Direct ethylenene oxyfluorination with perovskite-like materials

With the target of decreasing the ozone depletion layer, hydro fluorocarbons have been proposed as CFC and HCFC substitutes since 1987 through the Montreal Protocol. At present, these products are industrially produced by reaction of a chlorinated hydrocarbon with HF. However, there is still some environmental concern with such processes, because of the production of huge amounts of HCl and the possibility of generating dioxins and chlorinated compounds. A possible alternative to develop an environmentally sustainable process to produce fluorinated alkenes is the direct fluorination of olefins with fluorinated solids. According to literature data [1] AgF has a mild fluorinating activity towards the target molecules, however due to its high thermal lability AgF has to be stabilized in a ternary structure with, i.e. CuF2. We synthesised several perovskite like materials according to the method reported in [1] and characterised them using X-ray diffraction spectroscopy. We observed that, after thermal treatment, the equimolar mixture of the two fluorides yields to the AgCuF3 compound even though this synthesis also leads to the formation of small quantities of Ag and Cu oxides. Catalytic tests carried out with the single metal fluorides - AgF and CuF2 - and with the ternary compound show that: i) CuF2 has a slight oxyfluorinating activity towards ethylene, ii ) AgF decomposes to Ag° during the stabilizing thermal treatment previously to the catalytic tests and shows high ethylene conversion to non-fluorinated compounds, iii) AgCuF3 shows the highest catalytic activity in vinyl fluoride formation.