Study of temperature treatment on aluminum hydroxide and its subsequent effects on platinum-ceria-alumina catalyst structure

Abstract

For a catalyst to be industrially utilized, it is important that its structure is synthesized uniformly and maintained under harsh conditions. In the case of catalysts using precious active metals, controlling the structure at the atomic level can reduce the cost of catalyst production and improve activity. However, atomic-level catalysts have the disadvantage of sintering under various practical conditions, including reaction conditions. In this thesis, heat treatment of aluminum hydroxide was carried out to adjust the density of surface hydroxyl groups and the phase of alumina. It was confirmed that platinum and cerium oxide supported on the pre-treated support exhibited resistance to sintering under the conditions of a hydrothermal aging at 800°C, showing that ceria domain sizes are withheld the sintering. In addition, it was confirmed through spectroscopic analysis that the hydroxyl groups that caused the anchoring effect are μ_bridgedOH, type II or III hydroxyl groups. To investigate whether the effect of these hydroxyl groups extends to the structural control of platinum atoms, a catalyst that can achieve structural control at the single atom level even after reduction at 300°C was developed under pH-adjusted conditions, and an analysis was conducted on it.