FTIR and 19F MAS NMR investigation of the interactions between p-fluoroacetophenone and MFI structure type zeolites

Abstract

Interactions between PFA molecules and MFI structure type zeolites were studied by FTIR and ¹⁹F MAS NMR spectroscopies. In the purely siliceous ZSM-5 sample, PFA molecules were physisorbed. In the acid samples, the interactions implicated the carbonyl group of the PFA molecules and the Brönsted acid sites of HZSM-5. This interaction could be a hydrogen bond or a protonation of the carbonyl group. The complementarity of the IR and ¹⁹F NMR spectroscopies was shown: IR specified the type of interaction whereas NMR allowed quantification of the strength of the interaction and the amount of active acid sites of the zeolite.