TitlePhotochemical reduction of carbon dioxide in aqueous and ionic liquid solutions in a microreactor with TiO2 catalyst : experiment and modeling
Publication TypeThesis
Year of Publication2013
AuthorsCampbell, TJ
UniversityOregon State University
CityCorvallis, Or.
Thesis TypeMasters Thesis

Microtechnology was used to study the chemical reduction of dissolved carbon dioxide into useful products. A novel TiO2 photocatalyst was used to activate the reaction under ultraviolet irradiation. CO2 was dissolved in aqueous and 50% BMIM-BF4 (ionic liquid) solutions. The introduction of an ionic liquid increased the solubility of CO2 by 60%. Both solutions were pumped through a continuous photochemical microreactor and analyzed for products. The aqueous photochemical microreactor process produced 5x108-1x106 moles of methane per liter of solution processed. These values vary with mean residence time within the 0.016 mL microreactor volume. Serial reduction intermediates are likely present in solution below the detection limits of our analytical instruments. The 50% ionic liquid process produced 4x108-1x107 moles of methane per liter of solution processed. Similarly, no intermediates were measured. Mathematical models for the kinetic mechanism, momentum transfer, and mass transfer within the reactor were developed. These models were added to a numerical simulation and compared to experimental values. An optimization scheme was executed to extract meaningful reaction rate constants from the simulation that best fit the experimental data. Reaction rate constants reflect the feasibility of operating these processes and the numerical models can be used as design tools.