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Characterization Of Silica Supported Cu Monometallic And Ru Cu Bimetallic Catalysts By Hydrogen Chemisorption And Nmr Of Adsorbed Hydrogen
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Book Synopsis Characterization of Silica Supported Cu Monometallic and Ru-Cu Bimetallic Catalysts by Hydrogen Chemisorption and NMR of Adsorbed Hydrogen by : X. Wu
Download or read book Characterization of Silica Supported Cu Monometallic and Ru-Cu Bimetallic Catalysts by Hydrogen Chemisorption and NMR of Adsorbed Hydrogen written by X. Wu and published by . This book was released on 1989 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Characterization of Silica-supported Ru-Ag and Ru-Au Bimetallic Catalysts by Hydrogen Chemisorption and NMR of Adsorbed Hydrogen by : X. Wu
Download or read book Characterization of Silica-supported Ru-Ag and Ru-Au Bimetallic Catalysts by Hydrogen Chemisorption and NMR of Adsorbed Hydrogen written by X. Wu and published by . This book was released on 1989 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Characterization of Silica Supported Ruthenium Catalysts by Hydrogen Chemisorption and Nuclear Magnetic Resonance of Adsorbed Hydrogen by : X. Wu
Download or read book Characterization of Silica Supported Ruthenium Catalysts by Hydrogen Chemisorption and Nuclear Magnetic Resonance of Adsorbed Hydrogen written by X. Wu and published by . This book was released on 1988 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Fundamental Investigations of Supported Monometallic and Bimetallic Catalysts by Proton Magnetic Resonance Spectroscopy by :
Download or read book Fundamental Investigations of Supported Monometallic and Bimetallic Catalysts by Proton Magnetic Resonance Spectroscopy written by and published by . This book was released on 1990 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proton magnetic resonance spectroscopy, or nuclear magnetic resonance (NMR) of hydrogen, has been applied to investigate silica-supported Group VIII monometallic and Group VIII-Group IB bimetallic catalysts and alumina- and silica-supported platinum-rhenium bimetallic catalysts. Two adsorbed states of hydrogen, i.e., irreversible and reversible hydrogen, on the surfaces of monometallic Ru, Pt, and Cu particles and bimetallic Ru-Group Ib, Pt-Group Ib, and Pt-Re particles were observed directly via proton NMR. The same amounts of the irreversible hydrogen adsorbed on pure Ru catalysts were measured by both proton NMR and the volumetric technique. The electronic environments on surfaces of monometallic catalysts are sensitive to changes in metal dispersion, state of adsorbed hydrogen, and residual chlorine. Surface compositions for the Ru--Cu and Pt--Cu bimetallic catalysts were determined by NMR of adsorbed hydrogen. 297 refs., 96 figs., 19 tabs.
Book Synopsis Fundamental Studies of Supported Bimetallic Catalysts by NMR Spectroscopy by :
Download or read book Fundamental Studies of Supported Bimetallic Catalysts by NMR Spectroscopy written by and published by . This book was released on 1996 with total page 67 pages. Available in PDF, EPUB and Kindle. Book excerpt: Various hydrogenation reactions on transition metals are important commercially whereas certain hydrogenolysis reactions are useful from fundamental point of view. Understanding the hydrogen mobility and kinetics of adsorption-desorption of hydrogen is important in understanding the mechanisms of such reactions involving hydrogen. The kinetics of hydrogen chemisorption was studied by means of selective excitation NMR on silica supported Pt, Rh and Pt-Rh catalysts. The activation energy of hydrogen desorption was found to be lower on silica supported Pt catalysts as compared to Rh and Pt-Rh catalysts. It was found that the rates of hydrogen adsorption and desorption on Pt-Rh catalyst were similar to those on Rh catalyst and much higher as compared to Pt catalyst. The Ru-Ag bimetallic system is much simpler to study than the Pt-Rh system and serves as a model system to characterize more complicated systems such as the K/Ru system. Ag was found to decrease the amounts of adsorbed hydrogen and the hydrogen-to-ruthenium stoichiometry. Ag reduced the populations of states with low and intermediate binding energies of hydrogen on silica supported Ru catalyst. The rates of hydrogen adsorption and desorption were also lower on silica supported Ru-Ag catalyst as compared to Ru catalyst. This report contains introductory information, the literature review, general conclusions, and four appendices. An additional four chapters and one appendix have been processed separately for inclusion on the data base.
Book Synopsis Dissertation Abstracts International by :
Download or read book Dissertation Abstracts International written by and published by . This book was released on 1997 with total page 876 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:
Download or read book Chemical Abstracts written by and published by . This book was released on 1991 with total page 2682 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Efect of Silica Support on Monometallic Ruthenium and Ruthenium-Copper Bimetallic Catalysts by : Allan Jixian Hong
Download or read book The Efect of Silica Support on Monometallic Ruthenium and Ruthenium-Copper Bimetallic Catalysts written by Allan Jixian Hong and published by . This book was released on 1988 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Synthesis, Characterization, and Catalytic Activity of Silica Supported Homo- and Heterodinuclear Metal Complexes by : Samantha Ranaweera
Download or read book Synthesis, Characterization, and Catalytic Activity of Silica Supported Homo- and Heterodinuclear Metal Complexes written by Samantha Ranaweera and published by . This book was released on 2012 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt: Stable dinuclear complexes bis(heptane-2,4,6-trionato)dicopper(II) [Cu2(daa)2], bis(1,5-diphenyl-1,3,5-pentanetrionato)dicopper(II) [Cu2(dba)2], bis(1,5-diphenyl-1,3,5- pentanetrionato)dicobalt(II) [Co2(dba)2], and [6,11-dimethyl-7,10-diazahexadeca-5,11- diene-2,4,13,15-tetranato(4-)-N7N10O4O13;O2O4O13O15] copper(II)cobalt(II) [(CuCo(daaen)] were supported on Cab-O-Sil by the batch impregnation technique. The upported samples were characterized by UV-Vis, elemental analysis, X-ray powder diffraction (XRD), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and thermal gravimetric analysis (TGA). Elemental analysis and TGA data confirm that the Cu2(daa)2 complex loses one of its coordinated ligands upon adsorption onto silica in THF at greater than 4.43 wt% Cu loading. By contrast, at all Cu loadings the Cu2(dba)2 complex was adsorbed on the silica surface in CH2Cl2 without loss of ligand. XRD and DRIFTS results confirmed the formation of Cu2(dba)2 multilayer films on the Cab-O-Sil surface for samples containing greater than 2.64 wt% copper. The dinuclear cobalt complex and copper-cobalt complex also do not lose their coordination ligands upon adsorption on the surface. These two metal complexes are amorphous and did not produce XRD patterns. However, DRIFTS results confirm that the binuclear cobalt complex and the copper-cobalt complex begin forming multilayer films between 1.21and 2.53 wt% Cu. The Cu2(dba)2/silica precatalysts were subsequently converted to the catalysts by decomposing the organic ligands at 450 degrees Celsius followed by activation with 2% H2 at 250 degrees Celsius and were evaluated for methanol synthesis and methanol decomposition reactions. Kinetic studies demonstrated that the 3.70% Cu/silica[Cu2(dba)2] catalyst is more active for methanol decomposition than it is for methanol synthesis. The supported dinuclear cobalt and copper-cobalt precatalysts were converted to the catalyst by heating at 450 degrees Celsius followed by activation of the catalysts with 50% H2. Four different catalysts, 3.5% Co/silica[Co2(dba)2], 6.7% Co/silica[Co2(dba)2], 2.3% Co/silica[CuCo(daaen)], and 5.5% Co/silica[Co2(daa)2] were evaluated for the Fischer-Tropsch reaction at 350 degrees Celsius in a batch reactor. The supported binuclear cobalt catalyst produced C1−C7 alkanes and a significant amount of CO2. By contrast, the catalyst formed from heterobinuclear CuCo(daaen) showed the ability to convert syngas to aromatics with a narrow product distribution. In addition, the 6.7% Co/silica[Co2(dba)2] multilayer catalysts have above 98% conversion rates and 60% liquid hydrocarbon selectivity in a flow reactor.
Book Synopsis Synthesis, Characterization, and Catalytic Activity of Silica Supported Bimetallic Copper Catalysts for Organic Oxidation Reactions and the Study of Benzylation of Triketones by : Nuwan Dileepa De Silva
Download or read book Synthesis, Characterization, and Catalytic Activity of Silica Supported Bimetallic Copper Catalysts for Organic Oxidation Reactions and the Study of Benzylation of Triketones written by Nuwan Dileepa De Silva and published by . This book was released on 2013 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt: The dissertation describes research work on development of bimetallic heterogeneous catalysts for oxidation of organic compounds. Binuclear metal complexes are an interesting class of compounds due to their catalytic activity. The approach involves anchoring a triketone ligand to Cab-O-Sil via a linker. Specifically, silica gel was allowed to react with p-chloromethylphenyltrimethoxysilane followed by coupling with deprotonated triketone compounds. The viability of this approach was verified by performing the benzylation reaction of triketones with benzyl halides under basic conditions. The benzylation of 2,4,6-heptanetrione and 1,5-diphenyl-1,3,5-pentanetrione is achieved with benzyl bromide using n-tetrabutylammonium fluoride as base. These benzylation reaction conditions were used to attach the triketones to the surface-attached linker. Once the ligand is attached to the silica gel, the catalyst is formed by coordinating two copper(II) ions from solution to the deprotonated triketone. The coordination of copper(II) ions to the triketone was monitored using UV-vis spectroscopy. The modified silica gel is characterized by diffuse reflectance infrared Fourier spectroscopy (DRIFTS), and thermal gravimetric analysis (TGA) at the different stages of catalyst formation. All techniques indicated significant attachment of linker and triketone to the support. The oxidation of 3,5-di-tert-butyl catechol (DTBC) and benzyl alcohol was carried out under aerobic conditions using these catalysts. The kinetics of the DTBC oxidation and benzyl alcohol oxidation was studied using bimetallic and monometallic catalytic systems. The copper complexes of the triketone ligands were also evaluated as catalysts for the oxidation of DTBC. New bimetallic metal complexes with triketone ligands having a benzyl group were synthesized and characterized by high resolution mass spectroscopy and IR spectroscopy. In addition to a detailed description of the synthesis and characterization of new triketone compounds, and the heterogeneous catalyst systems, a comparison of the kinetics of the oxidation of DTBC using these catalysts will be discussed.
Book Synopsis Supported Copper, Nickel and Copper-nickel Nanoparticle Catalysts for Low Temperature Water-gas-shift Reaction by : Jiann-Horng Lin
Download or read book Supported Copper, Nickel and Copper-nickel Nanoparticle Catalysts for Low Temperature Water-gas-shift Reaction written by Jiann-Horng Lin and published by . This book was released on 2012 with total page 191 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydrogen is being considered worldwide as a future replacement for gasoline, diesel fuel, natural gas in both the transportation and non-transportation sectors. Hydrogen is a versatile energy carrier that can be produced from a variety of widely available primary energy sources, including coal, natural gas, biomass, solar, wind, and nuclear power. Coal, the most abundant fossil fuel on the planet, is being looked at as the possible future major source of H2, due to the development of the integrated gasification combined cycle (IGCC) and integrated gasification fuel cell technologies (IGFC). The gasification of coal produces syngas consisting of predominately carbon monoxide and hydrogen with some remaining hydrocarbons, carbon dioxide and water. Then, the water-gas shift reaction is used to convert CO to CO2 and additional hydrogen. The present work describes the synthesis of model Cu, Ni and Cu-Ni catalysts prepared from metal colloids, and compares their behavior in the WGS reaction to that of traditional impregnation catalysts. Initially, we systematically explored the performance of traditional Cu, Ni and Cu-Ni WGS catalysts made by impregnation methods. Various bimetallic Cu-Ni catalysts were prepared by supported impregnation and compared to monometallic Cu and Ni catalysts. The presence of Cu in bimetallic catalysts suppressed undesirable methanation side reaction, while the Ni component was important for high WGS activity. Colloidal Cu, Ni and Cu-Ni alloy nanoparticles obtained by chemical reduction were deposited onto alumina to prepare supported catalysts. The resulting Cu and Ni nanoparticle catalysts were found to be 2.5 times more active in the WGS reaction per unit mass of active metal as compared to catalysts prepared by the conventional impregnation technique. The powder XRD and HAADF-STEM provided evidence supporting the formation of Cu-Ni particles containing the Cu core and Cu-Ni alloy shell. The XPS data indicated surface segregation of Cu in the bimetallic Cu-Ni catalysts after reduction. The colloidal Cu5Ni5 alloy catalyst exhibited the WGS reaction rate that was higher than that observed over colloidal Cu and Ni catalysts indicating for the very first time a favorable bimetallic effect for the Cu-Ni system. The presence of Cu in these bimetallic catalysts induced favorable structural and electronic effects not only for enhancing the WGS activity, but also for suppressing methane yield. Bimetallic Cu-Ni catalysts possessing a core-shell structure were synthesized that provided important insights into their structure-activity relationships in the WGS reaction. We employed a successive reduction route to synthesize Cu@Ni and Ni@Cu core-shell nanoparticles and deposited them onto alumina support to obtain supported bimetallic catalysts. The powder XRD patterns, CO chemisorption data, and UV-vis spectra indicated the formation of core-shell structures in the bimetallic Cu-Ni nanoparticles. Cu@Ni catalysts showed similar WGS activities to supported Ni catalysts but lower methanation activity. Suppressed methanation activity observed for Cu@Ni nanoparticles may be due to Cu segregation to the surface. Supported Ni@Cu catalysts displayed WGS activity comparable to supported Cu catalysts. Therefore, these findings strongly suggested that supported Cu, Ni and Cu-Ni alloy nanoparticle catalysts prepared from metal colloids are very promising as highly active WGS catalysts.
Book Synopsis Nanocatalysis by : Vivek Polshettiwar
Download or read book Nanocatalysis written by Vivek Polshettiwar and published by John Wiley & Sons. This book was released on 2013-09-06 with total page 670 pages. Available in PDF, EPUB and Kindle. Book excerpt: Exhibiting both homogeneous and heterogeneous catalytic properties, nanocatalysts allow for rapid and selective chemical transformations, with the benefits of excellent product yield and ease of catalyst separation and recovery. This book reviews the catalytic performance and the synthesis and characterization of nanocatalysts, examining the current state of the art and pointing the way towards new avenues of research. Moreover, the authors discuss new and emerging applications of nanocatalysts and nanocatalysis, from pharmaceuticals to fine chemicals to renewable energy to biotransformations. Nanocatalysis features contributions from leading research groups around the world. These contributions reflect a thorough review of the current literature as well as the authors’ first-hand experience designing and synthesizing nanocatalysts and developing new applications for them. The book’s nineteen chapters offer a broad perspective, covering: Nanocatalysis for carbon-carbon and carbon-heteroatom coupling reactions Nanocatalysis for various organic transformations in fine chemical synthesis Nanocatalysis for oxidation, hydrogenation, and other related reactions Nanomaterial-based photocatalysis and biocatalysis Nanocatalysts to produce non-conventional energy such as hydrogen and biofuels Nanocatalysts and nano-biocatalysts in the chemical industry Readers will also learn about the latest spectroscopic and microscopy tools used in advanced characterization methods that shed new light on nanocatalysts and nanocatalysis. Moreover, the authors offer expert advice to help readers develop strategies to improve catalytic performance. Summarizing and reviewing all the most important advances in nanocatalysis over the last two decades, this book explains the many advantages of nanocatalysts over conventional homogeneous and heterogeneous catalysts, providing the information and guidance needed for designing green, sustainable catalytic processes.
Book Synopsis Silica Supported Iron-bimetallic Catalysts for the Fischer-Tropsch Synthesis by : Jeffrey Allen Amelse
Download or read book Silica Supported Iron-bimetallic Catalysts for the Fischer-Tropsch Synthesis written by Jeffrey Allen Amelse and published by . This book was released on 1980 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Preparation and Characterization of Silica Nanosprings-supported Fischer-Tropsch Catalysts for Biofuel Production by : Abdulbaset M. Alayat
Download or read book Preparation and Characterization of Silica Nanosprings-supported Fischer-Tropsch Catalysts for Biofuel Production written by Abdulbaset M. Alayat and published by . This book was released on 2018 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation presents findings on the preparation and characterization of silica nanosprings (NS) supported Fe and Co catalysts for Fischer-Tropsch (FT) reactions. Silica NS with a high surface area of 400 m2/g were chosen as a new 1-dimensional nanostructured support for Fe and Co based FT catalysts and divided into three sections. Section 1 involved the preparation and characterization of Co/NS catalysts as well as to examine the effects of two different reduction temperatures on the FT catalytic performance of this Co/NS catalyst. The prepared Co/NS catalysts were characterized before the FT reaction by various analytical techniques such as surface area, X-ray diffraction, transmission electron microscopy , energy dispersive X-ray spectroscopy, temperature programmed reduction (CO and H2), X-ray photoelectron spectroscopy, fourier transform infrared spectroscopy and thermogravimetric analysis. The activity and selectivity of all catalysts were evaluated in a quartz fixed bed micro-reactor (H2/CO of 2:1, 230-270 °C). The effect of reaction temperature on the catalytic performance of Co/NS catalyst was studied. The results showed that the catalyst reduced at a temperature of 609 °C had higher production rate of C6-C17 hydrocarbons than the catalyst reduced at 409 °C. It also was found that the Co/NS catalyst resulted in more stability compared to with conventional catalysts. Section 2 examined the effect of three preparation techniques (impregnation, precipitation and 2-step sol-gel) and activation conditions (H2, CO or H2+CO) on catalytic performance of these Fe/NS catalysts. It was found that the Fe/NS catalyst prepared by impregnation technique and activated with CO displayed the highest CO conversion (76.6%) and a wide distribution of light hydrocarbon (C6 to C14). Moreover, the XRD and XPS results of Fe/NS catalysts showed three different Fe crystalline phases with different particle sizes. Section 3 examined the addition of Ru, Mo, Co and Cu as promoters on the Fe/NS catalysts. It was found that the promotion of the Fe catalyst supported on NS with Ru, Mo, Co and Cu increased the CO conversion, shifted the FTS product distributions and improved the selectivity towards C6-C16 olefins instead of aromatics in unpromoted Fe/NS catalyst. New types of Co and Fe catalysts were synthetized using silica nanosprings (NS) as a new 1-dimensional nanostructured support, and used in the Fischer-Tropsch synthesis. By using these catalysts, good activity, selectivity to C6-C16 hydrocarbons (liquid fuels) and catalytic stability have been achieved. Furthermore, the incorporation of promoters, such as Ru, Mo, Co and Cu, into these catalysts can have effect leading to both high conversion and selectivity.
Book Synopsis Synthesis, Characterization, and Catalytic Properties of Interfacial Sites on Supported Metal Catalysis by : Insoo Ro
Download or read book Synthesis, Characterization, and Catalytic Properties of Interfacial Sites on Supported Metal Catalysis written by Insoo Ro and published by . This book was released on 2017 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: Previous studies have shown that the type of support and the addition of promoting materials can influence the catalytic activity and selectivity due to the formation of interfacial sites. However, the nature of the active sites and the reaction mechanisms governing these catalytic reactions are not known in detail. This is primarily because the synthesis of catalysts by traditional methods produces a wide distribution of metal particle sizes and compositions, impeding the accurate assessment on the nature of the surface, the active sites, and the catalytic behavior. Accordingly, this thesis presents the new synthetic route developed to prepare bimetallic nanoparticles with controlled particle size and interfacial sites to achieve an effective link between characterizations and reactivity. This thesis also focuses on elucidating catalytic active sites with well-defined catalysts by developing approaches to estimate the concentrations and intrinsic activity of monometallic and interfacial sites. In Chapter 3, we discuss the synthesis of well-defined Cu catalysts synthesized by controlled surface reactions (CSR) and atomic layer deposition (ALD) methods containing varying amounts of zirconia for the selective conversion of ethanol to ethyl acetate and for methanol synthesis. We found that the dominant active sites for the production of acetaldehyde are monometallic Cu, while Cu-ZrO2 interfacial sites are necessary for the dehydrogenative coupling reaction between ethanol and acetaldehyde to produce ethyl acetate and the effective synthesis of methanol from CO2 and H2. In addition, we quantified the concentration of Cu and Cu-ZrO2 interfacial sites using a combination of sub-ambient CO Fourier transform infrared spectroscopy and reactive N2O chemisorption measurements. In Chapter 4, we prepared the supported Pt catalysts with different Mo contents by the CSR method for the reverse water gas shift (RWGS) reaction under dark and visible light illumination conditions. We demonstrated that Pt-MoOx interface formation and photoexcitation by visible light irradiation increase the catalytic activity for the RWGS reaction by alleviating CO poisoning on Pt surface. In Chapter 5, we showed that the deposition of Mo onto Au nanoparticles by the CSR method occurs preferentially on under-coordinated Au sites using reactivity measurements, CO FTIR studies, Raman spectroscopy, and X-ray absorption spectroscopy (XAS). Correlations of RWGS reactivity with changes in FTIR spectra for samples containing varying amounts of Mo indicate that interfacial sites are an order of magnitude more active than Au sites for RWGS under dark and visible light illumination conditions. In Chapter 6, we showed that the formation of Pt-FexOy interfaces by the CSR method increases the catalytic activity for the hydrogenation of carbonyl groups and CO oxidation. The presence of Pt-FexOy interfacial sites may enhance the catalytic activity by stabilization of the adsorbed reactive intermediates through bonding with C=O groups for carbonyl groups hydrogenation. The enhanced activity over Pt1Fex/SiO2 catalysts for CO oxidation compared to Pt/SiO2 can be associated with a lower energy barrier for O2 adsorption and activation over Pt-FexOy interfacial sites. We conclude with a discussion of future directions.
Book Synopsis The Preparation, Characterization and Catalytic Behaviour of Silica Supported Rhodium-copper Catalysts by : Katherine Rooney
Download or read book The Preparation, Characterization and Catalytic Behaviour of Silica Supported Rhodium-copper Catalysts written by Katherine Rooney and published by . This book was released on 1987 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt:
