Engineering Commons^™

Electrochemical Hydrogen Separation Via The Solid Acid Electrolyte Cesium Dihydrogen Phosphate, David Leon Wilson

Doctoral Dissertations

Abundant, inexpensive, high purity molecular hydrogen as a medium for energy distribution is potentially enabling for adoption of alternative electricity generation schemes. Steam reforming of natural gas remains the dominant method of producing large amounts of hydrogen. However, this process also creates by-products, most notably, carbon monoxide and carbon dioxide. Separation to ultra-high purity hydrogen from these syngas reformate streams by traditional methods, such as pressure swing absorption, has its disadvantages including long cycle times, contamination and a large equipment footprint. Alternative methods of hydrogen separation, such as electrochemical pumping, are a viable alternative to this separation dilemma due to …

An Exploration Of Basic Processes For Aqueous Electrochemical Production Of Hydrogen From Biomass Derived Molecules, Brian Fane

Doctoral Dissertations

Polymer electrolyte membrane fuel cells(PEMFCs) are energy conversion devices with significant potential. The factors preventing them from becoming widespread concern production and distribution of hydrogen. Developing an efficient hydrogen infrastructure with an approachable rollout plan is an essential step towards the future of fuel cells. Water electrolysis is limited by the thermodynamics of the process, which leads to high electrical consumption and significant materials challenges. Alternative methods for cleanly generating hydrogen while using a lower cell voltage are required. PEM based electrolyzers can operate with a "depolarized anode", whereby they become significantly less power hungry.

This thesis explores two techniques …

Multiscale Modeling Approach To Understand Active Sites In Non-Conventional Catalyst Layers For Fuel Cell Applications, Diana Constanza Orozco Gallo

Doctoral Dissertations

Fuel cells development required stable, active and more abundant catalytic materials. Oxygen reduction reaction (ORR) is the key process to enhance better activity and reduce the fabrication costs. Pt-based has proven to be the best catalyst for ORR and greater efforts has been made in terms of reducing the Pt content in the electrodes, reduce electrode thickness and enhance better catalytic activities. To overcome many of the challenges present, the catalyst layer studies are the great importance in the fuel cell community. Understanding catalyst layer with new catalytic materials, and configurations requires the development of methodological approach to relate structure, …

Computational Studies Of Structure–Function Relationships Of Supported And Unsupported Metal Nanoclusters, Hongbo Shi

Doctoral Dissertations

Fuel cells have been demonstrated to be promising power generation devices to address the current global energy and environmental challenges. One of the many barriers to commercialization is the cost of precious catalysts needed to achieve sufficient power output. Platinum-based materials play an important role as electrocatalysts in energy conversion technologies. In order to improve catalytic efficiency and facilitate rational design and development of new catalysts, structure–function relationships that underpin catalytic activity must be understood at a fundamental level. First, we present a systematic analysis of CO adsorption on Pt nanoclusters in the 0.2-1.5 nm size range with the aim …

Analyses Of Densely Crosslinked Phenolic Systems Using Low Field Nmr, Jigneshkumar Patel

Doctoral Dissertations

A uniform dispersion of reactants is necessary to achieve a complete reaction involving multi-components, especially for the crosslinking of rigid high-performance materials. In these reactions, miscibility is crucial for curing efficiency. This miscibility is typically enhanced by adding a third component, a plasticizer. For the reaction of the highly crystalline crosslinking agent hexamethylenetetramine (HMTA) with a strongly hydrogen-bonded phenol formaldehyde resin, furfural has been traditionally used as the plasticizer. However, the reason for its effectiveness is not clear. In this doctoral thesis work, miscibility and crosslinking efficiency of plasticizers in phenolic curing reactions are studied by thermal analysis and spectroscopic …

Nanoporous Solid Acid Materials For Biomass Conversion Into Value-Added Chemicals: Synthesis, Catalysis, And Chemistry, Hong Je Cho

Doctoral Dissertations

Growing environmental concerns associated with diminishing reserves of fossil fuels has led to accelerated research efforts towards the discovery of new catalytic processes for converting renewable lignocellulosic biomass into value-added chemicals. For this conversion, nanoporous solid acid materials have been widely used because of their excellent hydrothermal stability and molecular sieving capability. In the thesis, hierarchical Lewis acid zeolites with ordered mesoporosity and MFI topology (three dimensionally ordered mesoporous imprinted (3DOm-i) Sn-MFI) were successfully synthesized within the confined space of three dimensionally ordered mesoporous (3DOm) carbon by a seeded growth method. The obtained 3DOm-i Sn-MFI showed at least 3 times …

Catalytic Hydrodeoxygenation And Dehydration Of Bioderived Oxygenates To Renewable Hydrocarbon Building Block Molecules: Enabling Renewable Carbon Fiber, Andrew Walter Lepore

Doctoral Dissertations

It is our goal to develop inexpensive catalytic pathways that can effectively remove oxygen from bio-derived carboxylic acids and alcohols under mild reaction conditions to produce propene which can be converted to renewable carbon fibers. Carboxylic acid hydrodeoxygenation and alcohol dehydration are necessary for successfully producing propene from bio-mass derived precursors and are also broadly relevant to bio-oil upgrading. This body of research adds to the understanding of both known and novel catalyst materials and develops and optimizes pathways for valorizing oxygenates. Dehydration and hydrodeoxygenation catalysts were examined under both batch and continuous flow operation. Product selectivity and reactant conversion …