Design, Synthesis and Characterization of Metal Oxide Adsorbents and Catalysts for Environmental Applications

In this thesis, I will focus on the design and synthesis of metal oxides as adsorbents and catalysts for different types of environmental applications,such as water remediation, biogas cleanup. Controlled synthesis of these materials with unique crystalline structures, physical, and chemical properties will be carried out to achieve an improved performance. Correlations between the material property and performance will be investigated by varieties of characterization methods. In the first part, I will employ perovskite materials for catalytic wet air oxidation (CWAO) reactions for water remediation. LaNiO3-δ (LNO) was applied for degradation of methyl orange (MO) azo dye in aqueous solutions under dark ambient conditions (room temperature, atmospheric pressure) without additional lights or chemical stimulants. The mechanism behind MO degradation by LNO under dark ambient conditions was unraveled by a series of characterization methods. Considering the large variety of perovskites in terms of constituents and composition, an excellent perovskite material should be tailorable for water remediation applications. Fuel cell performance for the double perovskite material PrBaCo2O5 (PBC) was briefly shown. In the second part, I will demonstrate a facile way for synthesizing mesoporous aluminas (MAs) with uniform and monomodal pores via a modified inverse micelle synthesis method. The effects of reaction times, surfactant chain lengths, and heat treatments on the textural properties of MA were adjusted to optimize the texture properties for biogas cleanup. The tuned MA of the large mesopore volume achieved high octamethylcyclotetrasiloxane (D4 siloxane) adsorption capacity, and maintained approximate 85% of its original adsorption capacity, demonstrating a sustainable adsorption performance and high potential for related industrial applications. Arsenic adsorption was performed to illustrate the application of MA for heavy metal removal. The third part, I supported transition metals on optimized mesoporous alumina for methane oxidation. The texture properties were summarized and Temperature-programmed studies were used for understanding the mechanism for methane partial oxidation. Different ratios of copper supported on alumina were designed for methane combustion and exhibited improved performance with regard to the loading amount, which was explained by further characterization methods.