RADIOTRACERS IN FLUORINE CHEMISTRY .17. CESIUM AND POTASSIUM FLUORIDES SUPPORTED ON FLUORINATED GAMMA-ALUMINA

Exhaustive fluorination of CsF or KF supported on gamma-alumina, by SF4 or OSF2, nominally at room temperature, is an effective process for the removal of hydroxy groups and/or strongly bound H2O from the surface of these materials. Anhydrous HF and OCF2 are less effective reagents; the former can be used however if the surface is pretreated with SO2. The physical properties of CsF and KF supported on fluorinated gamma-alumina and the behaviour of these materials towards SF4 and CIF, labelled with sulphur-35 and chlorine-36 respectively, indicates that the Lewis base character of the surfaces, which is ascribed to surface MF, M=Cs or K, particles, is retained after fluorination. Although the surface areas of the materials are reduced compared with their unfluorinated counterparts, they are greater than those for the unsupported fluorides.