Adsorption of CO on the catalytic system Ks[SiWI jRhO391/AI~O3 was studied by diffusereflectance IR spectroscopy. The electronic state of rhodium and thermal stability of the system in the redox cycles were studied. The oxidized heteropotycompound (HPC) contains the charged forms Rh +. Rh 2+, and Rh 3~. Their ratio strongly depends on the pre-treatment temperature of the sample. In the reduced HPC two main forms of rhodium exist: the ionic Rh + and metallic Rh ~ The supported HPC structure is stable in an oxidative medium at temperatures below -900 K. The properties of the K dSiW~ )RhO39]/AI203 system are retained in the redox cycles up to --670 K. and the highly dispersed state of rhodium is observed up to 9O0 K.
Structural hydroxyl and deuteroxyl groups within the K4[SiWI20.~0]/AI20 3 and K6[SiW )IPdO391/A1203 systems were studied by diffuse-reflectance FTIR spectroscopy in a spectral range of fundamental stretching vibrations, first overtones, and combination bands of stretching and bending vibrations. For hydroxyl groups, the region o[' combination vibrations is the most informative. The calculated frequencies of bending vibrations of hydroxyl groups (865 and 730 cm -t) are characteristic of acidic OH groups.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.