Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 47 for “"reaction temperatures"”.
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The catalytic conversion of low chain length hydrocarbons to liquid fuels using ion exchange resin
… strongly influences the overall rate of the reaction. An increase in liquid production rate is obtained with increasing macroporosity, increasing degree of functionalization and decreasing catalyst bead size. A minimum acid strength of pKA = -2.4 is required. The liquid production rate is …
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The chemical effects of ultrasound
… the reactivity of heterogeneous, liquid-solid reactions has become a routine synthetic technique. Typically, ultrasound reduces reaction temperatures and increases rates of reaction while improving product yields. In spite of this, our understanding of the nature and range of sonochemistry is …
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Palladium (II) Mediated Transformation: Exploring Synthetic Methodology for the Synthesis of Cyclopentenones from Tertiary-Cyclobutanois
… cyclopentanone followed by Saegusa-Ito reaction to furnish final cyclopentenone product. Extensive efforts to transform this reaction into a catalytic process by screening various palladium(II) sources, ligands, oxidants, bases, solvents and reaction temperatures failed. Interesting and …
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The reductive animation of ethanol using supported metal catalysts
… to ethylamine product was obtained between reaction temperatures of 140 and 200°C, between ammonia to ethanol molar ratios ranging from 1 to 4 and between hydrogen to ethanol molar ratios ranging from 2 to 5. Depending on the partial pressures of the ethanol, ammonia and hydrogen feeds, …
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Synthesis and characterization of high performance polyimide homopolymers and copolymers
… either thermal or solution imidization at high temperatures to give the fully cyclized polyimides. This research focuses on the development of a low temperature solution polymerization route utilizing a transimidization method to make fully cyclized polyimide homopolymers and polyimide siloxane …
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Synthesis and characterization of heterocyclic polymers: polybenzoxazoles and cyanate ester networks
… 2-pyrrolidone (NMP). It was demonstrated that reaction temperatures of about 0 Cor lower were highly desired in order to obtain high molecular weight polyhydroxy amides. It was postulated that this lower temperature prevented pyridine catalyzed side reactions with the phenol group, which would …
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Desilicated ZSM-5 zeolite as catalyst for the dehydration of ethanol
… was higher for the parent zeolite at lower reaction temperatures. This was a direct consequence of the higher density of acid sites on the desilicated zeolite, which is comprised of BAS II in the presence of "unusual" Lewis acid sites of type II (LAS II). These Lewis acid sites were also …
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Testing of Burton's method to synthesize diamonds
… to increase the solubility of carbon in lead. Reaction temperatures between 775 K and 1025 K were used. The resulting precipitate, analyzed by both chemical and physical means, was found to be well-crystallized graphite. No diamond formation was found to occur.
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Characterization of fluorinated carbon nanotubes
Reaction temperatures and time are probed to get the optimal fluorination conditions in order to produce C2F carbon nanotubes. Possible fluorotube structures are optimized with molecular mechanics calculation. Results show that fluorines would like to add along the circumference of the tubes …
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Reaction Synthesis of HfB2 in a Variety of Metallic Environments
… due to its hardness, stability at elevated temperatures, as well as electrical and thermal conductivity. Experimental testing included differential scanning calorimetry (DSC) to reveal reaction initiation temperatures and enthalpies of reaction; and optical pyrometry to measure maximum …
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Zeolite deactivation during hydrocarbon reactions: characterisation of coke precursors and acidity, product distribution
… and aromatics respectively, at different reaction temperatures, time-on-streams and composition. Three novel techniques, coke classification, thermogravimetric method for characterising coke precursors and indirect temperature programmed desorption (TPD) for catalyst acid sites …
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Crystal Growth, Structure Determination and Physical Property of Complex Oxides
… advantages over other methods, including low reaction temperatures and easy reaction setup. Novel Fe, Co, Rh, Hf and Ln containing oxides have been synthesized from molten hydroxide fluxes. Their crystal structures were solved by single crystal X-ray diffraction, and their magnetic and …
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Synthesis and Characterization of New Aryl Phosphine Oxide and Ketone Containing Poly(arylene Sulfide Sulfone)s
… acetate, and deionized water, in NMP at elevated reaction temperatures and pressure. The effect of these variations, e.g., reaction temperatures and times, molar ratios of H2O-to-NaSH, NMP-to-H2O, etc. were investigated. Optimized conditions were defined, which produced Tg as high as 222°C, very …
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CO2 reduction over noble metal/carbon nanotube catalyst
… independently synthesized by a microwave reaction technique, show good catalytic activity for CO2 reduction in the contexts of dry reforming (DR) of methane (CH_4 + CO_2 -> 2CO + 2H_2) and reverse water gas shift (RWGS) (H2 + CO_2 -> CO + H_2O). Reaction temperatures range from 773 to 973 …
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The effect of metal type and loading on n-paraffin hydrocracking conversion and selectivity
… sulphur into a clean feedstock. Moreover, at reaction temperatures of around 250°C, transition metal sulphide catalysts display little activity. Thus, one may consider noble metals such as palladium or platinum, whilst shape selective zeolites may be used as the acid component.
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Development of a 3D Printer for Oxide-free Aluminum Transportation
… an inert oxide layer on its surface, preventing reaction. High reaction temperatures are required to overcome the oxide layer leading to a high energy penalty. This thesis proposes a novel concept of aluminum encapsulation with water-soluble polymer. A 3d printer was designed and fabricated which …
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Hydroxypropylation of lignin and lignin-like model compounds
Copolymerization reaction of propylene oxide and Kraft lignin with various catalysts, catalyst concentrations, at several temperature levels were studied. The reaction rate of propylene oxide was estimated from the pressure vs time diagram of the reaction and the copolymerization extent was …
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Hydrothermal liquefaction of wild-harvested cyanobacterial bloom from hypereutrophic Lake Tainter, Wisconsin
… strategy for air and water quality. HTL reactions were conducted over a range of reaction temperatures (280-350°C), holding times (30-60 min), and feedstock total biomass solids content (10%-25%TS) using fresh and aged biomass. Bulk biocrude properties (e.g., yield, elemental analysis, …
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Rational Design of Supported Metal Catalysts for Carbonyl Reduction During Biomass Upgrading
… of hydrogenation of acetone. The apparent reaction orders of hydrogen and acetone, apparent activation energies, and observed kinetic isotope effects over a large range of temperatures and concentrations (compound partial pressures) are reported in this document. Generally speaking, the …
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INVESTIGATION OF PROCESSING-STRUCTURE-PROPERTY RELATIONS IN VAPOR PHASE MODIFIED CELLULOSIC MATERIALS
… technique can be conducted at relative lower reaction temperatures (25 – 300 ℃) and realize a conformal coating on substrates with high aspect ratios. Reported literatures on ALD modified cellulose are more focus on functional coatings, replicas, physicochemical property of new generated …
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