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Granulation is a process within particle technology where a liquid binding agent is added to a powder bed to create larger granules to modify bulk properties for easier processing. Three sets of experiments were conducted to screen for which factors had the greatest effect on granule formation, size distribution,

Granulation is a process within particle technology where a liquid binding agent is added to a powder bed to create larger granules to modify bulk properties for easier processing. Three sets of experiments were conducted to screen for which factors had the greatest effect on granule formation, size distribution, and morphological properties when wet granulating microcrystalline cellulose and water. Previous experiments had identified the different growth regimes within wet granulation, as well as the granule formation mechanisms in single-drop granulation experiments, but little research has been conducted to determine how results extracted from single drop experiments could be used to better understand the first principles that drive high shear granulation. The experiment found that under a liquid solid ratio of 110%, the granule growth rate was linear as opposed to the induction growth regime experienced at higher liquid solid ratios. L/S ratios less than 100% led to a bimodal distribution comprised of large distributions of ungranulated powder and large irregular granules. Insufficient water hampered the growth of granules due to lack of enough water bridges to connect the granules and powder, while the large molecules continued to agglomerate with particles as they rotated around the mixer. The nozzle end was augmented so that drop size as well as drop height could be adjusted and compared to single-drop granulation experiments in proceeding investigations. As individual factors, neither augmentation had significant contributions to granule size, but preliminary screens identified that interaction between increasing L/S ratio and decreasing drop size could lead to narrower distributions of particles as well as greater circularity. Preliminary screening also identified that decreasing the drop height of the nozzle could increase the rate of particle growth during the 110% L/S trials without changing the growth mechanisms, indicating a way to alter the rate of steady-state particle growth. This paper screens for which factors are most pertinent to associating single-drop and wet granulation in order to develop granulation models that can ascertain information from single-drop granulations and predict the shape and size distribution of any wet granulation, without the need to run costly wet granulation experiments.
ContributorsLay, Michael (Author) / Emady, Heather (Thesis advisor) / Muhich, Christopher (Committee member) / Holloway, Julianne (Committee member) / Arizona State University (Publisher)
Created2019
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Description
Rotary drums are commonly used for their high heat and mass transfer rates in the manufacture of cement, pharmaceuticals, food, and other particulate products. These processes are difficult to model because the particulate behavior is governed by the process conditions such as particle size, particle size distribution, shape, composition, and

Rotary drums are commonly used for their high heat and mass transfer rates in the manufacture of cement, pharmaceuticals, food, and other particulate products. These processes are difficult to model because the particulate behavior is governed by the process conditions such as particle size, particle size distribution, shape, composition, and operating parameters, such as fill level and rotation rate. More research on heat transfer in rotary drums will increase operating efficiency, leading to significant energy savings on a global scale.

This research utilizes infrared imaging to investigate the effects of fill level and rotation rate on the particle bed hydrodynamics and the average wall-particle heat transfer coefficient. 3 mm silica beads and a stainless steel rotary drum with a diameter of 6 in and a length of 3 in were used at fill levels of 10 %, 17.5 %, and 25 %, and rotation rates of 2 rpm, 6 rpm, and 10 rpm. Two full factorial designs of experiments were completed to understand the effects of these factors in the presence of conduction only (Case 1) and conduction with forced convection (Case 2). Particle-particle friction caused the particle bed to stagnate at elevated temperatures in Case 1, while the inlet air velocity in Case 2 dominated the particle friction effects to maintain the flow profile. The maximum heat transfer coefficient was achieved at a high rotation rate and low fill level in Case 1, and at a high rotation rate and high fill level in Case 2. Heat losses from the system were dominated by natural convection between the hot air in the drum and the external surroundings.
ContributorsBoepple, Brandon (Author) / Emady, Heather (Thesis advisor) / Muhich, Christopher (Committee member) / Holloway, Julianne (Committee member) / Arizona State University (Publisher)
Created2019
Description
This honors thesis is focused on two separate catalysis projects conducted under the mentorship of Dr. Javier Pérez-Ramírez at ETH Zürich. The first project explored ethylene oxychlorination over supported europium oxychloride catalysts. The second project investigated alkyne semihydrogenation over nickel phosphide catalysts. This work is the subject of a publication

This honors thesis is focused on two separate catalysis projects conducted under the mentorship of Dr. Javier Pérez-Ramírez at ETH Zürich. The first project explored ethylene oxychlorination over supported europium oxychloride catalysts. The second project investigated alkyne semihydrogenation over nickel phosphide catalysts. This work is the subject of a publication of which I am a co-author, as cited below.

Project 1 Abstract: Ethylene Oxychlorination
The current two-step process for the industrial process of vinyl chloride production involves CuCl2 catalyzed ethylene oxychlorination to ethylene dichloride followed by thermal cracking of the latter to vinyl chloride. To date, no industrial application of a one-step process is available. To close this gap, this work evaluates a wide range of self-prepared supported CeO2 and EuOCl catalysts for one-step production of vinyl chloride from ethylene in a fixed-bed reactor at 623 773 K and 1 bar using feed ratios of C2H4:HCl:O2:Ar:He = 3:3 6:1.5 6:3:82 89.5. Among all studied systems, CeO2/ZrO2 and CeO2/Zeolite MS show the highest activity but suffer from severe combustion of ethylene, forming COx, while 20 wt.% EuOCl/γ-Al2O3 leads to the best vinyl chloride selectivity of 87% at 15.6% C2H4 conversion with complete suppression of CO2 formation and only 4% selectivity to CO conversion for over 100 h on stream. Characterization by XRD and EDX mapping reveals that much of the Eu is present in non-active phases such as Al2Eu or EuAl4, indicating that alternative synthesis methods could be employed to better utilize the metal. A linear relationship between conversion and metal loading is found for this catalyst, indicating that always part of the used Eu is available as EuOCl, while the rest forms inactive europium aluminate species. Zeolite-supported EuOCl slightly outperforms EuOCl/γ Al2O3 in terms of total yield, but is prone to significant coking and is unstable. Even though a lot of Eu seems locked in inactive species on EuOCl/γ Al2O3, these results indicate possible savings of nearly 16,000 USD per kg of catalyst compared to a bulk EuOCl catalyst. These very promising findings constitute a crucial step for process intensification of polyvinyl chloride production and exploring the potential of supported EuOCl catalysts in industrially-relevant reactions.

Project 2 Abstract: Alkyne Semihydrogenation
Despite strongly suffering from poor noble metal utilization and a highly toxic selectivity modifier (Pb), the archetypal catalyst applied for the three-phase alkyne semihydrogenation, the Pb-doped Pd/CaCO3 (Lindlar catalyst), is still being utilized at industrial level. Inspired by the very recent strategies involving the modification of Pd with p-block elements (i.e., S), this work extrapolates the concept by preparing crystalline metal phosphides with controlled stoichiometry. To develop an affordable and environmentally-friendly alternative to traditional hydrogenation catalysts, nickel, a metal belonging to the same group as Pd and capable of splitting molecular hydrogen has been selected. Herein, a simple two-step synthesis procedure involving nontoxic precursors was used to synthesize bulk nickel phosphides with different stoichiometries (Ni2P, Ni5P4, and Ni12P5) by controlling the P:Ni ratios. To uncover structural and surface features, this catalyst family is characterized with an array of methods including X-ray diffraction (XRD), 31P magic-angle nuclear magnetic resonance (MAS-NMR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Bulk-sensitive techniques prove the successful preparation of pure phases while XPS analysis unravels the facile passivation occurring at the NixPy surface that persists even after reductive treatment. To assess the characteristic surface fingerprints of these materials, Ar sputtering was carried out at different penetration depths, reveling the presence of Ni+ and P-species. Continuous-flow three-phase hydrogenations of short-chain acetylenic compounds display that the oxidized layer covering the surface is reduced under reaction conditions, as evidenced by the induction period before reaching the steady state performance. To assess the impact of the phosphidation treatment on catalytic performance, the catalysts were benchmarked against a commercial Ni/SiO2-Al2O3 sample. While Ni/SiO2-Al2O3 presents very low selectivity to the alkene (the selectivity is about 10% at full conversion) attributed to the well-known tendency of naked nickel nanoparticles to form hydrides, the performance of nickel phosphides is highly selective and independent of P:Ni ratio. In line with previous findings on PdxS, kinetic tests indicate the occurrence of a dual-site mechanism where the alkyne and hydrogen do not compete for the same site.

This work is the subject of a publication of which I am a co-author, as cited below.

D. Albani; K. Karajovic; B. Tata; Q. Li; S. Mitchell; N. López; J. Pérez-Ramírez. Ensemble Design in Nickel Phosphide Catalysts for Alkyne Semi-Hydrogenation. ChemCatChem 2019. doi.org/10.1002/cctc.201801430
ContributorsTata, Bharath (Author) / Deng, Shuguang (Thesis director) / Muhich, Christopher (Committee member) / Chemical Engineering Program (Contributor, Contributor) / School of Sustainability (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
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Description
The current research is based on the principles of three-dimensional discrete element method (3D – DEM) through simulations, by using heat transfer models in EDEM, to investigate the effects of fill level, rotation rate and particle size on the steady-state conduction heat transfer in rotary drums. The high heat and

The current research is based on the principles of three-dimensional discrete element method (3D – DEM) through simulations, by using heat transfer models in EDEM, to investigate the effects of fill level, rotation rate and particle size on the steady-state conduction heat transfer in rotary drums. The high heat and mass transfer rates obtained through rotary drums make them very useful for powder mixing and heating processes in metallurgical, cement, mining, pharmaceutical, detergent and other particulate processing applications. However, these complex processes are difficult to model and operate since the particles can have a wide range of properties, and there is currently no way to predict the optimal operating conditions for a given material.

Steady-state heat transfer by conduction forms the basis for understanding other steady-state and unsteady-state heat transfer in a rotary drum – conduction, convection and radiation. Statistical analysis is carried out to determine the effects of these process parameters and find optimal operating conditions, which will thereby improve the heat transfer efficiency in rotary drums. A stainless-steel drum with a diameter of 6 inches and a length of 3 inches was modeled in EDEM with silica beads of sizes 2 mm, 3 mm and 4 mm at fill levels of 10%, 17.5% and 25%, and at rotation rates of 2 rpm, 5 rpm and 10 rpm. It was found that the heating uniformity increased with decreasing particle size, decreasing fill level and increasing rotation rate. This research is the first step towards studying the other heat transfer modes and various other process parameters. Better understanding of the various heat transfer modes, when used in combination for heating the particles, will be beneficial in improving the operating efficiency, reducing material costs and leading to significant energy conservation on a global scale.
ContributorsBheda, Bhaumik (Author) / Emady, Heather (Thesis advisor) / Muhich, Christopher (Committee member) / Nielsen, David (Committee member) / Arizona State University (Publisher)
Created2020
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Description
Lithium-ion and lithium-metal batteries are deemed to be the choice of energy storage media for the future. However, they are not entirely safe and their performance in terms of cycle life and charging rates is sub-optimal. A majority of these issues arise from the currently used flammable polyolefinic separators and

Lithium-ion and lithium-metal batteries are deemed to be the choice of energy storage media for the future. However, they are not entirely safe and their performance in terms of cycle life and charging rates is sub-optimal. A majority of these issues arise from the currently used flammable polyolefinic separators and carbonate solvent based electrolytes. This work utilizes in-house developed and specific property tuned electrode-coated inorganic separators in combination with a fire-proof electrolyte to resolve the above stated concerns.Firstly, to improve the safety of the lithium-ion cell with a commercial polypropylene separator a thermally stable in-house developed electrode coated quartz silica separator is utilized. The silica separator due to its better electrolyte wettability, electrolyte uptake and lower resistance also offers better capacity retention (~ 15 %) at high rates of discharge. Subsequently, research on developing a completely safe lithium-ion battery was conducted by replacing the traditional carbonate solvent based electrolyte with a fire-proof lithium bis-fluoro sulphonyl-imide salt/tri-methyl phosphate solvent electrolyte. However, this electrolyte has a high viscosity and low separator wetting rate. A microporous in house synthesized silicalite electrode-coated separator due to its high surface energy functionalizes the viscous fire-proof electrolyte and together they are tested in a full-cell. The intra-particle pores of the silicalite separator result in a thinner and more robust solid electrolyte interface on graphite. This results in about 20 % higher capacity retention during long term cycling when compared to the polypropylene separator used in the same full-cell. To enable stable and fast charging lithium-metal batteries free from dendrite propagation related failure, plate shaped γ-alumina and silicalite electrode-coated separators with high tortuosity are developed and used in a lithium-metal full-cell battery, with the former separator having no intra-particle pores and the latter having them. The γ-alumina separators show improvements in dendrite propagation prevention up to 3 C-rate of charge/discharge but a loss in active lithium is seen beyond the 75th cycle. However, microporous plate-shaped silicalite separators did not show any loss in active lithium even at 3 C-rate for 100 cycles due to the homogenized lithium-ion flux at the anode, while also preventing dendrite propagation.
ContributorsRafiz, Kishen (Author) / Lin, Jerry Y.S (Thesis advisor) / Muhich, Christopher (Committee member) / Kannan, Arunachala (Committee member) / Deng, Shuguang (Committee member) / Green, Matthew (Committee member) / Arizona State University (Publisher)
Created2021
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Description
Siloxane, a common contaminant present in biogas, is known for adverse effects on cogeneration prime movers. In this work, the solid oxide fuel cell (SOFC) nickel-yttria stabilized zirconia (Ni-YSZ) anode degradation due to poisoning by siloxane was investigated. For this purpose, experiments with different fuels, different deposition substrate materials, different

Siloxane, a common contaminant present in biogas, is known for adverse effects on cogeneration prime movers. In this work, the solid oxide fuel cell (SOFC) nickel-yttria stabilized zirconia (Ni-YSZ) anode degradation due to poisoning by siloxane was investigated. For this purpose, experiments with different fuels, different deposition substrate materials, different structure of contamination siloxane (cyclic and linear) and entire failure process are conducted in this study. The electrochemical and material characterization methods, such as Electrochemical Impedance Spectroscopy (EIS), Scanning Electron Microscope- Wavelength Dispersive Spectrometers (SEM-WDS), X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction (XRD), and Raman spectroscopy, were applied to investigate the anode degradation behavior. The electrochemical characterization results show that the SOFCs performance degradation caused by siloxane contamination is irreversible under bio-syngas condition. An equivalent circuit model (ECM) is developed based on electrochemical characterization results. Based on the Distribution of Relaxation Time (DRT) method, the detailed microstructure parameter changes are evaluated corresponding to the ECM results. The results contradict the previously proposed siloxane degradation mechanism as the experimental results show that water can inhibit anode deactivation. For anode materials, Ni is considered a major factor in siloxane deposition reactions in Ni-YSZ anode. Based on the results of XPS, XRD and WDS analysis, an initial layer of carbon deposition develops and is considered a critical process for the siloxane deposition reaction. Based on the experimental results in this study and previous studies about siloxane deposition on metal oxides, the proposed siloxane deposition process occurs in stages consisting of the siloxane adsorption, initial carbon deposition, siloxane polymerization and amorphous silicon dioxide deposition.
ContributorsTian, Jiashen (Author) / Milcarek, Ryan J. (Thesis advisor) / Muhich, Christopher (Committee member) / Wang, Liping (Committee member) / Phelan, Patrick (Committee member) / Nian, Qiong (Committee member) / Arizona State University (Publisher)
Created2022
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Description
This thesis presents the development of idiographic models (i.e., single subject or N = 1) of walking behavior as a means of facilitating the design of control systems to optimize mobile health (mHealth) interventions for sedentary adults. Model-on-Demand (MoD), an adaptive modeling technique, is demonstrated as an ideal method for

This thesis presents the development of idiographic models (i.e., single subject or N = 1) of walking behavior as a means of facilitating the design of control systems to optimize mobile health (mHealth) interventions for sedentary adults. Model-on-Demand (MoD), an adaptive modeling technique, is demonstrated as an ideal method for modeling nonlinear systems with noise on a simulated continuously stirred tank reactor (CSTR). Comparing MoD to AutoRegressive with eXogenous input (ARX) estimation, MoD outperforms ARX in terms of addressing both nonlinearity and noise in the CSTR system. With the CSTR system as an initial proof of concept, MoD is then used to model individual walking behavior using intervention data from participants of HeartSteps, a walking intervention that studies the effect of within-day suggestions. Given the number of possible measured features from which to design the MoD models, as well as the number of model parameters that influence the model’s performance, optimizing MoD models through exhaustive search is infeasible. Consequently, a discrete implementation of simultaneous perturbation stochastic approximation (DSPSA) is shown to be an efficient algorithm to find optimal models of walking behavior. Combining MoD with DSPSA, models of walking behavior were developed using participant data from Just Walk, a day-to-day walking intervention; MoD outperformed ARX models on both estimation and validation data. DSPSA was also applied to ARX modeling, highlighting the use of DSPSA to not only search over model parameters and features but also data partitioning, as DSPSA was used to evaluate models under various combinations of estimation and validation data from a single participant’s walking data. Results of this thesis point to ARX with DSPSA as a routine means for dynamic model estimation in large-scale behavioral intervention settings.
ContributorsKha, Rachael T (Author) / Rivera, Daniel E (Thesis advisor) / Deng, Shuguang (Committee member) / Muhich, Christopher (Committee member) / Arizona State University (Publisher)
Created2022
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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

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
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Description
This study presents an evaluation of the predicted flow behavior and the minimum outlet diameter in a computationally simulated hopper. The flow pattern in hoppers was simulated to test three size fractions, three moisture levels of microcrystalline cellulose (MCC), and two hopper wall angles in Multiphase Flow with Interphase eXchanges

This study presents an evaluation of the predicted flow behavior and the minimum outlet diameter in a computationally simulated hopper. The flow pattern in hoppers was simulated to test three size fractions, three moisture levels of microcrystalline cellulose (MCC), and two hopper wall angles in Multiphase Flow with Interphase eXchanges (MFiX). Predictions from MFiX were then compared to current literature. As expected, the smaller size fractions with lower water content were closer to ideal funnel flow than their larger counterparts. The predicted minimum outlet diameter in simulations showed good agreement with close to ideal flowability. These findings illustrate the connection between lab flowability experiments and computational simulations. Lastly, three fluidized bed simulations were also created in MFiX with zeolite 13X to analyze the pressure and velocity within the bed. The application of flowability simulations can improve the transport of solids in processing equipment used during the production of powders.
ContributorsBuchanan, Lidija (Author) / Emady, Heather (Thesis advisor) / Muhich, Christopher (Committee member) / Deng, Shuguang (Committee member) / Arizona State University (Publisher)
Created2023