계면활성제와 공침법을 이용한 망간 산화물 입자 및 알루미나-망간 산화물 복합체의 제조에 관한 연구

Abstract

Manganese oxide materials have attracted considerable interest in various industrial fields such as catalysis and rechargeable batteries due to their remarkable structural flexibility and novel chemical and physical properties. Among the kinds of manganese oxide materials, Mn2O3 has been proposed as an inexpensive and an environmental-friendly catalyst for removal of carbon monoxide and degradation of organic pollutants. Also, Mn2O3 has been used as a significant substrate for preparation of Li-Mn-O cathode materials for rechargeable lithium batteries.. In this study, Mn2O3 and alumina-grafted Mn2O3 were synthesized through coprecipitation process and the effect of surfactant on their properties such as particle size, crystal structure, and thermal stability was investigated. In chapter I, we prepared Mn2O3 particles with controlled particle size and crystallinity by using cetyltrimethylammonium bromide, tert-butanol, and ammonium oxalate monohydrate as a surfactant, a cosurfactant, and a chelating agent, respectively. The effects of these organic additives on the formation and the crystallinity of manganese oxide nanoparticles were studied with the variations of their concentration. In chapter II, alumina-grafted Mn2O3 was synthesized through coprecipitation method using polyoxyethylenesorbitan monolaurate and tert-butanol as a surfactant/cosurfactant system. The morphology and the crystal phase of alumina-Mn2O3 composites could be controlled by varying the concentrations of Al salt and surfactant and the calcination temperature. Also, the influence of introduction of alumina onto the surface of Mn2O3 on the thermal stability of composites was investigated. The morphologies and the crystal structures of prepared products were analyzed by using field-emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), and X-ray diffraction (XRD). In addition, the characterizations of alumina-grafted manganese oxide materials were performed by using energy dispersive spectroscopy (EDS), differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA) in order to confirm the formation of aluminium oxide on the surface of manganese oxide.