Heat of adsorption of carbon monoxide on a Ru/Al2O3 catalyst using adsorption equilibrium conditions at high temperatures

Effect of the metal precursor on the surface site distribution of Al2O3-supported Ru catalysts: catalytic effects on the n-butane/H2 test

“…On the other hand, 3RuNOAl shows a higher CO initial adsorption heat (ca. 190 kJ/mol), closer to that found by Dulaurent et al [33] for a Ru/Al 2 O 3 catalyst (175 kJ/mol). Also, the population of sites with such a high CO adsorption heat is small, and a sharp decay of the differential heats (from 190 to ca.…”

“…Also, for this wavenumber zone (ca. 1850-1750 cm À1 ) other studies have described the apparition of bands due to bridged CO species (Ru 2 CO) [27,33,44]. For both 1RuNOAl and 3RuNOAl, two overlapped bands are shown at ca.…”

“…2126 and 2070 cm À1 shown by these two catalysts have been previously ascribed to the asymmetric and symmetric stretching vibrations, respectively, of gemdicarbonylic or polycarbonylic adsorbed species over partially oxidized Ru atoms (Ru d+ (CO) n , n ! 2) [24,33,39]. Other studies also attributed band at ca.…”

“…The presence of residual NO species (of the metal salt precursor) at the surface of these catalysts as stabilizing agents of partially oxidized Ru species, previously suggested for reduced but non-calcined Ru catalysts [42,43], can be neglected, as these samples were calcined at 773 K. The band that appears as a shoulder at a wavenumber of ca. 2045 cm À1 has been ascribed, generally, to linearly adsorbed CO over Ru 0 [24,33,[39][40][41]. Band at ca.…”

A rate equation approach to the gas sensitivity of thin film metal oxide materials

“…Turning to the subject of chemisorption of CO and its catalytic conversion to CO 2 via reaction with adsorbed oxygen species, it is found that adsorption energies are strongly coveragedependent. Dulaurent et al [48], for instance, find that the heat of adsorption of CO on a Ru/Al 2 O 3 catalyst decreases from about 1.8 eV at Θ = 0 down to 1.2 eV at Θ = 1. In [49] the authors find that there seems to be no competition between oxygen and CO in finding adsorption sites on a Pt/SiO 2 catalyst because the two species do not tend to adsorb at the same sites.…”