Oxophilicity as a Descriptor for NO Cleavage Efficiency over Group IX Metal Clusters

Zooming in on the initial steps of catalytic NO reduction using metal clusters

“…To understand the specific role of rhodium in these experiments, the adsorption of NO onto clusters of other metals was also examined with IR-MPD spectroscopy. 110–112…”

“…39 In comparison with the dissociation of NO on Rh (100), that on Rh(111) occurs at higher temperatures, illustrating the higher reactivity of the (100) surface. The largest difference between Rh (111) and Rh(100) is seen in the temperatures of second-order desorption of N 2 due to the disproportionation reaction NO ads + N ads -O ads + N 2 , from the surface at low coverages (where repulsive interactions between O and N atoms play a minor role): B670 K on Rh (111) but B810 K on Rh(100). 40 By comparison with the extended Rh surface, the reactivity of NO with Rh catalysts supported on SiO 2 is not fully explained by analogy with the Rh surface.…”

“…For NO adsorption on Rh (111) there is disagreement regarding the adsorption site. EELS measurements have revealed that the N-O stretching mode shifts from 1480 to 1630 cm À1 with increasing NO coverage.…”

“…To understand the specific role of rhodium in these experiments, the adsorption of NO onto clusters of other metals was also examined with IR-MPD spectroscopy. [110][111][112] NO adsorption onto Au n + clusters was studied earlier, but the spectral range probed only allowed observation of NO stretch vibrations. 110 Despite the observation of odd-even alterations of the vibrational frequencies, no upper limit for the relative population with molecular NO was reported.…”

Catalytic conversion of NO and CO into N2 and CO2 by rhodium–aluminum oxides in the gas phase

“…Common knowledge on catalytic reactions is that each elementary step in the catalysis should be exothermic, and thus, a catalyst can be regenerated. The higher oxygen affinity of a catalyst favors NO reduction, 48,49 while the strongly bonded oxygen may conversely result in the low activity of the resulting product for CO oxidation. 50,51 Thus, the subsequent supply of the accumulated oxygen atom in RhAlO to oxidize CO is a vital criterion to validate the ability of RhAl as a catalyst.…”