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

Doctor of Philosophy, Case Western Reserve University, 2021, Civil Engineering

As people spend most of their time inside the buildings, the improvement of the indoor air quality has received considerable attention. The major contaminants inside the building is volatile organic compounds (VOCs) referred to the carbon-contained organic substances in the air. VOCs are usually not acutely toxic, but they cause an adverse health effect when human are exposed to a concentration of ppmv level of VOCs. Thus, it is critical to mitigate the VOCs level inside the building. To achieve the purpose of removing VOCs and improving the indoor environment, an innovative photocatalytic membrane we designed and fabricated. This new photocatalytic material can be applied to the indoor surface and used as a smart functional surface. Furthermore, the fundamentals related to its photocatalytic activities and practical applications were explored by integrating the experimental, physics-based and data-driven approaches. Nitrogen-doped TiO2 photocatalysts were synthesized using a sol-gel method and a post-annealing heat treatment. The annealing temperature and time affect their microstructures and surface chemical compositions. It was found that these characteristics are relevant to the adsorption and photocatalytic activities of the nitrogen-doped TiO2 photocatalysts. Therefore, a physics-based kinetic model was developed to distinguish the impact of three different mechanisms, including adsorption, photocatalysis, and direct light photolysis, on the removal of VOCs. The kinetic modeling and experimental results show that a higher annealing temperature leads to not only less adsorption, but also nitrogen loss. To predict the kinetics of contaminant degradation and facilitate the choice of the optimal photocatalyst, three data-driven machine-learning (ML) models were developed to predict the photocatalytic degradation performance. The ML model inputs include tens of organic contaminants and other experimental variables, including light level, photocatalyst dosage, (open full item for complete abstract)

Committee: Xiong Yu Dr. (Advisor); Chung-Chiun Liu Dr. (Committee Member); Anna Samia Dr. (Committee Member); Michael Pollino Dr. (Committee Member); Huichun Zhang Dr. (Committee Member) Subjects: Civil Engineering; Materials Science