Studies on the CrF3/AlF3 catalyst for synthesis of HFC-134a as a substitute for CFC-12 - (V) - Interaction of CrF3 and AlF3

The effects of Cr3+ content in CrF3/AlF3 catalysts on activity for synthesi s of HF-134a from reaction of HCFC-133a with HF were investigated, FTIR, EP R and XPS have been employed to characterize the CrF3/AlF3 catalysts. The r esults show that CrF3 existed in a monolayer dispersion where the interacti on between CrF3 and AlF3 support became stronger when Cr3+ content less tha n 1%. The CrF3/AlF3 catalyst with 0. 1% Cr3+ exhibits the highest turnover frequency. The residual oxygen in the catalyst forms surface active species of CrAlOmFn from the interaction of CrF3 and AlF3, which is the cause of h igh selectivity to HFC-134a in F/Cl exchange reaction.