Steam Reforming of Hydrocarbons on Noble Metal Catalysts (Part 5)

Steam reforming of methane, n-pentane and n-heptane over Rh catalysts supported on γ-alumina and silica has been carried out under atmospheric pressure and at 550°C to investigate the influence of the degree of dispersion of Rh on steam reforming and aromatization. The specific catalytic activity expressed by the initial rate of reaction per unit surface area of Rh was found to depend on the degree of dispersion. A good correlation was obtained between the gasification activity and the appearance of surface atoms existing in crystal faces and between the aromatization activity and the appearance of surface atoms existing in low-coordinated positions such as edge or corner atoms. The difference in the active sites on Rh crystal for gasification and aromatization was further confirmed by the study using a pulse technique.