<p> The quasi-steady state optimization of a single tubular fixed bed chemical reactor with a slowly decaying catalyst is considered. The optimal choice of temperature T(z,t) distributed in both the space of the reactor and in chronological time is sought so as to maximize the total amount of reaction in a fixed given period of time. A single irreversible reaction is considered with a rate expressible as a product of separate functions of temperature, activity and conversion. The rate of catalyst decay is also a product of separate functions of temperature and activity but independent of conversion. Upper and lower bounds are placed on the permitted temperature. Theoretical characterization of the optimal policy is obtained using Sirazetdinov and Degtyarev's maximum principle derived for first-order partial differential equations and the influence of the ratio of reaction activation energy to catalyst deactivation energy on the derived optimal policy is indicated. Numerical calculations are presented to illustrate the optimal policies.</p> / Thesis / Doctor of Philosophy (PhD)

A study has been made of the liquid-phase oxidation of p-cymene with air in the presence of cobalt naphthenate at temperatures 50, 105, and 160°C. A solid carboxylic acid product has been isolated and a chromatographic procedure developed for its quantitative separation into the following compounds: cumic acid, p-acetylbenzoic acid, p-(α -hydroxyisopropyl)benzoic acid, and p-(α-hydroperoxyisopropyl)benzoic acid. The hitherto unreported hydroperoxy-acid has been characterized by (a) neutralization equivalent, (b) peroxidic oxygen content, (c) reduction to the above mentioned hydroxy-acid, and (d) metal-catalyzed, decomposition to the hydroxy- and keto-acids. Two previously reported products of cymene oxidation, p-toluic acid and terephthalic acid, were not produced in the present study. Large amounts of tarry products were formed at the higher temperatures, and lower yields of the carboxylic acids were obtained. / Thesis / Master of Science (MS)

Ring-opening metathesis polymerization (ROMP) has gained attention over the last few decades for its versatility and robustness. Through the use of highly active metal catalysts, such as Grubbs' first-generation catalyst [G1, (PCy3)2(Cl)2RuCHPh] and Grubbs' third-generation catalyst [G3, (H2IMes)(Cl)2(pyr)2RuCHPh], ROMP can exhibit living characteristics for some monomer classes, most commonly substituted norbornenes. The high livingness of ROMP makes it well-suited for the synthesis of complex polymer architectures (e.g., bottlebrush polymers, star polymers, and (multi)block copolymers, among others). However, compared to other living polymerizations, quantitative studies on the kinetic factors affecting living characteristics in ROMP are lacking. This work describes the effects of several reaction factors on the livingness in Ru-mediated ROMP of norbornene-based monomers. We performed thorough studies on the effects of the anchor group, the series of atoms directly attached to the norbornene, in the synthesis of both linear and bottlebrush polymers. Using small molecule norbornene monomers, we studied monomer HOMO energy, rate of propagation (kp), catalyst decomposition [a proxy for the termination rate constant (kt)], and livingness in ROMP as measured by the kp/kt ratio. HOMO energies were used to predict the reactivity of various monomers based on the hypothesis that high HOMO energy would lead to high monomer reactivity and high kp values. We observed a positive correlation between the HOMO energy and kp with both G1 and G3 catalysts, but we observed a plateau in kp for monomers with the highest HOMO energy when polymerized with G3 catalyst. These results suggested that above a certain level, HOMO energy no longer influenced the rate-determining step. Additionally, the anchor group had no apparent effect on catalyst decomposition with either catalyst. Therefore, when examining the livingness in ROMP of linear polymers, differences in the kp/kt ratios were primarily controlled by the kp value. When studying the synthesis of bottlebrush polymers, we found a similar positive correlation between HOMO energy and kp for five macromonomer (MM) species. To evaluate livingness of MMs, we targeted various backbone degrees of polymerization (Nbb), 100–2000, and found that MMs with high kp,obs values reached higher conversion with lower dispersities (Đ) at high target Nbb values than MMs with low kp,obs values. Finally, we investigated the synthesis of bottlebrush pseudo-pentablock copolymers using MMs with the highest and lowest kp anchor groups. This study revealed higher MM conversion and lower Đ values for each block for the MM with the highest kp anchor group, compared to the lowest kp MM. Furthering the anchor group study, we synthesized a small molecule monomer and two macromonomers containing a norbornene–benzoladderene structure. We found this anchor group had a higher HOMO energy than all other (macro)monomers previously studied. However, kp was not higher for the small molecule monomer compared to the other monomers studied, supporting the plateau in rate observed for monomers above a certain HOMO energy. The higher HOMO energy for MMs did increase kp for one of the MM compared to other MMs previously studied, however the MM with side-chains in the ortho position on the anchor group had a lower kp than expected. This low kp was attributed to the side-chains being in closer proximity to the reactive chain end, compared to the MM with side-chains in the meta position, hindering addition of new MM units. Altogether, these experiments revealed how the anchor group impacts kp and livingness in ROMP, two factors that are essential for the synthesis of precise bottlebrush (co)polymers. The final chapter of this dissertation evaluates the effect of reaction atmosphere on livingness in Ru-mediated ROMP. Here we envisioned that changing the atmosphere, from under air to on a Schlenk line under N2 to in an N2-filled glovebox, would reduce the rate of chain termination and improve livingness in ROMP of small molecule and macromonomers. We synthesized linear or bottlebrush pseudo-pentablock copolymers to evaluate the livingness of foud (macro)monomer structures in three different atmospheres. We found better agreement between Mn,expected and Mn,obs as well as lower overall and apparent Đ values for the bottlebrush polymers polymerized in N2 atmospheres. Interestingly, the effect was more prominent for low kp (macro)monomers; in other words, ROMP reactions of (macro)monomers with high kp values were successful under air, but for those with low kp values, a glovebox was required to observe good control. / Doctor of Philosophy / Ring-opening metathesis polymerization (ROMP) is a powerful chemical method used to make a wide variety of polymers. With use of ruthenium-based catalysts, ROMP can exhibit living characteristics for some monomer classes, making it well-suited for the synthesis of precise linear and bottlebrush polymers. However, compared to other living polymerizations, quantitative studies on the kinetic factors affecting living characteristics in ROMP are lacking. This work describes the effects of several reaction factors on the livingness in ROMP of norbornene-based monomers. We thoroughly studied the effects of the anchor group, the series of atoms directly attached to the norbornene, in the synthesis of both linear and bottlebrush polymers. Using small molecule norbornene monomers, we studied the monomer HOMO energy, rate of propagation (kp), catalyst decomposition, and the livingness in ROMP. We used HOMO energy to predict the reactivity of various monomers and found that high HOMO energy led to high kp values. Additionally, the anchor group had no apparent effect on catalyst decomposition; however, the large variations in kp meant that the anchor group influenced livingness in ROMP. When studying the synthesis of bottlebrush polymers, we found a similar positive correlation between HOMO energy and kp for five macromonomer (MM) species. Attaching a polymer side-chain to the norbornene decreases kp significantly, therefore our goal was to evaluate the livingness in ROMP under conditions that experience lower kp than linear polymers. We targeted large bottlebrush polymers, backbone degree of polymerization (Nbb) up to 2000, The final portion of this dissertation evaluates the effect of reaction atmosphere on the livingness in Ru-mediated ROMP. A large factor of livingness is kt, which in ROMP is typically decomposition of the catalyst chain end evidenced by low molecular weight tails in size exclusion chromatography traces. Here we envisioned changing the atmosphere, from air to inert, would prevent chain termination and improve the livingness in ROMP. We again used the synthesis of linear and bottlebrush pentablock copolymers to evaluate the livingness of six (macro)monomer structures in three different reaction atmospheres, air, N2, and in a glove box. Polymerizations under N2 or in the glove box produced more well-defined polymers than polymerizations in air by a marginal degree. Therefore, the livingness in ROMP improves when air is removed.

This investigation consisted of a study of the break-in behavior of a tungsten oxide on silica catalyst during propylene disproportionation. A catalyst of 10 percent WO3 on silica gel (223 square meters per gram B.E.T. surface area) was used in a microcatalytic reactor. During the initial contacting of freshly activated samples of this catalyst with propylene, significant increases in disproportionation activity were observed for periods of up to 20 hours. The object of this study was to investigate the phenomena responsible for this break-in. The rate of approach to steady-state activity data were obtained using catalyst samples which were first saturated with each of the three gases involved in this reaction (propylene, ethylene, and 2-butene) by pulsing at .94 and 2.7 atmospheres before.starting the propylene flow. Effects of each gas on the break-in behavior of the catalyst were determined. A material balance around the reactor was made for each gas by pulse reactor techniques. / Ph. D.

Urban catalysts are new redevelopment strategies comprised of a series of projects that drive and guide urban development. Redevelopment efforts in the past, such as urban renewal and large-scale redevelopment projects, have often jeopardized the vitality of downtowns. The difference between the urban catalyst and these redevelopment strategies is that catalytic redevelopment is a holistic approach, not a clean-slate approach, to revitalizing the urban fabric. Many cities have considered urban catalysts as a means for revitalization. Among the most noted catalytic projects are sports stadiums and arenas: however not all catalytic projects have to be designed at such a grand scale, nor do all cities possess a threshold of support to successfully sustain such developments. This thesis design project examines the significance of the urban catalyst as a means of urban revitalization. The urban catalyst theory says design can be linked to place through the study of contextual factors in urban design. These factors include: morphological, social, functional, perceptual, visual, and temporal. For the urban catalyst to respond to its setting it also must possess a strong sense of place and authenticity. Each component of my research supports my position that each city has unique attributes that can serve as basic models or seeds for urban redevelopment. These components are used as a basis for developing a design framework that is applied to two sites in Memphis, Tennessee. This position is tested through the contextual analysis and design of two projects that are of major significance to Downtown Memphis, Tennessee. The first demonstrates the role that Court Square plays as a critical social and spatial element in the revitalization of the center city. The second is the revitalization of the South Side Neighborhood, an area full of history and character. / Master of Landscape Architecture

Electromagnetic and heat transfer analysis is used to determine possibility of selective heating of nanometer-sized, metallic catalyst particles attached to a ceramic support through microwave irradiation. This analysis is incorporated into a macroscopic heat transfer model of a packed and fluidized catalyst bed heated by a microwave field to predict thermal effects associated with selective heating of the catalyst sites. The model shows a dependence on particle size and microwave frequency on the selective heating of the catalyst sites. The macroscopic thermal effects are shown to be small for a typical experiment. However, changing the support material and catalyst particle size are shown to distinguish the thermal effects associated with selective heating of the metallic catalysts. / Master of Science

No / Mechanochemistry enabled the selective synthesis of the recherche´ orange polymorph of Wilkinson’s catalyst [RhCl(PPh3)3]. The mechanochemically prepared Rh-complex catalysed the solvent-free dehydrogenation of Me2NHBH3 in a ball mill. The in situ-generated hydrogen (H2) could be utilised for Rh-catalysed hydrogenation reactions by ball milling. / We thank the RWTH Aachen University for support from the Distinguished Professorship Program funded by the Excellence Initiative of the German federal and state governments, and the EPSRC for funding (EP/L019655/1).

<p dir="ltr">Additive manufacturing has introduced new possibilities for the design and manufacturing of monolith catalyst beds. Many hydrogen peroxide monolith catalyst beds are made of ceramics and washcoated through a complex process. However, creating a metal monolith bed with the tried-and-true silver catalyst could provide an alternative decomposition method for 90 wt.% hydrogen peroxide with easier manufacturing methods and similar or better decomposition efficiency. 91.2 wt.% hydrogen peroxide was decomposed with a lattice-type monolithic catalyst bed additively manufactured out of 316L stainless steel that was electroplated with pure silver. The variables investigated included the catalyst bed’s mass loading, chamber pressure, pressure drop, and length-to-diameter ratio (L/D). The catalyst bed had loadings of 0.1 lb_m/s/inch², 0.25 lb_m/s/inch², and 0.4 lb_m/s/inch². One catalyst bed configuration had an L/D of 2.6, while the other configuration had an L/D of 0.85. A modular throat controlled the chamber pressures for each catalyst bed loading case. The decomposition efficiency was calculated with the theoretical and expected characteristic velocity (c*) of the catalyst beds. The chamber pressures for the lowest bed loading and highest L/D ratio varied from 52 psia to 202 psia. The hydrogen peroxide decomposition efficiency was approximately 85% for the lowest chamber pressure and approximately 100% for the highest chamber pressure. The chamber pressures for the middle and highest bed loading and high L/D were 193 psia at the lowest to 325 psia at the highest. The decomposition efficiencies for all middle and highest bed loading tests with high L/D were 90% or higher for all tests. For all of the highest L/D tests, decomposition was also confirmed by observing videos of the exhaust plume, which was clear and showed no sign of flow channeling. For all of the highest L/D tests, the pressure drops in all of the middle bed loading cases were at or below 30% of the chamber pressure. The high chamber pressure, highest bed loading cases also had a pressure loss below 30% of the chamber pressure. The smallest L/D configuration performed significantly worse than expected, with efficiencies between 15-25% at chamber pressures between 33-75 psi. The silver electroplated on the stainless steel survived the 143 s of lifetime on the catalyst bed during testing with minimal to no silver loss determined by weight and visual inspection with a microscope post-test. The higher L/D catalyst bed tests prove that silver electroplated on to an additively manufactured stainless steel monolith is a viable method for creating a catalyst bed. More research is required to determine the lowest L/D possible, which resides somewhere between the two L/D cases studied, and higher bed loadings also require investigation.</p>

Two different catalysts (bis[N-(3-tert-butylsalicylidene)-pentafluoroanilinato] titanium (IV) dichloride and [1-(8-quinolyl)indenyl] chromium (III) dichloride catalysts) activated with aluminoxane based co-catalysts (MAO, PMAO, MMAO12 and MMAO3A) have been evaluated in the polymerisation of ethylene leading to UHMWPE having a reduced number of entanglements between the chains. The effect of a co-catalyst modifier (BHT) on the catalytic systems and the resulting polymers is also addressed. Both catalysts are capable to promote the synthesis of UHMWPE having a reduced amount of entanglements in the conditions used. Uniaxial solid-state deformation of UHMWPE samples of different molar masses have been evaluated and related with the entanglement state of the polymers synthesised. A clear relationship between some mechanical properties and the molar mass/entanglement density of the polymers synthesised has been found.

Thesis advisor: Amir H. Hoveyda / Catalytic enantioselective reactions are of great importance in synthetic organic chemistry. Thus, development of efficient, selective and easily accessible catalyst for various bond formations is the main task in our laboratories. First, we have developed the first broadly applicable enantioselective boryl conjugate addition reactions to a variety of α,β-unsaturated carbonyls, promoted by a chiral Lewis basic N-heterocyclic carbene. The valuable β-boryl carbonyls were further used in complex molecule syntheses. The mechanism of these C–B bond formations was studied in details. We have also developed a practical method for enantioselective addition of an allene unit to aryl-, heteroaryl- and alkyl-substituted Boc-aldimines. These efficient C–C bond formations, catalyzed by an aminophenol-derived boron-based catalyst, were further utilized in succinct syntheses of anisomycin and epi-cytoxazone. Finally, chiral NHC–Cu complexes were employed for site-, diastereo- and enantioselective silyl conjugate additions to acyclic and cyclic dienones and dienoates. The precious enantiomerically enriched allylsilane obtained can be converted into a ketone-aldol type product, which is difficult to access through alternative methods. / Thesis (PhD) — Boston College, 2015. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.