FTIR spectra of adsorbed fluoroform as a test for surface basicity have been studied on a number of oxides and zeolites. CHF3 does not dissociate even on strongest basic sites, and forms H-bond with considerable stretching CH frequency lowering. With weaker basic oxygen atoms it demonstrates the blue-shifting H-bond accompanied by CH band intensity decrease and a high frequency shift of bending vibrations. Dependence of the frequency and integrated absorption coefficient of CH stretching vibration on the strength of H-bond is discussed. The problem of basicity testing can be solved by using two different probe molecules for sites of various strength. While fluoroform is good for stronger sites, weak sites can be tested by pyrrole, acetylene or its derivatives that are more sensitive, but dissociate on the most basic oxygen centers.
Translated title of the contributionCHF3 as a probe for surface basicity: Фтороформ как мера основности поверхности
Original languageEnglish
Pages (from-to)73-80
JournalCatalysis Today
Volume226
DOIs
StatePublished - 2014

ID: 33771398