Advanced search options

Advanced Search Options 🞨

Browse by author name (“Author name starts with…”).

Find ETDs with:

in
/  
in
/  
in
/  
in

Written in Published in Earliest date Latest date

Sorted by

Results per page:

Sorted by: relevance · author · university · dateNew search

You searched for +publisher:"Oregon State University" +contributor:("Yokochi, Alexandre F."). Showing records 1 – 2 of 2 total matches.

Search Limiters

Last 2 Years | English Only

No search limiters apply to these results.

▼ Search Limiters


Oregon State University

1. Jones, Jacob Aaron. Deep desulfurization of diesel fuel using a single phase photochemical microreactor.

Degree: MS, Chemical Engineering, 2010, Oregon State University

There is an urgent need to lower the concentration of sulfur in diesel fuels. Growing concern over environmental effects caused by burning sulfur-containing diesel has led the world to higher standards in fuel refinement. Because of these lower standards, many techniques have been researched to remove sulfur containing compounds or otherwise reduce the sulfur content. Hydrodesulfurization remains the primary method to reduce most light sulfur-containing compounds. This process removes sulfides, sulfates, and thiols using high temperature and pressure reactions but is unable to remove aromatics and long chains containing sulfur molecules. Biodesulfurization has also been considered, utilizing microorganisms to target specific sulfur-containing compounds to remove the sulfur while leaving the high energy fuel intact. Oxidative reactions have also been considered including photocatalytic oxidation in an attempt to oxidize these aromatic compounds so that they may be removed using a polar solvent. An ultraviolet light assisted oxidative reaction occurring in a microreactor was studied. Dibenzothiophene was used as a model refractory organic compound mixed in Decane as a solvent. Dibenzothiophene undergoes a series of oxidative reactions which produce an intermediate, Dibenzothiophene Sulfoxide, and a final product, Dibenzothiophene Sulfone. This reaction only proceeds in the presence of Tert-Butyl Hydroperoxide and ultraviolet light. These reactions are reversible and an equilibrium is established between Dibenzothiophene, Dibenzothiophene Sulfoxide, and Dibenzothiophene Sulfone. The equilibrium is strongly affected by the molar ratios of the reactants. Increasing the molar ratio of Tert-Butyl Hydroperoxide to Dibenzothiophene reduces the concentration of Dibenzothiophene in the product stream or causes the reaction to shift its equilibrium towards the products. Equilibrium may not be affected by Temperature. Previous studies have shown that equilibrium concentrations have a temperature dependence. However, under the conditions of this research there was no indication of a temperature dependence. It is possible that because of the molar ratios used the reaction did not proceed appreciably regardless of temperature so the temperature dependence was not apparent. A Taylor dispersion apparatus was assembled to measure infinite dilution diffusion coefficients for Dibenzothiophene, Dibenzothiophene Sulfoxide, Dibenzothiophene Sulfone, and Tert-Butyl Hydroperoxide were measured. Values were close to those calculated using the Wilke-Chang equation. These coefficients along with measured absorption coefficients were important in developing an accurate mathematical model. A mathematical model was developed to include convective and diffusive flux, fluid transport, and reaction kinetics. COMSOL™ Multiphysics was used to numerically solve the mathematical model. Experimental data is fitted to the model to determine the reaction rate constants for each of the reversible reactions. The model was compared to previously reported… Advisors/Committee Members: Yokochi, Alexandre F. (advisor), Penner, Mike (committee member).

Subjects/Keywords: Desulfurization; Diesel fuels  – Desulfurization

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Jones, J. A. (2010). Deep desulfurization of diesel fuel using a single phase photochemical microreactor. (Masters Thesis). Oregon State University. Retrieved from http://hdl.handle.net/1957/18974

Chicago Manual of Style (16th Edition):

Jones, Jacob Aaron. “Deep desulfurization of diesel fuel using a single phase photochemical microreactor.” 2010. Masters Thesis, Oregon State University. Accessed October 14, 2019. http://hdl.handle.net/1957/18974.

MLA Handbook (7th Edition):

Jones, Jacob Aaron. “Deep desulfurization of diesel fuel using a single phase photochemical microreactor.” 2010. Web. 14 Oct 2019.

Vancouver:

Jones JA. Deep desulfurization of diesel fuel using a single phase photochemical microreactor. [Internet] [Masters thesis]. Oregon State University; 2010. [cited 2019 Oct 14]. Available from: http://hdl.handle.net/1957/18974.

Council of Science Editors:

Jones JA. Deep desulfurization of diesel fuel using a single phase photochemical microreactor. [Masters Thesis]. Oregon State University; 2010. Available from: http://hdl.handle.net/1957/18974


Oregon State University

2. Dickson, David J. Influence of processing parameters on diffusion of divalent nickel in wet silica sol-gel monoliths.

Degree: MS, Materials Science, 2010, Oregon State University

The diffusion of divalent nickel (Ni²⁺) from wet silica gels was investigated. Silica gel is gaining interest as an encapsulation matrix for biological components. The transport of biologically relevant species within the gel is determined by the structural characteristics of the gel, which are in turn governed by synthesis parameters. Gels were synthesized by an acid-base two step process from tetraethoxysilane (TEOS) precursors. Organically modified siloxane precursors, including methyltriethoxysilane (MTES), dimethyldiethoxysilane (DMDES), trimethylethoxysilane (TMES), and ethyltriethoxysilane (ETES) were also used for some samples at a concentration of 10 molar % of silicon. PEG200 was used as an additive in some samples. Sample space covered a full factorial design of three water ratios during hydrolysis of 4:1, 10:1 and 20:1, three acid catalyst concentrations as a ratio of silicon to acid, including 1:0.005, 1:0.01, and 1:0.02, and four dilution ratios during gelation to yield gels with a final silica content of 40:1, 60:1, 80:1, and 100:1, moles of water to moles of silicon. This processing space was selected due to its relevance to applications in the encapsulation of biological components. Using Ni²⁺ as a tracer due to its strong absorbance peak at 395 nm, diffusion coefficients were calculated for all samples using both an analytical solution to Fick's Law, appropriate for one-dimensional diffusion, and an exponential empirical approximation. Estimates were calculated using Microsoft Solver and ANOVA in SAS. It was found that the diffusion coefficient in TEOS gels ranged from approximately 1.4x10⁻¹⁰ m²s⁻¹ to 6.3x10⁻¹⁰ m²s⁻¹, with a mean of approximately 2.5x10⁻¹⁰ m²s⁻¹ corresponding to approximately 14% to 63% of D for Ni²⁺ in unconfined aqueous solution, estimated to be approximately 1x10⁻⁹ m²s⁻¹. The addition of 10 mol% ORMOSILS was found to have a small effect on the predicted value of the diffusion coefficient depending on silicon content. In samples with a final silicon content of 80:1, D was slightly decreased to approximately 2.0x10⁻¹⁰ m²s⁻¹, but in samples with a silicon content of 100:1, D was slightly increased to approximately 3.5x10⁻¹⁰ m²s⁻¹. Variations in hydrolysis ratio, acid catalyst content, and dilution ratio had relatively weak effects on overall diffusion rates of Ni²⁺ with the exception of a few anomalous samples which were either unstable or displayed some syneresis. It can be concluded that over this broad processing space, gels can be tailored to best suit the particular bioencapsulation application, altering the chemical environment for optimal performance with minimal variation in the diffusion transport of small cationic ions such as Ni²⁺. Advisors/Committee Members: Yokochi, Alexandre F. T. (advisor), Gibbons, Brady J. (committee member).

Subjects/Keywords: silica sol-gel; Silica gel

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Dickson, D. J. (2010). Influence of processing parameters on diffusion of divalent nickel in wet silica sol-gel monoliths. (Masters Thesis). Oregon State University. Retrieved from http://hdl.handle.net/1957/17401

Chicago Manual of Style (16th Edition):

Dickson, David J. “Influence of processing parameters on diffusion of divalent nickel in wet silica sol-gel monoliths.” 2010. Masters Thesis, Oregon State University. Accessed October 14, 2019. http://hdl.handle.net/1957/17401.

MLA Handbook (7th Edition):

Dickson, David J. “Influence of processing parameters on diffusion of divalent nickel in wet silica sol-gel monoliths.” 2010. Web. 14 Oct 2019.

Vancouver:

Dickson DJ. Influence of processing parameters on diffusion of divalent nickel in wet silica sol-gel monoliths. [Internet] [Masters thesis]. Oregon State University; 2010. [cited 2019 Oct 14]. Available from: http://hdl.handle.net/1957/17401.

Council of Science Editors:

Dickson DJ. Influence of processing parameters on diffusion of divalent nickel in wet silica sol-gel monoliths. [Masters Thesis]. Oregon State University; 2010. Available from: http://hdl.handle.net/1957/17401

.