Improvement and Microstructural Control of Environmental Catalyst Materials—Alumina Catalytic Support—

Abstract

The improvement and design of materials for automotive catalyst, especially alumina support is described by the author’s work. Since automobile engine exhaust sometimes becomes a high-temperature gas, the thermal durability of catalytic powders is very important. For this, the improvement in materials design and thermal stabilization is required for all composition of catalysts. The supported noble metals, thermal stable alumina support and zirconia-ceria sub-catalysts must be controlled by the resultant microstructures where each nanoparticles are mixed and rearranged even after harsh heat treatment. For the alumina catalytic support, the phase transition and surface modification are closely related to realize better heat stable materials with nanometer-order particles in size. The anti-sintering stabilization of γ-Al₂O₃ before a transformation is a research target, and is improved by an approach with both elements modification and ceramic sintering technique. The tailored La-modification to alumina support and its processing provides a novel nanostructured and stable catalytic composite support even at elevated temperatures. The wash-coating technique must allow obtaining coatings on most metallic substrate with the required homogeneity. This work also discusses the material parameter controlling the coating of FeCrAl alloy metallic monoliths by using thermal stabilized alumina with lanthanum through focusing on the microstructural development of sintered layer and alumina/alloy interface. The paper describes effect of surface modification especially surface La added on alumina powders in the anti-sintering, and composite formation and coating technology of forming catalytic coat layer.