CHARACTERIZATION OF RUTHENIUM SPECIES GENERATED IN H-X ZEOLITE - INTERACTION WITH CARBON-MONOXIDE, NITRIC-OXIDE, OXYGEN, AND WATER

The activation and subsequent interaction with absorbates of the Ru(NH3)6(3+) complex in H-X zeolite have been investigated by electron spin resonance, electron spin echo modulation, infrared, and X-ray photoelectron spectroscopies. Ru(NH3)6(3+) incorporated in the alpha-cage of X zeolite hydrolyzes into Ru(NH3)5OH2+ upon evacuation at 80-degrees-C. In contrast to M-X zeolite, where M is an alkali metal, in H-X the formation of the trimeric Ru red complex during activation is suppressed. This cation effect may be due to the availability of more space in H-X zeolite, which provides extra sites for the Ru monomer to be anchored and reduces the mobility of the monomer to decrease the probability of forming the Ru red trimer. Evacuation at 150-degrees-C produces a Ru(III) complex still coordinated with some NH3, H2O (or OH) and zeolite lattice oxygens. Evacuation at 300-degrees-C produces Ru(III) ion coordinated only with the zeolite lattice oxygens, probably at a six-ring site. The ESR signal of this Ru(III) ion is reported for the first time in X zeolite. The interaction of CO, NO, and O2 with the Ru(III) ion produces Ru(III)-(CO)2, Ru(II)-NO+, and Ru(IV)-O2- species in the alpha-cage. Infrared bands at 2146 and 2088 cm-1 are characterized by isotopic substitution as coupled vibrations from a ruthenium(III) dicarbonyl species. Electron spin echo modulation shows that NO adsorbed on H-X interacts with an aluminum nucleus within less than 0.37 nm.