Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 20 for “"Metal-support interaction"”.
-
Silica modified Co3O4 nanocubes as a model system for metal-support interaction in Co/SiO2 catalyst for Fischer-Tropsch synthesis
The aim of this study was to study the interaction between the silica and cobalt crystallites using a model of Co3O4-nanocubes whose surface was modified with tetraethyl orthosilicate. The model systems were prepared in two steps, viz. synthesis of the cobalt(III,II) oxide nanocubes via the sodium …
-
SiC and B₄C as electrocatalyst support materials for low temperature fuel cells
Supported nano-catalyst technologies are key for increasing the catalyst utilisation and achieving economically feasible platinum metal loadings in hydrogen polymer electrolyte fuel cells (PEFCs). High surface area carbons are commonly utilised as support materials for platinum due to low cost, …
-
Influence of preparation techniques on the Fischer-Tropsch performance of supported cobalt catalysts
… shift reaction and lower price compared to noble metals [22]. There can, however, be a large effective loss of active metal due to strong metal-support interaction forming complexes that are not reduced at temperatures below 400°C.
-
Evaluation of metal nitrides and borides as alternative electrocatalyst support materials for polymer electrolyte fuel cells
… Poor durability is mainly attributed to carbon support corrosion during start-up and shut-down of the fuel cell. Corrosion of the electrocatalyst support materials has numerous adverse effects on the performance of the fuel cell, such as weakening of metal-support interaction which results in Pt …
-
Fischer-Tropsch synthesis over SiO2, ZnO and MnO supported cobalt catalysts
Silica is well known as a support for cobalt supported Fischer-Tropsch catalysts. Silica has a high surface area with an amorphous structure that promotes dispersion of the active cobalt phase over the support surface. This dispersion is vital in terms of catalyst performance and derives from the …
-
The effect of temperature and crystallite size on the growth and morphology of carbon nanotubes
… crystallites with different crystallite sizes supported on y-A120 3 using the reverse micelle technique. It was hypothesised that changing the crystallite size of the synthesised iron oxide crystallites could lead to the control of the external nanotube diameter. The effect of temperature on …
-
ADVANCED BIFUNCTIONAL CORE-SHELL CATALYSTS FOR METHANE REFORMING USING CARBON DIOXIDE
… particle size, suppressing sintering, enhancing metal-support interaction, and incorporating redox-active materials to enhance coke oxidation and removal. At the same time, an endeavor is made to gain fundamental insights into the reaction mechanism on the developed catalysts in order to draw …
-
Mechanisms and catalyst design for heterogeneous Olefin metathesis
… in which olefins coordinate with catalytic metal carbenes to form metallacyclobutanes that then rearrange into metathesis products. While this mechanism has been proven for homogenous metathesis catalysts, for which the 2005 Nobel Prize was awarded, the mechanism over heterogeneous catalysts …
-
Steam Electrolysis Coupled with CO2 Conversion in a Pressurized Proton Conducting Solid Oxide Electrolysis Cell
… in the conversion of CO2 were analysed: the interaction between supported iron oxides and conducting substrates with oxygen vacancies, and the degradation of proton conducting perovskites in the presence of CO2. Ceramic supports containing oxygen vacancies as extrinsic defects (such as proton …
-
Research and development of nickel based catalysts for carbon dioxide reforming of methane
… can be ascribed to its high surface area, high metal disperation, small particle size, strong metal-support interaction, and synergy between Ni and Co. Kinetic studies have shown that the CH4 decomposition and CO2 activation could be the rate-determining steps. Both Power-Law and …
-
Catalytic activation of Rh,Pd nanoclusters supported on Ceria
… present on the surface of CeO2-x are reduced to metallic form under the reducing environment of the ESR reaction. Here we report X-Ray Photoelectron Spectroscopy (XPS), X-Ray Absorption Spectroscopy (XAS) and High Resolution Transmission Electron Microscopy (HRTEM) studies on the catalytic …
-
Inverse model systems to investigate metal-support interactions in Fischer-Tropsch catalysis
… thesis aims to gain insight into the effects of metal-support interaction in Co/SiO2 catalysts using an inverse model system by modifying Co3O4 nanocrystallites with silanes (i.e. tetraethoxysilane, trimethyl chlorosilane, triphenyl ethoxysilane). It is postulated that the formation of Co-O-Si …
-
Structure Sensitivity of Alkanes Hydrogenolysis and Alkynes Hydrogenation on Supported Ir Catalysts
… systems, the activity and selectivity of supported metal catalysts or extended metal surface catalysts would be affected by the metal surface structure, and this phenomenon is called structure sensitivity. Generally, structure sensitivity is led by the change of geometric and electronic …
-
Rational Catalyst Design for Direct Conversion of CH4 and CO2
… from molecular modeling.</p><p>Pt nanoparticles supported on ceria support have been selected based on molecular modeling and density functional theory analysis that provided the guidance for the catalyst structure optimization. Tetrahedral Pt nanoclusters, with a high fraction of edge and corner …
-
Aerosol Synthesis and Electrochemical Analysis of Niobium Mixed-Metal Oxides for the Ethanol Oxidation Reaction in Acid and Alkaline Electrolyte
… The latter criterion is achievable in mixed-metal systems. Platinum is an effective metal for catalyzing surface reactions of many adsorbates and is usually implemented in the form of Pt nanoparticles supported on inexpensive carbon. This carbon is believed to be neutral in the catalysis of …
-
Structural characterization of multimetallic nanoparticles
<p>Bimetallic and trimetallic alloy nanoparticles have enhanced catalytic activities due to their unique structural properties. Using <em>in situ</em> time-resolved synchrotron based x-ray diffraction, we investigated the structural properties of nanoscale catalysts undergoing various heat …
-
Carbon Monoxide Oxidation on Nanoparticle Catalysts and Gas Phase Reactions of Small Molecules and Volatile Organics with Metal Cations
… of a vapor phase method to synthesize supported and unsupported nanoparticle catalysts for CO oxidation. The method is based on the Laser Vaporization/Controlled Condensation (LVCC) technique. The first part of this dissertation presents the vapor phase synthesis and characterization of …
-
Structure-Sensitivity of CO Oxidation Over Supported Pt Catalysts in the Subnanometer Regime and Its Origin
Metal-oxide-supported Pt-group metal catalysts are regularly used in many industrially relevant reactions, including CO oxidation for automotive emission control. Being able to activate O2, these catalysts are also promising candidates for oxidative decomposition of chemical warfare agents and …
-
CO2 capture and utilization using dual-functional catalysts
… sequentially proposed a unique three-dimensional supported structure for the improvement of carbon capture capacity and cyclic stability, but also converts the captured CO2 into value added products or uses the carbonation of CaO to provide energy for low-temperature biomass gasification. Firstly, …
-
In-situ electron imaging of oxidation and reduction of rutile (TiO2) nanocrystals and interaction with palladium
Metal nanoparticles supported on oxides exhibit excellent catalytic properties for chemical reactions that impact several industries, for example, Pd/CeO2 is used in the catalytic converters of automobiles for environmental remediation, Rh/ZrO2 is used for fuel refinement, and Pt/TiO2 is an …