Doctor of Philosophy, The Ohio State University, 2022, Chemical Engineering

Catalysts play an important role in the chemical industry since they help increase the speed of chemical reactions and reduce waste generation. Catalysts are typically functionalized onto the surface of solid supports such as mesoporous silica materials to ensure easy separation from the product and make the manufacturing process more economically viable. Mesoporous silica materials (pore size > 2 nm) such as SBA-15 and MCM-41 are generally preferred for supporting catalysts because of their thermal stability, robustness, and tunable pore architecture. Whereas such silica supported catalytic materials hold promise, key synthesis-structure-activity relationships remain to be discovered to enable commercial implementation of these laboratory-based catalysts. Such synthesis-structure-activity relationship studies are important to make supported catalysts more industrially viable and better performing than their homogeneous counterparts. The current work focuses on obtaining synthesis-structure-activity relationships by varying design parameters for the mesoporous silica support and catalyst analogue. This is done using two catalytic systems: (i) Knoevenagel condensation catalyzed by tertiary amines functionalized on SBA-15, and (ii) Oxidative dehydrogenation of propane catalyzed by vanadium oxides functionalized on SBA-15. Whereas the SBA-15 support is predominantly mesoporous, it also has secondary micropores (pore size < 2 nm) in its structure. Our results reveal that reducing the micropore volume in the SBA-15 support (NMP SBA-15) enhances the catalytic performance of tertiary amines for Knoevenagel condensation in comparison to their regular micropore counterparts (REG SBA-15). Such performance enhancement is observed for a wide range of tertiary amine densities on the SBA-15 surface. This indicates the generality of the inhibiting effect of micropores on performance of tertiary amines for this reaction. The micropore volume of SBA-15 is observed to significantly d (open full item for complete abstract)

Committee: Nicholas Brunelli (Advisor); Aravind Asthagiri (Committee Member); Jessica Winter (Committee Member) Subjects: Chemical Engineering

Doctor of Philosophy, The Ohio State University, 2003, Chemistry

Polyesters derived from the ring-opening polymerization (ROP) of lactides formed from inexpensive renewable resources constitute one important class of biodegradable and biocompatible polymers. Herein, the preparation and characterization of a series of closely related magnesium and zinc compounds that are active for ROP of lactides are reported using three β-diiminate ligands L1, L2 and L3 where L1 = CH(CMeNC6H3-2,6-iPr2)2, L2 = CH(CMeNC6H4-2-tBu)2 and L3 = CH(CMeNC6H4-2-OMe)2. For the L1 ligand, L1Mg(NiPr2)•(THF), L1Zn(NiPr2), L1Mg(OtBu)•(THF), L1Zn(OtBu) and L1Zn(OSiPh3)•(THF) have been synthesized. All compounds initiate and sustain ROP of lactides. For a related series L1MX(THF)n, where n = 0 or 1, the reactivity follows the order M = Mg > Zn and X = OtBu > NiPr2 > N(SiMe3)2 > OSiPh3. Heterotactic polylactide (PLA) is produced from ROP of rac-lactide by the zinc catalysts in CH2Cl2. The magnesium catalysts produce atactic and heterotactic PLA in CH2Cl2 and THF, respectively. The resting states for Zn and Mg are proposed to be L1Zn(η2-OCHMeC(O)OP) and L1Mg(μ-OP)2MgL1. For the L2 ligand, L2MgNiPr2•(THF) and L2ZnNiPr2 are prepared. In solution, L2ZnNiPr2 exists as a mixture of syn- and anti-rotamers while L2MgNiPr2•(THF) exists only as a syn-rotamer. In the zinc compound, the syn-conformer is shown to be more reactive than the anti–conformer and is responsible for the polymerization. Heterotactic PLA is obtained in CH2Cl2 for the zinc compound and in THF for the magnesium compound. For the L3 ligand, L3MgN(SiMe3)2, [L3MgOtBu]2, L3ZnN(SiMe3)2, L3ZnOiPr and L3CaN(SiMe3)2•(THF) are prepared. The OMe groups of ligand L3 show little affinity toward zinc and in the ROP of rac-lactide give PLA with only moderately enhanced heterotactic tetrads. The OMe groups are shown to bind to Mg reversibly and display significant enhancement of heterotactic PLA. Herein, the first single-site calcium complexes of L1 and tris(pyrazolyl/indazolyl)borate ligands are reported and shown to (open full item for complete abstract)

Committee: Malcolm Chisholm (Advisor) Subjects:

Master of Science in Engineering, University of Akron, 2010, Chemical Engineering

Nitrogen Oxide (NO) and carbon monoxide (CO) are major pollutants in the exhaust streams of automobiles, power plants, and other combustion processes. The growing concerns for the environment have resulted in increasingly restrictive emission standards. The removal of NO and CO from exhaust gases is a challenging task. One method for harmful gas removal is using a catalyst for dissociation. This work explored an alternative method for catalytic reduction of NO. Polymer solutions with palladium catalyst and ceramic precursors were electrospun to form polymer nanofibers. These nanofibers were heated to form ceramic nanofibers with catalyst nanoparticles and were mixed with microfibers to form a nonwoven fibrous catalyst support structure. The concentration of the polymer was varied to create nanofibers with diameters ranging from 100 to 700 nm with a constant mass of catalyst particles per mass of fiber. The effect of the fiber diameter on the corresponding catalyst structure performance was tested. A surface area comparison test was completed to determine whether the reactions occur strictly on the surface of the catalyst or if diffusion occurs. An aging comparison was also completed which tested 1 week old catalytic filters compared to 6 months old. A conventional catalytic converter was tested to verify the performance was similar to the catalytic fibrous filter media containing only palladium. Experiments were carried out using a lab reactor to expose the media to a mixture of gases simulating an exhaust stream at room temperature to a maximum of 450°C. The reactor exhaust concentrations are measured using gas chromatography (GC) to determine the catalyst performance. Results indicated that the catalytic reaction performance was about the same for fiber sizes ranging from 100 to 700 nm on a mass basis with a reduction temperature of 325 – 350°C. The surface area comparison filter reduced at 275°C which showed that both surface catalyst particles and particles w (open full item for complete abstract)

Committee: George Chase Dr. (Advisor) Subjects: Chemical Engineering

Master of Science, Miami University, 2024, Chemical, Paper and Biomedical Engineering

Dehydrating glucose efficiently into 5-hydroxymethylfurfural (HMF) has been a heavily researched topic, particularly focusing on the use of more sustainable heterogeneous catalysts. This thesis highlights the potential of wood-derived biomass as a sustainable biomass source for catalyst production, contributing to the development of innovative, bio-based chemicals. This study presents the synthesis, characterization, and application of wood-derived catalysts derived from softwood, deinked paper sludge (DPS), and hardwood for the efficient conversion of glucose to 5-hydroxymethylfurfural (HMF). The prepared catalysts were characterized by BET, FTIR, TGA, and XRD analyses. Prepared catalysts were used in the conversion of glucose to HMF in a single phase at 130oC, and the effect of temperature was studied. The highest yield of HMF, 22.67% in a single phase was obtained from a sulfonated DPS catalyst. Dehydration of glucose to HMF in biphasic water: MIBK was also carried out, and an HMF yield of 30.34% was obtained. At the end of the reaction, the catalysts were easily recoverable through filtration. Overall, this work shows that biomass-based activated carbon catalysts are promising for converting glucose to HMF.

Committee: Keith Hohn (Advisor); Jason Berberich (Committee Member); Catherine Almquist (Committee Member) Subjects: Chemical Engineering

PhD, University of Cincinnati, 2023, Arts and Sciences: Chemistry

Carbon nanotubes (CNTs) offer unique properties that have the potential to address multiple issues in industry and materials science. But the synthesis of CNTs is expensive because of multistep catalyst preparation using physical vapor deposition (PVD) or chemical vapor deposition (CVD) techniques. This dissertation aims to develop protocols for the preparation of catalyst and catalyst support materials and their assembly into monolayer film using wet chemistry for the synthesis of vertically aligned carbon nanotubes (VA-CNTs). Chapter 1 shows the properties of CNTs, synthetic methodologies, limitations in catalyst preparation, and assembly for large scale synthesis. Chapter 2 covers the synthesis of spherical shape AlOx nanoparticles and their physical and chemical characterization. Monolayer assembly of catalyst support and catalyst nanoparticles were discussed in chapter 3. Chapter 4 covers the synthesis of bimetallic AlOx-Fe2O3 nanoparticles catalyst that contain both catalyst and catalyst support materials. A detailed characterization of bimetallic AlOx-Fe2O3 nanoparticles were addressed to understand the physical and chemical nature of the particles. Chapter 5 shows successful synthesis of VA-CNTs from monolayer assembly of bimetallic AlOx-Fe2O3 nanorice at different temperatures. Overall, my dissertation discussed the premade catalyst and catalyst support nanoparticles synthesis and their assembly into monolayer film using organic crosslinking molecules for successful growth of VA-CNTs. In conclusion, this work will benefit the CNTs synthesis process in different metal or metal oxide substrate with an easy and inexpensive approach.

Committee: Noe Alvarez Ph.D. (Committee Chair); Vesselin Shanov Ph.D. (Committee Member); Michael Baldwin Ph.D. (Committee Member) Subjects: Chemistry

Doctor of Philosophy (Ph.D.), University of Dayton, 2019, Mechanical Engineering

Heat removal capacity of catalytically cracked jet fuel using supercritical n- dodecane as a jet fuel analogue in a cylindrical packed bed reactor is examined. The cracking reactions are endothermic, and can be used in the design of a potential hypersonic vehicle fuel reactor. Fuel endotherm and product distribution were examined using three catalysts: a commercially available platinum catalyst on a ceramic support matrix, cerium applied to the platinum catalyst, and cerium applied to a ceramic support. Where much previous research has used catalyst coated tubes, this study made use of a solid catalyst structure in a packed bed to distribute the catalyst throughout the fuel flow in order to provide more surface catalyst sites. The packed bed was assumed to be an ideal plug flow reactor, with catalytic reactions that are radially uniform across the reactor diameter. For some experiments, water was added to the fuel mixture prior to heating for steam assistance to the n-dodecane pyrolysis reaction in order to examine the steam effect on carbon production and endotherm. Where previous research has used either used a catalyst to aid in endothermic thermal management or has focused on water addition to pyrolysis reactors in order to reduce coke formation, this study combines these approaches. A catalyst is used to initiate endothermic reactions at lower temperatures than would be achieved by thermal cracking alone, in conjunction with steam addition to reduce coking. The packed bed catalyst configuration provides continued catalytic action even as cracking temperatures increase and thermal cracking becomes dominant, thereby enhancing chemical heat sink. The cerium catalysts out-performed the platinum catalyst both in terms of increased endotherm and decreased carbon deposition. Steam assistance proved beneficial in decreasing carbon deposition, although at the cost of decreased dodecane conversion, hence endotherm. No appreciable product selectivity was observed for stea (open full item for complete abstract)

Committee: Jamie Ervin Ph.D. (Advisor); John Petrykowski Ph.D. (Committee Member); Thomas Reitz Ph.D. (Committee Member); Scott Stouffer Ph.D., P.E. (Committee Member) Subjects: Engineering; Mechanical Engineering

Doctor of Philosophy, Case Western Reserve University, 2014, Chemistry

A multilayer system denoted as Pt/TiN/Ti/Si(111) was created in UHV. Chemical and physical properties of these layers were studied with XPS and ARXPS. Results of the analysis shows that a ca. 1nm thick titanium nitride layer between platinum and silicon was sufficient to stop diffusion of Pt to Si at room temperature. Nature of the interaction of thin layers of Pt on titanium nitride showed that initially deposited monolayer of Pt produced Pt/Ti intermetallic compound while properties of subsequent layers suggested metallic Pt. Relevance and conclusions were discussed in relation to titanium nitride as a catalyst support in PEM fuel cells. Hydroxylamine was successfully deposited in UHV on well characterized clean and oxygen covered Pt(100). RAIRS analysis suggests specific orientation of hydroxylamine molecule on clean Pt(100) and non-specific adsorption in case of oxygen covered Pt(100). Subsequent heating was followed by desorption in case of clean Pt(100) and by chemical reaction in case of oxygen covered Pt(100).Relevance and conclusions were discussed in relation to nitrogen cycle and electrocatalytic denitrification.

Committee: Daniel Scherson (Advisor); Carlos Crespo (Committee Chair); Alfred Anderson (Committee Member); Gary Chottiner (Committee Member); Frank Ernst (Committee Member) Subjects: Chemistry; Physical Chemistry; Physics

Doctor of Philosophy, The Ohio State University, 2014, Chemistry

Strategic enhancement of urea organocatalysts using internally coordinated Lewis acids has allowed for the discovery of new and useful reactions. Specifically, the incorporation of transition metals onto urea scaffolds has been shown to improve catalytic activity when compared to traditional urea and thiourea catalysts. An example of this enhancement has been demonstrated in the development of hybrid urea palladacycles that have been shown to be highly active, hydrogen bond donor catalysts in the activation of substrates not amenable to traditional urea catalysis, such as alkylidene malonates. Other internal Lewis acids such as platinum, silicon and boron have also been incorporated onto urea scaffolds, and the new catalysts have been compared in their abilities to activate new substrates such as nitrocyclopropane carboxylates and nitrodiazoesters. Correlations between catalyst structure and activity show that increased acidity due to internally coordinated Lewis acids is one of the important factors in urea catalyst design. To compare the internal Lewis acids' effects on acidity and on catalyst activity, the pKas of differently internally-coordinated catalysts have been determined and found to range from a highly acidic 6.8 for a coordinated palladium to a weakly acidic 16.0 for a silicate urea. Boronate ureas surveyed had intermediate pKas of 7.5 and 9.5. The different catalysts' abilities to activate both nitrocyclopropanes and nitrodiazoesters by coordination to the nitro group have also been investigated by studying the rates of these reactions. An internally coordinated difluoroboronate urea has been determined to be the best catalyst for both reaction systems. Using urea catalysts, a new organocatalytic coupling strategy has also been discovered. Specifically, nitroamines and nitrimines have been identified as urea-activated handles allowing for useful carbon–heteroatom and carbon–carbon coupling reactions. This reaction mode has been shown to (open full item for complete abstract)

Committee: Anita Mattson (Advisor) Subjects: Chemistry; Organic Chemistry

MS, University of Cincinnati, 2010, Engineering and Applied Science: Electrical Engineering

Carbon nanotubes have excellent electrical and mechanical properties, which are ideally suited for field emission and sensor/actuator applications. The catalyst layer needed for CNT growth (Fe, Ni or Co) once coated on the substrate is subject to an annealing step, which results in the formation of tiny globules of randomly aligned particles. CNTs finally grow on these randomly placed catalyst particles after the substrate annealing. The disadvantage of the bottom-up approach is that the catalyst globules are susceptible to migration on the substrate during thermal annealing and the CNT growth process. The scope of this thesis includes: (1) Patterning arrays of nano-/micro- features by e-beam lithography, (2) shallow etches of the holes by plasma etching in these features (3) deposition of the catalyst material into the shallow holes, (4) CNT growth, and (5) characterization of the patterned nano/micro-scale CNT catalysts and CNT growth. The main objective in this thesis is to immobilize the catalysts on the substrate at a specific location with an array of shallow holes. We believe this will localize and anchor the catalyst producing patterned arrays of CNT's. This method process will also be compared with the current methods of catalyst immobilization developed by Dr. Shanov's group where an alumina layers acts as the catalyst anchor layer. Also CNT growth is compared and with a substrate with no immobilization of the catalyst. The differences in catalyst morphology between annealing the substrate in air and nitrogen will also be compared. All the comparisons are done across different diameters of patterned features on the substrate. This new process will allow for the controlled patterning of CNT growth and enable CNT's to be integrated into manufacture able devices.

Committee: Marc Cahay PhD (Committee Chair); Vesselin Shanov PhD (Committee Member); Robert Jones PhD (Committee Member) Subjects: Materials Science

Master of Science, Miami University, 2004, Paper Science and Engineering

The use of nanostructured V2O5 / TiO2 and WO3 / V2O5 / TiO2 catalysts was investigated for the low temperature oxidation of methanol. A wet incipient method was used to dope WO3 and V2O5 on the Ishihara ST-01 TiO2 support. The V/Ti mass ratios varied from 0 to 0.10 for the V2O5 / TiO2 catalysts, and the W/Ti mass ratios varied from 0 to 0.10 with constant V/Ti mass ratio = 0.02 for the WO3 / V2O5 / TiO2 catalysts. Characterization of the catalysts using X-ray Diffraction, BET surface area and Raman Spectroscopy showed that the thermal stability of catalysts decreased with increasing V/Ti mass ratio over 0.02 but increased with increasing W/Ti mass ratio. The catalytic activity for methanol oxidation increased with W/Ti mass ratio up to W/Ti = 0.05. The catalyst having 0.05 V/Ti mass ratio and calcined at 400 °C showed the highest catalytic activity.

Committee: Catherine Almquist (Advisor) Subjects: Engineering, Environmental

Doctor of Philosophy, Case Western Reserve University, 1993, Chemistry

The objective of this thesis research has been to study the electrochemical and electrocatalytic properties of lithiated nickel oxide. The major reaction studied in the present research was O2 reduction. Lithiated nickel oxide was used both as the catalyst for O2 reduction and as a catalyst support for platinum. The properties of transition metal macrocycles as O2 reduction catalysts were also examined on lithiated nickel oxide and other oxides. The first part of this work involved the synthesis of different forms of lithiated nickel oxides, including mosaic crystals with (100) faces, air-grown films and powder samples. The physical and chemical properties of these samples were characterized, including surface morphology, surface area and conductivity. The intrinsic electrochemical properties were also studied, using cyclic voltammetry both in acid and alkaline solution. The second part of this work involved the examination of O2 reduction on lithiated nickel oxide at different temperatures. In alkaline solution, O2 reduction proceeds at significant rates on this electrocatalyst but does not do so in acid solution. At room temperature, O2 reduction proceeds via a two electron reduction pathway, with peroxide as the product. At elevated temperatures, O 2 reduction becomes much more active, and a nearly four electron reduction process was achieved when the temperature approached to ∼200°C. The third part of this work involved the examination of lithiated nickel oxide as a catalyst support for Pt. At room temperature on single crystal-like mosaic crystal electrodes, it was found that the Pt/(Li)NiO junction plays an inhibiting role in the electrochemical reduction process due to the p-type character of (Li)NiO. However, at elevated temperatures and on powdered samples (having more defects on the surfaces), lithiated nickel oxide shows promising performance as a support for Pt. The fourth part of this work involved the study of the behavior of the O2 reduction catalyst (open full item for complete abstract)

Committee: Ernest Yeager (Advisor) Subjects: Chemistry, Physical

Master of Science, University of Akron, 2011, Polymer Science

The goal of this research project was to develop a catalyst for the copolymerization of carbon monoxide (CO) and epoxides and/or aldehydes. Zwitterionic palladium and nickel complexes were synthesized that contained bidentate phosphine-borate ligands. Under the assumption that a polymerization mechanism similar to the established cobalt-catalyzed copolymerization of CO and aziridines is applicable, the zwitterionic nature of the complexes were expected to posses the high activity of cationic metal-acyl bonds, while maintaining the anionic nature required for ion pairing during the polymerization. Characterization of the nickel complex was completed through NMR spectroscopy, FTIR spectroscopy, and X-ray crystallography. Upon completion of the metal complex syntheses a variety of polymerization conditions were screened, and the products were characterized by NMR and IR spectroscopy. Although the spectroscopic methods showed the system had activity, a pure polymer product was not obtained.

Committee: Li Jia Dr. (Advisor); Colleen Pugh Dr. (Committee Member) Subjects: Chemistry; Polymer Chemistry; Polymers

Doctor of Philosophy, University of Akron, 2024, Polymer Science

The large carbon footprint of plastic production and the detrimental environment impact of plastic waste demand sustainable substitutes for current non-degradable, fossil-based polymeric materials. Transition-metal catalyzed carbonylative polymerization (COP) offers a methodology to introduce organic carbonyl functional groups to the backbone of polymers in a potentially sustainable way. The organic carbonyl groups bring about degradability under various conditions that are met on the surface of earth. Utilizing carbon monoxide as a cost-effective, low-carbon footprint starting material is key to this process. Carbonylative polymerizations of olefins catalyzed by Pd catalysts have been well-studied since the 1960s. This dissertation studies the development of Ni catalysts for carbonylative polymerizations of olefins. A particular emphasis will be catalyst development to incorporate “defects” in the backbone of alternating CO-ethylene copolymer to improve processibility and mechanical properties of the polymer products. An overview of transition-metal catalyzed carbonylative polymerization will be provided in Chapter I. Chapter II will discuss our zwitterionic Ni catalysts for alternating copolymerization of CO and ethylene. Chapter III will explore new catalyst designs to achieve the non-alternating copolymerization of CO and ethylene. Chapter IV will discuss a novel family of Ni catalysts that are capable of catalyzing the terpolymerization of CO, ethylene and propylene.

Committee: Li Jia (Advisor); James Eagan (Committee Chair); Christopher Ziegler (Committee Member); Kevin Cavicchi (Committee Member); Junpeng Wang (Committee Member) Subjects: Chemistry; Materials Science; Organic Chemistry

Master of Science, Miami University, 2024, Chemical, Paper and Biomedical Engineering

Cyclohexane is used in the production of consumer products and fuels and as a solvent. Based upon its industrial relevance, cyclohexane was selected as a representative volatile organic compound (VOC) with which to investigate the role of metal oxide supports in potassium/manganese (K/Mn) – based catalysts. Mn-based catalysts are effective catalysts due to their several oxidation states, mobility of oxygen vacancies, and redox properties. Cryptomelane, a K/Mn-based catalyst material, has been shown by others to be an effective VOC oxidation catalyst. In this study, K/Mn-based catalysts supported on various metal oxide materials were investigated for cyclohexane deep oxidation. The short-term activity of K/Mn on supports followed the trend: Fe3O4 > MnO2 > Al2O3 > TiO2 > SiO2. The performance of Fe3O4-supported and MnO2-supported catalysts with varying K/Mn and Mn loadings were investigated further. The catalysts were characterized for surface area, pore size, morphology, crystallinity, and crystal structure. At 350°C, the catalysts with the lowest loading of 0.63 mmoles K/Mn/g Fe3O4 exhibited the best short-term catalytic activity in the deep oxidation of cyclohexane, while 0.63 mmoles K/Mn/g MnO2 performed best over 95 hours. FTIR spectroscopy was used to assess partial oxidation product build-up on used catalysts.

Committee: Dr. Catherine Almquist (Advisor) Subjects: Chemical Engineering

Master of Science, University of Akron, 2024, Polymer Engineering

Highly branched low-density polyethylene (HB-LDPE) synthesized from solely ethylene monomer through Brookhart-type α-diimine nickel or palladium catalysts have unique microstructure, low melting temperature and thermal plastic elastomer (TPE) properties. With the increasing demand for recyclable material, synthesis of HB-LDPE has been extensively studied. However, details of its microstructure and the impact of the microstructure on solid structure as well as mechanical/thermal properties have not been fully understood. In this study, various characterizations and mechanical testing are conducted on HB-LDPE entries synthesized by original Brookhart catalyst, 8-p-tolylnaphthylimino substituted sandwich catalyst, and a multinuclear heterogeneous crosslinked catalyst. First, 13C solution-state NMR spectroscopy was employed to obtain detailed insights into their branch structure, including branch density, identity and localization. Using chemical superposition methods, detailed localization structure of the branches were revealed. Formation mechanisms of several localization structures are proposed in supplementary for existing chain walking mechanisms. Second, the solid structure of HB-LDPEs was investigated by using differential Scanning calorimetry (DSC), X-ray diffraction (XRD) and solid-state NMR spectroscopy. The formers are no longer capable of quantitative characterization due to the low crystallinity. Through solid-state 13C NMR analysis, it was found that some entries are entirely amorphous, while the others are semi-crystalline entries which range between 1 and 5 %. The molecular dynamics in the crystalline phase is characterized through 13C spin-lattice relaxation time (T1C), which ranges from 4s to 80s, implying a variable crystalline size. By examining the combination of microstructure and crystalline structure, it is revealed that only those entries with both low levels of long chain branching (LCB) below 10 b/1kC and short chain branching (SCB) below (open full item for complete abstract)

Committee: Toshikazu Miyoshi (Advisor); Junpeng Wang (Committee Member); James Eagan (Committee Chair) Subjects: Materials Science; Molecular Chemistry; Molecular Physics

PHD, Kent State University, 2023, College of Arts and Sciences / Department of Physics

Photo-physical properties of various materials are investigated computationally, accounting for the effect of the condensed phase molecular environment. The polarizing molecular environment can strongly affect the fundamental properties of the molecular subunits, such as their ionization potential (IP) and electron affinity (EA). A caveat that limits traditional density functional theory (DFT) is the tendency to underestimate the orbital gap, whereas the orbital gap should correspond to the IP and EA. Functionals bearing a range separation hybrid (RSH) or a long-range correction (LRC) have been developed and shown to properly open up the frontier gap in the gas phase. However, their deployment to address condensed phase systems, for example, by invoking the polarizable continuum model (PCM), fails to provide a predictive description of environmental polarization effects. In a recent development, RSH functionals have been extended to condensed phase calculations using PCM by a framework that consistently accounts for environmental polarization. In this combined PCM-DFT framework, dielectric long-range (LR) interactions are also screened in the functional expression in addition to the inherent screening through PCM. These functionals are referred to as screened RSH (SRSH) functionals. In this dissertation, we develop the SRSH-PCM framework and extend it toward several new types of systems and applications. We address triplet excited states where SRSH-PCM was shown for the first time to address the singlet-triplet gap appropriately, similarly to the correspondence of the orbital gap to electron removal and addition energies that lie at the foundation of the RSH DFT level. Following the triplet formation at the special pair, P, we investigate the triplet-excitation energy transfer (TEET) in the bacterial reaction center (BRC). The antioxidative TEET is the crucial process for protecting the photosynthesis system from the formation of cell-damaging singlet oxygen speci (open full item for complete abstract)

Committee: Barry D Dunietz Professor (Chemistry & Biochemisctry), advisor (Committee Chair); John Portman Professor (Physics), co-advisor (Committee Member); Michael Strickland Professor (Physics), Chair (Committee Member); Schmidt Thorsten-Lars Professor (Physics) (Committee Member); Arvind Bansal Professor (Computar Science),Graduate Faculty Repr (Committee Member) Subjects: Physical Chemistry

Doctor of Philosophy, University of Akron, 2023, Chemical Engineering

Sustainable development becomes an important topic due to the escalating energy shortage and environmental change. Governments around the world have taken various steps and implemented several initiatives in addressing pressing environmental issues. Green technology and innovations have been largely promoted not only in cutting-edge research but also in industry and manufacturing sectors. Among those sustainable practices, methane conversion, hydrogen storage, and fuel cell play crucial roles that promote energy efficiency and contribute to a circular economy. The dissertation aims to understand the chemical aspects in these three fields for sustainable development. For example, (1) methane, as a potent greenhouse gas, significantly contributes to global warming. By converting methane into value-added chemicals under mild conditions, sustainable development benefits can be achieved. (2) Hydrogen as green energy is an important research topic but has great challenges in its storage with hydrogen's low density. Efficient hydrogen storage technologies are required to enable the efficient utilization of hydrogen. (3) Fuel cells offer a clean and efficient alternative to traditional energy conversion technologies, which convert the chemical energy of a fuel directly into electricity through an electrochemical reaction. A new concept of a regenerative fuel cell is being discussed that has the ability to convert electricity back to chemical energy. These sustainable practices: methane conversion, hydrogen storage, and regenerative fuel cell, drive technological innovation and opportunities in catalyst materials, new energy, and electrochemistry.

Committee: Zhenmeng Peng (Advisor); Qixin Zhou (Committee Member); George Chase (Committee Member); Chrys Wesdemiotis (Committee Member); Toshikazu Miyoshi (Committee Member) Subjects: Chemical Engineering; Chemistry; Computer Engineering; Environmental Engineering

Doctor of Philosophy, The Ohio State University, 2023, Chemical Engineering

Investigating the impact of the structure of heterogeneous catalysts on performance is crucial for designing catalysts with enhanced activity. A significant challenge is creating uniform catalytic materials since current synthetic methods tend to produce materials with a wide distribution of catalytic sites. Indeed, materials that are seemingly simple have been revealed to be staggeringly complex, including materials such as zeolites, alumina, silica, and aminosilane modified materials called amino-silicas. Amino-silica heterogeneous catalysts are widely used in many applications, including pharmaceuticals, carbon dioxide adsorption, and biomass upgrading. Amino-silica materials can be designed with cooperative interactions to enhance catalytic performance in different reactions, such as the aldol reaction and condensation. One common mesoporous support is Santa Barbara Amorphous 15 (SBA-15). SBA-15 has exceptional properties, including thermal stability and high surface area. The porosity of SBA-15 can be tuned through synthesis conditions. In this dissertation, we demonstrate that limiting the micropore volume in SBA-15 can further increase the overall catalytic performance. This result indicates that catalytic sites located within micropores are inactive during catalytic reactions, disproving the previous assumption that all sites have equal contributions. We conduct a poisoning test to quantify the catalytic sites on both regular (REG) and negligible-micropore (NMP) SBA-15. The results of site quantification demonstrate that amine-functionalized SBA-15 has multiple types of catalytic sites with different activities, including high activity, medium activity, low activity, and inactive sites. With our new understanding of different types of sites in aminosilica materials, it was intriguing to re-evaluate previous observations (e.g., surface density) through the lens of whether the difference was associated with the activity of the sites or the fraction of catal (open full item for complete abstract)

Committee: Nicholas Brunelli (Advisor); Yiying Wu (Committee Member); Lisa Hall (Committee Member); Aravind Asthagiri (Committee Member) Subjects: Chemical Engineering

Master of Science, The Ohio State University, 2023, Chemistry

In recent times, there has been a growing interest among scientists in the preparation of a low-valent calcium (Ca) complex, driven by its potential as a potent reductant capable of reducing nitrogen gas (N2), hydrogenation chemistry, or its application in the development of novel heterogeneous catalysts. Consequently, the objective of our research is to establish a solution-phase route for synthesizing a reduced calcium complex, investigate its electrochemical behavior, and gain insights into its properties. The present study centers on the reduction chemistry of calcium, employing both electrochemical and chemical synthesis techniques. Electrochemical investigations involving cyclic voltammetry and chronoamperometry in a tetrahydrofuran (THF) solution were carried out to determine the reduction potentials of the calcium precursors: i. Bis(N,N-di-i-propyl formamidinato) calcium(II) dimer and ii. Bis(2,2,6,6-tetramethyl-3,5-heptanedionato)calcium, [Ca(TMHD)2], as well as the lithium-naphthalene reducing agent. These experiments aimed to evaluate the feasibility of achieving calcium reduction to its zero-valency state and identify suitable reducing agents for the precursors. This research highlights the intricate nature and sensitivity of calcium reduction chemistry, underscoring the importance of careful selection of solvents and reductants. Future investigations will concentrate on alternative characterization techniques and the development of efficient synthetic approaches to further enhance the understanding and manipulation of molecular calcium complexes for diverse applications.

Committee: Dr. Joshua Goldberger (Advisor); Dr. Yiying Wu (Committee Member) Subjects: Chemistry

Doctor of Philosophy, The Ohio State University, 2023, Chemical Engineering

To meet the ever-growing demand for production of chemicals while lowering the environmental impacts of traditional processes, development of novel sustainable routes is the need of the hour. One such process is the production of nylon, wherein the precursors: adipic acid and caprolactam, involves the use of fossil-derived benzene as the starting material. Utilizing bio-derived feedstocks like lignocellulosic biomass for production of these chemicals is an alternative, which constitutes hydrogenation of phenols into cyclohexanone and cyclohexanol. Bio-oil, from lignocellulosic biomass, contains a significant amount of water (15-30 vol.%). A catalyst, which can upgrade this bio-oil with optimal activity, selectivity, and stability in an aqueous medium, is desirable. Swellable Organically Modified Silica (SOMS), a novel, hydrophobic, animated organic-inorganic hybrid material with a high affinity for organics, is an excellent candidate for a catalyst support for upgrading the aqueous fraction of bio-oil. This study explored the applicability of SOMS for aqueous phase hydrogenation of bio-oil using phenol as a model molecule. Studying the properties of SOMS and its application as a catalyst support for aqueous phase hydrodechlorination (HDC) of trichloroethylene (TCE) provided insights to extend SOMS to phenol hydrogenation. The study involved identifying the effect of surface hydrophobicity on adsorption of phenol, both in vapor phase and liquid phase. Various SOMS samples: modified hydrophilic surface underivatized SOMS (SOMS-UD), hydrophobic non-swellable post-drying derivatized SOMS (SOMS-PDD), were synthesized and compared with the conventional mesoporous silica, SBA-15, to determine the impact of structural changes on catalytic activity for phenol hydrogenation. To probe the interaction of phenol with organosilica supports, the aromatic content in the bulk structure of SOMS-UD was altered by blending in an ethane-bridged organosilane precursor along with t (open full item for complete abstract)

Committee: Dr. Umit Ozkan (Advisor); Dr. Jeffrey Chalmers (Committee Member); Dr. Xiaoguang Wang (Committee Member); Dr. Ioanna Papandreou (Committee Member) Subjects: Chemical Engineering