ASU Electronic Theses and Dissertations
This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.
In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.
Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.
Displaying 1 - 10 of 16
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- All Subjects: chemical engineering
- Creators: Lin, Jerry
Description
Emission of CO2 into the atmosphere has become an increasingly concerning issue as we progress into the 21st century Flue gas from coal-burning power plants accounts for 40% of all carbon dioxide emissions. The key to successful separation and sequestration is to separate CO2 directly from flue gas (10-15% CO2, 70% N2), which can range from a few hundred to as high as 1000°C. Conventional microporous membranes (carbons/silicas/zeolites) are capable of separating CO2 from N2 at low temperatures, but cannot achieve separation above 200°C. To overcome the limitations of microporous membranes, a novel ceramic-carbonate dual-phase membrane for high temperature CO2 separation was proposed. The membrane was synthesized from porous La0.6Sr0.4Co0.8Fe0.2O3-d (LSCF) supports and infiltrated with molten carbonate (Li2CO3/Na2CO3/K2CO3). The CO2 permeation mechanism involves a reaction between CO2 (gas phase) and O= (solid phase) to form CO3=, which is then transported through the molten carbonate (liquid phase) to achieve separation. The effects of membrane thickness, temperature and CO2 partial pressure were studied. Decreasing thickness from 3.0 to 0.375 mm led to higher fluxes at 900°C, ranging from 0.186 to 0.322 mL.min-1.cm-2 respectively. CO2 flux increased with temperature from 700 to 900°C. Activation energy for permeation was similar to that for oxygen ion conduction in LSCF. For partial pressures above 0.05 atm, the membrane exhibited a nearly constant flux. From these observations, it was determined that oxygen ion conductivity limits CO2 permeation and that the equilibrium oxygen vacancy concentration in LSCF is dependent on the partial pressure of CO2 in the gas phase. Finally, the dual-phase membrane was used as a membrane reactor. Separation at high temperatures can produce warm, highly concentrated streams of CO2 that could be used as a chemical feedstock for the synthesis of syngas (H2 + CO). Towards this, three different membrane reactor configurations were examined: 1) blank system, 2) LSCF catalyst and 3) 10% Ni/y-alumina catalyst. Performance increased in the order of blank system < LSCF catalyst < Ni/y-alumina catalyst. Favorable conditions for syngas production were high temperature (850°C), low sweep gas flow rate (10 mL.min-1) and high methane concentration (50%) using the Ni/y-alumina catalyst.
ContributorsAnderson, Matthew Brandon (Author) / Lin, Jerry (Thesis advisor) / Alford, Terry (Committee member) / Rege, Kaushal (Committee member) / Anderson, James (Committee member) / Rivera, Daniel (Committee member) / Arizona State University (Publisher)
Created2011
Description
The use of petroleum for liquid-transportation fuels has strained the environment and caused the global crude oil reserves to diminish. Therefore, there exists a need to replace petroleum as the primary fuel derivative. Butanol is a four-carbon alcohol that can be used to effectively replace gasoline without changing the current automotive infrastructure. Additionally, butanol offers the same environmentally friendly effects as ethanol, but possess a 23% higher energy density. Clostridium acetobutylicum is an anaerobic bacterium that can ferment renewable biomass-derived sugars into butanol. However, this fermentation becomes limited by relatively low butanol concentrations (1.3% w/v), making this process uneconomical. To economically produce butanol, the in-situ product removal (ISPR) strategy is employed to the butanol fermentation. ISPR entails the removal of butanol as it is produced, effectively avoiding the toxicity limit and allowing for increased overall butanol production. This thesis explores the application of ISPR through integration of expanded-bed adsorption (EBA) with the C. acetobutylicum butanol fermentations. The goal is to enhance volumetric productivity and to develop a semi-continuous biofuel production process. The hydrophobic polymer resin adsorbent Dowex Optipore L-493 was characterized in cell-free studies to determine the impact of adsorbent mass and circulation rate on butanol loading capacity and removal rate. Additionally, the EBA column was optimized to use a superficial velocity of 9.5 cm/min and a resin fraction of 50 g/L. When EBA was applied to a fed-batch butanol fermentation performed under optimal operating conditions, a total of 25.5 g butanol was produced in 120 h, corresponding to an average yield on glucose of 18.6%. At this level, integration of EBA for in situ butanol recovered enabled the production of 33% more butanol than the control fermentation. These results are very promising for the production of butanol as a biofuel. Future work will entail the optimization of the fed-batch process for higher glucose utilization and development of a reliable butanol recovery system from the resin.
ContributorsWiehn, Michael (Author) / Nielsen, David (Thesis advisor) / Lin, Jerry (Committee member) / Lind, Mary Laura (Committee member) / Arizona State University (Publisher)
Created2013
Description
Amine-modified solid sorbents and membrane separation are promising technologies for separation and capture of carbon dioxide (CO2) from combustion flue gas. Amine absorption processes are mature, but still have room for improvement. This work focused on the synthesis of amine-modified aerogels and metal-organic framework-5 (MOF-5) membranes for CO2 separation. A series of solid sorbents were synthesized by functionalizing amines on the surface of silica aerogels. This was done by three coating methods: physical adsorption, magnetically assisted impact coating (MAIC) and atomic layer deposition (ALD). CO2 adsorption capacity of the sorbents was measured at room temperature in a Cahn microbalance. The sorbents synthesized by physical adsorption show the largest CO2 adsorption capacity (1.43-1.63 mmol CO2/g). An additional sorbent synthesized by ALD on hydrophilic aerogels at atmospheric pressures shows an adsorption capacity of 1.23 mmol CO2/g. Studies on one amine-modified sorbent show that the powder is of agglomerate bubbling fluidization (ABF) type. The powder is difficult to fluidize and has limited bed expansion. The ultimate goal is to configure the amine-modified sorbents in a micro-jet assisted gas fluidized bed to conduct adsorption studies. MOF-5 membranes were synthesized on α-alumina supports by two methods: in situ synthesis and secondary growth synthesis. Characterization by scanning electron microscope (SEM) imaging and X-ray diffraction (XRD) show that the membranes prepared by both methods have a thickness of 14-16 μm, and a MOF-5 crystal size of 15-25 μm with no apparent orientation. Single gas permeation results indicate that the gas transport through both membranes is determined by a combination of Knudsen diffusion and viscous flow. The contribution of viscous flow indicates that the membranes have defects.
ContributorsRosa, Teresa M (Author) / Lin, Jerry (Thesis advisor) / Pfeffer, Robert (Thesis advisor) / Dai, Lenore (Committee member) / Nielsen, David (Committee member) / Arizona State University (Publisher)
Created2010
Description
Lithium-ion and lithium-metal batteries represent a predominant energy storage solution with the potential to address the impending global energy crisis arising from limited non-renewable resources. However, these batteries face significant safety challenges that hinder their commercialization. The conventional polymeric separators and electrolytes have poor thermal stability and fireproof properties making them prone to thermal runaway that causes fire hazards and explosions when the battery is subjected to extreme operating conditions. To address this issue, various materials have been investigated for their use as separators. However, polymeric, and pure inorganic material-based separators have a trade-off between safety and electrochemical performance. This is where zeolites emerge as a promising solution, offering favorable thermal and electrochemical characteristics. The zeolites are coated onto the cathode as a separator using the scalable blade coating method. These separators are non-flammable with high thermal stability and electrolyte wettability. Furthermore, the presence of intracrystalline pores helps in homogenizing the Li-ion flux at anode resulting in improved electrochemical performance. This research delves into the preparation of zeolite separators using a commercial zeolite and lab-scale zeolite to study their safety and electrochemical performance in lithium-ion batteries. At low C-rates, both zeolites exhibited excellent capacity retention and capacity density displaying their potential to advance high-performance safe lithium-ion batteries. The commercial zeolite has demonstrated remarkable capacity retention and good performance in terms of charge and discharge cycles, as well as stability. This makes it a valuable resource for the scaling up of electrode-coated separator technology.
Furthermore, the previous study demonstrated the superior electrochemical performance of plate silicalite separator (also a lab-made zeolite) with both lithium-ion and lithium-metal batteries. However, the process of scaling up and achieving precise control over plate silicalite particle size, and morphology using the existing synthesis procedure has proven challenging. Thus, the modification of process conditions is studied to enhance control over particle size, aspect ratio, and yield to facilitate a more efficient scaling-up process. Incorporation of stirring during the crystallization phase enhanced yield and uniformity of particle size. Also, the increase in temperature and time of crystallization enlarged the particles but did not show any significant improvement in the aspect ratio of the particles.
ContributorsNalam, Ramasai Dharani Harika (Author) / Lin, Jerry (Thesis advisor) / Emady, Heather (Committee member) / Seo, S. Eileen (Committee member) / Arizona State University (Publisher)
Created2023
Description
Lithium-ion batteries are widely used for high energy storage systems and most of the commercially manufactured lithium-ion batteries use liquid electrolytes and
polymeric separators. However, these electrolytes and polymeric separators pose safety
issues under high temperatures and in the event of short circuit which may lead to
thermal runaway and cause fire. The application of fire-retardant high salt concentrated
electrolytes can be used to address the safety issues that arises in the use of liquid
electrolytes, but these electrolytes have high viscosity and low wettability when used on
polymeric separators which are commercially used in lithium-ion batteries. To address
this issue, zeolite powder has been synthesized and separators were prepared by coating
on the electrode using scalable blade coating method. Zeolite separators have higher
wettability and electrolyte uptake compared to polymeric separators such as
polypropylene (PP) due to their intra-particle micropores. The zeolite separators also
have higher porosity compared to PP separators resulting in higher electrolyte uptake and
better electrochemical performance of the lithium-ion batteries. Zeolite separators have
been prepared using spherical-silicalite and plate-silicalite to analyze the effect of
morphology of the particles on the electrochemical performance of the cells. The platesilicalite separators have higher capacity retention during long-term cycling at low Crates and better capacity performance at high C-rates compared to spherical-silicalite.
Therefore plate-silicalite is very promising for the development of high-performance safe
lithium-ion batteries.
ContributorsLINGAM MURALI, DHEERAJ RAM (Author) / Lin, Jerry (Thesis advisor) / Muhich, Christopher (Committee member) / Torres, Cesar (Committee member) / Arizona State University (Publisher)
Created2022
Description
Adsorption is fundamentally known to be a non-isothermal process; in which temperature increase is largely significant, causing fairly appreciable impacts on the processkinetics. For porous adsorbent particles like metal organic frameworks (MOFs), silica
gel, and zeolite, the resultant relative heat generated is partly distributed within the
particle, and the rest is transferred to the surrounding ambient fluid (air).
For large step changes in adsorbed phase concentration and fast adsorption rates,
especially, the isothermality of adsorption (as in some studies) is an inadequate assumption and inspires rather erroneous diffusivities of porous adsorbents. Isothermal models, in consequence, are insufficient for studying adsorption in porous adsorbents. Non-isothermal models can satisfactorily and exhaustively describe adsorption
in porous adsorbents. However, in many of the analyses done using the models, the
thermal conductivity of the adsorbent is assumed to be infinite; thus, particle temperature is taken to be fairly uniform during the process—a trend not observed for
carbon dioxide (CO2) adsorption on MOFs.
A new and detailed analysis of CO2 adsorption in a single microporous MOF-5
particle, assuming a finite effective thermal conductivity along with comprehensive
parametric studies for the models, is presented herein. A significant average temperature increase of 5K was calculated using the new model, compared to the 0.7K
obtained using the Stremming model. A corresponding increase in diffusivity from
8.17 x 10-13 to 1.72 x 10-11 m2/s was observed, indicating the limitations of both
isothermal models and models that assume constant diffusivity.
ContributorsNkuutu, John (Author) / Lin, Jerry (Thesis advisor) / Emady, Heather (Committee member) / Deng, Shuguang (Committee member) / Arizona State University (Publisher)
Created2023
Description
Cyclical chemical looping involves the thermal reduction of metal oxide to release O2 at high temperatures, followed by its oxidation using O-containing molecules like O2, H2O, or CO2. This process is a promising method for solar thermochemical water splitting (STCH), oxygen separation, and thermochemical energy storage (TCES). The efficiency and economic viability of this process hinge on the thermodynamics of metal oxide reduction. This dissertation presents innovative methods to enhance the performance of these processes, with a specific focus on STCH and TCES by advancing thermodynamic characterization and screening of potential metal oxides, thereby reducing H2 costs.A novel CALPHAD approach, the CrossFit Compound Energy Formalism (CEF), integrates theoretical (density functional theory) and experimental (thermogravimetric) data to develop thermodynamic models for desired materials. The CrossFit-CEF was applied to BaxSr1-xFeO3-δ identifying matching thermodynamics and off-stoichiometric values to literature (~100-180 kJ/mol O2 reduction enthalpies across the BaxSr1-xFeO3-δ compositional range). Comparisons with the traditional van ‘t Hoff thermodynamic extraction technique reveal that the CrossFit-CEF method significantly outperforms conventional methods. For instance, the CEF method was employed to extract thermodynamic data for CaFexMn1-xO3-δ and identify optimal TCES CaFexMn1-xO3-δ compositions. The CrossFit-CEF method found the same thermodynamic trends on less than half the data utilized in a van ‘t Hoff approach and determined that the optimal CaFexMn1-xO3-δ composition had the minimal Fe concentration synthesized (x=0.625), achieving ~60 kJ/mol TCES.
Bayesian Inference was employed was employed to expedite data collection. When combined with the CrossFit-CEF method, Bayesian Inference assesses the likelihood that the current model accurately describes the data, providing confidence intervals for the model. This approach reduces the amount of data needed for accurate thermodynamic modeling by 50%.
Finally, the CrossFit-CEF and Bayesian methods are integrated into a system-level STCH model to optimize and accelerate materials design for specific plant operating conditions. Overall, this dissertation introduces methods that yield more accurate thermodynamic models with reduced data requirements. The time saved in data collection enables screening of more materials, expediting material identification and optimization. The materials identified through these techniques are expected to enhance chemical looping cycles, leading to increased H2 production efficiency and reduced costs.
ContributorsWilson, Steven A (Author) / Muhich, Christopher L (Thesis advisor) / Rivera, Daniel E (Committee member) / Stechel, Ellen B (Committee member) / Lin, Jerry (Committee member) / Deng, Shuguang (Committee member) / Arizona State University (Publisher)
Created2024
Description
Crystalline polymeric materials play an increasingly important role in daily life.Understanding and controlling the development of crystallinity is integral to improving the
performance of crystalline polymers in packaging, drug delivery, water treatment, gas
separations, and many other industries. Herein, fluorescence and Raman spectroscopy have
been applied for the first time to study the crystallinity of polymers, including traditional
semicrystalline thermoplastics and covalent organic frameworks (COFs; an emerging class
of crystalline polymers with highly ordered pore structures). On one hand, by incorporating
a fluorescent dye segment into a semicrystalline polymer matrix, it is feasible to accurately
monitor its crystallization and melting. The flexibility of dye incorporation allows for new
fundamental insights into polymer crystallization in the bulk and at/near interfaces that
may otherwise be out of reach for established techniques like differential scanning
calorimetry (DSC). On the other hand, Raman spectroscopy has been identified as a
technique sensitive to the crystallinity of COFs and applied alongside well-established
characterization techniques (X-ray diffraction and N2 adsorption) to monitor the
crystallization of COFs during synthesis. This has enabled careful control of COF
crystallinity during solvothermal synthesis for improved application in the field of drug
delivery. The monitoring of COF crystallinity has been extended to more complex film
geometries produced by interfacial polymerization. The high molecular sieving potential
of COFs remains out of reach in part due to a lack of understanding of the interplay between
crystallinity, crystallite orientation, and filtration performance. A careful study of these
relationships is suggested for future work to provide key insight toward applying COFs as
molecular sieving materials in water treatment and other separation applications.
ContributorsNile, Richard Gabriel (Author) / Jin, Kailong (Thesis advisor) / Lin, Jerry (Committee member) / Acharya, Abhinav (Committee member) / Seo, S. Eileen (Committee member) / Chen, Xiangfan (Committee member) / Arizona State University (Publisher)
Created2024
Description
Among the alternative processes for the traditional distillation, adsorption and membrane separations are the two most promising candidates and metal-organic frameworks (MOFs) are the new material candidate as adsorbent or membrane due to their high surface area, various pore sizes, and highly tunable framework functionality. This dissertation presents an investigation of the formation process of MOF membrane, framework defects, and two-dimensional (2D) MOFs, aiming to explore the answers for three critical questions: (1) how to obtain a continuous MOF membrane, (2) how defects form in MOF framework, and (3) how to obtain isolated 2D MOFs. To solve the first problem, the accumulated protons in the MOF synthesis solution is proposed to be the key factor preventing the continuous growth among Universitetet I Oslo-(UiO)-66 crystals. The hypothesis is verified by the growth reactivation under the addition of deprotonating agent. As long as the protons were sufficiently coordinated by the deprotonating agent, the continuous growth of UiO-66 is guaranteed. Moreover, the modulation effect can impact the coordination equilibrium so that an oriented growth of UiO-66 film was achieved in membrane structures. To find the answer for the second problem, the defect formation mechanism in UiO-66 was investigated and the formation of missing-cluster (MC) defects is attributed to the partially-deprotonated ligands. Experimental results show the number of MC defects is sensitive to the addition of deprotonating agent, synthesis temperature, and reactant concentration. Pore size distribution allows an accurate and convenient characterization of the defects. Results show that these defects can cause significant deviations of its pore size distribution from the perfect crystal. The study of the third questions is based on the established bi-phase synthesis method, a facile synthesis method is adopted for the production of high quality 2D MOFs in large scale. Here, pyridine is used as capping reagent to prevent the interplanar hydrogen bond formation. Meanwhile, formic acid and triethylamine as modulator and deprotonating agent to balance the anisotropic growth, crystallinity, and yield in the 2D MOF synthesis. As a result, high quality 2D zinc-terephthalic acid (ZnBDC) and copper-terephthalic acid (CuBDC) with extraordinary aspect ratio samples were successfully synthesized.
ContributorsShan, Bohan (Author) / Mu, Bin (Thesis advisor) / Forzani, Erica (Committee member) / Dai, Lenore (Committee member) / Lin, Jerry (Committee member) / Liu, Jingyue (Committee member) / Arizona State University (Publisher)
Created2019
Description
Polymer-gold composite particles are of tremendous research interests. Contributed by their unique structures, these particles demonstrate superior properties for optical, catalytic and electrical applications. Moreover, the incorporation of “smart” polymers into polymer-gold composite particles enables the composite particles synergistically respond to environment-stimuli like temperature, pH and light with promising applications in multiple areas.
A novel Pickering emulsion polymerization route is found for synthesis of core-shell structured polymer-gold composite particles. It is found that the surface coverage of gold nanoparticles (AuNP) on a polystyrene core is influenced by gold nanoparticle concentration and hydrophobicity. More importantly, the absorption wavelength of polystyrene-gold composite particles is tunable by adjusting AuNP interparticle distance. Further, core-shell structured polystyrene-gold composite particles demonstrate excellent catalyst recyclability.
Asymmetric polystyrene-gold composite particles are successfully synthesized via seeded emulsion polymerization, where AuNPs serve as seeds, allowing the growth of styrene monomers/oligomers on them. These particles also demonstrate excellent catalyst recyclability. Further, monomers of “smart” polymers, poly (N-isopropylacrylamide) (PNIPAm), are successfully copolymerized into asymmetric composite particles, enabling these particles’ thermo-responsiveness with significant size variation around lower critical solution temperature (LCST) of 31°C. The significant size variation gives rise to switchable scattering intensity property, demonstrating potential applications in intensity-based optical sensing.
Multipetal and dumbbell structured gold-polystyrene composite particles are also successfully synthesized via seeded emulsion polymerization. It is intriguing to observe that by controlling reaction time and AuNP size, tetrapetal-structured, tripetal-structured and dumbbell-structured gold-polystyrene are obtained. Further, “smart” PNIPAm polymers are successfully copolymerized into dumbbell-shaped particles, showing significant size variation around LCST. Self-modulated catalytic activity around LCST is achieved for these particles. It is hypothesized that above LCST, the significant shrinkage of particles limits diffusion of reaction molecules to the surface of AuNPs, giving a reduced catalytic activity.
Finally, carbon black (CB) particles are successfully employed for synthesis of core- shell PNIPAm/polystyrene-CB particles. The thermo-responsive absorption characteristics of PNIPAm/polystyrene-CB particles enable them potentially suitable to serve as “smart” nanofluids with self-controlled temperature. Compared to AuNPs, CB particles provide desirable performance here, because they show no plasmon resonance in visible wavelength range, whereas AuNPs’ absorption in the visible wavelength range is undesirable.
A novel Pickering emulsion polymerization route is found for synthesis of core-shell structured polymer-gold composite particles. It is found that the surface coverage of gold nanoparticles (AuNP) on a polystyrene core is influenced by gold nanoparticle concentration and hydrophobicity. More importantly, the absorption wavelength of polystyrene-gold composite particles is tunable by adjusting AuNP interparticle distance. Further, core-shell structured polystyrene-gold composite particles demonstrate excellent catalyst recyclability.
Asymmetric polystyrene-gold composite particles are successfully synthesized via seeded emulsion polymerization, where AuNPs serve as seeds, allowing the growth of styrene monomers/oligomers on them. These particles also demonstrate excellent catalyst recyclability. Further, monomers of “smart” polymers, poly (N-isopropylacrylamide) (PNIPAm), are successfully copolymerized into asymmetric composite particles, enabling these particles’ thermo-responsiveness with significant size variation around lower critical solution temperature (LCST) of 31°C. The significant size variation gives rise to switchable scattering intensity property, demonstrating potential applications in intensity-based optical sensing.
Multipetal and dumbbell structured gold-polystyrene composite particles are also successfully synthesized via seeded emulsion polymerization. It is intriguing to observe that by controlling reaction time and AuNP size, tetrapetal-structured, tripetal-structured and dumbbell-structured gold-polystyrene are obtained. Further, “smart” PNIPAm polymers are successfully copolymerized into dumbbell-shaped particles, showing significant size variation around LCST. Self-modulated catalytic activity around LCST is achieved for these particles. It is hypothesized that above LCST, the significant shrinkage of particles limits diffusion of reaction molecules to the surface of AuNPs, giving a reduced catalytic activity.
Finally, carbon black (CB) particles are successfully employed for synthesis of core- shell PNIPAm/polystyrene-CB particles. The thermo-responsive absorption characteristics of PNIPAm/polystyrene-CB particles enable them potentially suitable to serve as “smart” nanofluids with self-controlled temperature. Compared to AuNPs, CB particles provide desirable performance here, because they show no plasmon resonance in visible wavelength range, whereas AuNPs’ absorption in the visible wavelength range is undesirable.
ContributorsZhang, Mingmeng (Author) / Dai, Lenore L (Committee member) / Phelan, Patrick E (Committee member) / Otanicar, Todd P (Committee member) / Lin, Jerry (Committee member) / He, Ximin (Committee member) / Arizona State University (Publisher)
Created2015