The effect of subcarbonyl surface intermediates resulting from Ru3(CO)12 molecular clusters supported on Al2O3 in the CO hydrogenation has been investigated by using an isotope-labeling technique. It has been established that single ruthenium atoms are stabilized in the form of dicarbonyl species, characterized by 2072- and 2001-cm-1 IR frequencies, when temperature-programmed decomposition (TPDE) is carried out in the temperature range between 473 and 573 K. Despite the presence of RuII(CO)2, free ruthenium sites are responsible for the catalytic activity in the 13CO hydrogenation reaction. The high mobility of the CO ligands in the surface ruthenium dicarbonyl species, demonstrated by CO molecular exchange during the reaction, makes the CO from the dicarbonyl species compete successfully with that chemisorbed from the gas phase labeled in the form of 13CO. An explanation for the stability of the highly dispersed ruthenium particles and detailed mechanisms of the surface reactions are given.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry