Design, Synthesis and Characterization of Transition Metal Oxide Nanomaterials as Efficient Sorbents and Emerging Catalysts and Investigation of Carbon Structure-Oxidation Activity Correlations

Design, Synthesis and Characterization of Transition Metal Oxide Nanomaterials as Efficient Sorbents and Emerging Catalysts and Investigation of Carbon Structure-Oxidation Activity Correlations Lakshitha Randimal Pahalagedara, Ph. D University of Connecticut, 2015 Keywords: Mesoporous, Metal oxides, Desulfurization, Microwave, Hydrothermal, microwires, Doped, Carbon, Soot, Oxidation This thesis is delineated into three parts. The first part describes the synthesis of mesoporous cobalt oxides with tunable porosity, and crystallinity based on an inverse micelle soft template method and investigation of these materials as desulfurizing sorbents in a fixed bed reactor in the temperature range of 25-250ºC. Very high S sorption capacities were observed in the temperature range of 175-250ºC (65.0-68.9 g S/ 100 g sorbent). The second part presents a microwave assisted hydrothermal synthesis and characterization of cobalt doped cryptomelane type manganese oxide (K-OMS-2) microwires. Their catalytic activity was tested in an oxidation reaction with benzyl alcohol as the substrate and the cobalt doped OMS-2 materials showed 100% selectivity towards benzyl aldehyde with a conversion of 55%. The cobalt doped OMS-2 materials were also investigated as a desulfurization sorbent in a fixed bed reactor at 250ºC where high sulfur sorption capacities (49.4 g sulfur/100 g sorbent) were observed. The third part demonstrates a comprehensive investigation of structure-activity relationships for a diesel engine soot sample (Corning) and ten commercially available carbon black samples. Particle sizes were determined using Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM); specific surface area was determined by nitrogen sorption studies; while the microstructure was investigated by X-ray Diffraction (XRD) peak profile analysis, Raman spectroscopy, and TEM