. As a result of the ongoing progress in materials science, nanotechnology, and characterizations, great advances have been achieved in heterogeneous catalysis by nanomaterials. Efficient approaches and advanced methods for the design of nano-structured composite materials (up to atomic level), subject to specific nano-morphologies with enhanced metal–metal and metal–support interactions favorable for catalysis (that enable fine-tuning of the critical properties of the designed catalysts), provide optimized catalysts with outstanding performances in numerous eco-friendly and cost-effective applications. Accordingly, great progress has been achieved involving, for example, emissions control, waste treatment, photocatalytic, bio-refinery, CO2 utilization, and fuel cells applications, as well as hydrocarbon processing for H2, added-value chemicals, and liquid fuels production. The themed Special Issue has succeeded in collecting 10 high-quality contributions that cover recent research progress in the field for a variety of applications (e.g., environment, energy, added-value chemicals/organics synthesis, and bio-transformation) declaring the prospect and importance of nanomaterials in all the directions of heterogeneous catalysis.

Download or read book Nanometal Catalysis in Organic Synthesis written by Ming Bao and published by Springer Nature. This book was released on with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Colloidal Nanoparticles for Heterogeneous Catalysis written by Priscila Destro and published by Springer. This book was released on 2019-02-04 with total page 89 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book explores the formation of colloidal gold–copper (AuCu) alloy nanoparticles and evaluate their application in heterogeneous catalysis. Metal alloys are extremely versatile materials that have been used since the Antiquity to improve the properties of commonly used metals, therefore the understanding of their properties has fostered the applications in areas such as photonics, sensors, clinical diagnostics, and especially in heterogeneous catalysis, which allows catalyst active sites to be modulated. In this book, readers will appreciate the fundamental aspects involved in the synthesis of AuCu nanoalloys, including real-time information about their atomic organization, electronic properties, as well a deeper understand about the behavior of AuCu supported nanoalloys under real catalytic conditions, providing interesting insights about the effect of the support on the nanoalloy stability. The results presented here open new horizons for using metal alloys in catalysis and also other areas where the metal–support interface may play a crucial role.

Download or read book Adsorption of Transition Metal Complexes on Metal Oxide Supports written by Ahana Mukhopadhyay and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Widespread industrial applications and large impact of supported late transitionprecious metal catalysts on the global economy serves as the prime motivation for thededication of academic researchers towards focusing on the scalable and affordable design ofefficient catalysts. Catalyst design requires a fundamental understanding of how the differentsynthetic steps (adsorption, drying, pretreatment, etc) influence the properties of the finalcatalyst. Moreover, in current times, single-atom catalysts represent an exciting new class ofmaterials that have demonstrated high activity for chemical reactions relevant to energyproduction. Among the various stages involved in catalyst synthesis, the initial adsorptionstep between the support and the precursor is believed to be of most importance as thisinteraction influences the unit operations that follow and affects the final size distribution ofthe catalyst nanoparticles. The ability of metal oxide supports to enhance the dispersion ofthe active metal on their surface and control their morphology and sintering kinetics isfundamentally related to the nature and strength of the metalsupport interaction which isdetermined at the time of adsorption at the solid-liquid interface. Documented studies on theimportance of the adsorption step on the overall characteristics of the catalyst nanoparticleare limited in recent literature due to challenges associated with probing a buried solid-liquidinterface. In this work, we have examined the molecular level details of catalyst synthesiswith substantial emphasis on the adsorption thermodynamics occurring at the solid-liquidinterface during the initial adsorption of transition metal complexes (TMCs) on metal oxidesupports and its influence on nanoparticle size, growth and stability.Using a number of surface analytical tools, we have probed at the interface during theadsorption process to quantify metal uptake and measure the kinetics and enthalpy of binding in order to identify the effect of different precursors and their ligand chemistry on the electrostatic driving force. Isothermal Titration Calorimetry (ITC) is used to contact reducible and refractory supports like SiO2, -Al2O3 and CeO2 with pH adjusted TMC solutions of Pt, Pd, Rh, Ir and Ag at adjusted pH values, providing a strong electrostatic driving force for adsorption and measure equilibrium binding constants, stoichiometry and enthalpies of adsorption. This study is unique in context that it truly probes the interface during adsorption (in situ) of metal precursors on supports rather than as-synthesized nanoparticles. The trends in the estimated thermodynamic parameters as a function of pH for both the cationic and anionic Pt complexes on silica and alumina respectively captures the effect of ligand speciation and complex solvation at acidic and basic solution conditions. Equilibrium adsorption isotherms from bench top bulk uptake studies aid in quantifying the amount of metal adsorbed on the support surface and by varying choice and weight loading of the precursors, we are able to identify that chloride ligand speciation chemistry around main metal center and solvation strongly influenced metal uptake. Next, we compared bulk and interfacial adsorption mechanisms through ex-situ synthesis to determine how the particle size distribution and metal dispersion of the catalysts were influenced by the mode of adsorption. Thereafter, we looked at cerium oxide which is an important support for transition metal catalysts due to its high oxygen storage capacity; thus allowing it to successfully stabilize noble metals, inhibit sintering and maintain small sized nanoparticles on its surface compared to other oxide supports. The thermodynamic adsorption parameters of a comprehensive list of late transition metal complexes in Group 9-11 on shape controlled faceted cerium oxide nano-crystals demonstrated by ITC and DFT calculations showed a trend in the enthalpies of binding between support and metal precursors that correlates with the oxide formation tendency of the transition metal and the reducibility of the support. The ability of metals to form atomically dispersed metal nanoparticles on cerium oxide through formation of an M-O-Ce bond under strong oxidative conditions was examined using XPS and TEM. Several combinations of catalysts were synthesized using precursors having various ligand chemistries deposited on different facets of cerium oxide nano-crystals and surface analytical tools were used to evaluate the optimal conditions for stable, highly dispersed catalysts. From these design rules, a series of ceria supported low weight loading single atom Pd catalysts were synthesized and examined for low temperature methane combustion that is highly in demand to reduce methane slip from lean-burn natural gas vehicles. Here, we probed into the effect of the transition from nano-clusters to single atoms on the activity of the reaction. A possible mechanistic change in the Pd catalytic redox cycle is believed to enhance the catalytic turnover at low temperatures while maintaining reduced precious metal usage.

Download or read book Asymmetric Heterogeneous Reduction Over Modified Supported Metal Catalysts written by Nick Chambers and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis Characterization and Application of Heterogeneous Noble Metal Nanoparticle Catalysts written by William Harrigan and published by . This book was released on 2010 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis and Characterization of Support modified Nanoparticle based Catalysts and Mixed Oxide Catalysts for Low Temperature CO Oxidation written by Andrew Justin Binder and published by . This book was released on 2015 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heterogeneous catalysts are responsible for billions of dollars of industrial output and have a profound, if often understated, effect on our everyday lives. New catalyst technologies and methods to enhance existing catalysts are essential to meeting consumer demands and overcoming environmental concerns. This dissertation focuses on the development of catalysts for low temperature carbon monoxide oxidation. CO [carbon monoxide] oxidation is often used as a probe reaction to test overall oxidation activity of a given catalyst and is an important reaction in the elimination of toxic pollutants from automotive exhaust streams. The work included here presents three new heterogeneous catalysts developed over the last 4 years in our group. The first type Au/SiO2 [gold/silica] catalyst synthesized using a new method for the deposition of Au nanoparticles onto SiO2 via a nitrogen-containing polymer, C3N4 [carbon nitride]. C3N4-modification of SiO2 allows us to ignore unfavorable electrostatic effects that hinder standard Au deposition onto this support. While removal of the C3N4 is necessary for good CO oxidation, this new method is an improvement over the standard deposition-precipitation procedure for supports with low isoelectric point that enables the successful deposition of Au nanoparticles onto SiO2. The second type includes precious metal catalysts deposited on an “inert” silica support but promoted by the addition of an “active” metal oxide. Here we present a Au/FeOx̳/SiO2 [gold/iron oxide/silica] and a Pd/ZrO2/SiO2 [palladium/zirconia/silica] catalyst which show increased activity and stability effects due to the presence of the metal oxide promoter. They are synthesized by a C3N4-deposition and sol-gel methods, respectively. These catalysts were also tested in simulated automotive exhaust streams. The results show that inhibition effects play a major role in the activity of these catalysts. The third type of catalyst is a mixed oxide catalyst, CuO-Co3O4-CeO2 [copper oxide-cobalt oxide-cerium oxide], developed with the goal of overcoming the inhibition effects seen in the previous precious metal catalysts. The catalyst was synthesized by co-precipitation method and shows exceptional activity for CO oxidation under simulated exhaust conditions. Also noteworthy is the observation that this catalyst also shows a lack of inhibition by a common exhaust component, propene.