Mines Repository (Colorado School of Mines)
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Development of catalase like nanomaterials for tandem systems in the industrial synthesis of keto acids
No full textIncludes bibliographical references.2024 Spring.The pursuit of novel strategies for conducting multi-step chemoenzymatic catalysis within a single reaction vessel remains a challenging undertaking. A chemoenzymatic process represents a distinct category of reactions wherein two or more consecutive transformations take place in a single reaction vessel, and subsequent post-reaction processing is minimized. This process leverages both enzymatic and chemical catalysis to efficiently generate desired products from commercially available starting materials, while removing the need to isolate intermediates. Driven by emerging techniques for designing biosynthetic materials that employ enzymes and inorganic species within single-pot systems, innovative use of catalytically active mesoporous nanomaterials as enzyme supports has potential to significantly enhance the overall performance and capabilities of the combined catalysts.
In this work, we investigate material properties that influence the catalytic activity of metal phosphate materials. Specifically, we focus on further understanding the structure-function relationship of these materials which have catalase-like activity by synthesizing bulk and mesoporous cobalt phosphate materials with varying levels of crystallinity and surface areas. Catalases, which are known for their proficiency in decomposing hydrogen peroxide in biological systems, are used in a wide range of applications such as in medicine, catalysis, and environmental remediation. Our research demonstrates the impact of synthesis and aging temperatures on morphology and material properties of cobalt phosphate materials, as well as the resulting catalytic activity bringing structure-function relationships together. Furthermore, we explore the potential of employing mesoporous cobalt phosphate with enlarged pores and increased surface area as catalysts and stabilizing agents in a chemoenzymatic system to efficiently synthesize keto acids. By encapsulating and covalently immobilizing enzymes such as L-amino acid oxidase or L-glutamate oxidase within the pores of cobalt phosphate materials, we aim to develop a more efficient and recyclable hybrid tandem system that effectively bridges bio- and chemo-catalysis
Utilizing spectroscopy and electrochemistry to understand europium, terbium, and uranium redox chemistry in novel media
No full textIncludes bibliographical references.2024 Fall.The projects in this thesis span three different solution matrices—highly basic media (potassium carbonate) in Chapter 2, aqueous media (water) in Chapter 3, and highly corrosive and ionic media at high temperatures (lithium and potassium chloride molten salt) in Chapter 4. In Chapter 2, the redox properties of europium and terbium are investigated through X-ray absorption spectroscopy, UV-visible spectroscopy, near-infrared spectroscopy, and electron paramagnetic
spectroscopy showing the prevalence of trivalent oxidations states and a unique, red-hued Tb(III) complex. Chapter 3 sets the stage for Chapter 4 in which it investigates the well-known reversible redox couple of ferrocyanide in aqueous media using less common spectroelectrochemical approaches to support diffusion coefficient assessment. In Chapter 4, a multiscale electrochemical approach was used to study redox chemistry in a high temperature molten salt. In part one of this chapter, the concentration of uranium tetrachloride in the salt mixture was increased far beyond what has ever been reported and diffusion coefficients were measured through cyclic voltammetry. The second part of this chapter focused
on developing a hybrid technology capable furnace that was able to monitor the oxidation of uranium in molten salts through UV-visible spectroelectrochemistry to calculate a conditional diffusion coefficient value. Overall, this thesis provides fundamental understandings on select redox elements across a wide range of solution environments using various electrochemical and spectroscopy methods
Huebnerite
No full textPhotographed by Ron Wolf.Vitreous grey black blades of huebnerite on glassy mass of small crystals, Bonita mountain, San Juan County, Colorado
Correlating lost circulation materials' size and shape with sealing effectiveness in a lab setting
No full textIncludes bibliographical references.2024 Fall.The uncontrolled loss of fluid during drilling operations has been an existing and costly issue throughout the history of the Oil and Gas industry. The cost and frequency of lost circulation (LOC) events is exacerbated when drilling through producing and depleted plays while exploring deeper source rock. The severity of LOC events varies in scale as a function of drilling fluid rheology, density, wellbore and pore pressure, and rock properties. Fluid loss may occur in pore space, fractures (occurring naturally or induced), or subsurface caverns. The most often severe or “total loss” events typically occur in the natural and induced fracture intervals.
Currently the industry lacks common testing data and practices to engineer mitigation techniques to address these lost circulation events, specifically losses in fracture networks (induced and natural).
The purpose of this research is to provide size, shape and testing data using common lost circulation materials found in the field. Materials were provided by major oil and gas service companies. A lost circulation study laboratory was created on the main Colorado School of Mines campus. In this lab setting, particle size and shape data were gathered using a combination of sieving and image analyses. Slot testing was completed using an automated plugging and permeability device, provided lost circulation materials, and a pre-designed fluid or “mud” system. Material testing successes were determined by measuring fluid loss at pressure, through standard slot sizes. Testing results were compared to the size and shape data previously gathered.
When comparing size and shape data to sealing pressures, common material characteristics were identified in their overall sealing effectiveness. Comparing materials physical properties and using our current understanding of fracture conductivity, it became apparent that a material blend’s sealing effectiveness was directly related to its combined ability coarse materials to create a stable infrastructure fine fibrous material. The study results should supplement lost circulation materials design and engineering material blends in tailored applications
Essays on the economics of energy transition in the U.S. electricity markets
No full textIncludes bibliographical references.2024 Summer.This thesis, titled ”Essays on the Economics of Energy Transition in U.S. Electricity Markets,” explores critical economic aspects of integrating renewable energy sources into the United States’ electricity grid. The research is structured into three main essays, each addressing distinct but interconnected questions related to the economic impacts, technological innovations, and policy implications of the energy transition. The first essay examines the economic implications and benefits of employing Volt/VAR Optimization (VVO) technologies within U.S. electricity distribution networks. Traditionally used for energy efficiency, VVO technologies are evaluated for their potential to mitigate power interruptions caused by the volatility of renewable energy outputs, particularly from solar photovoltaics (PV) and wind turbines. The second chapter delves into market barriers to demand response participation in organized wholesale markets by analyzing empirical data on realized energy savings from demand response across residential and commercial customer classes after the FERC Order 745. Using a difference-in-differences (DiD) approach, the research evaluates whether the prior pricing structures targeted by FERC Order 745 hindered the market participation of demand response resources. The study grapples with extensive missing data, employing a multiple imputation methodology. The third chapter provides empirical investigation using instrumental variable estimation technique and scrutinize if utilities in the U.S. are expanding the size of their demand response programs as a mean to confront rising supply intermittency in their local electricity markets. Overall, this thesis provides comprehensive insights into the economic challenges and opportunities associated with the energy transition in the U.S. electricity markets. It underscores the importance of strategic investments in grid technologies, effective policy measures, and innovative market mechanisms to achieve a reliable, resilient, and economically sustainable energy system. The findings offer valuable guidance for policymakers, industry stakeholders, and researchers committed to advancing the transition to a low-carbon energy future
Titanite with epidote
No full textPhotographed by Ron Wolf.Yellow-green prismatic crystal of epidote and black needle-like titanite
Search for nuclear two-photon decay with GRIFFIN
No full textIncludes bibliographical references.2024 Summer.The nuclear equation of state requires rigorous benchmarking of experimentally observable properties, such as the electric polarizability of nuclear matter and its difference for an excited nuclear state. This difference can be extracted through measurement of the second order electromagnetic process of nuclear two-photon emission. Nuclear two-photon, or double-gamma (2), decay is the simultaneous emission of two gamma-rays from an excited nuclear state. Searching for this decay mode in systems where the first excited and ground states have spin/parity, where single photon emission is forbidden, provides significant experimental advantages. The first excited state of Zr satisfies these conditions, and has been previously observed to undergo two-photon emission. A proof-of-concept measurement of the 1760 keV two-photon transition in Zr, using a Sr source, has been performed using the GRIFFIN spectrometer at TRIUMF-ISAC, and is the first measurement of this transition using a general-purpose HPGe array. The techniques developed in this measurement informed the first direct search for the 691 keV two-photon transition in Ge, where a statistically-limited branching ratio upper limit of was set. These results are consistent with recent observations of two-photon decay in Ge using bare ions and provide new insights into using general-purpose arrays to measure nuclear two-photon decay
