The interpretation of CO adsorbed on Pt/SiO2 of two different particle-size distributions

Influence of Crystallite Size of TiO2 Supports on the Activity of Dispersed Pt Catalysts in Liquid-Phase Selective Hydrogenation of 3-Nitrostyrene, Nitrobenzene, and Styrene

“…There existed CO absorption bands in the range of frequency of 2000 -2100 cm -1 and the absorption occurred in different frequency regions depending on the catalysts examined. The absorption band at around 2050 cm -1 may be due to a linear type of CO adsorption; the absorption band at 2070 -2100 cm -1 should be the absorption of CO adsorbed on highly coordinated Pt surfaces like Pt(111) and Pt(100) while that at 2000 -2066 cm -1 on low coordinated Pt sites like kink, edge, and corner ones [18][19][20][21][22][23]. An attempt was made to separate the absorption band measured into two (or three) independent bands to estimate the relative quantities of saturated (highly coordinated) and unsaturated (low coordinated) Pt sites on the catalysts.…”

Deconvolution and Curve Fitting of IR Spectra for CO Adsorbed on Pt/K-LTL: Potassium Promoter Effect and Adsorption Site Distribution

“…The frequency of carbon monoxide molecules adsorbed onto group VIII metal particles has been shown to be influenced by the coordination number of the metal adsorption site involved. 27,[41][42][43][44][45][46][47][48] The linearly bonded CO frequency decreases with a decreasing number of neighboring metal atoms, i.e., with an increasing degree of coordinative unsaturation. Theoretical and experimental results [73][74][75][76][77][78] indicate that coordinatively unsaturated metal sites have a higher d valence electron band filling at the Fermi level due to the narrowing of the local density of states (LDOS) and a center-of-gravity shift to lower binding energy.…”

“…[19][20][21][22][23][24][25][26][27][28][29] The stretching frequency of CO is very sensitive to the electronic structure of the metal surface onto which it is chemisorbed. [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48] The CO spectra obtained for the nonacidic Pt/LTL zeolites differ in two ways from those obtained for platinum supported on SiO 2 , Al 2 O 3 , and H + -exchanged zeolites. 26,27 Instead of one linear-CO band in the region 2100-2040 cm -1 , for Pt/LTL there are two absorption bands: one centered around 2060 cm -1 and one at 1960 cm -1 .…”

“…Another hypothesis proposes that the frequency of CO species absorbing in the 2100-2000 -1 region depends on the degree of coordinative metal atom saturation. 27,[41][42][43][44][45][46][47][48] The series of overlapped peaks in the spectrum of Pt/K-LTL may therefore represent surface platinum atoms which vary in electron density due to their different coordination numbers. 27 To understand the origin of the high-frequency CO band components and the effect of ion-dipole interactions induced by promoter ions, we have examined the infrared spectra of a Pt/K-LTL zeolite in the presence and absence of coadsorbed water in more detail.…”

DRIFTS investigation and DFT calculation of the adsorption of CO on Pt/TiO2, Pt/CeO2 and FeOx/Pt/CeO2

“…The systems of CO/oxide-supported Pt and CO/Pt single crystal surfaces have been frequently studied by FTIR and other methods. Brandt et al [6] have reported the adsorption of CO on Pt/SiO 2 and they observed one band at 2057 cm −1 and a small shoulder at 2067 cm −1 , which were attributed to CO adsorbed on corner Pt atoms.Tanaka et al [7,8] have studied the activity performance of Pt/TiO 2 , Pt/CeO 2 and FeO x /Pt/CeO 2 catalysts for the selective oxidation of CO in excess of H 2 . The in situ DRIFTS method was used to identify the process of CO adsorption and transformation [9].…”