Oxidation–reduction behaviour of highly dispersed ruthenium in RuNaY zeolite

Abstract

The thermal decomposition of the [Ru(NH₃)₆]³⁺ complex ion exchanged in a NaY zeolite followed by reduction in H₂ at 623 K leads to highly dispersed Ru metal in the zeolitic pore system. X-ray diffraction techniques have been used to identify atomically dispersed Ru⁰ inside the sodalite cavity at the site II′. This high dispersion sample can be produced either by heating under high vacuum conditions or by heating under hydrolysing conditions where an H₂O+H₂ mixture is present in the system. The Ru⁰ in the sodalite cavity is not stable under oxidation as it is irreversibly removed upon the addition of O₂ at ambient temperature and cannot be regenerated by subsequent reduction in H₂. Na⁺ ions within the zeolite always occupy sites I′ and II and are generally unaffected by the redox chemistry involving the ruthenium.