NOBLE-METAL CATALYSTS PREPARED BY THE HIGH-TEMPERATURE AEROSOL DECOMPOSITION (HTAD) PROCESS

An aerosol synthesis technique was used to prepare a variety of metal supported catalysts including Pt, Ir, Pt-Ir, Pt-Sn, and Ag supported on alumina. Characterization of these materials showed that the metals had a novel structure and were exceptionally well dispersed within the alumina matrix. XRD analysis demonstrated the presence of no reflections due to the noble metal components. The silver-alumina preparations demonstrated no reflections for bulk, metallic silver until the silver concentration was increased to 65% and calcined to 900 degrees C. The data suggest that the metal is partially embedded within the alumina structure which leads to its high dispersion and maintenance of dispersion until high temperatures. The fact that the metals were available for catalysis was demonstrated by their facile conversion activity in the dehydrogenation of methylcyclohexane to toluene in exceptionally high selectivities. An examination of the alumina produced by the aerosol process suggests a high-surface area form of alpha-alumina.