Infrared spectroscopic investigation of CO adsorbed on Pd aggregates deposited on an alumina model support

In situ surface characterization of the intermetallic compound PdGa – A highly selective hydrogenation catalyst

“…In the first case, the full isolation of the Pd-CO was not achieved because at low CO partial pressures the bridged Pd 2 -CO species becomes energetically more favorable. However, a significant red shift of ~30 cm -1 was detected for single crystals and nanoparticulate Pd samples [23][24][25][26][27]. Isolating the Pd atoms by alloying Pd with Ag leads to the formation of a disordered Pd-Ag alloy and causes a red shift of the on-top Pd-CO band from 2078 cm -1 for Pd/SiO 2 to 2048 cm -1 and 2034 cm -1 for different PdAg/SiO 2 samples depending on the Pd:Ag ratio.…”

“…The other set of signals in the region of 2130-1885 cm -1 exhibited a higher [29]. The dipole-dipole coupling of neighboring CO molecules had a strong impact on the position of the bands, resulting in a pronounced CO coverage dependence [23]. For example, the band at 2107 cm -1 shifted to 2099 cm -1 with changing CO coverage.…”

“…Such an isolation of the adsorption centers can lead to a significant red shift of the CO vibrational frequency [23][24][25][26][27][28]. Up to now, the isolation has either been achieved by decreasing the CO partial pressure [23][24][25][26][27] or by alloying Pd with another metal, e.g. Ag [28].…”

The Effect of Chromium on Sulfur Resistance of Pd/HY–Al2O3 Catalysts for Aromatic Hydrogenation

“…Freund et al (31) studied CO adsorbed on Pd aggregates deposited on a well-defined alumina model support Al 2 O 3 /NiAl(110) using infrared spectroscopy. They found that CO is preferentially bridge- bonded on Pd at 300 K, i.e., the population of linear bonded CO is near zero.…”

Photochemistry of Methane on Pd/Al2O3 Model Catalysts: Control of Photochemistry on Transition Metal Surfaces

“…[4,5] The size of clusters and, hence, their geometrical and electronic structures can be controlled by changing formation conditions such as metal deposition rates and surface temperature. [6] Thus, it is of great interest to know if surface (photo)reactions can be controlled by manipulating the electronic and geometrical structures of the metal clusters.…”