Abstract
The adsorption of ethene, ethyne, and carbon monoxide on silica-, γ-alumina-, and magnesia-supported platinum catalysts was studied by Fourier Transform Infrared Spectroscopy (FTIR). Based on the observed band frequencies and reported literature data, assignments have been made for the bands detected in the spectra. The addition of ethene and ethyne to freshly reduced Europtl (6.0% Pt/SiO2 resulted in the formation of an ethylidyne (C-CH₃) species, as evidenced by the development of bands at 1297 cm⁻¹ (δs(CH₃)) and 954 cm⁻¹ (ν(C-C)), in addition to the vs(CH₃) at 3074 cm⁻¹.
While on ethylene/hydrogen deactivated catalysts, bands characteristics of surface species such as, PtCH=CHPt (band at 1693 cm⁻¹), νs(C=C) and of hydrocarbon polymeric moieties (bands at 2974-2884 cm⁻¹, δs(CH3) and 1374 cm⁻¹ νs(CH3)), were detected.
On freshly reduced catalysts, carbon monoxide was found to adsorb in the linear form ( Pt-C=O ) at vs C-O (2086 cm⁻¹, 2112 cm⁻¹ depending on support type). Exposure of the catalysts to air tends to convert the linear form of carbon monoxide to bridged form ( PTc=o c=o at Vs C-O (1886 cm⁻¹, observed on silica-supported Pt catalysts).